Don Terrill’s Speed-Talk

i have a manual trans c4 vet, but no matter what i do i seem to be stuck in the 2.0 60 ft range with my best being a 1.86 after 50 runs . i have treid all sorts of rpm ranges. i even bought the new nittos thinking it might be the tires but to no avail . can anyone give me some ideas to explore . ps the car has 400 rwhp. and has run a best of 12.23 @116.80 with a 2.02 60ft on that run .

How is the car leaving. spinning, dead hook? what rpm seems to work best? If it's hooking and you have stock gearing.... I'd change that first.

this car has 3.92s .if i try to leave at higher than 2400 the car spins up to a 2.18 and runs 12.70 @115.66 . this was done last fri at famoso bets run was 12.307@117.23 mph 60ftwas 2.029 330 ft5.372 1/8 8.076@92.80 1000 ft 10.375 worst run 12.741@115.66 mph 60 ft 2.18,5.641,1/8 8.442@89.52,10.783. runs done on the new nitto nto1 . 315x35x17 pressure 25lbs. the car is a 91 zr1 corvette, fidanza flywheel jeal headers 3 in exhaust with 3 in super turbo mufflers. car also has coil overs with the fx3 system still working

havent run the new nittos yet but the old ones worked best for us at 18-20 psi whenever we tried them.

after talking with the tech dept of nitto. they say that the nto1 will hook better running 26-28 lbs of pressure cold .its the way theydesigned the tire . when i had my mickey t drag radials i used to run 16-19. i am thinking i may need to go to a 16 in tire so i can get a larger sidewall. which might help the car hook . either that or bite the bullet and put a auto trans in her .

Any one who has run new nittos . What you have feel the difference on the performance basis as compared with old one . I would be thankful if someone would share ideas here .

Reviving an olde.

I would definately try the lower pressure. MT drag radials act that way. Assuming you weigh in at aound 3500 your only looking for another tenth or so i would drop the pressure. Are you chasing a certain ET?

were those numbers better with the MTs or identical? in other words, for you , which work better???

your dealing with 17" rims too. not gunna do much else for you I would think. go buy some 15's or 16's and some more side wall (if they fit).

Your next best bet, is to get a some sort of lauch controller, take out some timing to get the wheel speed. Are the coil overs on the front or back? loosen up the front some more possibly. Add/move some weight... take your nocks low, accelerate faster on the top end.

olddragguy wrote:i have a manual trans c4 vet, but no matter what i do i seem to be stuck in the 2.0 60 ft range with my best being a 1.86 after 50 runs . i have treid all sorts of rpm ranges. i even bought the new nittos thinking it might be the tires but to no avail . can anyone give me some ideas to explore . ps the car has 400 rwhp. and has run a best of 12.23 @116.80 with a 2.02 60ft on that run .

>>I would get skilled pictures of your car at launch, side and rear. I suspect it's "squating", and this will cause the tires to "decamber", reducing the footprint. "Maybe" something like a urethane, tall pyramid bump stops, to limit compression travel. If this is doable, then get the rear camber to zero, at this load height. I like the taller sidewall suggestion, as for more forgiving of camber change and might like the bump stops for benefical tire shock,(larger footprint). Good Luck, flyingwedge.

that is not a very forgiving tire at those pressures, i would agree that you are loosing most of your surface area on launch.

I would stiffen the rear if possible or like mentioned before go with longer bump stops to keep the car from "squating" as much.
we have ran many older vettes but we used much bigger tires