I was doing a little SWAG on the Sprint-T and tires and I came up against another problem. I can only hook up so much HP no matter how big I get the tires, because of weight. Traction is a function of weight and tires, and there is a hard limit to traction with a car as light as the Sprint-T trying to use UTQG 200 treadwear tires. I can get a little more power to the ground with sticky race rubber, but depending on the weight of the car I’m looking at 300 to 500 HP without boiling the tread off the tire before getting the pedal to the metal. More than that and I’m never getting my foot to the floor.
What I’m looking at is with the Subie engine and the T5 transmission I can stop cranking up the boost around 300 WHP, with the Pentastar V6 and the 8 speed transmission I can stop trying for more than 375-400 WHP because that transmission just weighs that much, the LS3 and the 4l70 I can pretty much leave in stock tune, and the LS7 I will need to put a block of wood under the gas pedal to keep rear tires on the car unless I’m running the softer compound of the race slicks I have available. Street tires will require really feathering the gas to maintain traction with just the stock 505 HP tune.
Now these are just what they used to call “back of the envelope” calculations but they are the best I can do with the data I can get, and the low precision of the data. Seriously I’m looking at ±0.1 G precision on a 0.8G predicted grip for the 200 wear tires, or 0.7 to 0.9G and a huge difference in performance between those numbers, so lets say we are talking about the LS7/3 we are looking at maybe 400-430 WHP on the low end, just shy of 500 at the high end. And as far off as I was on the unsprung weight at the front end I’m not putting much faith on these numbers either. But if the data is correct and I used to correct formulas, If I’m running an LS7 then I don’t need to use the dyno for anything more than fine tuning for gas mileage and verifying the stock tune is working correctly. Pretty much the same for the LS3 except I have more room on the other side of the equation, I could get away with maybe the 480 HP tune, but not the 525 HP tune.
And I didn’t get much sleep last night, and I’m starting to get a headache, so bedtime.