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Everything posted by Grant

  1. I got tired of trying to convince standing miles guys they need less wing, or something active Excessive rear downforce seems to be unreasonably common in motorsport.
  2. This thread is mostly not about VPI. Seems pretty obvious those decisions are made behind closed doors anyway. If I had a roofed NC I'd definitely experiment with wings and splitters since your power / drag starts out so much better. You'd have more points to play with too, since you don't have lots of miscellaneous materials.
  3. That was on RS4s. This is the thread link: https://forum.miata.net/vb/showthread.php?t=710665 No plans to go to COTA sorry. I think the last race we'll do with the car after Sebring is the championship at Ozarks. I just don't see points as being very relevant to the performance of a champ car, unless you have spare fuel and can add power. Most of the things which make fast champ cars fast (weight, tires, suspension setup) do not and never have cost points.
  4. I would imagine we're quicker than Spec MX5s. Toyo RRs aren't exactly a great tire. Their minimum weight is 2,500, and we're about 2,100 as we come off the track. Granted they make more power, and can bump draft because spec racing. Turbogrill I thought we'd discussed this on miata.net? A half quart overfill cured the starvation on RS4s, but on Coopers it never completely goes away. See attached scatter plot.
  5. A few people have asked me why we didn't move away from coilovers to get us the points to run cams, which could maybe pick up 15whp (160 to 175, I'd guess). Or do other mods. I think cams are a really bad idea. You're spending 50 (!!) points to burn more fuel and break more often. Yes the car will be a lot faster in terms of peak lap times, but you'll have to conserve fuel more. I doubt there will be much of a net benefit, and with cams comes a higher likelihood of valvetrain failure. For non-fuel limited platforms I think spending points on power makes a lot of sense. Because our power / drag ratio is so terrible, I don't think a wing + splitter is a good idea. An air dam could help us if it reduces drag and front-end lift. We're already at the limit of our oil pan though, even with an over-fill. i.e. I didn't find anything good to spend the points on. We will test an air dam before Sebring, though based on testing on other platforms I'm not hopeful it will reduce drag.
  6. It's probably on R888Rs; those work better for most of the 1000+ whp roll racing guys. I'm pretty sure the car in the pic above was twin turbo.
  7. I think there are a few things going on with the ACR tires: Firstly the fronts have tiny sidewalls and the load rating is only 1,323 lbs. I think this probably explains the catastrophic failures the fronts sometimes experience, e.g. on the Nurburgring (heavy car + bumps + downforce). Just like the Gen 4 ACRs, the car has a massive downforce imbalance. It probably only understeers at speed, so ham-fisted drivers could easily be giving it too much front slip angle. Here's a picture of a twin turbo ACR Extreme at a standing mile event: Lastly the fronts are said to be a different compound. This isn't unheard of in motorsport. Though I don't know anyone who's tried the rears on a different car, a 355 square setup should be an option for us in WRL.
  8. Clearly. Tires were at the same temp when I Longacre durometered them, say 75F.
  9. Man if you guys get heavily penalized because some lunatics built a car 400 lbs lighter than you... that's rough, I'm sorry. In most classes minimum weight is as the car is weighed coming off the track. So very little fuel. All the interior sheet metal pieces (the long trans tunnel brace, all OE seat mounts, whatever else there is) I think weighed 30-40 lbs? I could be wrong as for some reason I didn't write this down. It was an absurd PITA to remove. There was 27.5 lbs of metal removed where the door hinges go and windshield lands, which you guys obviously can't remove. Our forward hoops land there instead. I've got 9.1 lbs down for gutting the trunk. This is mostly hinges as all non-PRHT cars have aluminum trunks. We didn't cut away much in the trunk area because it's outside the cage structure. The factory dash bar I have at 13.2; cage tubing should be lighter. Windshield weights, in case you're interested: windshield + trim -23.8 windshield frame -15.3 Yes, everything within the cage structure was removed. I think this just leaves the two long, thin braces on the rear subframe. Some weights I have here: steel underbody brace -7.3 spot welded steel underbody brace mounts -4.8 Al underbody brace -1.7
  10. There's only a few pounds in the hood, but it's easy so do it. We left the outer structure and stock hood latch. I think we got more like 30 lbs out of wiring, but ours is extremely minimized. Doors are usually where a lot of the weight is. There's 2.5 lbs in excess front fascia plastics. 11 lbs in headlights. We removed all the chassis bracing within the cage structure: the bolt-on stuff under the car as well as the spot-welded bits on top. The transmission tunnel is no longer safe to step on. The factory strut brace I could move around with my hand, so that got tossed. What diameter and thickness is your cage tubing?
  11. lulz, my emails with RJ over the new minimum weight concluded with him telling me the lightest WRL MX5 was around 2350 lbs. I guess that was probably your car. I wonder if we'd be able to make the Coopers work at that weight. My guess is no.
  12. Out of curiosity, what do other ChampCar NCs weigh? With a windshield, doors that open, Chillout system, and OE hardtop I think my car would gain 130 lbs, so 2080 lbs. A fiberglass half-top like is available for NA/Bs would drop that down to 2050. I have a swapped NA Miata with a top. Though I haven't done as extreme of weight reduction as we did to the NC, it weighs 1950 despite having a heavier motor, trans and full aero. In ChampCar trim my guess is it could be 1860.
  13. We have a new set of Cooper RS3-Rs and Conti Extreme Forces. We may test them this weekend, or it may wait until AMP. The Coopers (255/40-17s) weigh in at 26.7 lbs and durometer 71. The Contis weigh 23.7 lbs and durometer 78.
