240 | Methanol Tuning Considerations
Methanol is the fuel of choice for most top level drag engines, however it does come with some significant downsides and considerations. In this webinar we’ll cover what you need to know if you’re considering running on this fuel.
- Hey guys it's Andre from High Performance Academy, welcome to another one of our webinars where today we're going to be discussing some of the intricacies and some of the dos and don'ts with methanol fuel. Now as usual, we will be having a question and answer session at the end of the lesson so if there's anything that I talk about today that you'd like me to dive into in a bit more detail or maybe something you didn't understand, please ask your questions in the chat and we'll jump into those at the end. Now in terms of methanol as a fuel, it is a relatively specialised fuel, this is a fuel that you're not going to come across every day and for some tuners you'll probably never come across that fuel ever so that is one consideration, it's not a fuel that you're going to be using particularly on the street and in fact at least here in New Zealand, it's actually illegal to use for a lot of sanctioned motorsport events as well. So where we tend to see it most often turn up is on the drag strip. We also tend to see it being used in the likes of stock cars or sprint cars as well as the likes of jet sprint boats.
Now obviously that's not an all encompassing list of every place that you're likely to find an engine running on methanol fuel but just a few of the examples. So obviously again quite specialised. Now the reason that methanol fuel is used or is an attractive option as a fuel is due to some of its chemical properties. In particular, I'm going to cover some of the advantages and then we'll go over the not insignificant disadvantages. One of the questions that I quite often get asked about methanol fuel is how do we make more power on methanol when it actually has less energy contained in it for a given volume or given mass I should say compared to our normal pump gasolines.
And specifically there, I did grab some numbers here so I could talk with a little bit of authority about it, the energy contained in gasoline is, sorry in methanol is about 23 MJ per kilogram. If we compare that to gasoline, it's around about 46 MJ per kilogram. I mean there's probably going to be some variation depending on exactly where you get that information but you get the point, it's significantly less in terms of the energy it contains for a given mass of fuel. The thing that's important and why methanol still works and does give us more power is that we are burning around 2.5 to three times more fuel by mass compared to gasoline so because we're burning so much more of it, we do end up with overall a gain in the amount of energy that's being released as we burn it. What this means is that even if we aren't building an engine specifically to take advantage of the other properties of methanol fuel, there is still the potential for us to see a power gain when we switch from gasoline or a gasoline based fuel to methanol.
The other really key advantage with methanol is it does have a very high octane rating and again depending on exactly what source you're looking at, you're going to find that the octane rating of pure methanol's going to be somewhere around about maybe 108, 107. So much much higher than most of the pump fuels that we're going to have as well as most of the racing fuels, specifically blended racing fuels that we'll see. The other key which we can't overlook here and one of the real advantages with methanol, to a lesser extent also ethanol blends but obviously we're not talking about those today, is the latent heat of evaporation or latent heat of vaporisation of the fuel. So this is a chemical term, we don't really need to understand too much about the chemistry behind it. Essentially this term just defines how much heat is absorbed from the combustion charge as the fuel goes through a phase change from liquid to vapour.
It's obviously injected as a liquid and essentially absorbs heat out of the intake air temperature as well as the combustion charge temperature as it goes through that phase change into a vapour. So this is important because in round numbers again, the latent heat of evaporation of methanol, around about 11 KJ per kilogram versus 300 KJ per kilogram for gasoline. So significantly more. So why that's important is it has a massive cooling effect on our combustion charge temperature. And if we consider detonation for a moment, or knock, the main driver behind what causes knock is a situation where the heat inside the combustion chamber becomes so great that pockets of unburned fuel and air spontaneously combust.
Knock of course, one of the big killers of any performance engine so anything we can do to get away from knock is going to be a big advantage. Now why this becomes more important with methanol is that it then allows, between the higher octane rating, so it's a more stable fuel anyway, less prone to auto ignition or spontaneous combustion, the other advantage there, because it's drawing heat out of the combustion charge temperature, this is why we can get away with very high compression ratios, insane levels of boost, often 100 plus psi easily run on methanol fuel with little to no fear of knock occurring. Now there is a flipside of this because while methanol as a fuel is much more stable and less prone to knock, alcohol fuels in general are actually more prone to suffering from pre ignition so two different sides of the coin there, I'm going to just briefly mention the differences there because they are often confused. Pre ignition is very different to detonation. Detonation or knock occurs after the spark event has started the combustion process, so that's really important, it occurs after the spark event.
