006 | Turbo Tuning MoTeC M1
So far the majority of our webinars and training courses have detailed tuning as applied to a naturally aspirated engine. Really the approach to tuning with forced induction is no different, although our lambda targets and ignition timing will need a little more thought. In this webinar we will look at the approach to tuning a turbocharged engine on the dyno. In particular we will look at the fuel and ignition tuning.
This webinar will use our Toyota 86 fitted with a MoTeC M150 ECU and a Borg Warner EFR Turbo.
- Hey guys, Andre from the High Performance Academy here and welcome to another one of our webinars. Now tonight we're going to be using our Toyota 86 test car which unfortunately has actually been off the road for about the last 4 months while I've tried to find time to complete a turbo upgrade on it so a lot of you may not have even seen this car before. We've got a 2012 Toyota GT86 and it's fitted with a MoTeC M1 plug and play ECU package for that car. We had an AVO turbo kit on it, we fitted that probably back about October or so last year. And ran that for a few months and I decided that we needed to upgrade the turbocharger and a few other bits and pieces along with that so it's been off the road while I've tried to find time to do that and we've now got it fitted up with a Borgwarner EFR 6758 turbo.
We're going to be using this car extensively in the near future for some of our upcoming courses so it's kind of become a bit of a mobile test bed for HPA and we're really excited about some of the data we're going to be able to get out of it. So just to name a few of the sensors on it, we've got an AEM 4 channel individual cylinder UEGO sensor kit, controller. So that has 4 individual cylinder lambda sensors as well as a turbine inlet pressure sensor so that the lambda sensors can be compensated for turbine inlet pressure or manifold back pressure pre turbocharger. We've also got 4 exhaust gas temperature sensors fitted into the manifold as well so we're going to have individual cylinder lambda as well as individual cylinder EGT. On top of that, the EFR turbo's also fitted with the optional turbine speed kit so we can monitor compressor speed or turbocharger speed and we've got pre and post turbocharger or post compressor temperature sensors so we're going to be using this in some of our boost control and boost, we're going to call it boost camp course that'll be coming out early next year so look forward to that.
That's digressing a little bit from tonight's webinar though. Now before I move on, obviously as always if you've come to one of our webinars, we will have an opportunity for questions and answers so if you've got anything that you want to know more about or anything I've glossed over and you didn't quite understand, feel free to put that into the comments and I'll address them when I stop or at least at the end of the webinar anyway. Few other current news points that we'll cover before we get into the webinar, if you've been to a couple of our recent courses, you'll have already heard this but our Understanding AFR course is now available and you can get that at courses.learntotune.com so if you want a full understanding of how to choose the correct AFR for any application, this is the perfect course for you. It dispels a whole lot of the misconceptions, misunderstandings and frankly a lot of the BS surrounding choosing AFR and also how to change your AFR and monitor the results in your tune to figure out what specific air/fuel ratio your particular engine actually wants to run. The golden rule when choosing an air/fuel ratio to run an engine at is there is no one single number that's going to suit absolutely every engine.
Some engines want to run a little richer and some engines want to run a little leaner so this course gives you a thorough understanding of all of those concepts. It's just $89 USD and as usual, it still comes with our 30 day money back guarantee. We've also got some really exciting news coming up, Ben particularly has been working really hard on this behind the scenes and our VIP members will have a bit more of an insight into what's going on. We know that you guys currently have been battling on with a website and forum that, let's be honest is pretty far from ideal. To the point where, in some situations, it's actually plain embarrassing for both myself and Ben.
The dual log ons for the course content versus the pro tuner content is also a frustration and my personal hate is every time I log into the forum, I have to re enter my username and password. All of that is going to be a thing of the past. We basically had a proof of concept website that Ben put together himself and made it work to see if our concept of High Performance Academy was going to be appealing. Obviously it is, we're getting huge amounts of support and we really can't keep up. And to take HPA to the next level, it was pretty obvious we needed a proper dedicated website so we've been pouring a lot of time, a lot of effort, and definitely a huge amount of cash into getting a purpose built website developed specifically for us.
It's going to be everything encompassed in one place, it's going to be much easier to use, it's going to be much more user friendly and hopefully that's going to make your lives a whole lot easier. We finished filming, moving onto other topics, we've finished filming our MoTeC M1 training course last week. Which has been a really big task, we've still got some filming, some screenshots to do for that and then some editing and hopefully that will be out within the next month. So looking forward to having that out there, it's going to be a really good resource for anyone who is moving into the M1 ECU range from MoTeC. They do present a fairly steep learning curve for those that are not familiar with them or haven't seen them before so this is a perfect course to fast track your learning and get you up to speed tuning on the M1 platform in no time.
Other news as well, we will be heading again to World Time Attack in Sydney in October. Ben and I went over there last year, actually we've been for the last 2 years now. We created some content from there last year, it's a great event. Particularly if anyone is in the Sydney region or prepared to travel, I highly recommend it. You're going to see some of the world's, a wide range of the world's fastest time attack cars all gathered in one place.
The technology that is going into these cars is really impressive and it's the best place to see all of that in one place. So we'll be bringing you all of that content as we normally do so watch our YouTube channel, if you're not subscribed to that, please do, learn to tune on YouTube. Our Nissan 350Z, our last little update for today, is still away getting its cage, we've finally got some body panels for it so hopefully we'll be able to fast track getting that back together and hopefully we might actually be able to use it on the racetrack in the near future rather than it just sitting dormant and being used on the dyno which is obviously what we bought it for in the first place. OK so to get onto today's topic of turbo tuning, and it's a fairly broad topic but I thought it was easiest just to deal with some of the main principles. I know that most of the tuning in the webinars and the course material that we've presented so far has all been done using a naturally aspirated engine and there's a couple of reasons we've done that.
One of them is because tuning a naturally aspirated engine is generally a little bit easier than a turbocharged engine. Actually easier's probably not the right word, probably more to the point, a naturally aspirated engine is a little bit more tolerant of say detonation, a lean mixture etc than a turbocharged engine. So that's one of the reasons we've used a naturally aspirated engine for most of our course material. The reality is though, the techniques that we're using, the techniques we're applying to actually tuning the engine are absolutely no different. Regardless if the engine is turbocharged, supercharged or naturally aspirated.
For that matter, even if it's running nitrous, the same principles still apply. However we are adjusting our tuning targets I guess if you like to account for the boost pressure. So before we jump into the laptop screen, I just wanted to talk a little bit about what we're trying to do and more importantly why we're trying to do it. So this is quite a complex engine, we've got quad cam control, we've got drive by wire throttle and ultimately we'll also have boost control. Just to keep everything simple, we're going to not talk about any of that stuff, we're not going to be adjusting cam timing, we're just simply going to be looking at those two bare bones basics which is fuel delivery and ignition timing.
