201 | Creating the Ultimate Wet Sump
Oil starvation is a leading cause of engine failure in competition vehicles. While a dry sump system is the ultimate solution, this adds significant expense and complexity to your vehicle. In this webinar we’ll look at options for improving lubrication reliability with a wet sump.
- It's Andre from High Performance Academy, welcome along to another webinar. And this time we're going to be looking at modifications we can make to a factory wet sump lubrication system in order to provide a cost effective upgrade that's gonna help keep a competition engine alive. Particularly this is a big problem for cars that are run hard on a racetrack. So one of the problems we find is that when we start modifying any vehicle, particularly when we start modifying the suspension, adding stickier tyres, wider tyres, et cetera, the ability for that car to pull higher levels of lateral g force, as well as for that matter, higher levels of g force longitudinally in both braking and acceleration, do increase. Now the problem with this is as we're increasing the ability to corner, brake, and accelerate harder, the factory oiling system generally is not going to be designed to cope with those forces.
And the problem with this is when we start getting the oil sloshing away from the oil pickup inside our sump, we end up with the potential for the oil pickup to draw air and that's going to almost instantly result in bearing failure inside our engine. So this is probably in my experience, one of the most common causes I see for catastrophic engine failures in cars that are driven hard on the racetrack. It's not just limited to the racetrack though, we can see these same problems crop up when we are driving hard on the street potentially in some cars, and also for gravel hill climbs, those sorts of things although generally the g forces aren't quite as great there. So not just limited to circuit cars but that's definitely where we see the mainstream problems. And if we just jump across to my laptop screen for a moment, we've got some data from one of our development cars here that I just wanted to show you.
So at the top here we've got our engine speed in purple, we've got our throttle position below this in green. And just an aspect that we've got that's important to this log is in blue, we've got our lateral g force so this is our cornering force. And then we've got our oil temperature, which we'll talk about a little bit later in the webinar. We can see for this particular lap that's pretty consistent at 103 degrees c. And then finally in the bottom group here in yellow we've got our engine oil pressure in psi.
So our oil pressure generally is linked to our engine RPM. The speed of the oil pump is directly related to our engine RPM. So we do tend to see our oil pressure fluctuate naturally with engine RPM, that's pretty natural. And a good rule of thumb is that we generally wanna see around about 10 psi of oil pressure per 1000 RPM. Now through the majority of this log we can see we're pretty close to that.
The point that I've just randomly grabbed there, we've got 65 psi of oil pressure at about 6200 RPM. The concerning aspect here though is within this log file we've got some significant areas where we're seeing drops in our oil pressure. And this is indicative of oil surge, this is what we're trying to avoid. So particularly in this instance here, if we look at what we've got going on, we're dropping all the way down to about 27 psi. And that is pretty worrying.
We do need to take into account here that our engine RPM has dropped down as well. But we're still at 4600 RPM so not what we wanna see. A redeeming feature for this particular lap is that in all of the cases where we have got oil surge, if we look at what we're doing on the throttle, you can see that the driver is actually off the throttle. So at this particular point here, the driver's off the throttle, however we can see that we're pulling almost one g. So lots of cornering force but not a lot of throttle.
And the reason that the engine can live through this is because when we're not on the throttle, there's not a lot of load on the bearings so we kind of get a little bit of a breather and basically a bit of a get out of jail free card. Likewise we can see exactly the same thing's happening at this point in our log file, we're down here to about 30, 32, 34 psi and again we're actually downshifting there, so the little blip on the throttle there is just to match revs. So we're actually braking and this is, we can also see we've still got some lateral g force going on there. So while there is some significant oil surge going on in this particular lap, we've been very fortunate that the positions on the track where we have got that oil surge, correspond to areas where we're not applying any load to the engine. But depending on the layout of your track, is just as likely to happen where you are actually at reasonable level of load, and this is also pretty common to occur at sustained high g force corners.