So what happens during the combustion process is that the spark occurs, the combustion begins and we start seeing the pressure and also the heat inside the combustion chamber start to rise quickly. So it's that heat as I mentioned there that creates the chance for spontaneous combustion to occur. Pre ignition, there's a really big hint in the name here, it happens before the ignition event occurs. So what this means is it can happen very early in the compression cycle. So even when the piston is down close to bottom dead centre.
it's caused by heat inside the combustion chamber pre igniting the fuel. This is normally as a result of dilution of the fuel with oil or something of that nature. There's lots of studies on this, we're seeing particularly outside of methanol tuning, this is also a big issue with low speed pre ignition on direct injected high output turbocharged engines as well. So there's a variety of aspects that add up to this. Pre ignition however, very very damaging, much more so than detonation because it's got so much longer for the heat to act on the piston and all of the components inside the engine.
So we'll just actually have a quick look at the results of pre ignition. And that's a piston out of one of our old 4G63 drag engines. The result, or what caused this was a situation where we had three injectors on each cylinder and we had one of them start to operate erratically, so we actually ended up with a lean condition in the cylinder. But pre ignition, you can see that it's melted the side out of the piston. Often they are confused between pre ignition and detonation and some of the symptoms, some of the aspects that we see with pre ignition and detonation are very similar.
The damage from pre ignition happens much much faster than detonation. Also, it's a bit hard to see on this overhead shot, pre ignition's actually caused the crown of the piston to get so hot it's melted and it's actually got a big hollow here so one of the keys with pre ignition that we'll often see is it actually melts a hole directly through the top of the piston whereas with detonation we start by seeing that sandblasted appearance on the piston crown. Alright so we've talked about some of the advantages with the methanol fuel. Doesn't come without some disadvantages so we need to talk about those as well. So the first one of these is the actual fuel flow requirements.
We're going to need massive amounts of fuel flow in order to be able to support the amount of fuel that is required on methanol fuel. There's a couple of reasons for this, one of them is the stoichiometric air/fuel ratio of methanol fuel. So we're talking about a stoichiometric air/fuel ratio of 6.4:1 versus obviously 14.7:1 for our pump gas. So on that basis alone we need around about 2.3 times more fuel mass when we're running on methanol than we do when we're running on gasoline. Now that's not the full story though, we also tend to find that methanol fuel likes to run significantly richer than a gasoline blended fuel so when we take this into account we're normally closer to 2.5 to three times more fuel flow requirements than what we'd need on gasoline.
So one of the considerations is that it's very difficult to support this sort of fuel flow on a lot of the electric pumps around. Now there's an argument that these days we are seeing a lot of fuel pump development and we've got some pretty big electric pumps on the market these days, particularly the likes of the brushless pumps that can support in excess of 2000 horsepower even on an ethanol blended fuel. But for pure methanol it's still much more common to use a mechanical pump. So if we just jump across to my laptop again for a moment. This is just a quick shot from an Instagram that I put up the other day and it's a Nissan RB26 based drag engine and we can see it's got a Kinsler mechanical fuel pump mounted off the exhaust cam there.
Quite common to either mount the mechanical pump off the cams, because they're driven at half engine speed, or if the engine is dry sumped you can often mount the fuel pump directly off the back of the dry sump pump, again typical to run a dry sump pump at 50% of engine speed. So the nice thing about a mechanical fuel pump is we can basically size them to support just about any fuel flow that we want and mechanical pumps are right up to the most powerful engines in the whole world which is the likes of Top Fuel, or internal combustion engines at least, the likes of Top Fuel, that's exactly what you'll see there to flow nitromethane. There are some disadvantages with mechanical fuel pumps though, particularly at cranking speed they do a horrible job of priming the fuel system, they're basically not spinning fast enough. Normally once the engine's fired for the first race of the day, the first startup of the day, it will retain enough fuel pressure that after that it will fire up but certainly cranking the engine for the first time, if the whole fuel system has lost pressure, can be very very difficult to get them to fire up. Two solutions there, we see a lot of competitors use something like a aerosol engine start just to get the engine fired up.
Alternatively if you want to get a little bit more sophisticated and a little bit flasher, you can use a small electric pump as a primer pump and that's just used while the engine is cranking to build pressure, after that the engine starts and the electric pump can be switched off. Right so while we're talking about fuel pumps, obviously the other consideration we've got there in the fuel system is we need to supply that fuel into the engine. So the injector sizing is just as important there. So again if we're using that factor of about 2.5 to three times the fuel flow requirements compared to what we were running on pump gasoline, that's probably going to get you into the ballpark. So this is the next problem we tend to see with methanol fuel is that if we size an injector big enough to support a powerful engine under full load, high RPM, you're almost certainly going to have trouble controlling that injector well enough to supply the relatively2 small volumes of fuel required at idle and light load.
