Veloce Raptor

Hey. It's a track forum. Bite me.






Professional Racing and Driving Coach

mark kibort

there we go. more data points for the sand baggers. 415hp, thats near 350rwhp-ish.

VR, just PM me a the naked version of your avitar.

85Gold

I am sure the weight advantage was significant. I refuse to gut the GT2 as I did with my One Lap E46M3 which I turned into a pure track car, except it still has AC and Cruise.


Yes it was HOT. I think Ian with more time on the track, it was his 1st time @ VIR, would have gotten in the 1:58's especially since it was hard to get more than 1 clean lap I also think we would have been better on A6's than the Hoosier Slicks for our spring rates and alignment.

Now back to VR/Kibort bashing

Peter

Bryan Watts

Understandable. I'd like to run the One Lap one of these days...a fast, but comfortable car sounds like the way to do it.

It was interesting to see the differences between our two cars. I definitely had Ian in the corners (lighter weight), but he had me in acceleration and top speed (better power/weight and power/drag). In braking, that rear engine makes for some impressive stopping distances despite the weight of the car. It looked like he had to work hard to pedal all that weight through the uphill esses.

The traffic was awful. And since we were both on slicks, neither of us ever got a clean run on tires that were up to temp/pressure. The slicks take a lot longer to come up to speed than the A6's for sure. I suspect the A6's would have been a better choice for both of us given the format of the event.

We ran A6's and R6's the rest of the weekend, albeit, on a much lower powered tune in order to fit into specific GTS and TT classes. I was very impressed with their speed compared to the slicks.

mark kibort

you didnt tell me you ran R6s and A6s!

well, what was the difference between the two?

we have a couple of REAL fast guys in our races that are running both these and slicks as well as R6s. they are saying there is not so much of a time difference, but the way they last during a race and what you need to do to preserve them in battles. also, pressures are much different between the r6 and A6.
what size and pressures did you run?

What was this UTCC race you ran the same time as that other poster?
Not like the battle with the 911 which was a NASA race in GTS-4, right?
mk

Circuit Motorsports

Aero is HUGE at Road America. Having raced many times there in the formula car we would always trim out the car and give up braking and cornering to get as slippery as we possibly could. I've seen cars that were mid to back fo the pack on tight courses immediately become front runners just because they were so slippery in regards to aero.

Bryan Watts

Hard to say. Ran A6's in time trials and R6's during races. Traffic in both events prevented any worthwhile comparisons between laptimes.

Hot pressures between A6 and R6 didn't seem all that different, both from experience and from talking to the Hoosier rep. However, cold pressures were definitely lower in the A6 in order to reach the same hot pressures.

I kept getting advice from some Corvette guys that the A6's like a LOT less pressure than R6's, but after further prodding, they were talking about cold pressures rather than the far more important hot pressures. Seems sorta backwards to make your air adjustments cold to me.

UTCC is the Ultimate Track Car Challenge...it's a time trial style setup. You can read about it in the next issue of GRM. It was held on the Friday before the NASA race weekend. We did fairly well despite running quite a bit slower than our best times at VIR. Even running our max power tune (rather than the 313 rwhp tune we ran in the race you are thinking of), we were WAY underpowered compared to everyone in front of us, and even a few behind us. Considering the amount of traffic, power proved to be the way to go fast.

Veloce Raptor

Which is EXACTLY what I said above. I doubt Mark will ever change any of his preconceived notions, though.






Professional Racing and Driving Coach

Bryan Watts

Never raced there, but on TV it definitely looks like a course that favors a slippery car. The FM guys who raced there always seemed to run a really trimmed out wing setup based on pictures I've seen.

mark kibort

No Dave, that is not what you "said above".

I was giving the information of what the effects might be with the different types of sized cars with same HP/weight ratios.

Big difference in much lighter cars,

all the same shape, playing with more effective aero packages in my opinion. of course, aero is a factor,the extent of which is what is the discussion. hp/drag ratios are important at any of the speeds you spend time at.

can you tell me what 100lbs more downforce on just the rear wing of a cup car might cost in drag? how much might that be in actual rear wheel torque?
If you can answer this question, I will listen to your "feelings" on the subject.

you wanted to discuss it. Im game , but lets discuss. seriously. what do you think the advantage of the cup car were, given that it had near the exact same lap time as the much larger viper, before it broke.

Circuit Motorsports

Depends on factors you aren't listing.

mark kibort

thats what i was suspecting. its one of the few times, ive ONLY listened to the guys going faster and not tried a few things myself. so, what you are saying, they might be running lower cold temps, but running up to the same hot temps. These guys Im watching and listening to, with the same size car but much more power, are running 30psi hot and starting out at 20psi cold. Im thinking that i can run that hot temp at 24psi cold and thats exactly what i did. tire temps were hot and even. should I try go get toward 35psi hot, as I usually run 38psi hot with the toyos? what would be the effects that you might see in that kind of pressure change.

Thanks,

Mk

Veloce Raptor

WRONG.

Check post #63 above.

Next?






Professional Racing and Driving Coach

mark kibort

VR, im turning over a new leaf here. lets just discuss from now on, ok?

Now, you said:
"No, with all DUE respect, I don't. At Road America, you also have to figure aero efficiency and driver skill in additon to grip and engine characteristics. That little 6 banger cuts thru the air a whole lot better than its competition, it would seem to me."

what you are failiing to understand,is that the "cutting through the air" is very relative. drag coefficient is more important, as is the drag, to HP ratio. a formula ford has a quarter of the frontal area, and can not keep up with a big dodge viper with the same power to weight ratio.

You have to look at total drag, total net forces at the rear wheels. Its that simple.
You didnt answer my question. What is the approximate drag for a wing producing 100lbs of downforce. what would that drag number reflect back to the engine at 100mph lets say? (assume rear tires are 24" diameter)

Anyone?




mk

85Gold

""Understandable. I'd like to run the One Lap one of these days...a fast, but comfortable car sounds like the way to do it."""

You and your dad should really do the One Lap. I watched you drive and you are surely good enough to place well. My One Lap experience's can be summed up in a few words. The Most Fun I have Ever Had with My Clothes On The preliminary info I have on the 2010 route looks like a lot of great tracks and a couple of Ho Hum ones.

""It was interesting to see the differences between our two cars. I definitely had Ian in the corners (lighter weight), but he had me in acceleration and top speed (better power/weight and power/drag). In braking, that rear engine makes for some impressive stopping distances despite the weight of the car. It looked like he had to work hard to pedal all that weight through the uphill esses. """"

Yes the uphill esses were a challenge. We really need a Cup Car rear wing for more downforce. That would also improve our braking

Peter