SR86 Won A Race, Then ABS Caused A Crash
- Hey team, Andre from High Performance Academy here, welcome to another one of our webinars. Today we're going to be talking about some of the tuning considerations when it comes to a VTEC style switched cam control system and this doesn't just necessarily mean a Honda VTEC system, we've got a Nissan VVL cylinder head on our SR20 turbo racecar. Exactly the same technology essentially as Honda's VTEC system. We could also be talking about switched cam control like Nissan's VTC, slightly older technology which is where the cam was advanced and retarded but not continuously while the engine was running. So we'll have a look at how those different systems work and what we need to know when it comes to configuring and tuning for that style of cam switching.
Before we get into that though, just an update on what's been going on over the last two weeks and for those who have been following us pretty closely, you'll know that we had our first race of the SIERDC endurance series coming up on the weekend just gone. This has been a very long road for us. Again, long time followers will know that last year, before the series we were snookered a little bit and the parts for our new V8 engine to replace the damaged engine were stuck in the US due to COVID restrictions and basically 4.5 weeks out from the start of the series, we were faced with two options, one, don't race and sit out the series, never really fun, or two, engine swap the car in a 4.5 week period with the SR20VE turbo that we already had sitting in the shop for our 350z.
And again if you haven't been following the series of videos that we did over that time, spoiler alert, it worked out just about as well as you could expect. Trying to do a complete engine swap, redo the fuel system, cooling package, complete wiring for the whole car in 4.5 weeks, I mean I'm not going to say it's not possible, we did get the car running and we got it to the first event but we were essentially plagued with reliability problems which is probably exactly what I would have told a customer who came to me years ago when I was running my old shop and told me what they expected, what they were going to do. So anyway we learned from our lesson, pulled out of the rest of the series and basically we've spent about the last 10 or 12 months going over the car from front to back and basically redoing every single part of it, including adding aero to it and I'm happy to say, that it is now a reasonably fast and so far reasonably reliable car.
Let's jump across to my laptop screen, I'll just bring you up to date with a couple of other changes. So the front end of the car, particularly here you can see the front bar, this is a complete homemade. Brandon and Jimmy basically built this to suit our Top Stage composites front splitter and also incorporating the inlet and outlet for the cooling duct. So it's a little hard to see here, obviously in the centre here we've got our radiator and our intercooler. And then on each side here we've got ducting for our oil cooler, sorry actually that's one's a gearbox cooler, and on that side we've got ducting for our engine cooler. Down the bottom here we've also got ducting for our brakes so a lot of thought went into the cooling, happy to say all of that worked really well.
Also last minute addition was a couple of canards, these are probably more there for good looks than anything else, trying to keep the car looking like it is actually a proper racecar but if they do give us some aero downforce then that's not going to be a bad thing either. So we headed out to HIghlands, the first round of the series is our local track so at least I am reasonably comfortable driving around that track, we've probably done a couple of hundred laps in testing just over the last few weeks so I didn't really expect anything untoward. The qualifying for our series which is a one hour race, I ended up coming in P2 here which obviously pretty stoked with. The car in front here, Scott O'Donnell was in a Hyundai i30 TCR so TCRs are a factory built racecar, for the international touring car racing class.
Taking on a factory built race car, even though they do have less power than us, in a home built car is always a little bit daunting. We also had a couple of TCRs further behind us but essentially pretty good place to start. I will mention that with the qualifying session, we only had a 15 minute session on track and there is a big difference in the lap time speeds between the faster cars like ourselves and the slower cars. I mean that goes right down the bottom here but cars in the mid to late 1:50s and that created a few problems because getting clear track and only 15 minutes to get in a qualifying lap was really really tricky so I only actually got 3 flying laps, all 3 of those were compromised by slower cars so feel like I had a 41 in the car but that was what we got out of it.
So the end of the race though, we got 1st place, pretty stoked. I'll just give you a quick rundown on how that went without going into all the nitty gritty. It's a rolling start for these races and obviously I was lined up P2. Our car is faster than the TCR in a straight line, also used push to pass off the start line, got a great jump on the pole sitter and ended up getting about a 4 car length lead by the time we got to turn 1.
And that's where the differences between my car and the TCR really came into being obvious. The TCR definitely got more pace through the corners and I basically held the car off for about 3 laps where it became quite clear that I was over driving the car and driving very defensively in order to keep the car behind me, there was no way I was going to be able to do that for 60 minutes so I decided to let Scott pass and basically just concentrate on our own race which is exactly what we did. By about halfway through the race, Scott was about 15 seconds up the road from us and I was just concentrating on not over driving the car and getting consistent lap times which I was doing pretty well. We were very fortunate that there was a safety car incident. So when the safety car was called, we dived straight into the pits, did our compulsory driver change, or in this case, I'm the only one driving the car, it was a run around the car, we dumped 20 litres of fuel into the car and got straight back out. Scott who was in P1 had a radio problem, he didn't know the safety car was deployed so basically ended up staying out on track, did a full lap behind he safety car and by the time everything resolved, after the safety car period, we basically had a 40 second lead and the last half of the race was essentially just managing that 40 second lead.