So while it's not always the case, we will generally find that on a methanol fuel engine, stage injection is the preferred method to go through there, allows you to use two sets of injectors, one at idle and low load before bringing in the second set of injectors once the load increases. Now the other considerations here or downsides with methanol fuel are around the properties in that it is corrosive particularly to aluminium so this is a problem because when we're running on methanol fuel, we don't really want to leave the fuel in the system. So we want to go through a process that's just referred to as pickling the fuel system after a race event. This essentially just means that we're going to drain all of the methanol fuel out of the fuel system, refill it with pump gas and then we're going to pump that through and actually start and run the engine, otherwise we risk problems with corrosion particularly if the engine is going to be left for an extended period of time. It can also play havoc with some brands of fuel injector.
So some considerations there, it's not without its share of responsibilities in order to make sure that your engine is going to be reliable. The other issue with methanol fuel is it is a very dry fuel, it doesn't have any lubricating properties like pump gasoline does so this can be problematic, there are some pretty simple additives though that you can buy that are designed to blend in with methanol fuel really easily and that will fix that issue but it is a consideration. Most often we won't be running on a pure 100% methanol, it will have some additives in there. In terms of some other disadvantages, because we tend to run very rich air/fuel ratios with methanol, we will tend to find that just due to the sheer volume of fuel, we are injecting into the engine, we're going to have problems with the fuel diluting the oil so quite often you'll find that drag competitors will change the oil after every drag race and the oil comes out looking a little bit like a caramel milkshake. Now not necessarily a problem if you're using a good oil over the course of one or two race meetings but if you were to run that for extended periods of time, obviously the methanol fuel does break down the lubricating properties of the oil and that can result in damage to the rest of your engine components so again lots of things that you do need to consider here.
The other one which is a big one is fire risk and while I wouldn't necessarily say that methanol in its own right is more likely to cause you an instantaneous fire ball than if you're running on pump gas, this is really a consideration if you are involved in an accident, the fuel system is compromised and it does catch fire, the problem with methanol fuel is it burns with no visible flame, it burns clear, so the problem is you can actually end up finding that you've got a fire and you don't immediately know that you are on fire and obviously that could end quite badly. So considerations around that, this is why also competitors that do run on methanol fuel generally, we see the likes of Pikes Peak for example where methanol is allowed in some classes, the cars will have an M symbol in the car so that fire marshals know that that car is running on methanol fuel. Alright so one of the other ones that we need to consider here is the use of an intercooler. Now this is one of those aspects that we see kind of a 50/50 mixed result with methanol fuel. Because it does such a great job of cooling the combustion charge temperature, plus the sheer volume of fuel that we are injecting, there's sort of a mixed result as to whether or not a tuner or engine builder will add an intercooler.
So we'll just have a quick look over at my laptop and these are a few shots we took from Sydney Jamboree a couple of months back. And this is a 13b drag engine where we can see that the outlet from the turbo basically runs straight to the injection manifold there so no intercooler at all. Likewise this is another 13b drag engine and again you've got the turbo located behind this carbon fibre intake and really simple plumbing there, straight into the injection throttle bodies. So no intercooler, quite common particularly on rotary drag engines, we find. However, let's just get to the point I wanted to show you, this one here, this is a 2JZ, this is run by Rod Harvey, at the time we shot this, the fourth fastest and I think third quickest import in the world running 5.60s at about 236 mph, don't quote me exactly but close enough for the purposes of our discussion.
And he on the other hand, even being, knocking on the door of the fastest in the world, is running an ice water to air intercooler which is what we can see here. So considerations around this, and I'll come back to my own experience with methanol fuel on my own drag car, we looked at the pros and cons and we decided to run an intercooler on our own car which was a turbocharged 4G63 drag engine. The reason we did this was that while it might not have been necessarily an essential, I wanted the consistency of the intake air temperatures as the car went down the strip and this is something that can be quite hard to get if you are running with no intercooler on a methanol fuel. So by running the intercooler I was running an ice water slurry through that intercooler and I could pretty much guarantee that my air temperatures were going to be relatively consistent. While I was talking, I just grabbed a photo here so just head across to my laptop again and this is the engine bay of my old drag car here and we can see that we've got a PWR barrel intercooler there.
So the reason I chose, and we talked to Rod about his options as well, the reason he went with the intercooler is again just getting that consistency of the air temperature. The problem with methanol fuel is that because it does have such a cooling effect, the problem we can't actually measure specifically what that cooling effect is so we can't measure the charge temperature, we're only measuring the air temperature maybe in the intercooler plumbing or the inlet manifold so we're not actually getting a direct measurement of what the charge temperature is so that makes it a little bit tricky. What we can find is if you're not running an intercooler, you can get your air/fuel ratio can change as the car goes down the strip and the air temperature does climb. So those are some considerations there, the downside of course of running the intercooler, it does add a significant amount more weight and complexity to the car. Less of an issue of course if you are already below the weight break for a particular class and you need to add that.