So if you've got a very long corner, this is a really key point where you can run into problems with the oil getting away from the oil pickup. I should mention here that of course as usual, we will be having questions and answers at the end of this webinar, so if there's anything that I talk about today, please feel free to ask questions and we'll get to those at the end. So when it comes to fixing these problems, we have a variety of solutions. I'm gonna deal with the top shelf option which is a full dry sump system. So if we head across to my laptop screen, this is some really nasty shots that I've just taken of our V8 Toyota 86 just before we came live for this webinar.
So please excuse the mess, it's in the middle of some fabrication work. But here we are looking at the front of the engine. And off to the right hand side of the engine here, we've got our dry sump pump. So the dry sump system basically evacuates all of the oil out of the sump, and forces that to an external oil reservoir which we'll have at in a second. So the dry sump pump, as we can see we've got a drive hub that is bolted to the front of the crankshaft, and the dry sump pump is externally driven via this belt.
Now on our next shot, this is the interior of the car, so this is our dry sump tank here. And this is where all of the oil evacuated out of the sump is pumped through to. But you can get a variety of different pumps with a different number of stages. We've actually got a pretty basic set up there with a three stage pump. But often we'll have multiple scavenge stages, maybe four different scavenge stages and that term scavenge means that's what's drawing the oil and air out of the crank case of the engine and pumping it back into this tank.
The important part with this tank is the shape of it. You'll notice that it's quite tall and narrow and the pressure supply back into the engine is drawn out of the bottom of this tank. So that's our pressure supply coming out there. So what that means is that basically this tank, in normal operation is going to be about 2/3, 3/4 full. There's always a good head of oil above the oil pickup, the pressure oil pickup.
So we're always gonna get constant oil supply. The other aspect with these dry sump tanks is that they are also designed to remove aeration from the oil that's been returned. When you're pulling a lot of oil and a lot of air out of the sump, the oil that's being returned is quite highly aerated and we need to get rid of the air out of that oil so we are just pumping pure liquid oil back into the engine. So we've got another shot here, this is from underneath and this shows our dry sump pump here. So we've got two that are labelled as scavenge, so these are the pumps that, the stages of the pump that draw our oil and air out.
And then at the back of the pump we've got our pressure stage. So this draws that oil from the reservoir, pumps is through our oil cooler, pumps it through our oil filter, and then finally into the engine. And as an added advantage as well, there's an external oil pressure regulator on these pumps. So we can actually set our oil pressure with these pumps as well quite easily. Lastly there's an under shot, so this is our modified sump.
Again pretty basic setup on this particular engine, we see much more elaborate setups with full CNC billet sumps. In this case it's the simple setup with our two scavenge stages, drawing oil out of the sump. So that's what it looks like if you're going for a top shelf setup. And the problems with that is that there's a lot of cost and a lot of complexity with a dry sump system. It's easy to spend somewhere in the region of USD$3000 to maybe USD$4000 just on the parts for a dry sump system before you even consider running the system and fitting it to your car.
And then on top of that you're also often going to have quite long runs of very expensive abraded AN hose and fittings in order to plumb that system between the pump, the engine, your dry sump tank and also any oil coolers and filters you've got in the system. So great if the budget is there for it and it is the ultimate option. Well set up this will give you a very reliable lubrication system that's not going to present any issues with oil surge. However it is going to be beyond the scope of most people, particularly at the enthusiast level. So what we're going to talk about is what we can do at the enthusiast level, which is modifying our wet sump design instead.
So when we're doing this, what we're going to be doing is modifying the sump that bolts to the bottom of our engine, and we're going to be designing a new sump to help try and trap oil around the oil pickup and make sure that it's not going to slosh away from that oil pickup under sustained cornering, accelerating or braking forces. So what we obviously need is some way of trapping that oil around the oil pickup. As an added bonus, generally when we are building an aftermarket modified sump, what we're probably also going to want to do as a matter of course is add some additional oil capacity. Now again the oil capacity or adding additional oil capacity, it's not a silver bullet to fix our lubrication problems but additional oil capacity coupled with proper design with some trap doors around the pickup, is definitely going to help us keep that oil where it's supposed to be. The other aspect which is a little bit separate to our sump design, but is definitely worth touching on here, is we also may need to address the oil return.
