RX-7 For autocrossing

[Andrew7dg]

Well i am determined to compete in an automotive sport (insted of on the street) I thought Autocrossing would be a good way to start. I like the RX-7 with rotory engines with 50/50 weight and I think it would be a good car to start out with. Unfortunatly I don't have a budget for an FD. I was thinking of an FC though and wondering which year would be the best to start out with the older FC(86-88) with lighter bodies and a little less horse (or so i been told) or the newer FC(89-91) with heavier bodys but more horse? Am i starting out with the right car or should i look toward the FB? I like the FC styling more though.

I am building this car strickly for autocrossing or other competition (unless i want to have some fun just doing some weekend driving) I was wondering which motor I should also start out with. The turbo II motor or the N/A GTU. From what i have heard, they are the same car but with a different engine.

I would like to build this project up slowly so i was thinking about getting a GTU and then putting a turbo motor in it later and buying other mods when i can afford them.

I was wondering if I would violate any rules in autocrossing by swapping motors to create a TII. So should i get a GTU and mod it later or Get a TII right away and not have to deal with the headaces (headaces of autocross not with the turbo motor because I know that will give me headaces)

Anyother advise to get the car autocross ready would be helpful to me. This would be my first RX-7 that i would own so i am kind of new to this. All my friend play with mustangs and i want something just a little different.

Also are there RX-7 clubs around (from Minnesota) that go and race at tracks? I think I know of a couple however they seem to welcome FDs more then FCs? Other auto clubs? All i want to do this summer is race

Thanks

[G-man422]

I would personally just go w/ an FC and get some weight out.

[drftk1d]

get teh rx7 that fits your budget, if you can afford the TII then get the TII.

if you dont get a tII try to get one of the cars with the 4 piston brakes

[Chris V]

Ok, this was my regional champion. Built to be cost effective.

It was an '86 Sport. The sport models in '86/87 had all the suspension of the turbo, including the vented discs at all 4 corners and 4 piston aluminum calipers in the front. The GTU did not have this, though the later, rarer, GTU-s did.



It was running Tokiko sport springs and Tokiko HP struts (you do NOT want multi-adjustable yet. YOU as the driver will be the largest variable between events and between runs. Having single position shocks/struts gives you a stable unchanging platform in order to perfect your driving skills, instead of trying to compensate between each run for changes that are usually caused by your own driving inputs)

Here is the alignment spec sheet. It's assymetrical due to being set up to have the driver in the car. This was taken from a national championship winning RX7, and worked just as well on my car, which was still rotary powered when I raced it as shown above.

[drftk1d]

did the springs have to compensate for the v8 or what

[Chris V]

Originally Posted by drftk1d

did the springs have to compensate for the v8 or what

No. I actually autocrossed it with those springs in rotary form (that was the setup when the car was still silver). There was only about 50 lbs added to the nose during the coversion, so the springs didn't even care. 150 lbs was added in total, but a hundred lbs of that went rearward, and the car ended up with a 49/51 f/r weight distribution. the car actually weighed less than a stock FC Turbo II up front. (heck, it weighed less than a stock FC Turbo II in total)

So no changes were done to the suspension for the V8 other that revising the front swaybar to miss the V8 oil pan. The suspension worked identically in both rotary and V8 form. it's an outstanding, and inexpensive, suspension setup for any FC: N/A, turbo, or V8.

[Chris V]

Originally Posted by Andrew7dg

. I like the RX-7 with rotory engines with 50/50 weight and I think it would be a good car to start out with.

Remember this, not all RX7s have 50/50 weight distribution, and it's not ideal ANYHOW. it's just an even number, but you want a slight rearward bias.

The N/A early sports weighed just under 2600 lbs, and teh Turbo II wighed just over 2800 lbs. That's a 200+ lb differnce and it's all ahead of the firewall. So they both can't have 50/50 weight distribution...

Personally, I prefer the earlier cars. The power difference isn't critical for autocross (though an early Sport with 145 hp will be quicker than a later GTU with 165 hp, and almost as quick as a 185 hp early TII), but the lighter weight means less mass to hustle through the slaloms. What you're looking for is the better suspension and brakes. And fewer options (the sunroof adds weight way up high, for example). Don't start witha 4 lug car (teh base versions have 4 lug wheels). And when looking at a 5 lug car, look for 4 piston finned aluminum front calipers. That tells you it's got the same suspension as the turbo, with the best brakes and swaybars, and heavier duty components. Lastly, look for a limited slip diff, and the aluminum hood. ther was no rhyme or reason for the way Mazda equipped some cars with steel hoods and some with aluminum hoods. But the aluminum hood shaves of a LOT of weight off the nose.