Right so we're going to jump into some questions in a moment so I see we've got one in there at the moment, this is a great time to remind you if you have got any more questions, please ask them but I want to take you through some logging and I'm going to talk about some of the considerations when you are tuning on methanol fuel. The big one obviously is what sort of air/fuel ratio should we be running? And this is where methanol is quite unique compared to if you've been running on a gasoline based fuel. Typically with gasoline based fuels or gasoline based race fuels, we'll tend to find that there is a small but noticeable improvement as we move the air/fuel ratio towards the lean limit and generally on a gasoline based race fuel that's a relatively safe place to tune. We obviously need to take some care but we don't tend to drop off a cliff in terms of our power or our engine reliability as we move leaner. So we can be relatively close to the lean limit and still keep a safety margin, the engine's going to perform well.
Methanol on the other hand does not like that sort of tuning technique. If you want to tune methanol fuel at a lean limit, you'll find that A, there's almost no power to be gained by leaning the air/fuel ratio out, really makes almost no difference to the power. The downside is there's a very sharp cliff that we fall off where basically you're going to tear up your engine components very quickly, maybe ending up with a result similar to our little piston friend here. So the key to tuning on methanol fuel is rich is safe, you really want to basically give the engine as much fuel as you can, tuning with a nice, safe air/fuel ratio. Generally the limit on how rich we can go with a methanol based fuel is defined by the ignition system.
Actually another consideration I should have mentioned, with the ignition system, because you're running so rich, the methanol fuel tends to be quite hard to ignite so you do need a very very strong ignition system to deal with that. So let's have a look at a couple of examples here. Actually no we'll go back for a second. I want to show you one of the engines that I wanted to cover here, yeah let's jump across to my laptop screen here. This is a Nissan VK56 twin turbo jet sprint boat that I was involved with the tuning of for a number of years.
And it's a fairly heavily modified Nissan VK56, in stock form, 5.6 litre naturally aspirated engine. This is out to six litres and it is now running on methanol fuel and obviously twin turbos so you can actually see we've got the injectors fitted here. Interestingly above the throttle butterflies, the idea behind this was down to the engine builder, I didn't really have a lot of input on this but they were trying to get better atomisation of the fuel. Those particular injectors are a Moran Billet atomiser injector. These are available in massive flow rates, I think these ones were 235 pound per hour.
Off the top of my head I think they go up to about 500 pound per hour so massive fuel flow, just basically a big old fire hose that's pouring the fuel in there. This engine ran, at the time we had it on its limit was around about 20 psi of boost, on the engine dyno it was making about 1200 horsepower. So we'll have a quick look at some logging from that and first of all we'd better actually jump to the correct log file. That one there. And we'll have a look at it over here.
So I've just got some of the key parameters that are of interest. So jet sprint boats, a little bit unusual compared to cars just the way they operate. What we try and do is basically maintain a specific RPM at which the jet unit is efficient, it happens that's about 6000 RPM so that's why if you look at the RPM trace up above here, you can basically see that our maximum RPM, except for where we get cavitation or something of that nature, we're sitting generally around about 6000 RPM. The next trace down is our throttle position and I think this is fairly early on in our testing where the driver was really still getting to grips with this. You can see not really using a lot of throttle, if we look it didn't actually ever get to 100% throttle.
I can attest, having sat in the passenger seat of this, I'm not surprised, the things are insane, it'll pull in excess of 2 G from a standing start. Only tops out at about 135, 140 km/h on the water but that's plenty fast enough I can assure you. They also pull around about 6 G in a corner so the most insane thing I've ever been in with an engine bolted to it. Manifold pressure down below here, so as I say this is fairly early on in the testing, we really weren't pushing it too far, maximum boost just under 167 kPa absolute so 10 psi of positive boost pressure. Now our air/fuel ratio here is probably where it gets a little bit more interesting.
So on a turbocharged engine like this running on pump gas, I'd probably be tuning in the region of maybe 0.80, maybe 0.78 lambda. With methanol fuel we run much much richer so we've got a little bit of bank to bank variation here but generally we're actually targeting around about 0.72. So quite significantly richer. Given that this is relatively low boost, again only 10 psi of boost. The other key input that we do want to look at when we are tuning on methanol, not essential but certainly one I would strongly recommend is exhaust gas temperature.
So we can see our exhaust gas temperatures here and generally with this particular engine I've been trying to keep the maximum EGT at or below about 750°C. So looking at this data, basically we're pegged at that maximum EGT I want to see, I'd probably, the next change I would have made on this is to actually got a little bit richer, probably as rich as about 0.70, maybe even 0.68 and again we're not going to see any power drop off with that. So what I'm talking about here goes pretty well for all of the small displacement or small bore diameter import engines that I've been involved with and we'll talk about some other intricacies in a second. For now though, we'll just also switch across and have a look at a different form of motorsport which is this one here will probably do it, which is the Nissan R32 GTR that I was involved with the tuning of a long time ago. This at the time held the world record as the fastest four wheel drive and the fastest Nissan GTR.
