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Project S2000: Part 24 - Bridgestone Potenza RE-71Rs and DIY Brake Ducts

by Khiem Dinh

If we go way back to the very first episode (sorry, been listening to some old school Dre at work), we started Project S2000 off on a set of Bridgestone Potenza RE-11s. I have always been a fan of Bridgestone having gone through many sets of S03s, RE-01Rs, and the RE-11s back in the day. There had been a big lull from Bridgestone in releasing a tire after the RE-11 which had me wondering what they were up to. Well, as everyone in the auto-x world and track day scene will tell you, Bridgestone must have spent a lot of development time on the tires as the new RE-71Rs kick a lot of ass.

 

This is what was left of the Nitto NT01. Instead of putting a fork in it, I put a nail in it (unintentionally of course). It was done.
The new Bridgestone Potenza RE-71R (in 245/40/17) mounted up and about to get a good scrubbin’ with some auto-x with Speedventures out at Autoclub Speedway.
I got in around 20 runs and I had my buddy Ian McCune riding shotgun on this run. He has an FR-S and is starting to get serious about auto-x with the SCCA.

It goes without saying; these tires have a ton of grip. This has been proved out by all the auto-x’ers and track day junkies. They have similar sidewall stiffness (from what I can remember) to the RE-11s which is to say on the stiffer side for better transient response, but not super stiff like Yokohama Advans tend to be. They match my preference for mixed street and track use which is why I’ve used so many Bridgestones over the years.

 
The thing about tires is they all behave a little differently and therefore require slightly different suspension settings and tire pressures. I’m pretty lazy and I seem to recall setting the tire pressures to around 35psi hot (checking after a run) all around and not messing with them any more after that. With my current alignment settings (Front: 0 toe, -2.8 camber, -6.5 caster; Rear: 1/16” total toe-in, -2.8 camber), the car is a bit on the tight side. In steady state, lifting the throttle doesn’t get the car to rotate as much as with the NT01s. Using my trusty ole IR pyrometer, the temps across the front tires were about even.
The temps across the rear tires were not even. They were cooler on the outside and warmer on the inside by about 8 degF.
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Comments
ivan141
ivan141link
Wednesday, June 01, 2016 11:50 PM
If you still have the dust shields on you can drill a hole, weld on a bit of pipe and mount your duct to that in the rear (strap the duct to the LCA). Much more effective that way than removing the dust covers.
MDR
MDRlink
Thursday, June 02, 2016 10:05 AM
Don't use an IR gun for tire temps... All of that autox and you don't have a proper probe?

I probably missed it in an earlier article, but why don't you run the front ducts to the front bumper? Too much cutting?
spdracerut
spdracerutlink
Thursday, June 02, 2016 12:51 PM
I only auto-x like once a year and non-competitive event. I'm just out there for fun and generally testing something on the car. Even track days, I never use a transponder; it keeps me out of trouble by not tempting me to push too hard. That's why I really don't bother even messing much with tire pressures. I'm out there to have fun.

As for the control arm mounted brake duct solution, I have two reasons: way back I was thinking of going turbo so intercooler/piping/etc and I also don't want to run ducts on the street. It takes me less than 10 minutes to take mine on and off. So I put them on at the track and take them off before I head home.
Benjamin
Benjaminlink
Thursday, June 02, 2016 2:26 PM
Great article!
Next time you want to prototype something, check out www.shapeways.com.
I've used them many times and they are the cheapest available, and you can check the price of your design as soon as you upload it!
M-P
M-Plink
Thursday, June 02, 2016 2:49 PM
Even better find someone local to print it via 3dhubs.com. I used to offer printing services through there when I had more free time.
Benjamin
Benjaminlink
Friday, June 03, 2016 6:58 AM
Very interesting website! I didn't know about fiber reinforced 3d printed nylon!

But shapeways is still cheaper, for my application at least :)
slowpoke
slowpokelink
Tuesday, June 07, 2016 11:26 AM
just got to say love the fact that you bring actual data to your testing!!! thanks MotoIQ! more of this is better! the web is filled w/ anecdotal data and its refreshing to see science-y work. well done!
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