Horizontally Opposed Man

Is it realistic to expect 40 heat cycles out of the Kuhmo V-710s.Posts all over the mat from 15 hCs to 20 TRACK HOURS.What is your experience with them ?Do they last significantly longer than the Hoosiers?Thanks HOM

trumperZ06

I usually get 24 to 28 heat cycles from V-710's.

Approx. 2 to 3 times what I was getting with Hoosiers.

Horizontally Opposed Man

So what type of format where you running in HPDE 20-30 min sessions?Did you have them heat cycled before you ran them ?Did they have any grip left and where they going away slowly or just completely done and hopeless .Thanks so much for your input HOM!!!

jrgordonsenior

What size diameters? Guys out West running 17's love them, 18's not so much.....

Horizontally Opposed Man

I would be running 18s 245 and 305 whats the issue with the 18" diameter ?

jrgordonsenior

The 280 rears have been known to delaminate or bubble the sidewalls. Just that size though....

Horizontally Opposed Man

So jr is your car cup spec?Running that low in the front (judging from your avatar) what size tires and brand can you fit?

trumperZ06

30 minute to 60 minute session = 1 heat cycle.

I change tires when grip is borderline... gone.

I've done both... had TireRack heat cycle them and heat cycled them myself.

Tire size 315 x 18 all wheels. I do flip them... side to side/front to back.

jrgordonsenior

Not sure exactly what cup car spec you're refering to but I'll summarize:

I'm not that low in the front, about 93mm off Porsche's measuring points up front, 110 in the rear. It appears lower in my avatar photo because I'm hard on the brakes at about 150 and my splitter which is angled downwards. Cups are 85 mm front, 115-120 rear.

As for tires, I run Yokohama slicks. 250/650/18 front, 280/650/18 rear. They
are allegedly comiing out the larger cup car sizes this year, 250/640 front and 305/680 rears. If so I'll swtch to the lower profile fronts but not the rears as they work best for me. I run about -3.7 front, -3.2 rear.

Car is a 99'- 996 with 3.6 bottom end and 3.4 heads, cams, cable TB, and 5.2 DME.

Horizontally Opposed Man

Jr,93 is pretty low if I remember correctly !Car looks nicely sorted what splitter is that on the front looks bigger than the cup splitter to me but maybe not!How did you wind up with the 3.6 pieces in the the 3.4 ?Is that an 02 fender set on the car?Do you have an idea of what it weighs?

ProCoach

HOM, as you've gone faster in recent years, I think you'll find that the number of heat cycles before traction falloff is going to be a lot less than it used to be.

For example, for guys like Jim Lewis, now doing 2:08-2:10 in his 996 GT3 (since replaced by the GT2), he was at 20-24 cycles (and I define one cycle as reaching operating temperature or 160 degrees minimum) at 2:14-2:17 laps, 16-20 cycles doing 2:12-2:14 laps, 12-16 cycles doing 2:11-2:12 laps and 8-12 cycles at 2:10 or under.

Horizontally Opposed Man

Peter,That makes perfect sense to me!Am trying to get the most out of the cubic dollars I spend .I wonder if there's still a lot to be learned from an R compound that's at the far end of its life?Further if people are tossing them prematurely so they won't appear slow!You know what a weenie I am,cheers HOM

ProCoach

You sir, are NOT a weenie!

But yes, the car drives terribly when it falls off the traction cliff... Nothing to be learned.

Horizontally Opposed Man

What's weird is that for my car for a thousand bucks you can get the Nittos which are at least quicker than streets ?Grip goes straight up from there price wise and the more grip you get the shorter they last .There just doesn't seem to be a sweet spot in the whole R compound /slick group at least I'm still looking for it!And would like to find it! Cheers HOM

jrgordonsenior

The splitter is definitely larger than the cup splitter and more importantly it angles downward making more downforce and allowing less air under the car. On a level surface I can barely slid a flat 2x4 under it. It was copied from a WSC car. Fenders are 02's (I almost forgot) to fit with the GT3 front bumper and headlight covers. Still the fenders are rolled and pulled to get my 9.5" rims and wider tires to fit-barely.

3.4 and 3.6 are basically the same bottom end just different crank, carriers, rods, and pistons. Putting a real 3.6 with Variocam Plus into a 99' car requires the latter ECU, wiring harness, immobolizer, gas pedal, fuel pump, and more. It's a lot of work. Using the 3.4 heads, cams, TB nothing changes. It's plug-n-play and I gained an additional 30 RWHP, 272 to 304 on a Dyno Dynamics dyno, probably 320(+/-) on a DynoJet. I didn't even reflash it, it runs GIAC's "street" flash for 91 octane.

My car weighs 2450 on fumes, I know of another 99' that's about 50 lbs. lighter.....