Obviously all been since completely eclipsed but this was probably in the region of about 10 years ago. So if we, let's just, have a look here, no that's probably not the right data actually, let's go to this other one here, that's probably a bit more in line with what I was wanting to show you. Right OK so we've got our RPM up the top here and this wasn't really on a very good pass, I think it ran, yeah 7.84, 184 mph over at Willowbank in Australia. So the RPM trace, we don't see the driver lift off which is the green trace here of the throttle, he's running a clutchless Liberty air shifted gearbox. We've got our blue trace here is our corrected speed.
Boost pressure here in our blue trace and we can see that we're stepping up the boost, our maximum boost on that run, about 47 psi so again this is fairly early on in the piece, I think at the time I stopped being involved with this car, it was running 7.40s, maybe mid 190 mph. Our lambda though here is what's sort of more interesting. So we're down around about 0.7 again, 0.72 so again you can see in the top end we're richening that up to about 0.70, 0.69 so as the car gets to the deep end of the strip, we can start to see if we look at our EGT traces, we've got this constant trend here as the EGTs sort of tend to climb and again I'm sort of trying to keep that 750°C as a safe limit. A very different tuning technique there between drag racing and other forms of motorsport. With drag racing we're only looking at seven or eight seconds depending obviously on the car, down the strip, obviously under wide open throttle and high load.
So it's a lot of load but it's only for a short period of time which is why we can see that that EGT continues to climb through that trace. On the other hand if we're dealing with something where we are going to be running for an extended period of time, so the jet sprints, generally their runs are between 30 and maybe 50 seconds long. Top land speed record racing, that'd be another one where we might be at wide open throttle for literally minutes on end. Managing the EGT becomes a much bigger consideration and we would tend to use a richer mixture in order to combat that EGT and keep everything under control. Now the other interesting aspect though, and this doesn't really go so much for gasoline based fuels is that the numbers that we've talked about there, so 0.68 to maybe 0.72 lambda, those work pretty well in my experience for a lot of imports, small displacement engines.
If on the other hand we're looking at what some of the competitors are running in Pro Mod, maybe the big displacement 481X Pro Line style twin turbo engines, those engines there we'll be going to run much much richer, it's not uncommon for those engines to run in the vicinity of 0.50 to 0.55 lambda. So just absolutely pouring the fuel in there and again that's an indication that as long as you can light off the fuel, there's really no downsides to running them richer and in fact it improves the safety margin as well so a few considerations there. Alright we'll finish off now by jumping into our questions so if you do have any more, please ask them, we'll see what we've got in here. First question comes from Matt who's asked, how do you know when you're approaching the pre ignition limit when running on methanol? Generally when you are starting to sweep all of the engine components up off the dyno shop floor unfortunately. Pre ignition, unlike knock, is not something that we can really detect.
So it is problematic because the other aspect as I mentioned is pre ignition does its damage so quickly. So a lot of this will come down to first of all getting the engine combination right. I kind of mentioned some of the aspects that come into play that can make an engine more prone to pre ignition. So a lot of it really comes down to oil dilution of the intake charge. So basically good control over the oil, the type of oil is also key.
Those sort of aspects come into play but yeah pre ignition is something we want to try and avoid with the mechanical design of the engine and the build of the engine, it's not really a tuning consideration because if it happens the engine is essentially toast. Likewise we'll find that even sensing detonation, and I'm a massive advocate for audio knock detection, when I'm tuning a very high specific output drag engine, knock detection does become a bit of a moot point and the reason for this is that if knock occurs, you're almost certainly going to be doing some instant damage so it's almost like tuning a rotary engine, you don't get to live through a knock event at very high specific power levels and live to tell the tale. You don't get to pull a bit of timing out of that area of the map and have another go at it, it's probably going to need some fairly serious rebuilding so yeah it's a case of being conservative, creeping up on the tune and generally unless you're really trying to fight for world records, leaving a little bit of additional power on the table there in order to keep the engine alive. Guyomatic has asked if stoich for E85 is 9.7 and meth is 6.4, what air fuel ratio should I run on my six litre twin turbo LS on E85 with methanol? Boost for the street map is 14 to 16 and drag map is 24 psi. That's a good question, at this point I have never ever tuned on an E85 and methanol blend.
