RX7 Enduro Car
 

Hello, I'm new on this board and thinking of building a new enduro car for next season and making the switch from sprint races. I don't race RX-7s right now, but I've always been impressed with the durability and simplicity of the RX platform and wanted to ask guys that have been there done that what you like the most or stuff to consider about your 1st/2nd gen RX7 racecars, and do you think it would be suitable for long races (3-12 hours) - relative comfort, durability (brakes, fuel load), etc. For example, when I've driven them before they seem to get tail happy under hard braking and I've also talked with guys that the clutches and front brakes need upgrading. Given the long racing history I know all this has been addressed, but am doing my research. Also, is there still good engine/tranny/diff/body parts availiability? Sorry for the newb Qs, I run in another series but interested. Thanks in advance for your advice.

Yes, you can still get all kinds of great stuff for these cars. A quick list of places to check out for racing parts:

www.awrracing.com
www.racingbeat.com
www.corksport.com
www.mariahmotorsports.com
http://www.tripointengineering.com/

There is also mazda motorsports' own program with various parts available at a discount.

For the past few years I have crewed for a team at a 13-hour enduro. We ran a 1st gen and finished every race, winning the class at least once. Two years ago the overall winner in the same race was a Speedsource ITS 2nd gen RX-7.

So yes, the cars can do very well in the long races.

-bill

Thanks guys! Finishing is job one, and bonus to have a car that is competitive in class.

Bill, I'm curious - running NASA enduros by chance? Do you know what class the 1st Gen came in as? Was it possibly ITA which I think runs in E2, or possibly as Pro7? E2 is dominated here by Miatas, but I'm really interested in running a 1st gen.

The first gen was running in SCCA ITA. Actually here in the Southeast there are enough ITA first gens to where they run in their own sub-class called IT7. They just aren't really competitive against the higher-torque Hondas and Miatas anymore.

pro7 is gone. i think the 1st gen is in e2. not sure about the rx7 specifically, but e1 or e0 is just different minimum weight/engine mods

Thanks again, makes sense. The rules are pretty permissive on IT when compared with other options. I have a similar situation now - my current race car (a BMW) would class in as ITS/E1, but because it's older I don't think it would be competitive there when compared with newer BMWs and others in E1 unless I shed a lot of weight and then I have a different class problem.

One final (?) question - I'm not finding a class for 3rd gens in IT rules. Seems with a well set up 13B in a 3rd gen it would be possibly ITS. Do you think this would be a competitive setup, and would it class ITS, or would it bump up? (I have a good rotary engine builder/racer to help me on this project).

don't forget ReSpeed for race parts

http://mrcmfg.com/catalog/index.php?...2a2ca12e1da9fc

I found the answer to my 3rd gen / 13B question. It would class in one of the catchall IT classes since it didn't come from the factory configured as I was planning (no turbo, possibly carbed instead of FI). I still didn't find the 3rd gen in an IT class tho, it must be there somewhere as a stock configuration.

3rd gen was never classed in SS or IT (they had a thing again turbos it its day)

The 3rd gen does not compete in any Improved Touring class for a couple reasons:

1) No hairdryers (ie. turbos) in IT. It's too hard to police power levels and mods.

2) The FD has way more performance than even the top IT class (ITR). This is also why you don't see Vette's, Vipers, M3s, etc compete in IT. Heck, even the RX-8 has too high a performance envelope.

There are higher performance classes for these cars (Production, GT, SS, Touring) but those classes also tend to be much more expensive to run in. IT was intended to remain as a "entry" level class with more affordable racing.

A BMW is a very competitive car in ITS and ITR. In fact the impetus for the recent creation of the ITR class was that the BMWs were such overdogs in ITS that there was really a need for a new class to handle them as well as a slew of newer cars that were becoming eligible to run (Supras, certain Porsche's , Integra R's)

Go over to http://www.improvedtouring.com/ and look through the forums for more info.


-b

Thanks again, I really appreciate the guidance and that all makes sense. Will go over to IT.com to do more research.

3rd gens wind up in ITE here, a regional-only open class. You never know what's going to show up in ITE. :)

In other words, you're not going to be in a competitive class with an FD.

I've run ITA and EP Rx7s in 3 to 10 hour enduros for several years. Like any car you can tune around most chassis problems. Chassis set up is a compromise with multiple drivers. I always voted for a slightly softer and lightly understeering chassis. A harsh tail happy car on hard slicks with rear brake lock up makes for a long race. The biggest problem we have is poor gas mileage. It still is a lot of fun but we can't make up for the extra pit stops we have to make when fuel cell size is limited. A couple of the guys also had a problem with the heat running their second or third stint on a hot summer day. We solved that with more ducting, cool suits, etc. Stock gear boxes were a problem in EP trim as well. Some time some one would miss a shift, jam it back in and clean the teeth out of one of the gears. If you are just looking to have fun and go 9/10ths do it.

+1 on the tranny. Starting out the race on a nice fresh rebuild is a good idea. I think there were a couple times that we finished the 13-hour with less gears than we started with (and in one case a different tranny).