So there are a number of engines where there's known problems with the oil under sustained high RPM operation, being pumped up into the cylinder head, essentially faster than it can be returned back to the sump. This is a big problem with some of the Nissan RB series engine for example. And what this means is that at sustained high RPM which is quite easy to get on a racetrack application, we can literally empty the sump. Or not completely empty the sump but we're pumping all of the oil out of the sump into the cylinder head, it lowers the oil level in the sump around the pickup, and then it just makes it that much easier for that oil pickup to end up sucking up air under cornering, accelerating, or braking forces. So often, which again, outside of the scope but just so you are aware of it, you may need to consider restrictors in the engine block so that less oil is pumped up to the head.
You may also want to look at fitting external oil drains from the cylinder head back into the sump just to help all of that flow return. There are other engines where common modifications include drilling out the oil return galleries in the block oversize. Maybe some of them may also need some smoothing or essentially porting to again just help that oil to flow back. So what we're going to have a look at here is the sump that I designed and built for our Toyota 86 to help eliminate the problem that we just looked at. So there's all of those design elements that I took into account with the sump.
So we started here with the factory sump and I wanted to add some capacity into this. And you'll quite often see this where there's a lot of aftermarket sumps that are available off the shelf for popular engines, where the sump will be winged. So basically wings on the sump are added to add to that capacity. We're a little bit limited on the Toyota 86 because we don't have a lot of room around the headers. So this was designed to quite tightly fit around our turbo headers and our up pipe, givine us a little bit of additional capacity.
It's also a little bit deeper so it sits a little bit deeper than stock to add to that capacity. When you're making the sump deeper than stock you do obviously need to be mindful of clearance to the ground. Really it's not a good idea to have your sump as the lowest part of your car. It'd be nice if the sump was protected by a cross member or something of that nature or at least a sump guard below it. So that's the first aspect and what I did with this is it's basically a range of laser cut steel plates that I designed.
I made a mock up just using cardboard so there's not a lot of technology in this, it's not 3D modelled or anything of that nature. It's all just basic hand tools. Cutting out pieces of cardboard with some scissors to get the right shapes. And once I was comfortable with that, we had all of those plates laser cut. Now once that was done, they've all been tig welded and we've then cut out the rest of the sump so that that's got full access to the winged section that we've just created.
Now that on its own is not really gonna be a lot of help. Inside that sump there's nothing currently to stop our oil from sloshing away. So we need a little bit more than just our winged sump. And this is where the baffle box comes in. And this is really the key to designing a baffled sump.
Again we've got a couple of laser cut plates that are the basis of this. What we'll do is we'll have a look under our overhead camera to start with and then I'll try and get a little bit of a close up using our iPhone camera here. So we've got a plate that is designed to bolt into our sump. We've got some holes so we can bolt that in. There's a couple of oil returns and these are a factory part of the FA20 sump that we've needed to incorporate.
In the centre we've got a three inch tube. And this is where our oil pickups sit. So we've got some little cut outs here which clear that oil puckup. And I'll just grab that oil pickup. So basically that's going to sit inside that tube.
So the idea of that tube is that it prevents the oil sloshing away. So let's turn that over and we'll have a closer look. Alright I think we should be able to see that. And again we'll just go to our iPhone camera in a second. So we've got our inner tube there.
This comes down and seals essentially right against the base of the sump. And we've got four little cut out slots in this. So this allows the oil to come into our central pickup. The important point is that these are all on angles so if we're looking at the sump in cornering the oil's going to want to move left or right. In braking, acceleration we're going to be moving this way.
So in all of those directions we've actually got a hard wall that oil can't get out. Then on the outside of the box we've got another, or the outside of the sump we've got this square box made up which includes some little trap doors. So let's just jump across to our iPhone camera and we'll see if we can get a better look at these. So again we've got, no that's not gonna work, try this. We've got the central tube that we can see with those slots that I've just explained to you.
