turbogrill Posted November 29, 2019 Report Share Posted November 29, 2019 Hi We did a WRL race last weekend and had few drag races on the COTA straigts with an identical car as ours. The other car has narrower tires (225 vs 245) and 10-15hp less. However it was pretty even on the long straigts, I think we gained a little but not much. Could this be due to the tire width / pressure? I would expect us to be quicker on the straigts. Both cars looks identical (NC miatas) Quote Link to comment Share on other sites More sharing options...
LuckyKid Posted November 29, 2019 Report Share Posted November 29, 2019 (edited) Figure 0.9" width difference + 24.5" Tire Height x 2 tires = 0.30625sqft Cd could be about 1.2 for an open wheel if you don't have it covered. At 90mph its costing you about 1.786 HP https://www.rbracing-rsr.com/aerohpcalc.html - Ride height, mirrors, rake, under-trays, window nets, intake position, radiator ducting, fender liners. All of this would impact the speed about the same or more. Edited November 29, 2019 by LuckyKid Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted November 29, 2019 Report Share Posted November 29, 2019 Corner speed will have more of an impact than that little bit of drag. Now if you are pulling away through the corners, then you are even down the straights, I would be second guessing that hp... 2 Quote Link to comment Share on other sites More sharing options...
Snorman Posted November 29, 2019 Report Share Posted November 29, 2019 No. There are so many variables it's not even possible to compare based on a race setting. Unless both cars are on the gas EXACTLY at the same time and moving from the same speed. You can't get any real data unless there is a big delta in speed/power between the cars. You can be faster than him, but if he's back to WOT a second sooner, that car may appear to pull away (or stay even) when it really isn't. And there are probably a dozen other variables (see above). Quote Link to comment Share on other sites More sharing options...
Members MR2 Biohazard Posted November 29, 2019 Members Report Share Posted November 29, 2019 The more important factor is tire temps based on tire size for speed and grip. Figure that out to optimize tire size to speed ratio and consider tire wear. That is all I can say, the rest is trade secrets, but that should start you down the rabbit hole. Blue or red pill? 1 Quote Link to comment Share on other sites More sharing options...
Wittenauer Racing Posted November 29, 2019 Report Share Posted November 29, 2019 (edited) Wheel/tire weight probably makes a bigger impact than anything else... Edited November 29, 2019 by Wittenauer Racing Quote Link to comment Share on other sites More sharing options...
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