I picked up a 87 RX7 and I am building a 388 w/N2O to run at the strip. This is first car that I am actually making into a drag car. I mean its going to be tubbed, caged, etc. I have stripped it down to nothing, but I have some questions/concerns. Do people usually tub the cars themselves or have it done?? Taking cage measurements?? Also if I should be doing a complete tube subframe instead of just backhalving??

I plan on going to the track and talking to a few people, but I thougt I would get it out on here as well. The more info the better!

I am looking to run low 9's with this setup eventually, thats my goal anyways.

Any other suggestions at all would also be appreciated!!

TIA

It's all pretty much a matter of prefernce. All the people I know do all their work themselves. You could go with a 4-link narrowed 9" rear end and cut your own wheel wells.

Take the car to a guy and have him build the cage inside the car, chrome moly and certified for up to 8.50's. Don't buy the pre-made, weld in place kits. Chrome moly is light and strong.

Check out some RX-7 boards and see what people are doing. My brother's car goes mid-9's and the only thing we really changed was swapping for a tubular k-member.

Tuning the susbension will go a long way.

**EDIT**
To me, the way to go is look around, look at other cars of the same model to get ideas. Good Q&A will save you mistakes other people already made.

I have been reading a lot on some of the RX7 forums and sites. It seems as though there a lot of people running these car mini-tubbed, but there are only a few who actually use it as a race only car. Well so far the people agree with you in getting a chromoly cage done by someone and I was planning on the 4-link with 9 inch.

I have done some checkin around, and it looks like $2-3k to have the backhalved....looks like I will be doin that work.

What I am really curious about is the tubular subframe thing. Some people do it and some dont. I dont know if it will really benefit me at all, since it isnt mandatory.

Another one of my problems is that there really arent any good shops where I live that do any of this, guess I will be trailering the car a few hours. Any suggestions from anyone in the IA,NE,SD area??

Well, it's been a while, but if you're going to use it as a strip only car, and you have large fundage at your disposal, full tube chassis is the way to go. With a full tube chassis you can mount your suspension anywhere you want, set the engine behind the front axle, tub it as big as you want too and lighten the hell out of structural body members because they will no longer be responsible for carrying load. But at the same time, that is a shit load of effort for a 9-second car. If you back-half it, there should be no worries about tubbing. A ford 9" is definately the way to go, I'd say with a spool, cause you don't need to worry about corners.

Cougar is right about the suspension being key, that's what makes or brakes a car now-a-days. Anyone can build a million horsepower behemoth, but getting the power to the ground effectively with out turning your tires to coal is completely different, and breaking traction at 90-120mph on the strip is a scary endeavor indeed. Try to set that engine as far back as you can, thats what made the RX-7 such a wonderful car to begin with.

A chrome-moly cage is definately a good choice, it's light as hell. A buddy of mine from the shop I used to work at ran a '56 Chevy at about 7.5sec in the 1320, he switched from mild steel chassis to chrome-moly and same setup could run 6.5sec! But he still ran 7.5's all day long with a mild steel, so it's a viable solution for the financially concerned.

Another thing to consider, if this is a strip only car, switching to alchol can negate the need to run a radiator at all. Dave's (my old boss) Corvette run 8's with a 5**cu (I don't remember exact size, it was a Merlin block) and didn't even have freeze plugs! The alchol burns so cool that it would never heat up enough in a run to warrant the need of a water cooling system. I wouldn't recommend this on anything other than a strict drag car though.

I'll chime in again if I can think of something else worth saying, good luck man, sounds like fun :thumbsup

I have been starting to look at alcohol, I wonder if it still works well with N2O or if I should go super/turbo?? I guess it is time to hit the books again. Thanks for the info guys, much appreciated.

I would think that nitrous would work with alchol but honestly, I'm not sure. Guess I need to look that up too :P (always good to have a brain full of useless trivia)

Honestly the stock RX-7 chassis is so prime to put a V8 into and go drag racing already, sticks the engine very far back and the transmission low in the tunnel and all, a tube chassis is so completely overkill it is not even funny... you don't need that until you want to run 8.40s, 8.50s. For a 9 second car, the only real benefit that would get you is safety.

The nitrous setup might be cheaper in the end, but it has been done before with V8 RX-7s... now a single turbo 388 in a classic FC3S chassis, that would be something pimp, and probably more then enough to run 9s since the cars are so light and well set balanced for dragging. But then again, I would hate to be the poor bastard who has to tune a turbocharged car with a carburetor, so maybe the BDS 8-71 blowers that come already fuel injected with dual injectors and whatnot would be a better system since they are almost a complete bolt on deal (albeit pricey).

Who says it has to have a carburator??? That's why God invented MegaSquirt! FC's are pimp-titties too (it's not often I get to use that phrase :P )