Got the four of them, remembering that they aren't in line with our cornering, acceleration and braking directions. And then we've got our external box. And the key point with this is we've got these little rubber trap doors. So these rubber trap doors are designed so they're on the inside of the box. So we've got this big round hole that allows the oil to flow through.
Directly above the hole here, or below in the way I've got this set up, there's a slot that these rubber trap doors locate in. And the idea there is that the trap doors will allow the oil to flow into our central baffle box but if under accelerating or braking or cornering forces, if the oil sloshes to try and come out of that central baffle box, it's actually gonna close those trap doors against the plate that they're located in. And while at the moment obviously room temperature, these trap doors seem a little bit hard, particularly when the engine is at operating temperature and the oil temperature is up above maybe 80, 90 degrees, these are nice and pliable so they do a really good job of sealing. So this is a really good way of improving our wet sump design. We're going to get much more stable oil pressure, we're not gonna have as much risk of that oil running away from the oil pickup.
But that is only one option that we can go through so we'll talk about another option in a second. So basically how this all goes together, we get our iPhone out of the way and we'll just jump across to, oh actually let's have a better look at the inside of our sump with our iPhone camera. So again we can see how the sump has been cut out to make way for the extension that we've added in. And we've got these little mounting tabs that are welded in, they're tig welded in. Just to allow us to bolt that baffle box in place and we can actually see how tightly that fits, we can see a match mark in the bottom of the sump which is where that baffle box has been sitting.
So I'll just turn that sump over as well so you can get a better idea of the design of it. This is the oil drain, obviously pretty important to still be able to get our oil out, and we have put on some heatproof wrap there just to protect the sump, the headers actually run directly across the front of this. And I'll just turn that over, so this is all just been powder coated black as well. So pretty basic. And essentially, I won't bolt it in completely but essentially if we want to locate the sump in there, the baffle box in there, it just all sits in there, presses in place and then gets bolted in.
It's also worth mentioning there that the two factory oil returns that I did just briefly touch on, so those actually are returned straight into the centre of that baffle box just to make sure that all of the oil coming back out of the heads is returned into the centre so that again just helping keep a constant supply of oil around our pickup. Now one thing you're probably wondering is where do we get these rubber trap doors? So the ones that we have used on that particular sump are a product that Cosworth make. And if you search, because obviously depending on where abouts you are in the world, there's gonna be a variety of suppliers out there. If you search, just a Google search, for Cosworth, rubber trap door sump, something of that nature, a quick Google search before gave me about a dozen suppliers so pretty easy to find. They're priced around about $3 to $5 per trap door, per rubber trap door, so not particularly expensive.
And what you really wanna do with that is have the mounting plate that they're going to press into laser cut. So all it has is a little thin slot that the trap door is located in and you can just pull that trap door into that little slot and it'll positively locate in there so it can't ever get out. So that's my preferred technique but it does require a little bit of effort to actually make all of that and it's definitely not gonna be for everyone. So another option that is available, and these are quite a lot more common, if we go across to my laptop screen, we've got the likes of this Tomei sump for the SR20 and we're actually running something really similar on our SR20. Our one comes from Moroso and unfortunately I didn't take any photos of it before we mounted it.
But again we can see that on both ends of the sump we've got these wings to add capacity. To add a little bit of complexity, the SR20 is mounted on a bit of an angle so we can see that the sump is also angled. So essentially that's designed so that the bottom of the sump is parallel to the ground with the engine installed on its normal angle. And then what we've got is these plates that are located in the sump, either side of the pickup. And these have just got a little hinged trap door.
So this is all just made out of stainless steel and essentially the trap door can open in towards the oil pickup but of course if the oil tries to flow away from the oil pickup that trap door's gonna close and keep that oil where it's supposed to be. And just another one that I quickly found here which is pretty much, goes without saying. This is kind of what we're trying to do, when the car is accelerating, it stops that oil from ending up moving across away from the pickup. This is another shot actually of those little trap doors, so exactly the same thing there, and while it probably didn't, maybe it wasn't that easy to understand when I explained it, the trap door, we can see here has got a little tab on it, and this is what locates through the laser cut plate that we make. So we've got a little slot and that little tab just locates, we'll just pull that through, and it's basically got a little recess on it, so once we've pulled it through, it stays put, it can't move.
