Need help choosing model...

[swordfish]

Hi All,

I'm new to these forums and as yet don't have an E30, but that is about to change very soon. I have some quick E30 questions I'm hoping you can help with.

I am planning to purchase a cheap late 80s - early 90s E30 to turn into a race car, and part of these plans involve the installation of a Japanese turbo 4 or 6 CYL engine and matching manual gearbox. I know a japanese engine in a BMW is blasphemy, but it makes financial sense here...

It seems there are plenty of manual 318 4cyl models out there and I was thinking one of these would be a good choice over a 6cyl model as they are relatively cheap and I can get a good rust free body for minimal outlay.

However, as I understand it, the 6cyl models come with a stronger diff which would be beneficial for my application as I have plans for 500HP or so.

So my questions are this:

1) Bearing in mind that I will be replacing the engine and gearbox, is there any reason to choose a 6cyl model over a 4cyl model for my purpose (other than the stronger diff)? For example, are the brakes or suspension better/different?

2) Can the differential from a 6cyl model be installed in a 4cyl model without too much trouble (no welding). I assume the complete differential and rear suspension gear is interchangeable between the 4cyl and 6cyl models provided a new tailshaft is fabricated?

Any direction and advice you guys can provide would be great.

Greg.

[swordfish]

Oh well, guess I offended people or something.

Ended up buying the 318 anyway... hopefully the diffs will swap OK.

[borrihong]

yup

[87e30]

You can swap diffs. But the strut housings and brakes are different as well on the 325. I'm sure there are differences, but that's all I know off hand.

[george graves]

these plans involve the installation of a Japanese turbo 4 or 6 CYL engine

[Delhiteen]

U can have ideas from websites related to it...

[swordfish]

You can swap diffs. But the strut housings and brakes are different as well on the 325. I'm sure there are differences, but that's all I know off hand.

Thank you for your reply. Are you referring to the front or rear strut housings? Are these also interchangeable between the models?

The brakes won't be a problem as these will be completely aftermarket.

As for the Japanese engine and how blasphemous that is, I would love to use something else but the parts just aren't particularly common in Australia. I'm working with what I have.

[JGood]

What year is it? I don't know much about Australia spec cars, but US spec cars changed from the 84-85 production to the 88-91 production (I think they started again in 88?)

[swordfish]

What year is it? I don't know much about Australia spec cars, but US spec cars changed from the 84-85 production to the 88-91 production (I think they started again in 88?)

Hi JGood. It is a late 88 model.

Cheers,

Greg.

[JGood]

That's an m42 318, much better then the early m10 318 (84-85).

You have the normal 51mm front strut housings that all but the early 84-85 cars had (45mm). The rear is not a strut setup, it's a semi trailing arm with a shock (this goes for all e30's).

Only the early m10 had rear drum brakes, so you'll have the same discs as the 325's.

The diffs are interchangeable, they bolt right on.

[swordfish]

That's an m42 318, much better then the early m10 318 (84-85).

You have the normal 51mm front strut housings that all but the early 84-85 cars had (45mm). The rear is not a strut setup, it's a semi trailing arm with a shock (this goes for all e30's).

Only the early m10 had rear drum brakes, so you'll have the same discs as the 325's.

The diffs are interchangeable, they bolt right on.

Thanks a lot. You've been very helpful. Exactly what I wanted to know.

[swordfish]

BTW,

I originally bought the car with the intention of gutting it and installing a Japanese 4cyl turbo, but I have unexpectedly fallen in love with it. I now want to keep it all German and all intact. It's too nice to bastardise. I'm now looking into my engine swap possibilities...possibly a BMW E36 6cyl engine?? Any suggestions?