86 FC Rx7 Engine swap
 

I want to put the M30 B35 from my 91 535i into my 86 FC Rx7. I have a few questions about this. For starters would the engine even fit with a radiator? If so has anyone even attempted this before? Also what would a checklist be for what I need to start? For those of you wondering why I would do this, The E34 has main body wiring harness issues, it also has 360k miles on it. The 86 Rx7 has a roll cage and also weighs significantly less than my BMW.

it won't after you put that engine in it! those BMW engines are HEAVY

the 20B is about 22" long and you need to move the radiator a bit (or move the engine a little), so that should give you some idea of the space you have. also the FC engine bay is wedge shaped, so a big 6 like that is probably going to be really tall at the front. i think the people who do supra engines move them way back, by cutting the firewall

you'd be ahead by selling the BMW stuff and getting something else that fits better

^^ What he said.

The engine bay is designed such that the engine main pulley ends up right behind the steering rack. This is what makes the Rx7 a "front-mid" arrangement. It isn't a mid-engined car in the traditional sense but keeping the weight of the engine completely between the front axles helps weight distribution. The reason rear-engine cars tend to be snappy for example is that weight ends up behind the rear axle and the car wants to pivot around it.

After researching tons of different swaps it seems like the reason an LS fits so well is that it has a similar footprint to a stock 13B. It isn't much longer back to front or taller top to bottom, since the 13B intake manifold sits on top. Since LS engines are an OHV design, the valve covers sit much lower and put it under the stock hood line. Meanwhile the extra length front to back is minimal so the added front bias is not super significant.

Look up some of the other, more unusual swaps. There's a VQ35 swap over on GrassRootsMotorsports, where the OP had to make a custom low profile oil pan, has like 3" of clearance under the car, and still had trouble fitting the stock hood. Look up the 1UZ-FE swap where the DOHC V8 and it is so tall that it is interfering with the hood. Even a K-swap is tall for the same reason.

And all of the above options (despite being tall) still aren't super long. You're looking at putting an inline 6 where the little 13B used to go. And an inline 6 is both tall and long.

There are better choices than this if you want to do an engine swap. That being said, please post a build thread if you DO decide to do this swap. Just because it isn't optimal doesn't mean it won't be interesting :)

yes for sure. i've always wanted to put a BMW v12 into something, my friend wanted to do a 2002!