So we're going to move into some questions and answers shortly. If you do have any questions about the topic, please ask those in the comments and we'll get into those really shortly. Now there is a little bit more to improving your oil, the reliability of your oiling system than just your sump design though. Other things you need to consider is your oil temperature. And this is another area where factory cars really fall down when they are driven hard on a racetrack.
Factory cars aren't designed for continuous high RPM, high load operation which is what we get on the racetrack so it's not uncommon to take a car out on the racetrack, measure the oil temperature and find out that it's reaching 130, 140, or maybe even higher when you've done a few laps, so I'm talking degrees C there as well for those who are working in fahrenheit, sorry I can't swap over in my head, but definitely hotter than I'd like to see. Generally my sort of rough guide is I'd like to have my oil temperature somewhere between about 100 and maybe 115 degrees C. We don't want it running too cold but the bigger problem for us in competition use is running too hot. So common upgrade there is to fit an oil cooler. Problem is as the temperature of the oil increases, the oil essentially becomes thinner and it can in some instances break down as well and it doesn't do as good a job of lubricating.
So it's another common reason why we are going to see bearing failures in a competition engine. So an oil cooler's an essential addition there. We wanna also have some way of monitoring our oil temperature and just making sure that whatever we've fitted is going to work. Now of course we can instrument our sump with an oil temperature sensor and maybe have a gauge or run that into an ECU or a dash. If you aren't in that situation where you've got that sort of sensor, a really cheap and easy way it to use an external electrical temperature gauge.
I've got one that is basically like a multimeter and it's got a plug in K type thermocouple that's nice and thin and you can literally just put this down the dipstick hole when you come into the pits and it's gonna give you a pretty good snapshot of what your oil temperature is. A bit cheaper and easier than actually fitting a permanent oil temperature sensor. The other aspect of course is the grade of oil that you're using. So with our Toyota 86, in stock form it's a naturally aspirated 200 horsepower engine and in stock form it is designed to run with a 0W20 oil which is incredibly thin. And this is something we see, it's quite common with very late model engines, because the manufacturer's trying to improve the fuel efficiency of the engine by reducing the power lost to the lubricant in the engine.
However that's maybe not the best option for us. If we're looking at actually getting really good protection of the bearings inside the engine. So quite often I will, in that situation, step up to a slightly thicker oil, and in this case we've tried a variety of oils on our 86 and we're running a 10W40 full synthetic oil from Motul and found that that gives us a nice improvement in our oil pressure. And the oil is superior to the factory rated oil in terms of if it's going to give more protection to the bearing surfaces. So basically anything that you can do that's going to improve the chances of your bearings living, is going to actually be pretty cheap insurance.
Alright we'll head across and we'll have a look at some questions now. If you've got any more please continue to ask them. Michael has asked, can you comment on the usefulness of an oil accumulator as a solution to oil starvation? OK good question Michael, and it's probably something I should have dealt with during this webinar. So I haven't personally had a lot of experience with products such as Accusump. In a way I kind of, I guess I feel that they're a bit of a bandaid but I also do know that a lot of people do use them with pretty good success.
I just can't comment from a personal experience standpoint so it makes it a little bit difficult. The idea though is that that accumulator is going to basically store pressurised oil and if we do get an oil pressure drop, it's going to open up and basically supply pressurised oil back into the engine. The problem I have with this, and again not coming from personal experience, just the way I sort of think about this product, is it's sort of going to work after the case of the oil pressure dropping initially and what I'd probably prefer to do is actually prevent the oil pressure dropping at all. If our oil pressure doesn't drop then of course we don't need accumulator. So it's kind of, in a way I feel like a little bit of a bandaid fix there.