-bill

That's great input, I really appreciate it. Your post gives me a good view into the "cons", that most Mazda guys don't talk about. What's your typical run on fuel in an enduro with a 10-15g cell? In NASA enduros, pit stops can only fill 10gal at a time, so that's a big consideration like you said. I estimate my spec e30 would get >90 minutes on a tank, but plan to test to be sure.

Bill, it's kind of cool that you can actually swap a tranny in an RX7 during a race and still finish. That is the kind of maintainability I need with my resources (no shop support or a big crew around). I'm pretty sure I couldn't do that with my BMW.

I love my 7, and I love racing it. But, having said that, if you are starting from scratch you might want to consider doing this with a Miata instead. There are just so many advantages with them, and you will spend most of your time/money just trying to get even with them as far as performance goes. Also, they seem to always finish the race.

But iff you are in love with the rotary, then go for it. :)

miatas;

its tempting to run them, but in a spec miata trim, to be even mid pack you have to have a car thats fully prepped $$$$$.

the fuel mileage is about the same as the e30 (we think, havent checked the e30 actually).

the 1.6 cars have a small drivetrain, they are ok in sprints and short enduro's, but when you run a long one, plan on changing the trans, diff (sometimes twice) etc etc.

we've looked at doing another miata, but we keep deciding its not worth it.


rx7's;

these are more fun than the miata's but they get worse mileage, and arent faster enough to make up for it. a good effort will still do well

rx8:

mazdaspeed ran 3 last year at the 25, they looked pretty fast and reliable. its a great chassis, very forgiving. might be a good enduro car

I am currently building a 12A powered Miata for endurance racing. The engine swap was definitely more work than we thought it would be to convert to the rotary. Custom oil pan and modification of the tranny tunnel. As far as suspension, just planning on spec miata set up.

I think the oil capacity of the 1.6 diff is less than one quart. Put in a 1.8 Torsen and going to run tranny and diff coolers, just for the addition oil capacity.

Locally we are not limited on fuel cell size, I found a 21 gallon cell that would just barely fit in the stock tank location. Very tall, so the first hour or so will be fun on a full tank.

I thought about doing a rotary miata but after research the amount of work, plus questions about where it would class for racing I decided to not, but I commend you on doing one cuz I'll bet it's a blast and possibly the best of both worlds.

Miata is a great platform and some of the more competitive cars are with ITA (SCCA) builds or PTE (NASA) builds. Lots of upside.

Miata aside, I'm really on the fence between my SpecE30 (plus new ECU and better tires), vs. buying a pro7 and building to PTE (with trans, diff, intake, carb).

E30 is reliable and strong and I own it. RX-7 would be lighter with a lot of potential (easier on tires and brakes) but MPG might be an issue in long races as well as heat. Both are older platforms and rules tend to favor newer cars, but lots of advantages to either one. I like the RX7 from the standpoint of being easier to work on.


Understandable to have some bias, but appreciate any thoughts on RX7 vs. E30, pro and con.

we looked at the e30 too (we're running a rental spec e30 this year, its FUN)

we're looking at doing the 25hours of thunderhill, so some things become important.

the e30 seems to be durable enough, nobody in the class needs to open the hood at all in a race weekend. this is good

spec e30, is too heavy, it would have to run IT prep. the problem with this becomes the engine, we dont think it will make enough power (180 is needed) to keep up.

we also dont think the bmw 2.5 will get the fuel mileage of the 1.6/1.8 miatas.

Good points. What do you think of running the E30 in a PTB trim? Could lose a lot of weight, and also run S50 motor. There is a guy running one pretty competitively in Norcal right now. Downside is that I think that bumps up from E2 to E1 (or maybe E0), and probably wouldn't be as competitive. I think I answered my own question !

Bill I've too have changed trannys during enduros. But even in short races like the June Sprints between practice and qualifying one more got changed and one broke durning the race. I have friends using a turbo tranny, routing out the starter whole, tigging up bosses to stay EP legal. Other friends went to a dog shift and to stay legal added weight. The gear ratio in the miata boxes seem a little better but the miata boxes we tried aren't any stronger either.

It seems like the gear sets made for a 105 hp street driving rotary can't hold up to 200 hp+ unsprung clutches. Have you heard of any solution?

The trannies are definitely a weak link, but I think the biggest problem is that people are hard on them. I ran an ITA RX-3SP for seven years, the car had the same 5 speed that was in the first generation RX-7, at first I had issues with the tranny. After my driving improved, I had very little trouble, I know it was a pretty low horsepower engine, but racing is hard on equipment no matter what. I think the only solution is to be very precise and very gentle, in particular with your down shifts, but always have a good spare ready to put in. Whenever I would race out of town, that was always on the spares list.

I know people who have run 626 RWD trannies in EP 1st gens no prob no breaky. And a front tunning GT-3 semi-tubeframe 1st gen that ran a 626 RWD tranny for 2.5 years no breaky. Similar parts as 1st gen and Miata tranny. Sprints only, no enduro.

It seems to vary by driver and prolly how harsh the track is.

If it were me I'd like a nice dog box that can take more power, and just add the 50lbs or whatever SCCA mandates.

How about the EMCO trannies, anyone running one of those?