RX7 vs Z V8 swaps

[Pete84]

I recently became aware of http://www.grannysspeedshop.com/ , and they have swaps for just about every domestic V8 for each of the RX7 generations. Not that I would buy a kit, but the patterns would be useful for a home built kit

 

How do the RX7's compare to the Z for swapping? From what I have read, they had a solid rear axle with Watts linkage until the 3rd generation. Also, LSD's were fairly common, 2nd gens with rear discs seem to automatically have them. A quite competitive curb weight around 2600 lbs for the 1st gen and somewhere between 2600-3000 for the 2nd gens are a plus as well.

 

First hand experience? A good forum? Hearsay? Can the rear end take the torque of a V8, when built for a revving rotary?

[JMortensen]

The RX7 diff looks relatively small, at least in the 1st gen models. I'd guess smaller than 7", but it's been years since I've seen one out of the car. You might check the size of the ring gear online to verify my statment. Gearing is low as I recall, so that might make it less compatible with a V8 conversion.

 

As far as the weight is concerned, 2350 for a stock 240Z is tough to beat. For a race car, I'd go with the lightest weight car I could get, so that is going to be a 240.

 

The 3rd gen RX7 has some really good suspension and especially for a driver, I'd probably be inclined to go that way.

 

You should also consider rust. Won't be hard to find a rust free 3rd gen RX7. It will be much harder to find a rust free Z car, and fixing rust is time consuming and burns up $$$.

[mobythevan]

See the link below for my rx7 project and some pics of the LSx install option and ford 8.8 solid rear. I did not do a V8 z car, I had a L28et 240z. I decided to do the rx7 after Scottie went from a z car to an rx7. Mine is a second gen. Those are cheap and easy to find. I used all granny's engine/trans/rear end kits. I was happy with his parts and really like the way the car turned out.

 

here is the link to my project rx7

 

http://forums.hybridz.org/showthread.php?t=127466

 

Oh, and the forum is v8rx7forum.com

[Pete84]

From what I have found, the LSD on the 2nd gens is a 3.90 ratio. Not that bad, just have to get a transmission with a good ration, and fit some larger diameter tires on.

 

One reason why I am looking at the RX's is because they are newer, hence less rust prone, while still fairly light weight. Good condition Z's are getting spendy, but a blown 12A 2nd gen is downright affordable.

 

mobythevan, nice looking swap! I am going out the door right now, but your thread looks to be well illustrated with good progress write ups.

[Scottie-GNZ]

Go spend some time researching on the V8 RX7 forum as suggested. That will help clear up some of the misinformation you have.

 

In summary: 1st-gen is solid axle with a R&P equivalent to R180. 2nd-gen is IRS with the base models having a diff also equiv to the R180. Turbo II and some upgraded models have a diff equiv to the R200. LSD is not as common as believe and only in the bigger diff. Most common ratio is 4.10. If you plan to drive hard with a manual tranny or have a lot of power, then you want the Turbo II diff and stronger CVs. 3rd-gen is also IRS with a diff equiv to the Turbo II and 4.10s.

 

The choice on which to get is completely up to you. For me, the 2nd-gen is a little more modern and rides like a Caddy compared to a 240Z and has one of the lowest drag coefficient of any production car, ever. As mobythevan said, you can pick up "dead" 2nd-gens for a song.