All of the rest of the stuff we can get to at a later date but fuel and ignition timing, really those are the two core principles of tuning. So when we look at those two, let's start with fuel delivery and really when we're tuning the fuel delivery, we're trying to accomplish two things. First of all we're trying to match the fuel delivery to the airflow into the engine, so obviously as the airflow increases, we need to add additional fuel to match that airflow. Now if we just do that, in broad terms what we're going to do is get a consistent air/fuel ratio as the airflow increases or decreases. Now that's not strictly the full story though, that's not all that we want to achieve.
What we also want to do is match our target air/fuel ratio to the load that the engine's being placed under. So that's really important. And we're trying to do that to first of all control the combustion temperature. So as we add additional load we put our foot down further on the throttle and we move the engine from vacuum up into positive boost pressure, as we do that we need to richen the air/fuel ratio so add additional fuel, target a richer lambda number to help add additional fuel and control the combustion temperature. If we don't do that we're going to end up damaging the engine.
So that's obviously one of our prime concerns. Secondly, and you'll remember this from tuning a naturally aspirated engine, the technique's really no different, what we want to do is make sure we add enough additional fuel to properly combust all of the available oxygen in the cylinder. Now that's going to mean that we can achieve maximum power out of the engine. So that's, those two things really go hand in hand. So if we just consider back to a naturally aspirated engine, as we move our foot from partial throttle through to half throttle and then finally up to wide open throttle, we'll be targeting mixtures that start around stoichiometric, so lambda 1.0.
At half throttle we might be starting to target slightly richer, maybe around about 0.95 or 0.97 lambda and finally as we move to wide open throttle, we're going to be tapering richer still, maybe down to around about 0.90, 0.88 or thereabouts. OK so the same principles apply with a turbocharged engine. Obviously as we move into boost pressure, the engine is now consuming more air, we've got more load, we've got more air and fuel packed into the cylinder so we need to go richer still so that's one of the key things, as we move into positive pressure we're going to be targeting a richer mixture. So let's start by just opening up my M1 tune here and we'll have a quick look at how that is actually set up in the ECU. So just give me a second while this boots up and we'll have a look at the laptop software.
Now OK so just a recap, we haven't used the M1 for any of our webinars for a little while. So the M1 is a volumetric efficiency based ECU so here we have the VE or volumetric efficiency fuel table. So the numbers in this particular table here, we've got manifold pressure on the vertical axis and obviously engine RPM on the X axis. And the numbers in here directly represent the engine's ability to fill its cylinders with air. So we've got numbers very close to 100% VE around about 6500 and 7000 RPM.
So that works in conjunction in this particular ECU with the fuel mixture aim table. And that's this table here. So this is our table of target lambda numbers. So again, exactly the same load axis, we've got manifold pressure on the vertical axis and we've got engine RPM on the horizontal axis. And the numbers in here are what we want to tune the engine to run at.
So you can see up to around about between 0 and 80 kPa, so in the vacuum areas of the map, and up to 5000 RPM, we're targeting stoichiometric, lambda 1.0. So these are sort of the cruise, idle areas of our map and lambda one is going to give us nice fuel economy and that's obviously important when we're at idle and cruise. Now in a traditional naturally aspirated engine, obviously the highest load value number on this axis would be 100 kPa and if any of you have taken our courses or watched any of our webinars so far, you'll have known that generally I target somewhere around about 0.90 lambda in a naturally aspirated engine at wide open throttle, 100 kPa and generally might taper that a little bit richer at very high RPM. OK so that's because on a naturally aspirated engine, that is the maximum load we can actually get out of the engine so we're asking for maximum power and we've got our foot flat to the floor. You can see here though in this particular instance at 100 kPa, I'm now targeting 0.95 lambda and if we move over to the right you can see I taper it a little bit richer, so at 8000 RPM, we're asking for 0.93.
So at 100 kPa my target lambda number, in a turbocharged engine has actually become leaner than what I'd asked for in a naturally aspirated engine. And the reason for that is we're not thinking in terms of manifold pressure. We want to think in terms of load applied to the engine. And the reality is with most turbocharged engines, particularly an installation like this where the turbocharger's quite small, they're very very good at making boost with even a minimal amount of throttle position. And we would probably find that at cruise, maybe around 3000 RPM, we could have up to 100 kPa with perhaps only 20 or maybe 30% throttle onboard.
And that's the important point. So while we might be at 100 kPa, the actual airflow, the actual load on the engine is actually not very high. And that's why we want to target slightly leaner air/fuel ratio. By all means you could go and target the same numbers that we use on a naturally aspirated engine but it's not necessary, we don't need extra fuel to protect the engine and in reality all that's going to end up doing is using a lot more fuel. So again it's about matching the fuel delivery to the airflow or the load on the engine.
And that's now, in a turbocharged engine, this 100 kPa row, instead of being wide open throttle, becomes our transition area. So we're actually transitioning up onto boost pressure. OK so this is a completely stock standard engine in our Toyota 86 so we're not running a lot of boost. And we're targeting, our maximum boost is somewhere around about 140 to 150 kPa, around about 7 psi or so peak in imperial units. And you can see, as we move up, at 120 kPa, we're targeting 0.88 lambda and again right at the top end I taper this off a little bit richer.
At high RPM there's a lot going on, there's a lot of heat being produced and if we're at sustained high RPM, we can use a little bit of extra fuel to help safeguard the engine. Again as we move up in the boost pressure, so this area here, particularly from about 4000 RPM and up, we're running in these sort of rows of the fuel mixture aim table. You can see we're targeting between about 0.82 and 0.80 lambda. And that's reasonably flat right through to 8000 RPM. So now there's a couple of things about this.
If you were tuning a conventional turbocharged engine, those target air/fuel ratios that I'm using there are a little bit richer than probably what I'd normally use for what is really quite low boost pressure. On an engine that was built to be turbocharged... ...at 5-7 psi, boost pressure, I might be more inclined to target somewhere around about 0.84 to 0.85 lambda. In this instance though, we've got a naturally aspirated engine and it's not designed to have boost, it's also a high compression, it's 12.5:1 compression so what we want to do is take those factors into account when we're deciding how to approach tuning it. And with those factors in mind, I want to run this particular engine a little richer than I normally would, I know that's going to help control the combustion temperature which is really critical on a high compression naturally aspirated engine that now has boost pressure applied to it.
