25 hours prep - Rear Gear @ Thunderhill

[Marcus Miller]

NorCal guys; what final gear would be appropriate for 25 hours @ Thunderhill?
Eric? Tak? 4.8? 5.12? 4.44? 3.9?

This assumes a fresh motor, an easy redline of 7200 and 205/60/13's.
I'm thinking of leaving the stock 3.9...

Marcus

[Boswoj]

I just got back from the 25. Admittedly, we were not set up optimally but 4.88's were not a good fit in a couple of corners so we switched to 4.11's. That worked reasonable well with the low rpm limit we ran and not a lot of shifting. If we would have had 4.44's I would have tried them because we got caught just a bit low on the powerband going uphill on the back if you didn't get a great run up through turn 8, and two had to be taken a bit high in 3rd or a bit low in 4th.

Boswoj

[Tak]

Oops, didn't see this before writing my other post. As Boswoj has found, the long front straight, fast turn 1, medium turn 2, steep hill exiting turn 8, and slow turn 11 conspire against all known gearsets. If you're running 205's I recommend the 4.88. 4.44 works well with 225/50's and 225/45's. All of these combinations require touching 8000 RPM in places.
To conserve R's, you could try 205/60's and 4.44, but coming off 11 will be compromised.

Good luck!

Tak

[Marcus Miller]

Thanks Guys!

I'm leaning towards the 4.44 for reduced revs.
Any thoughts on fuel mileage?
The Honduh's and Miatas are better on gas I assume.... Worth trying to fight that battle?

Marcus

[Boswoj]

That battle is well worth fighting!

The 25's unique 10 gallon max gas per stop rule for the regular classes really helps keep gas stops pretty uniform. California's Best and Bobcat both run quality 1st gen programs there (among others!) and are plenty fast enough to take the victory with a little luck. (Don't fool yourself - no matter how well prepared you are, you still need some luck to win a race like this!!!!)

Boswoj

[wlfpkrcn]

NorCal guys; what final gear would be appropriate for 25 hours @ Thunderhill?
Eric? Tak? 4.8? 5.12? 4.44? 3.9?


Here is my experience from the two 12 hour races we did at Thunderhill. We ran both races with full tread 185's and 3.90 gears. We were shifting at 7k. The year it was dry we ran 1hr20min per stint. We would do a driver change + 10 gallons every stop. Other than a quick stop due to body contact we only added fuel all day. The only place we really worked the engine was from 2-3 wich we would take into the buzzer. Turn 8 we ran flat to the floor (no lift at night gives a serious pucker). The last 30 minutes the tires were total junk. That all being said we finshed 4th in class(behind the yellow Honda and 2 spec miata's), I think 12th overall and the highest placing rotary powered car.

I hope this helps,
Eric




[This message has been edited by wlfpkrcn (edited December 13, 2004).]

[Marcus Miller]

Bos, the CA's best team are a great group of guys, especially those running this year.
Bobcat is the speed I'm gunnning for. His car is always the fastest of the first gens over a single lap (2:04 this year); I just want to keep it together over the 25. I will be driver limited to a 2:10, I think...

Eric, that was very similar to the plan as I originally laid it out... unfortunately, the winning Honda avg. a 2:22 lap over the 25 hours including pitstops.
As such, I think we need more speed...

I guess that leads me to this question:
How much will runing a 4:44 or 4.88 gear help me over running the 3.90?
Over a single lap?
over a stint?
over 25 hours?

Thnkas Guys! I appreciate being able to bounce ideas off those with experience.
Marcus

[This message has been edited by Marcus Miller (edited December 10, 2004).]

[wlfpkrcn]

How much will runing a 4:44 or 4.88 gear help me over running the 3.90?

Sorry Marcus I can't help you with that. I only ran my car in Pro7 trim. I know if we would have run shaved tire's we would have beat at leat one of the Miata's. I don't know if you are going to beat that Honda unless they have a problem regardless of your gears and suspension (just my opinion).Since you are setting your car up for IT than it can't hurt.

[Marcus Miller]

I know, beating the Honda is going to be a tough one... I need more motor....

Marcus

[Tak]

This year I lost a bearing on my 4:88 gear set and threw in my 4:33 spare. With Hoosier 205/60's that change was a little over a second a lap. Going down to the Hoosier 225/50's got that second back.
My full on ITA prep car/motor will just go 60 minutes before I have pickup problems in my 10 gallon cell (shifting at 8k ).

Hope that helps,

Tak

[Marcus Miller]

just to irritate me, ( ) Mike Quan put the taxi cab up for sale today....
and for the record, I've decided on 4.88's.

Marcus