RX7 SBF. What gen?

I've got this 91 Putztang LX 5.0 I stick a key in and drive everyday, but I want the hot excitement of sex on wheels that is the RX7.

So I have a donor... but no recipient.

From the information I have gathered (Grannysspeedshop.com, V8rx7forum.com) it sounds like an FB requires less $/fabrication to swap than a FC. But I figure you guys are in the know, so I ask for your opinion.

My goal is a nice DD. That will make a 'Vette owner pee his chinos.

Mine is a 5.0 in an FB, swap didn't cost to much but the rest did, try out www.V8RX7forum.com

FB all the way. Literally falls right in. The Granny's basic kit is under $180. T5 falls right in place. Also the lightest. I don't know where you're at but I know of a few shells up here ;)

Oh what a bastardization

I KNOW! A fast bastard too.

My 5.0 with aluminum heads, roller rockers, lightweight flywheel and hi torque starter weighs 20 lb more than the original car did, mind you it makes 3 x the power, 4 times the torque and has the same RPM limit.....

the myth of the 5.0 being heavy is just that.

I'd also argue that Ford and Mazda are bedfellows so its not such a stretch.

I own a rotary-7 and I still like the idea of a 302 FB. No abomination here!

I still suspect there'd be a change in the center of gravity. How's it work on a track? What do you do for brakes? Doesn't the engine have to be in the wrong place to make room for the steering rack? At least I bet it'd get better gas mileage than an RX7 and still handle better than a Mustang...

Is that LX a hatch, notch, or a convertible?

If it's a notchback, find another donor car, those things are getting rare. If it's a convertible or hatch, crush the shell guilt-free.

First gen has a solid axle rear, and ancient pickup truck style front end (steering and suspension). Precise would not be a word used to describe the steering feel. I might be biased since I have 30 FB's in my backyard and only 4 FC's, but the FB is the way I'd go. If you want upgraded handling on the front end, the FC subframe (which nets you fancier control arms/struts/rack & pinion steering) is relatively easy if you're comfortable with a welder.

The 302 actually sits lower then the rotary and is still 100% behind the steering and crossmember. The handling is nearly identical, and if I'm honest maybe just a little better. It really does literally drop right in.

Interesting. I have a 5.0 sitting in my garage right now on an engine hoist. Just has the wrong kind of trans bolted onto it... BTW, having direct experience with Corvettes, road racing RX7s and 5.0s, that would take some effort and cash. Maybe just getting a C5 would get a better result :)?

I appreciate the constructive input from those in the know.

Additional thanks to ChrisTaylor for the FC front end schoolin'.

I think I'm gonna wait for the right FB to present itself. I'll keep you updated.

Canute wrote: I still suspect there'd be a change in the center of gravity. How's it work on a track? What do you do for brakes? Doesn't the engine have to be in the wrong place to make room for the steering rack? At least I bet it'd get better gas mileage than an RX7 and still handle better than a Mustang...

It works great on track as its faster, center of gravity on a rotary is high as the eccentric shaft is central in the engine while the piston crank is at the bottom. For brakes right now I have GSL-SE which work fine with quality pads, rebuilt calipers and good fluid, for my use right now but if I go to longer distance racing Respeed makes a conversion kit for the TII brakes.

To install with the Granny's kit you turn the 12a crossmember 180 degrees then the double sump pan clears it, the engine is about 35% forward of the crossmember.

FBs do not have steering racks

A stripped out FB with a 5.0 that has the lightweight parts could easily weigh 2000 lbs

By the by, Respeed also makes a rack and pinion conversion but it wont fit around the reversed 12a crossmember, damn it.

The FB is a cheaper swap if you use kits. if you can fabricate yourself, the FB or FC are equally cheap. In a DD, I personally like the sophistication of the FC over the FB, with it's much more modern suspension and bigger brakes, as well as a nicer (I think) interior. But the FB is going to be lighter.

I never noticed a problem with lightness in my 2720lb 5.0 powered FC, however. Weight distribution was better with the V8 version, and I'd think that CG was no worse than a stock example with a sunroof (mine had no sunroof, and the hood was the lighter aluminum version, saving some weight from higher up on the car). Brake choice on the FC is great, with the available 4 piston aluminum front calipers and vented disks. With good tires, stopping power is incredible. Since the FC turbo is 2800+ lbs, the mass you are trying to stop is the same, so you aren't going to overtax the bigger turbo brakes (that are a bolt on for the base level cars, but still stock on the upper trim levels and Sports).

This is a random question but can the sbf swap pull better mileage since the rotary jive is out of the way?

Sales ninja Greg Voth and I are considering an FB-5.0 swap for next year's challenge. He's got the shell, I've got the space. Neither of us have the time at the moment, but maybe soon.

First, the Berkeley needs to be finished, the Neon needs some love, and I've gotta fix or sell (or both) the Subaru Rallycross beast.

Thanks. If I did it, I'd absolutely go for the FC for the more sophisticated suspension...

These are sweet swaps, I didn't know the Ford was as popular a choice, I've mostly seen the LSx used.

Is the FC actually more sophisticated or simply more trouble, pumpkins hit the floor, rear steer is a royal pain, a IRS rear which is compromised and arguably the solid rear can equal the handling if well sorted.

From my experience in road racing, FCs are much better. EDIT: For my money, I'd rather have the longer wheelbase and wider track width, especially with the extra V8 power.

Except you can actually build a very nice 302/T5 FB RX-7 for under $3000 and you can't even touch a decent FC shell for that. If you wanted to be really cheap I bet a 302 FB can be done for under $1000 and still be HPDE worthy.

P71 wrote: Except you can actually build a very nice 302/T5 FB RX-7 for under $3000 and you can't even touch a decent FC shell for that. If you wanted to be really cheap I bet a 302 FB can be done for under $1000 and still be HPDE worthy.

If you think decent FC shells are worth $3k, I've got an FC shell to sell you. 10AE - one of 1500 (1633 actually). I'll make you a SWEET deal!

P71 wrote: Except you can actually build a very nice 302/T5 FB RX-7 for under $3000 and you can't even touch a decent FC shell for that. If you wanted to be really cheap I bet a 302 FB can be done for under $1000 and still be HPDE worthy.

umm, haven't we already had a couple nice FC V8 Challenge cars?

I know af numerous FC's for sale for under $2k, and non runners for way less. And I built the mounts for my V8 FC swap for about $20.

Up here that's what they go for unfortunately. Any FC under $3K is a primered, half-destroyed "dorifto" or some hacked up no-engine rusting thing that's been in a field for the last 10 years.

I guess they call it "drift tax" for a reason.