OK so that's a quick introduction to the M1 ECU. Now what we're going to do is have a look at a couple of aspects of how we approach tuning a turbocharged engine just so you can see that really the techniques that I'm applying are actually no different. So I'll just start the engine and I'll get the fan turned on on the dyno so we can run this thing. And what we're going to do is we'll start with doing some steady state tuning. Now I know again a lot of people are a little bit scared about tuning a turbocharged engine on the dyno, they feel that holding the engine, particularly at wide open throttle is quite scary when you've got some boost pressure in there.
And yeah it does take a little while to get used to but again the reality is that it is no different to what we're normally trying to achieve. What I might do is just jump through to another workbook I've got set up. OK so I'll just get rid of this parameter. 'Cause it doesn't need to be there. OK so what we've got here on this particular page, we've got set up with everything we need to tune the fuel delivery.
So we've got our main volumetric efficiency table here. That's also displayed graphically below it. Here we've got a representation of our current measured exhaust lambda and for this particular demonstration we're going to be looking mainly at the laptop screen rather than the dyno and then of course we've got our aim mixture table sitting straight above it. Down below we've got a couple of parameters, we've got engine RPM on our time graph, I'll just expand that, we've got engine RPM, we've got our coolant temperature, our inlet manifold temperature and then we've got our measured exhaust lambda in yellow and our current fuel mixture aim below it in orange. So that's all of the data we need.
Let's just get this thing running and we'll start with 2000 RPM on the dyno. OK so again just like tuning a naturally aspirated engine, my aim is to start with as little RPM and as little load as we can possibly get on the engine. And you can see at the moment we're sitting at 60 kPa at 2000 RPM and you can see we're a little bit leaner than ideal. Our target down here is lambda 1 and we're sitting at about, actually probably just a bit of heat soak that I had to get rid of, we've actually just come pretty much spot on. So we're sitting at lambda 1 now.
So once we've tuned that particular site, what I might do is just give us a little bit of work to do so it doesn't look like it's all too easy. We'll just highlight this particular area of the map and I'll make a change there, I'll take 10% out of those particular sites so now we should be a little bit lean. OK so we've tuned that particular 60 kPa zone so I've just moved up to 70 kPa and you can see now, sitting at 0.97, 0.98 lambda and again our target is lambda 1.0. So there's a few ways we can go about addressing that, we could manually make change which I can do with the page up and page down keys until I get that to meet my target of lambda 1.0 which you can see we're at now. So that's nice and easy, so we've tuned that zone.
Now we'd move up to the 80 kPa target. And we're on that now and again you can see we're about 8 or 9% lean. So I'll make another change there, just on 10% so let's add 10% in there, 1.1 and the multiply sign. Should take us back to, gone a little bit rich. OK we're pretty much, whoops I see what's happened there.
Sorry. Use the right key's always helpful, I'll try using the function key instead of the shift key. OK so we're pretty much bang on target there so again we'll move up now, first of all you can see we're going from, in this particular site that we're running the engine in right now, 65% VE. The next site up has got 56.7 so it's quite a big drop. So I would generally start by just copying the number from the site we've just tuned into it.
So when we move up to it we should be close, if not a little bit rich. OK so we're now in the 90 kPa row and you can see we are in fact a little bit rich, we're sitting at 0.93 lambda. So another function that the M1 uses which I find quite handy is the quick lambda function. So it'll just use the input from the wideband oxygen sensor which is what's giving us this input here and it'll apply correction automatically when I press the Q key which I've just done now. Doesn't generally try and correct the entire error in one go so occasionally we have to do two takes of that.
You can see straight away we're right on target. OK so now we're going to move up, so now we're in that 100 kPa so we would be normally, this would be normally wide open throttle. So again, you can see, remember our target was 0.95 and we're a little lean here, we're 0.99. So I'm just going to press Q and we'll autotune that particular site and get us on track. Which we are now so you can see down here, we're matching our target lambda quite nicely.
OK so first of all, you'll notice that I'm now holding the engine at 100 kPa and it's been running there for probably the last 10 seconds. So I'm not particularly concerned about the engine overheating or anything so we can jump back to this particular worksheet now and you can see our engine temperature's sitting at 89°, our air temperature's at 19.5°. The other thing remember I was talking earlier about, the throttle opening that we were using to achieve our 100 kPa, you can see at 3000 RPM I'm only using about 32, 33% throttle to get to 100 kPa so that's why we can tune a little bit leaner. OK so now let's just jump back to that custom workbook I've got set up. So now we're going to move up into positive boost pressure.
Now we do need to treat this with a little bit of care. Actually because we're going to spend a little bit of time in here, what I'll do, and I would recommend this anyway, remember we are starting our tuning, if you're tuning from scratch, you're going to be starting by, whoops that's not what I wanted to do. We're going to be starting by tuning our fuel delivery and when we do that, we want to start with conservative numbers in our ignition table so that we know that we're not going to encounter any knock or detonation while we're doing that. So what I've done there is you just saw me go into the ignition table and I just removed 2° of timing from the positive pressure areas of the map. OK so now we can move up to 120 kPa just by pressing the throttle.
And you can see actually at this point, our target's pretty much bang on, we're targeting 0.89 and we've got 0.89 lambda so that's spot on, we don't need to make any changes. Now we're at 2000 RPM, sorry I actually said 3000 before, we're at 2000 RPM and this point, 120 kPa, actually corresponds to wide open throttle so I've got the throttle completely open at this point to achieve 120 kPa. So again, people get scared about holding the engine under load, particularly at boost pressure, so the key parameters that we want to keep an eye on, we've got our coolant temperature, we want to make sure that that's not getting away on us. We've got our intake air temperature, again we want to make sure that that's not starting to skyrocket. And you can see again I've been sitting here at 2000 RPM at wide open throttle for the last 10 seconds while we've been talking and the engine hasn't melted down, it hasn't broken in half and everything's just running completely happily.
So at this particular point, the engine's really responding no differently to a naturally aspirated engine. It's just that the numbers we've got, that we're working with, the target lambdas are a little different and we're now working in positive boost pressure. OK so the principles again remain the same but let's start looking at a little bit more RPM where we can start getting a little bit more boost pressure. This time, just because I want to be able to monitor, and this is one of the key things with a turbocharged engine, we want to be able to make sure that the engine isn't detonating and with a turbocharged engine, particularly running on pump gas, detonation is more of a concern than what we'd get with a naturally aspirated engine. At least the ones that we've been using for our demonstrations.
OK so with that in mind I'm going to use this particular worksheet because down here we have a warning source set up which will tell me if the engine is suffering from detonation. I have another worksheet over here which I can use for monitoring it, this is a really nice way of just quickly noticing if the electronic knock control system is picking up any detonation. So on this particular worksheet, we've got our engine efficiency table here. Now we've got our exhaust lambda and our mixture aim being displayed down here. So let's go to 3000 RPM and see what we can do.