So good luck? What I would suggest is that the air/fuel ratio targets you're going to want are going to be very dependent first and foremost on what sort of level of methanol injection you're using. So is methanol going to incorporate 50% of the fuel volume making its way into the engine, is it 20%, is it 80%? That's obviously going to be the bigger driver. So what I would basically do is take the sort of lambda target, I'm going to talk lambda here because particularly when you're talking about two dramatically different fuels, in my opinion it makes no sense to be working in air/fuel ratio units because it just serves to confuse so let's stick to lambda, that way it doesn't matter what the stoich air/fuel ratio is. So on E85 for that particular combination, let's say on 14 to 16 psi, I'd probably be around about 0.78 and that's probably pretty convervative. On 24 psi on pure E85 and probably on that combination pure E85 is more than enough for that sort of boost level, I'd probably be around about 0.76 or thereabouts, again plenty safe.
If we were on methanol fuel on the other hand, 14 to 16 psi I'd probably want to be around about 0.70, 24 psi I might be around about 0.65. So what I'd kind of do is then look at, if we're a 50/50 blend, probably want to be midway between those lambda targets, erring on the side of my methanol targets. Again it's always safest to be rich and you're not going to be giving away any power, particularly with a methanol blend. So it's always safest to be on the rich side of your targets and then you can try leaning the engine out a little bit on the dyno and see if it picks up, try richening it up. This is all about testing rather than going into a dyno session with one fixed target in your mind that you're going to tune for regardless what the engine is trying to tell you, it's about testing and finding out what your particular combination wants.
Taylor's asked, is there any benefit pro or con of mixing methanol with E85? So pretty much comes into my last question, I've never done this. I don't honestly see any reason to do so. E85 in its own right is an exceptionally good fuel. It's got plenty of knock resistance, it's got a very high latent heat of evaporation which does a very good job of in cylinder cooling essentially just like we discussed with methanol. So there's a certain point where your boost levels are going to get to the point where E85 is not going to be able to safely support those but that's going to be probably well north of 40 plus psi, it's well proven that competitors are running those sort of boost levels of E85 fuel.
I like to keep my life simple so if there's no real benefit, there's no real reason to do so, I wouldn't, so that's my take on it. Next question, methanol's chemically capable of running 12.5 BSAC versus 10 for gas and ethanol, I've seen other tuners achieve this for example 2000 horsepower from 160 pound per minute turbo, brake specific fuel consumption, I see what you're saying. I always get, brake specific air consumption I should say, of 10 on all fuels, even methanol, even running very rich, any idea what's necessary to tap into that extra? To be perfectly honest, no. That's probably a little bit more of a laboratory style test than what we normally do. The problem is that most often when we're building combinations, unless you have a very large budget, we don't get to play around with a large range of iterative changes on a particular combination to see what's actually going to give you the best possible results so I can't speak for that personally.
We basically will develop an engine specifically to run on methanol fuel and I'm not getting into the intricacies of measuring brake specific air consumption, brake specific fuel consumption either so I'm sorry I can't really answer that much more. Next question comes from Curt2JZ who's asked, considering the air to water intercooler using ice water and methanol fuel, do you increase boost or decrease considering the air density? OK so basically the boost pressure that we're going to run, we're going to be basically targeting a specific power level if you like, depending on what you're doing with the engine and this is where the dyno's going to tell you how that turbo responds at a particular boost level. You're going to find that as you go up in the boost level, you're going to get towards the limit of the turbo's efficiency at which point you're going to start adding boost and seeing no more real power or air flow out of that turbocharger. Specifically though with your question with the ice water to air intercooler, I mean I don't deal with this any differently. I target my boost pressure based on what the car and the drag application can actually put to the ground and generally what we're going to do because of the torque multiplication aspect of the gearing, we'll tend to step that boost up as we go down the track and as the car's going faster and it's able to put more power to the track.
Obviously at the same time our air temperature is climbing and even with an ice water to air intercooler, my own car, we would start at the beginning of the run, maybe with our air temperature five to eight degrees below ambient because of the ice water slurry. At the end of the run, with 54 psi of boost, we were still seeing air temperatures in the mid 40°C vicinity so it's still going to climb, the air density is dropping because of that but what we don't get to measure, and this is what I was mentioning before, is the cooling effect of the methanol fuel as well. So the actual air density going into the combustion chamber is going to end up being quite different so I'm not sure if that quite answers your question there, hopefully that kind of gets there. Frank has asked, for a 95 mm bore, four cylinder 3RZ Toyota engine, I can use 0.7 lambda, if so up to what boost level? OK there's al lot goes into this here so for a start, what we also need to consider is what sized turbocharger you're using. 0.70 lambda, if that's what you're talking about, what also are you using the engine for, is this a drag engine or is it being used for another form of motorsport? Remembering that our air/fuel ratio targets, or our lambda targets are going to be dictated by the sort of use that the engine's going to get.
So what we can get away with for drag racing for six to 10 seconds is quite different as I mentioned in the lesson, to what we can get away with for an extended period of time. To try and give you some numbers around this, it is really really difficult, 0.70 lambda I would probably be comfortable running that up to maybe in the region of 30, 35 maybe even 40 psi. Above this I'd probably expect that I'd need to taper this a bit richer. But here's the thing, what we're always going to want to do is start richer than that and then test to see how the engine actually responds. And this is kind of what I was getting at with the answer to one of those previous questions.
