Peruvianrx7

iTrader: (25)

1993 Mazda RX-7 Touring Vintage Red

Under The Hood:
Air Pump Delete
Pettit Air Intake
3" Downpipe
Power FC
Steve Kan Tuned
Braille 17lb Battery

Suspension:
Mastercraft (MADE IN CHINA) Coilovers

Wheels/Tires:
Wheels: 16x8 OEM Factory
Tires: Front: 225-50-16s Bridgestone Potenza RE760 Sport
Rear: 245-50-16s Michellin Pilot Sport A/S

Exterior: ALL STOCK TOURING!

I will use this thread to update modifications/ask for input/ clear up some rules/ post polls/ show pictures and my results!

I been autocrossing for 6 years, however Ive never had money to afford slicks. My biggest competition is a Pettit Tuned Touring 93 RX-7 pushing 300+ whp. Like Him, My goals are to have a great ASP autocrossing car but keep in it a comfortable daily driver... I KNOW. Here is my first question... Should I replace my tires for 225-50-16 Hankook RS-3's, 225-45-16 RE-11's or run the ones I have to the ground - Probably another year or so and save up for RPF1's 17x9 with 255's.

Peruvianrx7

iTrader: (25)

I believe I might try 245-45-16's Z214 c71 compound. The other FD has 245 on the front and 275 on the rear on 17s.

kanundra

iTrader: (11)

I would definitely get stickier tires than what you have. I'll be running 235/255 R1R's in ASP, the street tire class is HUGE here in Milwaukee.

Good luck this year!

eage8

iTrader: (9)

I'm not really sure why you're staggering your tires... I would just run at least 275s all the way around. Fit as much wheel/tire are you can on there

everyone in SSM runs at least a 285/315 setup.

If you want to stick with street tires, I'd recommend moving up to some 18s and getting some 285/30/18 Dunlop ZIIs

Peruvianrx7

iTrader: (25)

Good Point. Ill make that my goal to get at least 17s if not 18's. The only reason I am staggering is because 245's wont fit my fender without rolling since im too low. I might raise the height and try to fit them in for now.

Alex

HadaVette

iTrader: (3)

If you want to keep the stock wheels (you won't find much, if anything, lighter) run 245/45-16 all the way around. There are several good, competitive, sticky dot legal-race choices out there in this size. I am on my second season with the Z214, C71 tires and am happy with the results, esp considering the cost. BUT - these are not a good choice for a daily driver. I have 17's for my DD wheels/tires.

Peruvianrx7

iTrader: (25)

So a few new things happened since I last posted... I been running 225-50-16s Bridgestone Potenza RE760 Sport up front and the 245-50-16s Michellin Pilot Sport A/S on the rear . Here are my results.

Final Results - MSCC February Event - Sun 02-10-2013 - Feb 2013
Final Results, #8 - May 05 - Daytona - Sun 05-05-2013 - May 2013

So... Pretty crappy not even mid-pack. So i asked... Is it me or the tires?
I went over to the s2000 forum and i got my hands on "OLD AS THE HILLS" hoosiers a3s from 2003 and 2005. They had only 4 runs on them and apperently were still sticky. For 180 bucks shipped they were worth a try...

FRONT:225-50-16
REAR: 245-45-16

Besides the weight... They were 1 lb heavier than my old set up of OEM rims.

Here are my results:

http://flc.pca.org/LinkClick.aspx?fi...d=383&mid=1276

I made a huge leap... I know its not the same course or the same conditions but if you notice a few of the competitors i raced on the February and May autocrosses were at this one. I improved approx 2-3 seconds and was at the top 25% of the pack

Fritz Flynn

iTrader: (263)

After 6 years of autocrossing I'm certain you know the answer to this question.

However I'd recommend running equal tires front and rear and as someone else said get as much as you can under there because as you and I and anyone who's involved in motor sports knows GRIP IS EVERYTHING

BLUE TII

iTrader: (9)

I am running ASP as well in my local auto-x club.

I was interested to hear you say you wanted to have clarification of ASP rules and such. I think we could use this thread or one similar to make the FD RX-7 a much stronger presence in ASP.

Let me know if you would rather I start my own thread, or if you would like to try to make this an ASP FD thread with a bunch of info.

Here is one question I have always wondered about. Sub frame connectors (SFC).

I have seen how they are implemented on the limp Mustang chassis, but could they be applied to the FD chassis to benefit its rigidity?

