mark kibort

We also have a Griggs racing monster mustang running near the same times as the NSX. (1 second slower) He has been using the A6s. We all thought that they would go away after a few laps, but so far, no issues at all. could be one of the best kept secrets for big budget club racing. ( we did hear that they heat cycle out faster though). Another thing, he would, in NO WAY be 2 seconds slower a lap with the R6. I would be willing to bet all the DOT variances are within a second of each other, no matter what the change, besides a heat cycled to death tire.

We are getting into that "this mod is good for 1-2 seconds a lap" . Its tossed around a little too freely dont you think? The only 1-2 second per lap mod Ive seen consistantly, has been real slicks vs DOTs, cooked hoosiers vs new hoosiers, or 50-75HP extra on the motor.

I would LOVE to think that just by going to a new hoosier, I would save 2 seconds a lap vs my old toyos, (1:37.7 to a 1:35.7) and then yet another 2 seconds for the A series hoosier (1:35.7 to a 1:33.7 which at Laguna was the Speed World challenge GT winning time a few years ago). This is just not reality though.
I think what they saw at Nationals was "National fever"! Adrenelin starts to pump and many drivers run plain faster. 1-2 seconds when it really counts.

mk

wanna911

I think it depends on the track, yes some people throw the terms around loosely, but I can see and have seen 3-4 seconds for a slick over DOT on a track like barber with long long sweeping turns. Much harder to get those seconds at a track like Road Atlanta.

Guys are running A6's at regular events too, not just nationals and seeing these reductions in times. When there are this many people who have seen the results and from quality drivers I'm inclined to believe otherwise.

333pg333

Can we digress slightly and address the point that quite a few have made. Setup. It appears that you can't / shouldn't just slap another set of wheels on with slicks after you've had eg R888 on. What is the major difference? Assuming that you're running some decent neg and a bit of toe out, what else do you have to account for? Sways, bump, rebound etc?
Also, most slicks seem to be quite a bit taller than Hoos or R spec. How does this affect handling and what changes, if any, need to be made for this?

wanna911

I know the height of the tire can affect your gearing significantly, the additional sidewall stiffness usually makes up for the increased sidewall height.

Just a guess, but I'd imagine the increase lateral G's from the softer compounds will result in more body roll so an increase in spring rate or sway stiffness may be required. Obviously full slicks can handle more negative camber as well, in fact most slicks start at at least -2.5 or greater for optimal life.

333pg333

Hmm, getting mixed signals on the camber for full slicks. Some say more, some say less....

Larry Herman

I say more. There is not a lot of difference anymore between sidewall stiffness on slicks or racing DOTs. Slicks will generate more grip, which will load the suspension more and produce more lean, resulting in the need for greater static camber. You don't need to look any farther than at your Aussie Touring Cars to see how much camber they run.

mark kibort

I agree, there are many factors, just some are more dominant than others.

I certainly expect that the A series would be more sticky than the R hoosier, but I think what im getting at is the amount of improvement from this change all things being equal. Its tough to control the conditions because there are so many factors involved. I was just tossing out some observations from folks that run very consistantly, and are doing the changes we are discussing here. Certainly, your results may vary.

mk

mark kibort

That also is a function of the chassis' suspension geometry. Anderson started running faster times when he took camber out of the front and rear of his 928 racer with slicks and DOTs. are the Kiwi cars solid rear axles too? obviosly the fronts are very camber'ed out. How much the camber changes under compression, as well as body roll amount, will determine part of the camber requirements. This is very different on many cars, right?

mk

mark kibort

Thats what I have seen and heard as well. Again, that camber thing depends on the car's geometry. As far as gearing effects, I dont know if i would go to go as far to say it would be a significant difference. 1" diameter is usually less than a 4% change to gearing. Because of the inherent trade offs with gearing, the effects are usually rounding errors at best, unless it forces awkward shift points. Gearing..... Now there is a 20 page topic in the making.

Mk

Larry Herman

Different on cars, yes. You cannot compare camber car to car. Different on tires, not so much. If car A needs more camber than car B running on DOTs, it will also need more if on slicks.

IcemanG17

MK
Didn't Anderson pick up a couple seconds a lap when he switched to new slicks vs used ones?

Considering the age-use of your Toyos and the "gains" others have found from new tires....I would say its worth it...... Yes the Hoosiers don't last nearly as long as the Toyos.....but even if you only get 1 second.....thats huge!!

mark kibort

Thats another discussion as well. There are heat cycled to death hoosiers that are slower than street tires. (well almost).
He had some bad slicks that were slow. he also had some used slicks where he has set his personal records at Laguna.



mk

mark kibort

True, unless the DOTs are as fast .

mk

wanna911

I agree with that. The true of the matter is that it would likely take a whole season prepping one car for it and finding a realy good set up for that particular tire/compound then the next season doing the exact same thing for the other tires and looking for averages. Track conditions and such make an exact comparison nearly impossible unless you save the settings from one season, and then convert back to those settings after knowing the other optimal setup.

333pg333

Mark, a Kiwi and an Aussie are two different animals. Be like calling you Canadian. No offence intended to any group either.

Ok so same car, same day...are we saying that you can't or shouldn't just take one set of eg R888s off and put on another set of wheels/tyres with slicks on while maintaining the same geometry? What's the possible outcome?