OK so again, we want to really start with as little load onboard as we can. So we start down, we can get down to the 50 kPa row here. And again what I'll do is I'll just make some changes so we've actually got some work to do. So we'll add 10% to that entire row. OK so, just store those changes, so hopefully you can, I'll just expand this a little bit so you can see, actually I'll get rid of some of the other parameters on here.
No I won't. Hopefully you can see we've got our exhaust lambda here in yellow and we've got our fuel mixture aim, so we're sitting at about 0.94, 0.95 lambda at the moment. So we're about 5% rich. Just for simplicity I'm just going to use the quick lambda to correct that. So you can see, two presses of the key there and we're tracking pretty much on our target where we want to be.
OK so once we've tuned that particular site, we can increase the throttle position and move up to the 60 kPa row. So again, no surprise we're a little bit rich, considering we just added that fuel, we'll just use the Q key. And that brings us back to just about perfect in one go. Increase the throttle position again and now we're sitting at about 0.89 so we're 10% richer than we want to be. So again we can do that manually, we're actually about 11% richer.
0.89 multiply, take 11% out of that, and you can see that we're pretty much on our target now. OK so just to clear up as well, the quick lambda function I'm using in the MoTeC there. All that does is the background calculation that we've already talked about from the EFI Fundamentals Tuning course so if you have a measured lambda and you've got a target lambda, if you've got a discrepancy, you can type into a calculator the lambda value that you've actually got, so your actual lambda. Divide that by your target lambda, so actual over target and that'll give you a correction factor that you can then multiply the number in your fuel table or your volumetric efficiency table by and that'll automatically correct your lambda so you'll be running at the right air/fuel ratio. OK so let's move up to 80 kPa now.
You can see actually we're a little bit lean at that point, we're at 1.03 so we're about 3% lean, I'll just correct that using the page up key to add a touch to the VE table. And we'll move up to 90 kPa. And here we're pretty much right on target. So we can move up to 100 kPa. So you can see here we're actually a little bit lean, we're at 0.97 vs our target of 0.95.
Now one thing that is important when you're dealing with turbocharged engines, you don't want to hold the engine in a lean condition for an extended period of time. So if we got to wide open throttle and the engine was clearly maybe 5 or 10% leaner than what we want, instead of sitting there while I manually made the correction, unless I could do that very fast, I'd probably be more inclined to back off, make the correction and then go back and check it out. So that is one area where tuning the turbocharged engine is a little bit different. OK so now let's move up to 120 kPa and we'll see what we've got there. OK so now we've gone a little bit richer than our target.
So still comfortably holding it at 120 kPa, I know nothing's going to go wrong. We're sitting at 0.83 where our target is 0.88 so we're about 5% richer than we should be. I'll use the Q key to correct that and you can see that now we're right on our target. So now we can increase the throttle further, this will take us up to 140 kPa. So we're now pretty close to wide open throttle and you can see we're about, actually pretty damn close, we're maybe 1% richer than target but I'm just going to leave that.
Then just to prove the fact, I'm now at wide open throttle. OK so while we were doing that, you can see over here, our engine temperature has started to creep up. And this is one thing you really do need to keep an eye on when tuning any turbocharged engine, they do create a lot more heat than a naturally aspirated engine and the cooling system has to get rid of that somehow. So it's very easy when you're in the middle of tuning your fuel table or tuning your ignition table to lose track of the engine's coolant temperature. So it's always a good idea to go back and keep an eye on it, make sure it isn't getting out of control and even if your ECU allows, you can set up a visual warning to bring that to your attention so you don't have to constantly think about it.
OK so at that point we got to, we were at about 140 or maybe about 142 kPa and that's wide open throttle on this particular engine. So when I'm tuning any turbocharged engine, what I'll do is map the engine, just like we're doing now, in steady state, up to the minimum boost pressure or wastegate spring pressure. So the minimum amount of boost that we can get the engine to hold. And so I'm really using the same technique that we used to tune a naturally aspirated engine, I will tune in steady state all the way up to around about 2/3 of the engine's rev limiter. So in that case we're talking about 4500, 5000 RPM.
So just to show you that that is actually quite safe, let's do that now. So we'll go up to 4500 RPM and we'll look at that row of the map. So again as long as the engine coolant temperature's under control, as long as our intake air temperature is not climbing out of range, and as long as the engine's not suffering from knock or detonation, we can quite happily tune the engine in steady state. So we'll just move through the map now and you can see we're a little bit lean so I'm just using again that Q key to add a little bit to the VE table. As I move up, so we're at 70 kPa now.
We'll move up to 80 kPa. You can see I am doing this a little bit faster than I was at lower RPM. Because we don't want to hold the engine under sustained high load any longer than we really need to. And I'm just looking across occasionally to make sure that my engine temperature is under control. We can move into boost now, we're at 120 kPa.
And you can see now we're at wide open throttle, about 150 kPa, 152 kPa and you can see I'm holding it there quite happily. OK so again as long as the engine's coolant temperature's under control, our air temperature's not sky rocketing and the engine isn't suffering from knock or detonation, tuning in steady state, even in positive boost pressure is totally safe and there's no problem with doing it. The key comes down to understanding that the engine will create heat faster than a naturally aspirated engine and we need to take that into account when we're tuning. So we don't want to take forever doing that, we don't want to hold the engine for minutes on end at wide open throttle at those sort of boost pressures because everything will start heat soaking quite quickly. The other aspect that that can affect is your ignition timing and we're going to look at ignition timing tuning next but what that will do is if we're at wide open throttle in a turbocharged engine, what will tend to happen is the whole combustion chamber will tend to start heat soaking if we hold sustained wide open throttle and what that can do is make the engine start becoming more prone to knock.
So we can find that if we go to say 3000 RPM on a cold engine, well one that's at normal operating temperature, go to wide open throttle and it's maybe 10 psi of boost pressure, maybe initially we might be able to get say 22° of ignition timing in at that particular point. If we hold it there though for say 30 or 40 seconds, what we'll find is that the engine may start to actually bring in some light detonation, we might find that we need to pull 2 or 3 or 4° of timing out of that particular site. So that's all to do with the heat soaking of the engine and we do need to be careful of that. OK so we've looked at the fuel tuning up to 4500 RPM there and as I said I would generally do this up to about 2/3 of the engine rev limiter. Now beyond that, if we're then doing multiple boost tunes, so maybe we've tuned the engine in this particular case to about 7 psi and we've got a boost switch and that's going to bring the boost up to say 15 psi.