The rules state-

E. Longitudinal (fore-aft) subframe connectors (SFCs) are permitted
with the following restrictions:
1. They must only connect previously unconnected boxed frame rails
on unibody vehicles.
2. Each SFC must attach at no more than three points on the uni-
body (e.g., front, rear, and one point in between such as a seat
mount brace or rocker box brace).
3. SFCs must be bolted or welded, but welding must be to the OE
subframe stampings, not to the floor pan in between.
4. No cutting of OE subframes or floorpan stampings is permitted.
Drilling is permitted for mounting bolts only.
5. No cross-car/lateral/triangulated connections directly between the
driver’s side and passenger’s side SFCs are permitted. Connec
-tions to OE components such as tunnel braces or closure panels
via bolts are allowed and count as the third point of attachment.
No alteration to the OE components is permitted.
6. SFCs may not be used to attach other components (including but
not limited to torque arm front mounts or driveshaft loops) and
may serve no other purpose.

If I am reading that correctly, we can weld/bolt rails from our front to rear subframes that connect at one point to the unibody as well.

To me it seems clear we would clearly want to connect to the unibody on each rail at the attachment point for the stock aluminum cross member bolt as the crossmember will feed the loads to the other side/rail.

The SFC wording always confused me because it states-

1. They must only connect previously unconnected boxed frame rails
on unibody vehicles.
2. Each SFC must attach at no more than three points on the uni-body

but then says-

3. SFCs must be bolted or welded, but welding must be to the OE
subframe stampings, not to the floor pan in between.

It sounds like they don't understand the unibody is one thing and the subframes are another.

I think they are trying to say you can weld/bolt to the subframes and only bolt to one point on the unibody in between while not crossing the center plane of the unibody.

However they are trying to leave it open for cars that might not have two subrames (Mustang rear) so you can bolt/weld to the front subframe and bolt to the rear unibody box section (faux frame rail) and bolt to one point in between.

Anyone have insight?

Peruvianrx7

iTrader: (25)

Thanx fritz! Blue II I think they mean as long as our chassis has Pre made holes for the bolts and no more than 3 different attachment places you will be good.

Alex

cdres

So I am actually thinking about doing a real fully prepped ASP build (or might just skip it and go straight to SSM). I am just not 100% exactly what my plans will be.

But is there a good reason to not have a complete and fully prepped ASP car? Shocks, custom delrin bushing, diff, fenders cut to fit the larger tires, etc...

I know that gearing can be an issue with the 285 hoosiers. Anyone do real world testing on what MPH you hit in 2nd at full rpm?

I might also be asking old questions as I did not "search yet" but I actually just joined the site and still don't even own an RX7. But I might (and when I say might... meaning I have one waiting for me to answer whether I want it or not?)

While I am not a well know autocrosser, some might know me and my DSP car (Chris Dressler). I do decent in my car, but never seem to be able to put back to back days together at national events.

That all said, I think I am a decent driver... but time will tell on that.

frankyrealtor

cool

BLUE TII

iTrader: (9)

You can fit 295 Hoosiers on stock body, no need to cut it up.

I just checked the specs and the 295 Hoosiers are narrower than the 295 Ventus TD I am running.

18x11 +45 295/30-18 front&rear with fender lips rolled under.

ASP FD won't be competitive against the Vettes without a little pioneering.

If you are worried about too tall a 2nd gear, dynamic balance the engine (allowed) and let it rev to 10,000rpm in 1st.

Or run 15x11 wheels and the 23" tall 275/35-15 Hoosiers as some others are doing on FDs now.

I wrote the board to confirm and turbo manifolds/extension housings are free so you can take the stock twin turbos and separate them so they have their own separate exhaust downpipes.

With some pre-turbo water injection to improve turbo efficiency and/or E85 fuel and short style intake manifold and aggressive air to water intercooling you should be able to hit 450rwhp or more.

Incidental roll center changes are allowed with new lower A arms for camber, so you can make longer lower arms with RCC (start with the RCC-ed lower arms and make them longer).

As far as I can see no one has really tried to make a fast ASP FD yet.

BLUE TII

iTrader: (9)

Duh on me- no more Corvette in ASP.

Is the ASP class ripe for the FD to pick, I think perhaps.

