FD RX7 and Porsche GT3
 

PCA Instructor School @ Roebling Road Feb. 2007

Perhaps it's time for some BNR's for the straights . . .

:-) neil

http://www.youtube.com/watch?v=aTiV6jFOFEc

Nice! I love watching videos of FD on the track where they belong.

Thanks for posting that. Fun vid to watch.

Nice video, smooth driving :).

From my experience, the BNRs will help quite a bit on the road course----you'll be able to run more boost while keeping temps down.

nice vid!

awesome vid.. where in florida you located?

sweet video

Here I finally passed the GT3, only to discover I was too low on fuel for the high-G's (you'll hear it sputter).

Also, I REALLY need a lower 5th gear, I'm topping out down the front straight with lots of room to keep accelerating.

Isn't there some baffle to retrofit . . .

:-) neil

http://www.youtube.com/watch?v=bhYz2obY-bg

Neil,
Nice driving. Always fun to play with the GT3's.
Be careful of that fuel starvation. A few hard hits and it will grenade your motor. I always top off after every 2nd session. there is no ready made auxilliary tank baffle. the tank already has a psuedo baffle/sump in it. It's just not very effective when you run sticky tires and can really push the car.

And yes a short 5th gear with a 4:30 rear is the way to go to get the most out of your RPM range.
Regards,
crispy

Thanks Crispy.

What would you install first, the shorter 5th gear or a 4:30 rear/diff ?

BTW: I'm getting just under 6.5 MPG at the track!

Which first - probably the short 5th gear. I have neither so can't say firts hand.
I too suffer the running out of revs top of 4th malady.

6.5mpg? Use the loud pedal more! j/k :D
No one said it was cheap to track and FD.
Crispy

That's not bad. I think I usually average about 4 mpg on the high side. ;)

how much boost/power making right now? Nice driving/footage. G

Last dyno was 325 RWHP BEFORE I went to a resonated MP.

Same nice conservative tune from Steve Kan.

:-) neil

Looks like you're topping 4th out not 5th? Maybe I'm mistaken but the video's are nice. Can't wait until I can track the FB once it's turbo'd

Yep, topping out in 4th, and just holding it there.

I tried going into 5th, and it just isn't worth it due to the overdrive ratio of 5th, and the amount of track left.

And then I would have to do a double-downshift into 3rd to be in the correct gear to power-out of Turn#2.

My balls aren't big enough (yet) to take Turn#1 in 4th gear, and keep the speed high-enough (90+) and the turbos spooled to be in the powerband.

I'm just now getting comfortable entering Turn#1 at 80 MPH.

I have to keep telling myself, it's a driver's education school, NOT a race . . .

:-) neil

Oh okay. I'm glad I'm not crazy LOL.

You'll love the 4.3 gears, definitely gave me a noticeable acceleration difference in the lower gears :icon_tup:

great video! what is your intercooler and cooling set up, if you dont mind me asking?

Damian has both in his car, he got the shorter 5th first a couple years ago, and then the 4.3 diff last summer. I've driven his car in all three configurations.

I agree with Crispy. Do the 5th gear first and see how it works for you.

If you go to the 4.3 diff and the shorter 5th on a (mostly) street car the rpms start to get a little buzzy (depending on exhaust of course) at highway speeds. Plus the combination of those two and then tire size can make 2nd nearly useless on the track if you make decent power. For small tracks that's going to hurt you. For bigger tracks where you never go to 2nd anyway it probably would help.

As it is on my car I'd like to get the shorter 5th and run slightly smaller than stock tires (285/30/18) and around 350-400 at the wheels. Good r-compounds should make 2nd work without spinning on the track and still make the car usable on the street.

Actually now that I think about it I ran Roebling in the One Lap last year with Damians car before he had the 4.3 diff and I was shifting to 5th on the main straight right near the start/finish line. Still accelerated another 5+ mph before I hit the braking zone at about 145-150ish.

I don't remember whether I was going to 4th or 3rd for turn one, I'd have to check the footage, but I know I would have to shift back to 4th in the middle of 3, back to 3rd for 4, and then to 4th again before that sharp left hander. That was a second gear turn, so if you want to optimize the car for that track you would have to make sure you keep 2nd gear usable.

I did only get 8 laps or so though, so I could be wrong on some of that stuff. :D

If you do the 4.3 ring and pinion, you're just going to hit the 4th gear wall even sooner. 5th will still feel low on power relative to 4th IMO.

In my car I have the 0.806:1 5th and I love it even with the 4.1 rear.

If you have the balls, you can do Turn #1 in 4th (87-90 MPH) but you have to keep the speed up unless you want downshift into 3rd as you enter into Turn #2. I'm most comfortable in 3rd at about 75-80 MPH with some throttle-lift rotation for Turn#2.

Out of Turn #2 and into Turn #3, I'm in 4th and flat out with a little left-foot braking to set the car into Turn#4, and back down to 3rd. I keep the speed up so I don't have to do Turn#5 in 2nd, just keep it in 3rd and left-foot brake into Turn#6.

Out of Turn#7, flat out in 4th, a VERY slight left-foot brake in Turn#8 to get the chassis set-up for flat-out in 4th for Turn #9 and upto 140 MPH just before the Start-Finish just like you.

This is on R-compound Kumho 710's 265/45R16 with 600lb/400lb springs and Advance Design coilovers.

I've attached a PDF of Roebling Road with the turns numbered.

:-) neil

BTW: I have taken 4,5,6,7,8,9 in 4th but it is scary fast for me. I like having the torque in 3rd just in case . . .

SR Motorsports SMIC, '99-spec duct, brass stock-sized radiator, Miata fan-sensor; G-05 (aka, Mercedes) coolant (40/60 distilled water).

:-) neil

Where did you get your 0.806 5th gear ?

Does anyone know for sure what the Pettit 5th gear ratio is ?

:-) neil