[drftk1d]

not trying to be a dick or anything

but my base model n/a has a rated curb weight of 2625 (unless the sports were lighter cause of the aluminum hood or something), and it has no sunroof.

im also pretty sure the fc has a rear bias stock as well

but what do i know

[Chris V]

Yeah, the Sport was under 2600 lbs as shown in the silver pics. Aluminum hood shaved a lot. It was about 50/50 in stock form, the TII is closer to 53/47, epending on options. The V8 didn't need the huge oil cooler under the stock radiator, that sticks way out in front of the front wheels. And the battery was relocated from the far front corner to the well behind the passenger seat when I started autocrossing. Having no sunroof removes weight from way up high, which helps the base and sport models with CG, but the base has a worse suspension and smaller brakes by far. Some base models had the aluminum hoods, though, so I can picture a virtually 2500 lb base model out there somewhere in pretty much stock form.

[Andrew7dg]

Thanks for all of your help and especially with the allignment spec sheet. So with my budget all i can probably afford is the older sport model (plus it will probably be a good beginner rotary and autocross car). I am dealing with a college budget, however i am just happy to make a well Handling car that would be fun to drive on the weekends. I just want to make sure i am going to look for the right thing though when i shop.

So just because it is a five lug model that doesn't mean it will have the 4 piston aluminum finned breaks and the aluminum hood right? If it has the breaks that means most likely it will have the posi right? Was there a badge for this sport model. You see i thought this was the GTU but i guess i was wrong. Is there any way to identify this on the car? Is there an easy way to identify the aluminum hood?

Just so i get a rough cost guest on how much this whole thing is going to cost me

How much do you think a car like that is worth or should be worth? 1500? 2500? I am not looking for a beauty queen but something without rust though

And how much do you think the Tokiko sport springs and Tokiko HP struts are going to cost 1000? How much did they lower the car if any lowering was involved (looks like it in the picture)

What class did you run in out of curiosity? Not stock i am guessing. Street Prepaired? I am guessing you ran Yokohamas on the car as well.

I was still wondering though if i switch engines (13bt) would my car be bumped to a modified class or would it then be considered a TII in competition?

Also some thought about weight, How much of the cars interior and say A/C and other components am I allowed to remove in this class? I would like to get it light as possible because i heard that is less ware on the tires and most importantly it improves handling.


Thanks again for all of the reply. This has been a neat thread to read.

one more thing to as (because i know i ask way too many questions already) what makes the later FC models weigh more then the earlier FC?

[Chris V]

Originally Posted by Andrew7dg

So just because it is a five lug model that doesn't mean it will have the 4 piston aluminum finned breaks and the aluminum hood right?

Correct. the GTU and many of the GXL models had single piston calipers all around, with solid discs in the rear.

If it has the breaks that means most likely it will have the posi right?

Unfortunately, no. In fact, many of the Sports did not have the posi, so you may have to look for a GXL center section if you find an otherwise decent Sport. The turbos had them, but the center and axles were quite a bit different and aren't direct bolt-ons.

Was there a badge for this sport model. You see i thought this was the GTU but i guess i was wrong. Is there any way to identify this on the car?

No badge, and really no advertising for it. In '86 it was a separate model 9that supposedly didn't exist according to many sources). In '87 it was a package that could be added to any of the RX7s, including the GXL. When new, they had small aero spats in front of the rear wheels, slightly deeper lips on the front airdam, and a small black lip spoiler on the rear. Of course, they also had the 4 piston finned calipers up front with the Mazda name cast into them. The GTU did not have this stuff. The model that was the equivalent was the ultra rare GTU-s.

Interestingly, all the converrtibles had the better suspension and brakes as well, as they weighed around 3000 lbs and Mazda apparently felt they all needed the upgrade.

Is there an easy way to identify the aluminum hood?

Yeah, a magnet. Opening and lifting it will tell you, too, as the steel hood weighs a ton, and the aluminum feels like lifting a sheet of paper...