I wouldn't tune in between those two load zones using steady state. I would tune the engine at the wastegate spring pressure, 7 psi, then what I'd do is step the boost control up to the new boost setting of 15 psi or whatever that happened to be and then I would interpolate my results between 7 psi and 15 psi in the VE table. OK so there's a couple of reasons why I'd do this, first of all, if we're running a 15 psi boost setting, the chances are we're not going to be operating IT at a consistent load between those two boost settings. So it would be very difficult for us to hold a consistent say 11 or 12 psi. We're only going to generally tend to transition through those zones.
So if we've got the engine correctly tuned at 7 psi, we've got the engine correctly tuned at 15 psi and we do a smooth interpolation between the 7 and 10 psi load points in the map, that's going to mean that the air/fuel ratio is probably going to be pretty accurate as we transition through those zones. Likewise if we're moving up say from 15 psi, maybe we've got another boost setting at 20 psi, we would do exactly the same. So in essence it's not essential to fill in every single load site in the fuel map when we're tuning a boosted engine. To be honest, the same goes for the ignition map as well, we can tend to interpolate between our sites. Before we go onto the ignition tuning, I'll just quickly look at doing some ramp runs.
Now I'm not going to bother doing a full ramp run on this particular engine, there's no real need, it's not going to prove our point. So what I'll do is just a little run between 2000 RPM and 5000 RPM. So once I've done my steady state tuning up to 4500, 5000 RPM, I'd fill in the rest of the wide open throttle tuning using the ramp run on the dyno. So we can just have a look now at the dyno and I'll just perform a run now to see where we got to. So what we can look at here is this is how I generally display the dyno screen when I'm tuning a turbocharged engine.
So we're going to use an overlay of manifold pressure vs lambda. So we can see this is going to give us a reference for where abouts in the table we were, where abouts in the efficiency table we were so we know, you can see particularly at the start of this run we were probably quite a bit leaner than I'd like to be, we were sitting up around about lambda 1. And you can see once we come onto boost, we sit down at around about our target. Let's jump back to the laptop software though because the MoTeC does make it quite easy to see exactly what was going on using the time graph function. And we will just zoom in now on the run that we've done.
And you can see, the main things we're looking at here is we've got our engine RPM. We can see we start at 1750 RPM and we went through to 5000 RPM. We've got our manifold pressure on the next part of the graph. Which shows in kPa the manifold pressure we were seeing. And we've got our throttle position but more importantly we've got our aim mixture vs our measured lambda.
You can see particularly in this first part of the run here, we were quite a lot leaner than our target. In the end it comes back to being pretty much on the money of where we wanted it to be. So we would use the feedback from this time graph to actually make changes to the volumetric efficiency table to suit whatever changes we needed to make. OK so I'm not going to do that now, it's basically the same process we've just looked at in steady state, only this time we're doing it in ramp runs. And what we'd do is we'd work that all the way out slowly but surely until we've got the engine tuned at our wastegate spring pressure all the way to the rev limiter.
And then as I say, if we're going to do multiple boost maps, we would then step up to the next boost setting and do the same job again. OK let's just jump back to the laptop software and we'll have a quick look at a couple of aspects of tuning the ignition timing. And this is one area we do need to be quite careful with a turbocharged engine and this one in particular makes our life a little bit more difficult because as I say it's a naturally aspirated engine we've added a turbo to and it is high compression. So what we're doing is exactly the same technique that we've already seen so what we'll do is we will start by taking some timing out of this 2000 RPM row and we will go through and see how we can tune that. OK so what we need to look at is, hopefully Ben's got this set up, he's pretty good so I'm going to trust that he can do it really quickly if he hasn't, we're going to need the axle torque readout on the Dynapack screen which is on the top right corner and hopefully at the same time we're going to be able to see this particular row here of our ignition timing map.
So I'm going to get the engine running and what you saw me do there was start by taking a whole bunch of timing out so that I know that we're definitely going to be retarded beyond the MBT point for all of this particular row. So we've got the engine running at 2000 RPM. I'm just going to add in a target, OK so we've got this little target over here which lets us see when we're in the middle of a zone. OK so we've got 10°, looking at the axle torque on the dyno, so we're looking at this number up here, we've got 130 newton metres, 170, it is jumping around a little bit. But let's, we know we're a long way away so let's go to 20° at that particular point.
You can see it's jumped up to 240 odd newton metres. Let's add another 10° and we'll go to 30°. So we've gone up to 270, 267 newton metres, let's try 35°. Because we're moving around a little bit inside these load sites, it's not being particularly accurate so I'll just try and get it back down. Actually I can't really hold that consistently so just to prove the point we'll come up to 60 kPa where I can hold a little bit more load and it's going to be a little bit more stable on the dyno.
So we've got 25° in there at the moment, we're sitting at 350 newton metres, let's try 30° and see what that gives us. OK so that's brought it up to about 360, let's try 35. And we're looking for the difference between when I press enter, or before I press enter, when I press enter. Try and get in the middle of the zone so we're sitting at 360, 370, I'll press enter. And we really haven't seen any change for that extra timing so I'll pull it back down to 30.
Mind you, only doing reasonably broad changes here just to illustrate the point. Once we want to start fine tuning it, we'd look at 1° increments or 2° increments to really get that particular zone dialled in. Now we'll move up to 70 kPa so we've got 10° in there. And again we're sitting at about 300, 320 newton metres. Let's try 20° in there.
OK so that's given us quite a big jump, we're up to 450 newton metres. Let's try 25°. Again we just want to see what it is before and after. 440 now, got up to 460, so we've got a change but it wasn't a very big one. So we'll try 30° now, so again we've got, just wait for it to stabilise.
Sitting at about 465. OK so that extra 5° I just put in there really didn't make any difference so again I'll just pull it back to 25°. So let's move up to 80 kPa, I'll just do this one quite quickly. So we know our surrounding sites are 22° and 25°. So we're probably going to be somewhere in the range of about 20 to 25.
So we'll just see what happens there if we go to 20°, got 540, let's try 25, 570. Now this does get it to a point where sometimes we will find that the engine becomes knock limited. Let's try 30°. OK so at 30° it hasn't made any difference so we'll leave it at 25°. We'll move up to 100 kPa and at this point I've started with 5° in there.
We'll start by moving it to 10. Sitting at 550 newton metres, press enter, lock in that change and you see we've got a big change, we've gone up to 650, 660 newton metres. Now we'll go to 15°. OK 730 newton metres, now we'll go to 20°. So again we haven't really seen a big change there, we'll go back to 15°.