We don't want to go into a dyno session with a pre determined idea of what the air/fuel ratio is going to be. We can have some ballparks that we expect to be in and 0.70, yep that's a pretty good place to expect to end up. But again we want to test and see how the engine actually responds. If the engine makes more power and is happier at 0.65 lambda, well clearly that's where we're going to end up tuning it we don't want to run it leaner for the sake of, that was the number we had in our minds, so always start richer. Basically the rich limit is the point where you're going to get an ignition misfire.
As long as you can safely and reliably light off the fuel air charge, then there's no real downsides to running the engine richer. And you will find at some point at the very very rich extremes, you will start to see the power drop away so that's your guide that you've gone a little bit too far the wrong way. Alexandro, will methanol work mixed in 98? OK well I've had this question before, I do not mix methanol with pump gas or with ethanol, I just, I don't do that. If you're running on an ethanol based fuel, that should be more than sufficient for most applications at lower boost levels. If you get to a point where you want methanol then you'd switch to a methanol fuel, that's generally the way I deal with it.
Next question comes from Andrei, he's asked, have you ever run methanol with closed loop? If so, just at idle and cruise or over the whole map? The drag engines that I was tuning, I did not run closed loop but that was more to do with the ECUs that we were using at the time and maybe the sophistication of the closed loop control. These days most of the competition engines that I set up run full time closed loop control. The reason being that they have fairly sophisticated wideband controllers that give a lot of diagnostic information back to the ECU. So it actually can be really beneficial because if you do have little errors in your air/fuel ratio, based on some atmospheric conditions then the closed loop control can fix that for you so still I would tend to reduce the amount of control the closed loop has on methanol fuel, at very high loads I would probably only want to give it the ability to trim maybe plus or minus 3-5%. Essentially we're using this as a last backstop in case something is not quite right, it's not a bandaid for doing our job properly in the first place and tuning things as they should be.
John has asked, does the flame speed of methanol vastly affect the ignition timing requirements? Yes absolutely so the combustion speed of the fuel is one of the big drivers on our MBT timing. So regardless of what fuel we're operating on, what we're trying to do is basically time our ignition events so that we're getting peak cylinder pressure occurring at a point in the engine cycle where we can take maximum mechanical advantage from that acting down on the top of the piston and being transferred through the connecting rod. Now a lot of this will vary depending on the specifics of the engine geometry but a good ballpark is that that point is somewhere around about 16 to 18 degrees after BDC, so after the piston's gone past, sorry top dead centre not BDC. So basically just after the piston has gone past top dead centre and started on the power stroke. So of course if we've got a fuel that is a relatively slow burning fuel, then we need to advance the timing or start that spark event earlier in the engine cycle in order to get to that point.
So yeah, flame front speed, combustion speed is really important. PerformanceSS has asked, I use C16 as my primary fuel with 100% methanol injection via two nozzles, any tips for timing on GM V8s? OK so again I've kind of touched on this a few times, I do not run mixed fuel so I'm not going to be able to speak here from my own personal experience. C16 on its own, a fuel that I've had a lot of experience with, we used that in the earlier days on high boost turbocharged engines until Q16 came in and basically did everything that C16 did but more, given it had a 5% oxygen content and it was also cheaper to buy so we sort of switched everything to Q16. So comparing Q16 to methanol fuel, or C16 I should say to methanol fuel, you'll make more power out of the same engine combination on methanol every time. So tips for timing, OK haven't really given me a lot to work with here, I'm going to assume that given you're running C16 and methanol that you're running a high boost application so basically the same rules apply to tuning any engine at all, regardless whether it's a street engine making bugger all power or something that's highly strung making very very high specific power levels.
What we're trying to do is find MBT timing and what we want to do is basically begin by using conservative timing and then do some sweep pulls on the dyno, some ramp runs on the dyno. Generally what I'll do is advance the timing curve by two degrees at a time. We're looking for whether we pick up power and torque. Now if we pick up power and torque everywhere, that's great, that means that we started our too retarded everywhere, we've moved towards MBT and we would continue to advance the timing. And at some point you're going to find that you'll pick up power at higher RPM but in the lower RPM range you might find that it makes no difference.