Scott, while he was faster, in the later half of the race, lap times were actually pretty similar because he was right at the back of the field and had to get through all of the lapped traffic so we ended up with a nice little trophy which I do have here. And I think this is a bit of redemption for myself and for the whole team given the heartache that we went through quite publicly last year with developing the car. There was a lot of things that went wrong, it was a lot of frustration and everyone at HPA put in a lot of hard work, a lot of blood sweat and tears so it was really frustrating last year to not get the success that we knew the car had in it. To get that on the weekend was really redemption and we're really stoked with how that all went down. Bit of a shot there from the podium as well so pretty excited to see how that all went down.
However, Sunday turned a slightly different direction because we had another race meeting at Highlands Motorsport Park and this is the sprint series so it's held on a different configuration of the racetrack. And it's a slightly shorter track as well so we decided we'll get our money's worth out of the weekend and head along to that as well so again if we jump across to my laptop screen, I'll just zoom in here a little bit, give you a bit of an idea of some of the cars we were up against. So in my particular class we had two Porsche GT3 cup cars, one of them the one that I've just circled here, this car over here is a New Zealand built racecar called a Super Tourer which is a tube frame chassis car with a GM LS7 in it. This was at one point the top tier of tin top racing here in New Zealand so a little bit more competition than we had the day before and certainly a few faster cars but we were still pretty excited to see what we could do.
In my class there I ended up qualifying P3 and two of those Porsche cup cars ahead of me, Garry Derrick in particular, 1:12.08, obviously a long way up the road, had no answer for him there. First race I started P3, finished P3. Second race of the day, there are only 6 lap sprint races, second lap of the day, started P3 and absolutely had a terrible start, basically got smoked by two other cars and spent the next couple of laps trying play catch up.
Got past one of the Porsches that got me and was chasing down a Porsche Cayman GT4 race car. However this one didn't end quite as well as Saturday so we'll just have a quick look at some in car here. So this is coming out of the hairpin, the car that I am chasing down here, this is the Cayman GT4 that got ahead of me, I'd beaten him in the last race. So this is coming down to the entry to the bridge at Highlands Motorsport Park. At the braking point here we're doing just a touch over 200 km/h, 120 odd mph. So this is where I hit the brakes there and things did not go quite how I expected.
Basically as you can see there, the second I hit the brakes just essentially a passenger, the car turned hard right and spun me across the in field. I actually ended up on an unused part of the longer track that we'd been running the day before. Really lucky to get off lightly although there was a little bit of damage and I sort of was left wondering what on earth had happened. It was an ABS fault and essentially with that ABS fault, when I hit the brakes it was basically like someone pulling on the handbrake and to give you a bit of an idea of what's going on I want to just take you through some data here.
Is that the data I wanted to show you? No it's not, try this one here. OK so up the top here we've got our engine RPM and we've got our wheel speed here. And we've also got throttle position and brake state, so actually I'll get rid of brake state, probably doesn't really matter too much. Brake pressure though, this is more relevant and then down the bottom here we've got our battery voltage. So this point about here, this is where I was exiting that hairpin so the start of that little video and let's just move over a little bit, we'll zoom in a little bit more on that area.
So you can see the wheel speed trace here from the hairpin here we've accelerating from about 62 km/h up to about 203 km/h where I touched the brakes. However there's a few funny things going on here that we didn't figure out until later on. If we look at our battery voltage, the point I've just clicked here is 12.1 volts so way lower
than it should be. Point here is 14.2 which is about where we'd expect the voltage to be. Interestingly this point here that I'm just clicking on, the battery voltage went up to 18 volts followed by this point here 17 volts, we've got another couple of spikes here to 15 and then finally up to 18 volts so it looks like the regulator in the alternator has died while we've been out on track and that's allowed the voltage to spike.
In an interesting aspect though what this has done is actually put the ABS unit into fault. So couple of things we can look at here, the wheel speeds. You can see in this instance here, which coincides with these spikes in voltage, the wheel speeds which are reported to the MoTeC ECU via the ABS system, these all flatlined so we've got a completely flat line in here and then another one here with that second jump and then we've got another flat line here and then finally right at the end so basically the ABS computer doesn't know what's going on. At the same time, interestingly it's reporting maximum brake pressure so it's showing all of these instances here, absolutely the maximum brake pressure value that it can record. If you want to see what an actual brake event looks like, this is my braking into the hair pin which is from quite high speed, we're doing 185 km/h odd coming into that hairpin so you can see reasonably normal brake pressure there. This isn't kPa as it's labelled, it's just a raw number but a value of 9500 versus 32000 so the ABS computer has just given up completely.
Now I'll actually bring up another couple of wheel speeds because the one there is front left so what we'll do is we'll just add another wheel speed channel. Actually we can add all 4 of them, may as well all go in there. And this is where it gets interesting. This is the part here where I actually hit the brakes and we can see what's happened, if we look at our wheel speeds we can see that essentially the rear wheels, left rear in particular which is our purple trace has gone down to 116 km/h while our fronts are still at 182 and 184 so like I say basically just like someone has pulled on the handbrake.