Again I reiterate, I'm only making fairly broad changes. If I was actually tuning the engine properly I would be using smaller change. But let's go into some positive boost pressure here, we'll get up to 120 kPa. So we start with 5° of ignition advance. Let's go to 10° and see what that gives us, so we're sitting at 910, 920 newton metres.
OK so straight away we've gone to 1000 newton metres. Now I know I've got my knock control system dialled in quite well here so we've got no knock, that would be indicated by this warning source here. So let's try 12°, you see I'm going to make smaller changes now. So that's given us another 20 newton metres so again a positive change and no knock. Let's try 14°.
So again we've picked up a little bit more torque, about another 20 newton metres, let's try 16° of advance. OK so at this point, the engine's not actually knock limited but I also haven't seen any gain in power from that extra 2° of timing so I'll pull it back to 14°. So again the technique that we're using is exactly the same as what we do when we're tuning a naturally aspirated engine. The only thing is we do need to be a little bit more wary of the engine becoming prone to detonation or knock as we move into positive boost pressure. So we need to keep that in the back of our mind, it's important to start, as we move into positive boost, as you saw me do there, start with safer numbers because we want to really start with retarded timing and advance it up until we find MBT or the knock threshold.
We don't want to start moving into positive boost pressure and find that as soon as do, we're already detonating, the engine's already knocking and we have to pull timing out so we want to start with safer numbers. Alright we'll turn the fan off now and we'll stop and have a bit of a chat about what we've just done and what we will generally do when we're tuning a turbocharged engine. Hopefully what you've seen there will have given you some confidence that really approaching the tuning is no different, we're just using slightly different targets. And we do need to be just a little bit more cautious of how quickly our engine temperature can build as we move into positive boost pressure. Now before we move into questions, I just wanted to talk about the high RPM area of the mapping.
I'll just see if we can bring that actually up on our laptop. For some reason this doesn't like connecting when it's on the network. OK it's going to connect this time though which is kind of handy. No it's not. Wonders of modern technology.
Alright try it this way. OK so what we're just going to have a quick look at again is our aim mixture table. And just an area that I didn't really discuss to start with. You can see that as we move into the higher RPM areas, even though we're in vacuum here, we're targeting quite a lot richer than stoichiometric, we're 0.97 and then as rich as 0.95 up at 7000 and 8000 RPM. OK so the reason for that is again a turbocharged engine's creating a lot of heat.
We're not going to be driving the engine in this area, it's only really going to transition through it, perhaps on a gearshift or on overrun so we can tolerate a richer mixture there, we're not worried about our economy and we can use that extra fuel to help again address the combustion temperature. OK so that's what I wanted to just discuss there, I'll just turn the car back off. Now we've talked about the area between, steady state up to 4500 to 5000 RPM. Beyond there we've tuned in ramp runs right the way through to the rev limiter so that leaves us with that chunk of the map that we haven't addressed in steady state between 5000 RPM and our rev limiter and in vacuum all the way up to our wastegate spring pressure. So that area of the map, we can't ignore it, obviously the engine may be driven in that area, you can't ignore it but we also don't need to spend as much time and be super critical of every area.
What we want to do, once we've tuned the engine at wide open throttle in our ramp runs, we can extrapolate basically the shape of our fuel map across and down from that point. At that point what I'd do is go and have a look at a few particular sites, so maybe I'll select 6000 RPM on the dyno and I'll do up 6000 RPM and I'll do this quite quickly. I'll start it again at very light throttle, as light as I can to hold 6000 RPM and I'll smoothly increase the throttle all the way up to wide open throttle and what I'm doing while I'm doing that is I can either log this or I can visually look and see what the lambda's doing, make sure that it's tracking. I'm really looking at this point for a safely rich mixture. Not going to go and spend a bunch of time making sure that it's exactly perfect because again we're not going to be driving the car, we just want to make sure that when the engine does operate in that area, the mixtures are safe.
So we can do that quite quickly, then we can drop the engine back to idle, make some block changes if we need to and then go back and have another look at it. So we're not making those changes live where we're holding a lot of stress and load on the engine. And the same goes for the ignition timing as well. So it's all about really understanding the implications of the turbocharger, the fact that it can create a lot more engine heat, it can make the engine more prone to detonation and it can make the engine overheat. And applying our tuning technique in a smart and sensible fashion to deal with those parameters.
And if we do that, there's really no problem with tuning it, it's quite safe to do and it's quite easy to do. The techniques as I said right at the start, don't vary. It's just that the application does need a little bit more thought. OK we'll stop now and I will see if we've got some questions here and yep it looks like we have. Again if you've got anything that's cropped up or anything else that crops up now while I'm talking, please feel free to punch that in and I will address them as I can.
TTM's said, with a turbo engine is it possible to really reproduce the road conditions, flow exposure to the intercooler on the dyno? Yeah that's a great question and the answer honestly is no. The dyno does a reasonably good job but definitely it's difficult if not impossible to truely replicate the airflow you're going to get on the open road. So what I'll generally do, and again anyone who's followed our webinars will understand I'm a big advocate for always confirming a tune that we've done on the dyno out on the road because then we do have real world conditions, lets us check and make sure that the air/fuel ratio that we're seeing on the dyno is the same as what we've got on the road and it also makes sure that if we haven't got any knock on the dyno we can confirm we haven't got knock out on the road. When I'm tuning a turbocharged engine on the dyno, what I generally will do is, particularly if it's making a lot of power and it's putting a lot of heat into the intercooler, that comes really with boost pressure rather than power but it's putting a lot of heat into the intake air temperature through the intercooler, generally I've got a squirty bottle where I'll actually pour water onto the intercooler to help get rid of some of that heat. So I'm just again trying to replicate those real world conditions.
And again TTM said what about airflow under the car, that's sometimes supposed to help with heat extraction. Yeah I don't know if I've got too much comment about that. I mean it depends on your engine bay design and the airflow through the engine bay. This particular car, our 86 we've found on the racetrack in particular it's got a lot of cooling problems which I've tried to address over the last 4 months so I guess we'll find out if I was successful the next time it goes to the track. And really on the dyno it comes down to how big your fan is and how good a job it's doing of pushing air through the intercooler and then the radiator.
Maddas has said, what is the general rule of thumb about ignition retard and boost conditions? There's no real good rule of thumb. If I was setting up a base map, probably a good starting point would be retarding the timing between maybe 2-4° per 20 kPa of boost pressure but that's definitely not a rule of thumb as such. You really need to just tune the engine to achieve MBT or until you find the knock threshold, just the same way you'd tune a naturally aspirated engine. But yeah I mean if you're setting up a base ignition table from scratch, taking somewhere between 2 and 4 degrees of timing out from our 100 kPa row as we transition up into boost, that should ensure that we've got a safe ignition timing number when we start tuning in boost pressure. TTM's said, under cruising conditions, constant vacuum and load, is it not interesting to target a lambda closer to 1.1 than 1.0? 1.1, I generally find is probably a little bit too lean.