Baz has asked, where is the oil pressure being measured from, pre filter, post filter or somewhere off the block? 70 psi max pressure, 27 psi oil pressure, would love to compare to my engine. OK so the oil pressure being measured there is actually from the factory location. And as is common on most engines, this is essentially the point where the oil goes into the main oil galleries. So that's the most relevant point. Of course if we're measuring pre oil filter, we're likely to get a pressure drop across the filter and the numbers aren't gonna be particularly realistic.
I'll also mention there, on our Toyota 86 when we were first testing it without the aftermarket oil cooler we fitted, so no oil cooler at all, we were getting about 137 degrees C oil temperature. Runnin on the rated 0W20 oil back when it was naturally aspirated, we were seeing maximum oil pressure on the racetrack only reaching about 45 to 50 psi. So pretty scary stuff. The 70 psi we were seeing there was with our 10W40 oil. Jay has asked, are we building a B18C engine sometime this year? Moroso offers a 5.5 quart oil pan with removable sump tray, magnetic drain plug et cetera, are these oil pans good? They sure are expensive.
Also why would someone want a removable sump tray? So I have got a Moroso sump that we have fitted to our 350z so right now I can hope that they are good. I mean essentially there's not a lot of technology in these sumps though. They're a pretty basic thing and short of having an oil leak because they haven't been welded up properly, there's much of a muchness between the lot. And particularly in our case, I know you've got a B18 there, in our case with the SR20 the aftermarket sumps available from the likes of Tomei and Moroso are all pretty much a copy of the same designs, they all look exactly the same. In terms of a removable sump tray, not 100% sure what you're talking about there.
In some engines there will be a baffle plate, which is what I'd refer to it as, that bolts into the engine. Or a windage tray sorry, which is what I'd refer to it as that bolts into the engine, designed to essentially help remove oil from the crankshaft or prevent oil getting onto the crankshaft, not sure if that's what you're talking about there. Craig has asked, would the first place to upgrade a factory dry sump be a larger oil tank, or a deeper oil pan? OK so if you are running a dry sump then the oil pan itself is almost irrelevant in terms of its depth. One of the advantages with a dry sump system is because we don't have to store the oil in the sump of the engine, we don't need anywhere near as much depth, and so this is the advantage we see in a lot of single seat racecars is that going to a dry sump system allows the engine to be fitted much lower in the chassis, because we've got no problems with clearance to the ground. So that's not to say the sump design doesn't matter.
Quite often it's quite intricate with the way the scavenge pickups are integrated and also there will often be some mesh screens to prevent any engine components being picked up by those scavenge pumps in the event that you do have an engine failure, dry sump pumps are pretty pricey, you don't wanna be ruining them by putting a piece of broken piston through one. So really I mean it depends Craig on what your problems with your dry sump system are. Most factory systems will be designed pretty well I would imagine. If you're starting to get too much heat into your oil, that's one issue. You'd probably be looking at adding in a larger oil cooler.
A larger capacity tank would be another option but yeah I've yet to see any real problems that I'd need to upgrade from a factory dry sump system. Jamieson's Evo has asked, any insight on keeping or blocking piston oil squirters on a drag street 4G63 Evo 8? Also any experience with under drive oil pump gear like the ones sold by English Racing for the 4G63 using an increased Moroso pan and deleted balance shafts? OK so all of the 4G63 engines that I've ever built, we did retain the under piston oil squirters. I know that some engine builders prefer to remove them. On the basis that you are potentially removing some of the oil from the main oil gallery that could be used to feed the bearings. Frankly I just never had any issues with keeping them in there.
And I'd like the idea of the under piston oil squirters providing cooling oil to remove heat from the piston crown. So I think on balance they are a good product but I do know that many engine builders remove them and have no issues, this has just been my own personal experience. Also had no experience with the under drive oil pump gear. Unfortunately I always ran the factory oil pump gear. One thing you need to be careful of with the 4G63 is the way you remove the balance shafts.