And that spun me across the track and the rest is essentially history. Now we did get off pretty lightly, there was a small amount of damage which we are going to have to sort out. I'll just see if I've got those photos, no I haven't, that's because that's zoomed in.
Let's see if we can get there. There we go. So it debeaded the left rear tyre, basically slid across the grass sideways and then slid up onto the other part of the track which we weren't using so that debeaded the left rear slick and destroyed that. But other than that we got off pretty lightly. It did do some damage to the rear diffuser and we also ended up with some damage to one of the strakes from the front splitter so a little bit of work ahead of us and while you might think that that's not ideal and obviously it isn't, this is actually a good thing as far as we're concerned because what it does is it gives us some insight into what would have happened at our next round of racing for the endurance series which is 2 weeks time. If that had happened at the next track which is quite tight. there's very little chance I'd have got
off so lightly. Even if I had it would have been very difficult to effect a repair on the car while we were there. So I do have to look at the upside of this. First of all the car really isn't damaged, it could have easily hit the bridge, could have easily hit another car or a wall and it could have easily also tripped over and rolled while it was sliding through the grass at 180 odd km/h so none of that happened, I do need to look at the positives. At the moment we are fitting a different style of alternator to the car which we're hoping is going to be more reliable. Little bit of patchwork on some of the aero parts and we'll be back into it.
Few other little minor upgrades as well such as air jacks going on the car before our next round so pretty exciting, all things considered. We're really happy to get that win, really happy that the car is showing real promise and we know that there's still a lot of areas that we can continue to develop the car so pretty excited about that. Now I'll just also talk about a couple of other things.
If you were following us for our last webinar I mentioned we have just released our suspension tuning course. And related to this is an Instagram that just recently went up about a motorsport suspension damper and this is something that a lot of people really don't understand, particularly with these high end dampers, we can see that we've got a lot of adjustment down here on the end of the damper. This isn't like your cheap road style coilover where maybe you might have if you're lucky one adjustment that might affect bump and rebound together. Motorsport dampers like these more often than not will have adjustable bump and rebound individually.
Usually like this one here they will be split into high speed and low speed bump and rebound as well and often they'll have a blow off valve as well which all sounds a little bit weird, obviously these aren't turbocharged dampers, why do we need a blow off valve? Simply put, the blow off valve is there for very high speed velocity, high damper velocity events such as where we run a curb. What that allows the damper to do is move very quickly so that the car can run a curb without getting bounced in the air and upset. So that's really important to allow the driver to run these curbs while still controlling the car nicely. High speed and low speed bump and rebound, not related to our car speed, this is related to the speed of the damper travel so low speed is normally related to stuff that the driver is doing.
So we're talking here about steering inputs, pitch and roll. So that sort of aspect is low speed, high speed is more to do with the bumps in the track. So understanding that's really important but also in this shot you can see there is shock pot there or a linear potentiometer that measures the damper position.
This is a really important tuning tool. Which also segways nicely into the latest video that we've just put up, if you want to learn a little bit more. This is covering some of the uses of damper data or shock position data. So this is taken from our suspension tuning course.
You'll learn about what shock pots are, the different types of shock pots, how to mount them, how they're calibrated and then really importantly, how they can be used. So there are a few key uses here for these. In particular you can use them obviously for monitoring the suspension position, goes without saying really. The other aspect there is that data then allows us to analyse the way the damper is behaving. In particular there you can use these for optimising your bump and rebound settings.
You can also learn a lot about the way the car is sitting on the racetrack in terms of ride height. We've used this to get a loose understanding of the amount of aero downforce that is being provided by the components that we've got on our car. So if you're interested, head across to our YouTube channel. If you haven't already, make sure you subscribe if you enjoy the video, give us a thumbs up and if you've got any questions, please ask them, we always do our best to get back to any questions that have been asked. Alright lastly today I just want to mention again our HPA Tuned In podcast.
This has been released only a little while ago now, it's relatively fresh, we're still building this up, we've got 8 episodes live here. We've got some really great guests that we've already covered, we've got some excellent guests coming up as well so if you are a podcast listener, you're going to find HPA Tuned In basically anywhere you'd normally listen to podcasts. You can also go to hpa-tunedin.com, that'll get you to the page we're looking at right now. The latest release there is an interview with Sander Marquez. Sander from Obsidian Motorsport Group.
And he's been involved with a Porsche GT2, GT3 cup car that has a twin turbo engine in it that has won its class at Pike's Peak for the last two years. Interestingly though, despite the level of the build on that particular car and all of the electronics involved, Sander actually remote tuned the vehicle, never actually set foot on Pike's Peak so if you're interested in learning a little bit more about that, go check out hpa-tunedin.com. We'd also love it if you could leave us a rating or a review.
We need those ratings and reviews, it gives us a little bit more visibility so that we can get our podcasts out there to more people. Alrighty, thanks for watching, give me a few moments and we'll get started with today's lesson. If you liked that video make sure you give it a thumbs up and if you're not already a subscriber, make sure you're subscribed. We release a new video every week. And if you like free stuff, we've got a great deal for you. Click the link in the description to claim your free spot to our next live lesson.
2021-10-17 00:34