I don't see much if any performance difference between a fully prepped ASP FD and current crop of SSM FDs.

eage8

iTrader: (9)

A lot of the current SSM FDs have 4.77 rear ends... and drop spindles. and of course aero...


285/18 and 295/18 hoosiers are the same width, they're just different heights. no reason to run a 295 unless your gearing is too short...

BLUE TII

iTrader: (9)

The aero is definitely an advantage SSM FDs would have- that is a good point.

I think current SSM champ Carter used SP spoiler though with the SSM front splitter, but maybe that was an older pic I saw.


It was decided incidental roll center changes with the allowed lower arm for more negative camber is allowed in Street Prepared. So RCC arms legal for front.

4.77 gears do match auto-x speeds to 2nd gear very well.

The 275/35-15 does about the same with 4.10 rear, but gives up over 1/2" of width (though it weighs 4Lbs less).

Riding a 26.8" tall 345/35-18 out to 10,000rpm with 3.90 rear in 1st only gets you to 59mph, so won't be fast enough.

An automatic transmission with 26.8" tall tire gets you 68mph in 1st @ 10,000rpm.

Again Carter's set up as an example (current champ with target on his back, right?), with his small turbo, it starts dropping torque hard at 5,000rpm and HP is completely gone by 7,000rpm. Stock turbos can spool as fast or faster and torque doesn't start to drop until 6,500rpm and HP tapers off after 8,000rpm with the standard shared turbo outlet dead heading exhaust flow.

With the right set up I think divorced stock twins would blow some minds.

2nd gear speeds can become 1st gear speeds.

I don't mean to take anything away from the bad *** SSM FDs, but I think with development a ASP FD could eclipse the SSM FDs' current level of performance.

Of course the SSM cars have much more room to develop and be much faster even then they are now.

$lacker

iTrader: (9)

In ASP, what is the best way to get wider front fenders?
You're not allowed to replace the fenders, but you can cut them and add flares. Are there are any flares that are properly shaped to be molded in and look good?

eage8

iTrader: (9)

yeah, he's since gone to a nice big dual element wing:


ASP FD should probably be pretty competitive, not really sure what cars in there you would have to worry about. evos, stis, and maybe a 911 turbo...

BLUE TII

iTrader: (9)

In ASP, what is the best way to get wider front fenders?
You're not allowed to replace the fenders, but you can cut them and add flares. Are there are any flares that are properly shaped to be molded in and look good?
__________________

You can just take a nice front wide fender and cut it up to fit on modified stock fenders.

Technically, I believe you only need "some part" of the stock fenders since the entirety of the front fenders is outward of the wheel mating surface on the FD.

I would use all of the stock metal fender mounting points to the body and blend the FG fender onto the visible part of the stock fender without cutting away more of the stock fender than necessary.

This would adhere to the letter and spirit of the rule which is to discourage fender replacement for weight savings and allow only cutting stock sheetmetal and overfenders for tire clearance.

The rule does not state it has to be ugly.

It would only be if you start with an aftermarket fender that has different vent or different profile for aerodynamics you would have to worry about getting into protest territory as you could then be seen as trying to get another use out of your fender flare besides the allowed wheel/tire clearance.

jkstill

iTrader: (11)

What are these RCC control arms you speak of?

More info?

BLUE TII

iTrader: (9)

For instance the MoonFace Roll Center Corrected lower arms for the FD.

These could be cut and lengthened to add negative camber and then would be legal in Street Prepared.





MOONFACE Super Lap Roll Center Arms Mazda RX-7 FD3S

BLUE TII

iTrader: (9)

I suppose you could just put in offset bushings to lengthen them which would be easier.

They have the added feature of a replaceable ball joint which is great.

jkstill

iTrader: (11)

Thanks, I have seen those arms before.
I was curious though about the 'RCC' that you mentioned.

As for the negative camber, that can be done with offset bushings on the upper control arms.
I made some of those a few months ago, and now have -3.3 in front.

BLUE TII

iTrader: (9)

For sure offset bushing in the upper arm is easiest.

In Street Prepared we are only allowed Roll Center Correction when it is an incidental change from switching to an allowed lower arm that provides more negative camber.

That is why I mentioned lengthening this RCC lower arm or using offset bushings in it to make it longer.

jkstill

iTrader: (11)

Ah, Ok, now seeing a couple of different posts together I see that:

RCC = Roll Center Corrected

I thought RCC was some brand you were talking about