[VaporPressure]

I've got a ZL1 1LE and I'd like to put some more aggressive aero on the car, for example hartman or 9lives wing, etc. Does anyone have input or good resources on how to calculate at what point I would need stiffer springs? I've seen spring rates of 1100 lbs/in in the rear and 450 lbs/in in the front, but not sure about motion ratio, etc. The hartman wing I'm interested in gets about 400 lbs downforce @100mph, up to 800+ @ 150mph. In the front hoping for 140ish lbs @100mph, 300 @150mph.

I vaguely recall a post from RSFR in the highly modified zle (2:15 at COTA) saying he didn't need stiffer springs but I can't find it and don't remember how much downforce he was getting.

Any help appreciated. Thanks

[Msquared]

If you end up with that big a difference in downforce between front and rear, you're going to have a lot of understeer at high speed. You'll probably want the rear of the car to squat a bit at high speed just to dump some downforce anyway. Then at lower speed, the downforce will be a lot lower and the stock springs will be fine. The stock ZL1 1LE spring rates are supposed to be 1100lb/in front and 450lb/in rear, with motion ratios of basically 1:1 front and 0.56:1 rear. I don't know of any replacement springs that are stiffer than that - you'd have to run aftermarket coilovers and pick your own springs.