So when we find that, we stop adding timing, in fact if we added two degrees, saw no effect from that, we'd pull the timing back out and we just keep doing that until we've either reached MBT, we've found the knock limit which in your combination would be very unlikely unless you're running some pretty insane boost levels or very high compression and both, or the other alternative we do need to be mindful of is in some instances we may purposefully choose to retard the timing from MBT leaving a safety margin to provide a little bit more safety buffer, reduce the load on the engine internal components. So that's really based on your own particular combination there. Particularly it's not uncommon to purposefully retard the timing around the peak torque area to just soften that hit as well. That's the area where the most load is going to be placed on the components. Frank has asked, what's the best sensor for measuring air/fuel ratio with methanol in your experience? Bosch 4.2, 4.9 or other? I actually use the NTK sensor, I find that that has a wider measurement range than the Bosch sensors.
Even there you do need to have the right wideband controller. For my purposes, I've used the MoTeC LTC, lambda to CAN unit. But I can't remember the specifics off the top of my head, there is an extended calibration that is suited to use with methanol fuel. So the stock calibration for the LTC won't really read rich enough for us to work with methanol at the very very rich limits, sort of I think it might be that it taps out at 0.65 so if you want to be richer than 0.65, you need the extended calibration there. YamahaSHO's asked, with your methanol drag car did you run with a radiator? No we did not.
Actually that's another area I didn't really touch on. The methanol fuel, because it does run so cool, does give you the ability to run without a radiator for obviously specific events such as drag racing where the engine only runs for a short period of time. We did still run water through the cylinder head and we used a little header tank, a swirl pot and a electric pump that circulated the water through the cylinder head but the block itself was solid filled with concrete or block filling grout, it was actually a specific compound. You'll also find most of the high end drag engines are billet alloy with no water jacket, no cooling passages at all. So obviously it improves the strength, the downside being that you only can run them for a short period of time.
Masoud has asked, do you use a different spark plug heat range with methanol fuel? Actually another really good question there that I should have touched on in the main body of the webinar. Yeah, absolutely it's always advisable to run a couple of heat ranges colder on methanol fuel compared to what we'd run on the likes of a gasoline based race fuel. So for the likes of my own drag car we were running on a heat range 10 in the NGK range. Obviously it's very specific on the sort of boost levels you're going to run. A lot of people will use a very cold spark plug for competition use which can make it harder to get the engine to cold start.
Less of an issue these days in my own experience but a consideration and a lot of people will then use a warmer heat range plug to start the engine and get it up to operating temperature and then swap to the cold plugs for the actual race use. The Bracket Racer Steffens has asked, do you know anything about methanol mixed with a compatible two stroke oil like Red Line in a two stroke snowmobile engine? Any thoughts on pre ignition potential since it's mixed with oil? I don't have anything to do with two stroke engines sorry so it's not something I can speak to with any personal experience. What I would say though is I have had plenty of experience with rotary drag engines running on methanol which, essentially the same deal, they're running a methanol compatible oil for pre mixing. And this is something, it's not just methanol related, it's something that I've never been 100% comfortable with with rotary engines that even in stock form they physically inject oil into the combustion chamber. And when we come from a piston engine background, that's really a no no.
We want to make sure that we don't get any oil into the combustion chamber, anything we do there, can have the result of diluting the effective octane rating of the combustion charge and make the engine more prone to knock. Or more prone to pre ignition, knock's probably the bigger consideration there. So this sort of comes down to, it's a necessary evil unfortunately, with two strokes or rotary engines, you're going to need that pre mix in there for lubrication so you can't really run without it. I do tend to be a little bit mindful of the pre mix ratio that you're running. And this becomes a bit of a balancing act with what the engine builder wants to run.
Obviously you can't really deviate too far from their recommendations but certainly I would tend to run on the lean side of the pre mix ratio compared to being very very rich there with excessive oil if we can avoid that. Obviously it's not going to be good having more oil in there than we want, or than we can get away with. Alright lots of great questions in there, hopefully everyone's enjoyed today's webinar, hopefully that's given some people a little bit more understanding on what goes into tuning on methanol fuels. As usual if you've got any questions after this webinar has aired, please feel free to ask those questions in the forum and I'll be happy to answer them there. Thanks for joining us and I look forward to seeing you all next time.
Now for those who are watching today on YouTube, this is just a little bit of insight into what we put on every week for our HPA gold members. We run these webinars every week, choosing a particular topic on engine tuning, engine building or wiring and we dive in deep for around about an hour. Obviously as you've just seen, if you can watch live, you can ask questions and get answers in real time. For our HPA members though they can also review these webinars in our archive at their leisure. Currently we've got 240 hours of existing content in that webinar archive.
There's some absolute gold in there, this is one of the quickest ways to expand your knowledge on a wide range of engine building, tuning and wiring topics. And if you are interested in learning more, you can become a gold member for just $19 USD a month. Alternatively though, you can get three months of free gold membership with the purchase of any of our courses. If you're interested you can check those out at hpacademy.com/courses. Should mention our gold members also get access to our private member's only forum as well which is the best place to get answers about your specific tuning questions.
Alright thanks everyone for watching at hopefully we'll see you next week, cheers.