  14. There aren't any other parts, unless he's talking about RX8 stuff. Those are stronger but heavier, and shouldn't be needed given how light a competitive ChampCar is. If they were free the only RX8 part I'd run would be rear hubs. You only gain 5 lbs, and some MX5 Cup cars (at 2600 lbs on DOT slicks) did experience failures. My car has all original arms and steering components from 2009, and whenever I have it apart everything still feels great. We hit all the curbs too. Weight reduction solves so many problems...
  15. I don't know what the final VPI is, but I'd like to apologize if we screwed over other NC teams. Going in to this we thought it'd be fairly obvious our car was fast because of the setup (tons of driving practice + great tire / weight ratio + soft rubber), not the platform. We chose the NC over other platforms in part because we thought the threat of a big points increase wouldn't be there, due to the presence of many other NCs in the series. If you use the VVT NB Miata as a benchmark, I still think a value of 400-425 points for the NC is reasonable. Anything over 450 strikes me as indefensible, again compared to the NB. Who? All of my Racelogic data is available from all of the Flatout cars. On other forums I've posted detailed breakdowns of how I tuned the NC and the power each change made. We log everything, including fuel consumption, individual wheel speeds, knock, etc. I would be surprised if another team had as much NC data as we do, but no one asked me for anything. I did volunteer some of my Racelogic daq to the BoD, but I have no idea if it was looked at or not. I am thinking this was an argument to value the NCs the same regardless of year, not an argument to increase the NC's value. After all, almost all cars can be upgraded with newer, nigh-undetectable parts. The NC2+s get you a slightly better 6-speed and a more reliable motor.
  16. That's great for NAs and NBs. Their Torsen is much better than the NC's clutch-type.
  17. Under ChampCar rules can you run a 5-speed and an LSD without taking points? I don't think the car was ever sold in that configuration. The Aisin 6-speed in my car is the best shifting transmission I've ever used, on par with the Aisin 6-speed in AP2 S2000s. I've never really driven 5-speed Miatas though. I'd certainly prefer the 5-speed's gearing and weight if they shift as well as a 6-speed. The super-short first gear ruins the 6-speed's gearing.
  18. At the Flatout #225 SC300's first race at Road Atlanta, a driver left it idling in a sand trap without a fan. It overheated and warped the head. Their solution was to upgrade drivers, but I don't think a small fan is unreasonable.
  19. If your radiator ducting is not great, a fan could help at 50 mph. But the best solution is to improve ducting and remove the fan. Or if you must run one, make it just big enough to keep the car cool when idling.
  20. OE swapped DCTs are only a 0.1 modifier in WRL's GPx classes. I expect this will change, but right now they're advantageous. Not that I'd go for flappy paddles; my C5 is staying H-pattern. If we have to we'll go with a dog box. And yeah, WRL cars are absurdly heavy. Seeing how much money gets spent on nonsense in series with relatively open rules makes me understand ChampCar's approach to rule-making. The NC fuel tank is 28 lbs. With 7 gallons of gas that's 70 lbs. Raise it 10" on a 2150 lb car with a 18" CoG height and you get a 18.33" CoG height.
  21. I did some more testing today, and saw 0.055 psi ΔP at 50 mph. No changes from the prior day's 0.034. Tried a new battery in the mamometer, new hoses, etc. nothing made a difference. I wonder if I had the units set wrong last time... I tried taping the hood up entirely, removing the back tape only, then removing the sides tape, then removing the front, and no configuration produced any change in hood ΔP. I'm really surprised taping up the back of the hood didn't raise pressure; since I don't have a windshield there I thought it'd serve as a vent. Tomorrow I'll try without fenders.
  22. A 17x10 with 255s is plenty of wheel. At the Firm I went from 1:17.2 to 1:17.8 going from 255s on 17x10s to 225s on the stock 17x7 wheels. Straight line performance with the stock wheels was maybe a half a mph better, so fairly negligible. We're pretty close to maxed out on tires. Wider wheels should help but 2 seconds from 1" of wheel increase is above and beyond anything I've ever seen. I would be thrilled to get 0.2s out of that. The wider wheel will feel crisper, which may help some drivers push harder? Too-low of tire pressure does something similar; the car feels like crap but can still be driven very close to as fast as it can with better pressures. Or maybe the 9" RS4s were cycled out. That's all I can think of.
  23. RJ thought it was their weight more than aero. He thought maybe it was weight / tire ratio, so had Stratus test on a 205. That didn't slow them down. In principal I agree a sports racer could have way better aero than a production-based car, but that may not be the case with the NP01? It's a spec racer after all; not built to out-do other other cars of its kind. Or maybe RJ was wrong. Looking at the thing it's hard to imagine how it couldn't have the best L/D on track. The figure I look at is power / drag, not Cd. A Miata needs to be lighter to work with its relatively small tires, which means less power. Frontal area does not drop enough to offset the drop in power and increase in Cd. The 'vette (especially C5 hatchbacks) are extremely low drag for its size. This also means it can get more downforce from high-efficiency items like flat undertrays (and it's fairly flat stock). I also have a few other ideas on how to take advantage of the Corvette's unique hydroformed rails for better aero performance. In our case we already had a roller C5, a parts car C5, a dry sump system, and tons of other parts. The total cost should come under what I spent on the NC. It's the running costs that will suck; $500 for a Conti ExtremeContact 345/30-19.
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