Uppity Supercharged Vipers!!!

[Paolo Castellano]

Paolo: Do run-flats have better or worse heat dissipation characteristics? I would imagine that the thicker sidewalls could provide a greater surface area medium to dissipate the heat with all other things being equal. I have made some preliminary calls to tire manufacturers regarding the possibility of there being a tire that is designed to go 200+ for a car of this weight and they said there is nothing of the sort. Does antbody have any suggestions?

TM: mmmm... pass. You are into one of my many areas of incomptetence... but you are doing the right things... sounds to me like the tire companies are covering their butts. Every race car at Le Mans has to run 200+mph lap after lap, Indy cars have to run it consistently, the Silverstate Classic top cars, the Bugatti Veyron! etc etc.... so there are obviously tires that are up to it... The question is the weight I guess, but you are unlikely to have enough down force to generate 2g. Why not find out who that guy is that averaged 200mph at the Silverstate Classic - I'm sure he'd be helpful. there's also a Mustang running 200mph and I think their website is www.200mph.com from memory - not sure but if interested I'll find it as they seemed really helpful about the things to watch for re holding that speed... good video download of them cruising at 200mph on the road too!

Let me know and I'll track down their site if the one above doesn't work. You really need to talk to people who have done it in something similar... for that matter there are some Viper guys who have gone 200+mph on pavement... you know who I'm sure they'd be happy to share their experience re tires. No one wants to see anyone get hurt, I'd expect the 200mph+ club will be pretty hepful to you. Let us know what you find out - Im sure others will be interested... maybe Ben and a few others would like to join you at the oval?

Torquemonster, I tried the 200MPH.com and it said the page is not available.

I also know I could never generate 2 G's of downforce on flat pavement or tractionwise. But I was wondering how one would calculate the additional downforce that would result from being on say a 32 degree banking. It has to exert a downward force equivalent to something. I have also from time to time read of several concept supercars that have some 240-250 MPH rated tires. I cannot remember who made them though.

 

[Tom86ZT]

Paolo,
I will briefly explane what I did here. Didn't want to get too deep into the dynamics of this problem so I took a 3800lb car, traveling at 200mph around a 32degree banking. To clarify right away, I assumed there were know lateral forces on the car. I know this severely scues the results since the car can withstand 1g of lateral force. Latger I will calculate this better.First off I have to say you must slow down for the corners. The centrifugal forces are unbelievable. With no lateral forces the perpendicualr G force (i.e. the force pushing you stright down into the seet is over 5 G's. If you think thats wrong remember the Texas Motorspeedway IRL (or it may have been formula 1) race they canceled 2 years ago. It was from the drivers experienceing over 6gs of downforce in the corners due to near 240-250mph speeds.
Paolo using a weight of 3800lbs for car weight (driver, fuel etc.) the car would experience 21000lbs of downforce in the corner. This is why you must slow down. However in addition to some forces going laterally to the car heloing to lower this number you also have a certain amount of lift being generated, unfortuately I don't know how much. You do have a front and rear spoiler on the GTS but not sure what there actuall effect is.
If you're wondering how I calculated this I used the old Dynamics problem of the car going aroung a level banked onramp on ice, and determiining the speed needed to not slide down or up the incline.

Tom

 

[Torquemonster]

Paolo - the site I meant was www.200mphracing.com but that seems to be down too.. not sure why. There is www.200mphmustang.com but their car is way under what you, Ben, Dr Roof, Gary and the other top guys have... but interesting notes re their experience at Silverstate... that car does not do anything near 200mph by the way...

Check out this site - http://www.fantasycars.com/sedans/html/ev12_new.html it shows the new Brabus E series 4 door sedan that does 211mph. It weighs a lot more than the Viper and runs Michelin ZR tires. Check out the torque - 738lb ft at 1750rpm!!! That's stonking even for TT.

Michelin also supplies tires to the 200mph Mustang whose site is down - the one that actually can do 200mph

The Lambo AWD is heavier than Viper and it runs 200+ and they used to run Pirreli tires - I'm sure they still do given they are Italian. Bugatti run a special 20" tire made just for them.

The tires run by Brabus, Lambo etc would be good starts as these guys would not like the bad press of their cars blowing off the road while testing. NDT testing of the tires would be a good precautionary move as you suggested.

Tire companies will be loathe to recommend a tire because of concern over lawsuits etc if anything happened... you may get better info by asking them if THEY were going to run a car at the track, what would they run. Then its a considered opinion not a company recommendation... just a thought. If that does not work - the Lambo runs a similar tire size at rear, and you know that has been tested by many!

 

[Torquemonster]

Geeze Tom - that's scary. But a 4 mile turn is not a 32 degree bank. Surely the track officials will have all the data you'd need - or access to the designers of the track who would. The data should all be readily available.

 

[Tom86ZT]

TM-
I know the banking was off but I don't know what it should be. Plus very few corners are the curve of a circle, they are generally larger. I assumed a 8.5mile track with 2 2.125 mile straights and 2.125 mile curves. There are a lot more other factors too, but for a 32 degree banking with no lateral forces this is the highest number you'll get. And if you really think about it, it does make sense. Especially when thinking back to that Texas race.
I think those Silver state guys would have the best info for tires since they drive on "unprepared" STREETS. Lingenfellter X-rayed his tires for safety and I believe he ran the narrower rear tires for aerodynamic reasons.

Tom

 

[Torquemonster]

Now we know why those NASCARS have such solid hard suspension for the banked ovals! ...there's an idea - the NASCAR tires must have to handle very high loads as they need to cope with steep banking. The Texas track would have a light banking by comparison surely by the size of it?

Without banking however, I don't see the downforce being ultra high, I see the centrifugal force being high... geeze, why can't it be as simple as turning up and giving it full throttle? it'd be ok in a Honda Civic!

I'm still sure that the track will have data about what loading there is around the circuit... if not then the teams that use the track professionally.