Nasa GTS2 rules have a 14.5 lb per hp rating for dot racing tires (Hoosier r7). Non-dot is 16 lb/hp. That would make my PTE car fit right into the class. But I would need to shave 5.5 seconds at Summit Point and nearly 10 seconds at VIR. Tire width has no limit so I could cram some 911 cup wheels in there for more contact as well. If anyone has comparative on track data, it would be fascinating. Go!
There are a ton of Porsche guys on www.dorkiphus.net. The active users drive HPDE at Summit a lot, and even race there once in a while. Many of them are fans of HoHos and other high-end goodies. The can give you a good idea whether you have any hope of getting 5.5 seconds with tires. They also hit VIR at least once a year.
I can't see how you could get 3 seconds, much less 5.5, off tires and wheels. Unless you're running on all seasons now, or your current wheels weigh 65 pounds each.
But I've never run anything better than an NT-01 there, and I'm always more interested in driving my car home than getting my lap time down another 2 seconds, so what do I know? The Dorki don't suffer from either limitation. P.S. they're all at WGI this weekend so you probably won't hear back until next week.
I am inclined to agree. The changes I could make and be legal for gts2 would be dropping 240 pounds of weight and adding 20% contact patch of stickier rubber. I could also run downforce if I needed it, but doubt I would really have to go there. I will see if the guys you mentioned chime in. The PTE group is growing quickly in NASA MidAtlantic so it's a partially rhetorical question anyway! I've only run dot race tires and was curious if GTS rightly puts such a premium on the tires.
Questions; what tires would the non DOT tires be? Are we talking full on slicks? Next can you actually shave 240lbs?
The 240lbs is probably worth about 10-12hp.
If you can run full on race slicks the difference is massive. The change from 200 treadwear to tires with 40 is 2 seconds a lap. I would expect another 2 second jump by going to slicks. Also the thing people don't factor is these tires tend to be shorter (lower gearing) and lighter (as much as 30%). What you need to be careful about is an over tired car.
If the changes are easy enough you could try them; grab a set of take offs take the weight out and see what that does for the lap time.
In reply to Tom1200:
The tires would be full race slicks...being new to this train of thought, I don't know what brand would be a good fit. Regarding weight, to comply with PT rules I am running 160 lbs ballast and a 20 pound seat. I have all glass, no lexan and all steel, no fiberglass so I could shed the 250.
How long are the races?
For sprint races, nearly everyone I see runs Hoosiers for full-on race slicks.
Avon also makes race slicks, but I usually only see them on sub 2000 lb cars and formula/sports racer cars.
Here is what I would do; buy a set of used slicks, fit them to your extra wheels, pull out the 160lbs of ballast and run a track day. If your within 2-3 seconds of the target, fresh slicks and further weight reduction would do it. Also remember the slicks are a big jump, it may take a couple of sessions to get to the limit with them. If they are bias ply slicks you'll need to make some slight set up changes (less camber than radials).
In reply to Tom1200: Good advice. If I make the leap I will report findings. While this is clearly written in the rules, I've never seen (noticed) anyone take advantage of this in a race.
In reply to
Typical nasa races in MA are 20 min or 40 min. Fairly short.
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