shm21284

I'm turning a 91 Turbo 2 into an NA SCCA E-Production Rx-7. The car previously made 407rwhp with a GT35R and a 13B-RE, but I got tired of driving it on the street and am ready to start racing on a regional level.

Minimum weight, with driver, is 2300 lbs with the stock transmission. I would like to either swap another synchronized 5 speed box into it (can't change the number of gears) that has better ratios for circuit racing than the stock turbo 2 trans, or put a dog box in it, but that is down the road... I'm open to suggestions for that.

Here are some pics of the fuel cell. It is a 12 gallon ATL bladder from a NASCAR with the NASCAR anti rollover devices. I fabricated the cover, fabricated the aluminum cage, and modified the can to include a flange for a removable cover. The can (not the cage) is being powder coated red, more pics of that and the fuel plumbing later.

shm21284

Per the 2009 GCR, the minimum height of the fuel cell is 6 inches from the ground.

farberio

iTrader: (7)

Looks pretty baller.

jgrewe

iTrader: (1)

Looks like a fun project. Better be sure the T2 stuff is legal in any form. IIRC its not. The diff and axles might be a problem. The T2 intake manifold won't fly either.

shm21284

I'm probably going to run the intake manifold anyway, as I won't be winning when I start racing. Once I get better, I'll swap that stuff out for more legal parts.

Copied from the 2009 GCR:

o. Final Drive
1. Drive shaft(s) are unrestricted.
2. Final drive ratio is unrestricted.
3. Internal differential components are unrestricted. Electric control of the differential is prohibited.
4. Substitution of the differential housing is only permitted on front engine/front drive or rear engine/rear drive cars through the use of an alternate transaxle.
5. Axle shafts, bearings, bearing carriers, hubs, and universal joints/CV joints are unrestricted.
6. Transverse engine cars can rotate the engine about the crankshaft centerline to align axle shafts/constant velocity joints. On rear engine/rear drive cars the engine/drive train can be relocated vertically upward, to a maximum of one inch, to allow alignment of suspension and driveline components.

jgrewe

iTrader: (1)

#4 is the kicker, I've never had a T2 but they have a different rearend housing right?

Just don't open your hood with anybody else around. lol The stock NA intake manifold is the problem when keeping the EFI.

And you're right, nobody will care until you beat them.

farberio

iTrader: (7)

But his car is a TII that has the turbo removed. The car was a TII as well, not just the engine.
I wonder if that effects anything.

jgrewe

iTrader: (1)

They don't care about VIN numbers in Production. Its all about the indivdual parts. Many of the T2 parts can be used because there are a lot of parts that are unrestricted in the rules.

Tha main parts that need to come from an 86-92 NA are the engine, brakes, diff housing, hood design(no scoop, but can be alternate material). Just about everything else can be replaced with an alternate material or alternate part performing the same function.

shm21284

I can use t2 brakes, they were also used on the GXL. The NA differential does use the same aluminum housing as the t2 diff; however, I'm not sure if the nose is the same.

Also, the control arms are unrestricted (but not suspension mounting points), so I could make tubular steel control arms if I desire. I am considering that option to lower the unsprung weight of the suspension system.

C. Ludwig

iTrader: (27)

The spec line is implied to apply to the NA cars only. The TII diff will not be legal. You won't need it anyway. The NA diff will hold the power of an EP car just fine and is lighter than the TII. You will want a 5.12 gear set for an EP car. Be prepared to shell out big money for this custom made gear set. A stock 4.10 will be horribly over geared.

You will need a high end dog-box to be competitive. The TII box should be legal, as alternate transmissions are legal, but the ratios will be terrible. The NA trans is fragile and the ratios are not ideal either. A Miata gear set in an NA case would have better ratios but will still be just as fragile. In the end you'll want/need a dog box.

I would suggest beginning your racing in IT instead of Production. Will allow you to dip your foot in a much shallower pool (ie. less expensive, less demanding of expertise). You can build the car as an ITS car and upgrade to EP specs later on. There will be more competition in IT as well. Mid-Ohio often has 20+ cars in ITS at a normal regional. There might be 2-3 EP cars at the same race.

Contact me through PM if you would like any advice on getting pointed in the right direction.

shm21284

You are spot on for the number of EP cars there. I work part time for a shop that races ITA and there are a ton of those. I have only seen 2-3 EP cars each time I was there. I'm not too worried about being competitive YET... and since I've already started down this path, I'm going to go ahead with it.

The T2 diff is legal, as the differential is unrestricted. The reason I want to use it is that I already have a KAAZ in there. However, a concern of mine is the higher rotating mass, as well as the higher fluid friction forces due to the larger diameter ring gear. I'm not 100% sure about the nose. If that is different, then I'm not going to run it, and will end up selling it.