A lot of people will just cut the balance shaft off the back of the driven gear on the oil pump. You don't wanna do that. In some instances it can be reliable, more often than not though over time, because that driven gear is no longer as well supported, you can actually gouge out the oil pump and result in quite a catastrophic failure. So use a proper balance shaft removal kit which still has full support for that driven gear. Jeremy has asked, is there a way to combat rev limiter aerating the oil? Is there a limiter that doesn't jog the engine? Not 100% sure what you're referring to there Jeremy.
I mean essentially the oil pump is going to be linked to our engine speed so the oil flow through the engine is obviously relevant to the engine RPM. I've never personally seen anything that I'd link in terms of oil aeration specifically to a type of rev limiter so sorry I can't probably give you too much more there, not an issue that I've come across. Allan has asked, can you use a wet sump on an every day driven built motor? Absolutely through my old workshop where we built hundreds of engines for a variety of different cars, I would say that less than 1% of the engines that we built were fitted with a dry sump system. In almost every road driven application, a wet sump system, in most road applications a dry sump system will be complete over kill. Dry sump systems are really only the realms of engines that have really catastrophic oiling problems, known oiling problems or more likely engines that are gonna be used in a circuit application.
Oliver has asked, what are your thoughts on increasing oil capacity via an oil cooler? Yeah I mean when you add an oil cooler, by definition you're going to end up increasing the oil capacity by some amount. It's not a bad thing but it's not really achieving the same aim as a winged sump because the idea with a winged sump is you're collecting more oil around the oil pickup. The winged sump, in conjunction with the baffles, or the trap doors, should help keep that oil around the pickup so that's something that the oil cooler won't really help with even though you've got more capacity. Jay has asked, when turbocharging a factory NA engine that runs say 5W30, should the oil viscosity change after turbocharging? I assume you want some thicker viscosity but I don't know how to judge which one I would need. OK so this really comes down to the specific engine and how far you're intending to push the engine.
Personally yes I will almost always step up the oil viscosity if I go from a naturally aspirated build to a turbocharged or supercharged build. There are a few factors that come in here though. One of them is that if you are dealing with a late model engine that uses cam control, then the cam control system can be quite fussy depending on the oil viscosity that you are running. So basically what I mean here is if you go to a very heavy viscosity oil, you may find that the cam control is now lethargic and it has a lot of latency built into it. 5W30 isn't a bad grade of oil for a moderate turbocharged engine.
You might want to step up just a little bit to maybe a 10W40 and it's probably going to be a pretty good combination in most instances I would think. Sea Marion has asked, in regards to a rotary engine, I've read that there can be issues with oil surge out through the oil filler neck with prolonged high RPM, and particularly long right hand corners. Are you aware of this issue and what's the best way to deal with this? I've seen aftermarket filler necks but not sure if this is a bandaid fix and not addressing the actual problem. OK so rotary engines are something that I don't personally build and I've had limited experience with rotary engines in a circuit application so I don't know for certain if that is an issue. And it may well be this is a common problem on a variety of engines where at sustained high RPM under cornering, oil may end up in a specific area of the engine that you don't want it.
In terms of the oil design though, the rotary engine is still fairly similar in terms of the oil pump and pickup. So I would probably be considering there a baffle sump with a little bit more capacity, not sure about the aftermarket filler necks, again just something I haven't dealt with myself. Daniel Hoi has asked, what's your opinion on building your own oil pan for the Barra into a JZA70 chassis? Biggest hurdle being building my own pickup tube. Maybe more of a square tubing design to lower the overall depth of the entire setup. Yeah and engine swaps can be a little bit tricky because now you are kind of trying to design a sump that may be compromised in terms of actually fitting into the new chassis around the cross member et cetera.
Really I mean you want to keep in mind the same design principles that we've already talked about today. You wanna add capacity where you can. A winged sump design, if you can add that around the pickup is a good idea. Try and get the pickup to sit nice and close to the base of the sump. We don't want that any higher than it needs to be or we risk running into problems with oil surge even earlier than we potentially could.