But your point is relevant, 1.0 lambda is basically the target for optimum emissions and that's why all the OEM developers will set up a system of closed loop control to target lambda 1.0 under idle and cruise for minimum emissions. If we want to actually target maximum fuel economy, you're going to find that generally that occurs somewhere closer to about 1.05 lambda. What you'll find is if you go much leaner than 1.05 lambda, what tends to happen is that the torque will drop off, so the engine will actually start making less torque and less power and what that means is we need to put our foot further onto the throttle in order to keep the car driving at the same speed. So the fuel savings will sort of be offset by the fact that we're actually increasing the load and hence then also increasing the fuelling. So 1.05, that's a pretty good place to be if you really want maximum fuel economy.
TTM's obviously got a few questions here, good on you for bringing these up, thank you. Next one is, for a certain map value, how is airflow going to be the same on the dyno when the engine is held on this load area while it won't be so on the road? Generally the load, the relationship between manifold pressure and throttle position at a fixed RPM is reasonably consistent, it's definitely not going to be a perfect relationship between what we see on the dyno and what we see on the road but it does tend to be quite close. Where I see the bigger problem is a real discrepancy when we're tuning an engine running multi throttle bodies and turbochargers. What we see on the dyno there tends to be quite dramatically different out on the road. And I kind of address all of that and how we deal with it in the 4D tuning webinar we did recently.
But yeah that's again, to answer your question more completely, that again is one of the reasons why I find it's important to confirm the tune out on the road, make sure that what we saw on the dyno was the same. In essence though, really what we're aiming to do is make sure that our cruise or vacuum areas are going to be tuned correctly to give good fuel economy so again around that lambda 1.0 area. As we transition up onto boost pressure, you'll find that generally the car will transition quite quickly up to that wastegate spring pressure, or our minimum boost pressure so the accuracy of the area, that transition area as we move up doesn't need to be absolutely 100% critical because the engine's going to quickly end up at that wastegate spring pressure and then we're looking at what we saw during our ramp run so it's important to make sure that's correct. OK Zuhas' said, can we use the same technique of road tuning an NA engine to tune a turbocharged engine? I.e. can you follow the same steps in the road course or is the dyno essential for tuning? No absolutely the road tuning course where we use a naturally aspirated engine, the same principles can be used when tuning a turbocharged engine out on the road.
The same things really apply, obviously we've now got a lot more load on the engine and particular when you're using the left foot braking technique, the engine's obviously, well at least we'd hope it's making more power than a naturally aspirated engine and hence that can put a lot more heat stress into the brakes so you do need to keep that in mind, be a little bit more wary of making sure your brakes are properly cooled after you've done some tuning. Cam said, obviously colder IATs are ideal, what about the upper limits of IATs on a turbocharged motor? That's a really good question Cam, yep you're right. Obviously the lower we can get our intake air temperatures the better. Now there's two things that really come into play here, one is our turbocharger efficiency. Naturally as we compress air, physics dictates that it will get hotter.
Beyond that though, generally we find that depending on how efficient the turbo compressor wheel is, will describe how much more heat above and beyond what physics dictates will be added to the intake air temperature. So as we start pushing a small turbocharger well outside of its efficiency, what it's going to do is start heating the air much higher. At the same time, not all intercoolers are created equal, some do a better job at getting rid of that heat than others. Generally, I like to see the intake air temperature sitting somewhere around about 30, 35°C. That's not always possible, particularly we see with, such as Subarus with a top mounted intercooler, the intake air temperature on those will get quite a lot hotter, it's not uncommon to see the air temperature sit in the mid to high 40s or even 50°.
Beyond that though, if we're getting much over 50°C, probably a good idea to start rethinking either your turbo size or your intercooler setup. The other problem that comes with high intake air temperatures into the engine will be more prone to detonation so we can address that with an ignition trim based on intake air temperature potentially. Manos has said, can you simulate the increased throttle position, load condition while tuning on the road and limiting the RPM to the specific RPM range? Yeah again it's the same as tuning the naturally aspirated engine, we're using the left foot braking technique out on the road to basically simulate what the dyno does and help apply load. Old Val's said, hi Andre, could you only achieve 120 kPa at 2000 RPM? You could only achieve, sorry, 120 kPa at 2000 RPM, how would you suggest to fill in the higher boost pressure cells in this RPM band that you couldn't reach? Would you just use the last value that you tuned or add some more fuel to the higher load cells? OK it's a good question, really it comes down to just being complete and thorough in our tuning process. Generally yes I will add a little bit of additional fuel over and above the areas we can get to.
Now you've got to question obviously how relevant is that when the engine can't actually get there? Probably isn't going to make much difference, we could just run the same number all the way up. What it's going to do is give the correct shape to our fuel map though so everything looks correct in the VE table. And probably not at 2000 RPM but perhaps in the higher areas, higher RPM ranges, if for some reason, maybe the wastegate, or the turbo manifold etc and exhaust housing starts heat soaking, we get a little bit more heat into the whole exhaust manifold, that can actually produce a little bit more boost and we've actually seen that in this car here, we've found on the racetrack after one or two laps, the boost pressure would actually increase by about 1-2 psi with the old turbocharger. The wastegate simply couldn't flow efficiently so if we use that technique where we're starting to add a little bit more fuel above the areas in the map we could actually tune on the dyno, it's going to mean if for any reason the boost pressure does increase and we move into those sites, we should be at least safely rich. So it's a good technique and a good policy to adopt.
The Sith said, I understand the car won't make 140 kPa at 2000 RPM but what about the cells from 100, OK you've pretty much asked the same question, sorry I didn't read that all the way through, so yeah, you've asked exactly the same question there as Old Val. Moving on R&R Autosports said, hi Andre, is there any difference in AFR when we set the AFR in steady state compared to a power run and also compared to actual runs on the road since we can achieve the same mount of boost but with different throttle openings on the road? And again, really that comes back to yeah the dyno we can only use it as a tool and you've got to understand its limitations and again that really comes back to why I recommend confirming and testing the tune on the road to make sure that those areas in the map are actually correct when we're on the road. Generally from my experience though, the dyno actually does a pretty damn good job and you should, if you tune correctly in steady state like we've just done, you should be within probably a few percent when you're actually out on the road so you should have very little work to do. Max Boost said, hi Andre, I believe normal ignition timing maps for boosted engines remove a couple of degrees timing around peak torque and then add it back in, plus some extra timing as RPM increases after peak torque? Can you confirm that's correct? Yeah absolutely and again honestly that's no different to what we see with a naturally aspirated engine. Remember there's two underlying tendencies with an ignition map.