Just so i get a rough cost guest on how much this whole thing is going to cost me

How much do you think a car like that is worth or should be worth? 1500? 2500? I am not looking for a beauty queen but something without rust though

You can get decent ones in that price range. Rust generally isn't much of an issue on them, and there are plaenty out there without rust.

And how much do you think the Tokiko sport springs and Tokiko HP struts are going to cost 1000? How much did they lower the car if any lowering was involved (looks like it in the picture)

That's about right. The springs lowered the front about an inch, and I had to modify the rears to get it to sit level (IIRC, they actually raised the car an inch). I used the fronts as delivered, and cut 2 1/2 coils from the rear.

What class did you run in out of curiosity? Not stock I am guessing. Street Prepaired? I am guessing you ran Yokohamas on the car as well.

Yup, then E-Mod with the V8. I used Yokohama A008 RSIIs for the first couple years, then switched to Yokohama A032Rs. Of course, in the last few years, newer, faster tires have become available. I'd look into the Hoosiers or Kuhmos now.

I was still wondering though if i switch engines (13bt) would my car be bumped to a modified class or would it then be considered a TII in competition?

Depends on what line the TII was in the rulebook. Usually you have to swap straight across to stock TII specs for that year/model. But, IIRC, the TII runs in a different class than the N/A version. I'ts been a few years, and I don't have the newest SCCA rulebook with me. I'll check when I get home.

Also some thought about weight, How much of the cars interior and say A/C and other components am I allowed to remove in this class? I would like to get it light as possible because i heard that is less ware on the tires and most importantly it improves handling.

In Street Prepared, you can do a lot of lightening, but not gutting.

one more thing to as (because i know i ask way too many questions already) what makes the later FC models weigh more then the earlier FC?

Additional sound deadening, options, some heavier components, etc.

[Andrew7dg]

I just wanted to say thanks for your help! I now have a better idea on what to look for when buying or looking for one. Hopefully I can find one before the season starts so I can get a head start. Thanks again for your help. Out of curriosity, just for one or two more questions, because the turbos came with a different rear end does that mean it would handle better on the road then the N/A? Would be harder later to do a conversion from a N/A to a TII later because of that?

[fcdriver]

The t2 rear is larger then the n/a and comes with limited slip although some GTUs and GXl's came with it like said above it is a smaller unit.
Also GXL's came with 4pot front calipers and single in the rear.

The n/a to t2 swap is somewhat of a hassle, you'll need all the wiring and the entire drivetrain from a t2 car to put in a n/a shell, ei. engine, transmission, drive shaft, rear differential. It's much easyer to buy a t2 then to convert a n/a to turbo and sometimes it's cheaper.

[drftk1d]

not all gxl's have 4 pistons, dont know where you got that from

[Vortec-Rx7]

whats the difference in the suspension?

do you mean it just has stiff springs/struts/swaybars or is there more to it then that? If one were going to change all those parts to aftermarket would it matter what model you got then?

I am looking for one for a v8 swap! I already have my transmission started(i'm getting together all the parts and THEN buying the car... wierd I know but its easier to keep an engine and tranny around then an entire car...)

Plan on running a Vortec Head, small block, edelbrock air gap RPM manifold, carb, 525 or so lift cam...similar to the LT4 HOT Cam, 10:1 compression, 1 3/4" conversion longtube headers..... Im aiming for 350+hp... Its gotta be able to walk LS-1's and new mustangs at the least.

200-4R transmission, Precision Industries 3000rpm stall lock-up converter, THE BEST! Alto Red band and clutches(the best), kolene steels, sonax billet servo, art carr shift kit, plus other various bulletproofing modifications. I'm really doing the transmission up with extreme attention to every detail the 200-4r can go wrong with, putting in all the best friction materials and the best converter, this transmission should be worthy for a good low 10 second pass, I am very proud of my work here. I wish I can do as good of a job on my engine but I don't have the experience with engines.

I got my 200-4r out of an 88 monte carlo SS, which are the better ones, for free. It has water damage but thats not a problem, I also got the converter for free... i might send it in for refurbishment but might just run it for awhile and see if it has lock-up... it is questonable if it works. so far this project just keeps getting better and better, cheaper and cheaper, my spirits are very high after finding out I had a 200-4r precision industries converter sitting on a shelf.... that is a big time money saver and the best one you can get. Hell I was worried about shelling out 400 bucks for a mediocre one....