And then of course trap doors or the little rubber flaps to try and help the oil stay around the pickup. Matty has asked can different oil filters cause different oil pressure? Yeah quite potentially, I mentioned just a little bit earlier that there's likely to be an oil pressure drop across the filter element, pretty common. What we will almost certainly be doing though is measuring the oil pressure as it goes into the engine. That's the important part, that's what the engine is seeing so that's what we want to be measuring there. But yeah definitely I would recommend always using a high quality filter on a competition car or any performance engine.
Jarrod has asked, are you using an AN cap as a drain plug on the modified oil pan? Yeah absolutely it was just a nice easy way of adding an oil drain so that's just a dash 10 AN fitting there. John has asked, synthetic 20W50, is that worth it for turbo cars or conventional is better? OK so I probably should clarify here, I am not an oil specialist. What I know has just come from my own experience with testing different oils mainly in our own drag car program. What we ended up settling on was Motuls range of 300V full synthetic oils. This isn't a paid advert for Motul, we pay for our oil just like probably every one of you so this isn't an ad campaign for Motul.
I just personally found from pulling my own engine down, and looking at the results after a race meeting, we tried a variety of different oils and the Motul 300V basically increased our engine life or bearing life by a factor of about five. So that was enough for me. But yeah I'm not an oil specialist so can't really give you too much more on that unfortunately. John's also asked opinions on an oil scraper? So there are a design that's intended to prevent or remove the oil from the crankshaft as it spins through the crank case. And you're going to get what's referred to as windage losses from that oil.
Again I haven't done any back to back tests on these, they make a lot of sense. I know that they are a very common option, they're used in a lot of competition engines so yeah probably worthwhile if you've got the ability to build one of buy one for your car, your engine. Tristan has asked, any tips to reduce wet sump pump cavitation at high RPM? OK so if you've got pump cavitation I'm gonna guess that you are pushing well past the rev limit of your factory engine. So at some point the pump essentially is going to cavitate and start pumping air. If that actually happens, then you've got some serious problems because it's going to no longer be pumping high pressure oil through your engine and you are gonna have problems with your bearing.
So this is really all about making sure that the components you are using are going to suit your aim. And if you've got an engine where the factory pump is known to be an issue at high RPM, then what I would recommend is either swapping to an aftermarket pump or you may look at it having to fit an external oil pump. So that's kind of along the lines of the dry sump system. But you can fit an external oil pump without actually having to go to a full dry sump system as well. Marlow has asked, thoughts behind using a half wet sump dry sump, i.e.
using the factory oil pump plumbed to an external tank and have an electronic scavenge pump moving oil from the wet sump into the dry sump tank reservoir? OK not something that I've investigated Marlow. What I would initially say there is my concern would be the ability of the factory pump to draw the oil all the way from the dry sump tank. So if you look at the size of the factory oil pump versus the pressure pump in a dry sump pump they're dramatically different in size and they're designed from very very different things. So I would be fearful that if you tried using a factory oil pump to draw the oil all the way forward from your dry sump reservoir which may in some instances be in the rear of the car in the trunk or the boot, you could be trying to draw that oil maybe 10 or 12 feet or further and I just don't think that's gonna work very well. So Jeremy has asked, OK sorry he's just clarifying a question from earlier.
Does hitting the rev limiter lower the oil pressure? OK so no it shouldn't. Again basically the rev limiter, you're holding your RPM constant so the RPM of the engine also relates to the RPM of the oil pump so you should see relatively consistent oil pressure when you hit the rev limiter. RIght OK I think that yeah, sorry just making sure that I've read all of that correctly. Alright guys that has brought us to the end of the webinar. So hopefully that's given you a little bit more insight into some of the options available for modifying a factory wet sump system.
Showing you that it's not always necessary to shell out a huge amount of money to set up a dry sump system, particularly on a street car. There's some pretty good options there, if you are a little bit creative and you wanna start getting your hands dirty and making something yourself. Now if you have got any other questions, please feel free to ask them on the forum and I'll be happy to answer them there. Thanks for joining us, and I'll look forward to seeing you all next time.