Basically as the RPM increases, we tend to need to advance the timing or start the ignition event earlier to achieve MBT. So that's with regard to RPM. However, in regards to airflow, as the airflow increases and we see our maximum airflow at peak volumetric efficiency, as the airflow increases or the VE increases, we tend to need less ignition timing to achieve MBT so we have a tendency for the ignition timing to retard a few degrees around peak torque and then increase back again at higher RPM. Mike DE's said at what IAT do you experience both detonation and power loss and shouldn't this be monitored while dynoing through the software? Yeah I mean I've already covered this to a little degree, yes absolutely it is important and that's why I mentioned that it's critical to monitor the intake air temperature, make sure that's not getting out of hand when we're tuning in steady state along with obviously our coolant temperature as well. Generally the point is, you really want to make sure that you're replicating the sort of intake air temperature that you're likely to see on the road and as I've already said, the dyno fan's not going to do a good job of that.
So if we hold the engine at steady state for a long period of time, particularly at high boost and we start building up a huge amount of intake air temperature, then that's not going to be very realistic of what we'll actually see on the road. It is handy though to be able to replicate that condition once we've tuned under normal, maybe we see 35°C normal intake air temperature. Once we've tuned the ignition timing at that point, if we let the engine heat soak, the intercooler heat soak a little bit and our intake air temperature build up, can start seeing if the engine does start becoming susceptible to knock and if so, that'll let us tune the intake air temperature ignition timing compensation table so that means that we're kind of safe guarding the engine as well so we know that if it's out on the road and for some weird reason the intake air temperature does reach some astronomical values, we know the engine won't suffer from detonation. Leo's said, when it's the first time tuning an engine with a new turbo that you don't know, what calibrated wastegate duty cycle to reach your boost target, how do you process to tune it? OK I always start the same way and the first step is to start with minimum boost pressure. So I really want to start with wastegate spring pressure, find out what that is first and get the engine properly tuned at our minimum wastegate spring pressure.
Then we can start adding some duty into the boost control system and start seeing how responds. Now there's no rule of thumb, there's no golden rule for how a boost control system will respond to wastegate duty cycle. It depends on the wastegate spring pressure and the whole turbocharger system as well. So generally I'll start by using a small number, maybe we'll start with 15 or 20% and I'll see what sort of increase that's going to give me over our wastegate spring pressure. So perhaps we see a 4 or 5 psi increase so that's given us a bit of a glimpse as to how much duty cycle we need to add to start gaining boost pressure.
So then beyond that, it's a simple job of again continuing to add duty cycle slowly but surely until we creep up on our boost target. And it's always better to start with less wastegate duty cycle, find out out boost is lower than we want, stop and go back and add more duty cycle rather than doing a run and finding that we've got excessive boost pressure. Cam said, what ballpark should you be keeping engine coolant temperatures in while it's on the circuit with a turbocharged engine? Realistically, cooler to a degree is going to be better, again it removes heat from the engine and more importantly from the combustion chamber because we've got water running through the cylinder head and that'll help make the engine less susceptible to detonation. Obviously we can go too cold though. Generally I like to see the engine operating somewhere between about 75 and 90° and probably around 80 is my sort of ideal spot.
If we're operating continually above sort of 90 or 95°, it's really going to make the engine that much more prone to detonation which is not what we want on a turbocharged engine. DMackNZ said, what kind of deviations are acceptable for AFR between different runs with heat soak? Really what we want to do is start by making sure that when the engine's being tuned on the dyno, we're not actually suffering from heat soak. So we're only going to really see heat soak if we've got the engine shut off after it's been hot, much like it is right now when we're talking and the engine's been running, it's been up to temperature and we've then shut it off. So the first run I do after starting the engine up, the air/fuel ratio may be too rich or it may be too lean but generally what I'd do is discard that, I wouldn't make changes based on that run, I would do a couple of runs, let the engine coolant temperature, the intake air temperature stabilise and then I can start making my tuning changes. So tuning for heat soak condition is not very relevant to the real world.
Madas has said, which gear do you prefer on the dyno to tune the car? 3rd or 4th? Generally it doesn't really matter too much, i generally try and use the gear that is closest 1:1, that's a pretty good place to be generally. He's also asked, do I prefer internal wastegate on the EFR turbo or external wastegate? So far my complete amount of dyno time with this EFR turbo with the internal wastegate has been about an hour more than you've seen with me tonight so I wouldn't exactly say I've got lot of experience with it yet. So I can't really comment on the EFR turbos, we just haven't seen enough of them. In general though, with most turbochargers, as they get bigger, an external wastegate is kind of an essential. Most of the bigger performance turbos don't even have an integration for an internal wastegate but if I believe the hype, which so far what I've seen suggests it's probably accurate, the internal wastegates on the EFR turbos are designed to flow very well and should do an exceptionally good job.
Lastly on the road, which gear should I choose, 3rd or 4th? Or the same logic as the dyno? OK so on the road, what we really want to do is choose a gear which first of all we're not going to encounter wheel spin in and as we get into a more powerful turbocharged engine, that becomes more likely. So 4th gear, if you're traction limited is probably the best gear to be tuning in. The other thing is using a higher gear will actually happy more load so the run will be longer, we'll get a better chance of seeing what the air/fuel ratio's doing under sustained high load so 4th gear is probably a pretty good place to do that. 3rd gear you can also get away with but generally I like to do a run at the worst possible set of conditions the engine's likely to experience and that would be high RPM and high road speed where the engine's really under sustained load. So 4th gear will probably achieve that, or 5th if you've got a 6 speed gearbox.
Alright look that brings us to the end of our questions. We've had quite a few tonight which suggests that obviously a lot of you were interested in this topic. Hopefully it has been informative and you've taken something away from it. If you've got through this and you want to know a little bit more about any of the aspects of what we've touched on, the techniques that I've used on the dyno, we explain those more thoroughly in our Practical Dyno Tuning course and of course we've talked a little bit tonight about AFR, choosing the correct air/fuel ratio for a turbocharged engine and again our recently released Understanding AFR course is the perfect place to go if you want to get a complete and thorough understanding of where to set your air/fuel ratio. Alright I'll leave it at that for tonight.
Again, thank you for joining us and I hope you have enjoyed the webinar and we'll see you all again in a couple of weeks. As usual, if you do have any questions that I haven't been able to answer here or anything else that crops up, feel free to enter those into the forum and I'll address them there. Thanks guys.