The T2 trans sucks. I won't run it for long. I am looking into a mazda factory race transmission as an alternative, but there are (i think) fairly affordable T5 dogbox conversions that can be readily adapted to rotary bolt patterns.

I am going to start by PDXing for a season to get my braking zones in tune, then hopefully move up to competition. Who knows, I may change my mind by the time that happens anyway.

C. Ludwig

iTrader: (27)

The 2nd Gen is allowed prep level 2. When you read through the level 2 rule set you'll see that the stock (NA) case must be used. You are allowed an alternate differential and ring and pinion, but that needs to fit in the stock case. The TII case is decidedly different than the NA. In the real world you could run the TII diff everywhere except the Runoffs and the June Sprints and get away with it. It wouldn't be legal though. Also, there are no worthwhile options for alternate ring and pinion sets for the TII. Though there is nothing off the shelf for the NA, there are guys modifying the short snout 1st Gen/Miata pinion gears for use in the NA housing.

The S4 clutch type diff is a good for racing when properly setup. There are a couple shops that can do it for you, or it's very easy to put the parts together yourself. Getting the right combination of clutch thicknesses to properly set the break out torque can be an important part of the setup though and having someone's experience to lean on is nice. If you build it yourself Mazda Speed has various thickness clutches available. IMO, the Torsen from the Miata (while popular in racing), is a poor choice.

shm21284

Thanks a lot for the info! I'll look at selling the KAAZ then...

NATEFRAME

seth, this is some nice work. I would give anything to be done with college and down there hanging out right now.

all in good time.

cheers bro!

farberio

iTrader: (7)

^ Who even are you. Look at me NATEFRAME, that man with the caps lock!!! Pfffttt... have fun in Flint.

BTW, hows teh 7 running Nate?

shm21284

I bought the tubing bender and flare tool today. Need to get some aluminum tubing and the Toyota Supra fuel pump, fab up a bracket for the pump, make the surge tank, and bracket for the external pump and filter this weekend. Probably won't all be done.

I'll post up some pictures of the powder coating tomorrow if I remember to take my camera in.

Ludwig, I think if I raced ITS first I would have to run a larger diameter roll cage. I don't want to order 2 die sets and make the cage twice...

C. Ludwig

iTrader: (27)

Hmm. You might be right. There is a guy that frequents the racing forum out of St. Louis that builds cages. Drop him a note and ask him about it. The GCR has weight charts in two different places (p 93 and Appendix G) and, to me, they contradict each other.

shm21284

Either way, the ITS rx7 is 2800 lbs, so it falls out of the weight range set forth on the contradicting tables.

Honestly, I like the level of build that is presented by E production. Being a mechanical engineer, I probably enjoy the build and design process more than the competition aspect. If my car turns out to be kickass, maybe someone else will drive it!

C. Ludwig

iTrader: (27)

Get it done then! I agree with you that IT is restrictive and Prod presents more of a challenge from the build/development aspect. Unfortunately, in any racing cubic dollars dominate. In the more expensive classes it's just a greater amount of cubic dollars.

If you need a coach/driver I know a guy that's won a race or two.

You got anyone working with you on the engine and engine management?

shm21284

I'm getting some advise from Carlos Lopez as far as rotors go. The immediate concern is to just get the RE going so the car is running, but eventually a dog box and a 6 port engine is in line.

I plan on using carbon apex seals, so a solid tune is a MUST.

Got any suggestions for engine prep and tuning? I plan to do all the porting and assembly myself. I don't have the $$ to pay for an engine prep. I understand most people don't like to share secrets, though...

C. Ludwig

iTrader: (27)

Carlos will point you in the right direction. I did notice poking through the rule book that rotors are free. That should allow you to run the aluminum rotors from E&J. Certainly expensive, but when you look at what it costs to get a pair of rotors setup from Carlos they're not too far out off the ballpark. I would imagine, given the promising results the aluminum rotors are seeing, they'll become THE thing in Prod before long.

The scalloping that Carlos does will work well with the street port requirement of Prod. Again, he's a wealth of knowledge and will point you in the right direction.

When you get ready for engine management give me a shout. Would love to work with a Prod car. We've had a lot of success in ITS. Would be nice to step up to the next level.

farberio

iTrader: (7)

^ I will vouch for C. Ludwig.

He was definitely helpful when I sent him 10,000 emails about setting up my Haltech. He even responded to one on his Honeymoon, much to his wife's dismay I am guessing.

NATEFRAME

farberio? what kind of a screen name is that. something tells me we have met before.
I bet i know where.
my seven is dead in the ditch. too much homework to finish wiring it.

shm21284

Powder coated red.

farberio

iTrader: (7)

Heh, that's probably a good answer though. The rest of us probably neglected grades to work on teh 7.
Shm, it looks pretty sweet in red!