Reliable engine builder for the M20B25

[twenty]

Hi There,

As some of you'll know I'm restoring my E30 (see by signature or see https://instagram.com/e30aw) and since it's on 169k miles, I thought I'd rebuild the engine too.
I was hoping that a certain forum member would do it, but he's very busy (you know who you are).

So far I have been recommended Corry Motors in Leighton Buzzard and another build from the place I'm doing restoration at.

Any other recommendations? Some place close to Bristol would be nice for sure.

[rix313]

BDS have done my M42 engines for me. They aren't a one trick pony, I've had them do an M20 stroker (car is still in build). Maybe ask the question.

Great progress BTW,

[twenty]

BDS have done my M42 engines for me. They aren't a one trick pony, I've had them do an M20 stroker (car is still in build). Maybe ask the question.

Great progress BTW,

Thanks.
Do you mean these guys? https://www.instagram.com/bds_motorsport

I've been tinkering with the idea of a 2.7 stroker also - basically post July 90 325i pistons (sadly mine is February 90) and M52B28 crank should do the trick I guess with stock everything.

[flybynite]

I've been tinkering with the idea of a 2.7 stroker also - basically post July 90 325i pistons (sadly mine is February 90) and M52B28 crank should do the trick I guess with stock everything.

One piece of advice from me, if you are doing a stroker, do it properly with 135mm rods or leave it as a 325 and get it running well

[twenty]

I've been tinkering with the idea of a 2.7 stroker also - basically post July 90 325i pistons (sadly mine is February 90) and M52B28 crank should do the trick I guess with stock everything.

One piece of advice from me, if you are doing a stroker, do it properly with 135mm rods or leave it as a 325 and get it running well

Appreciate that. Yes 135mm rods too I guess. Luckily plenty used on eBay.

Only reason for thinking stroker is that the block has seen 169k miles of action. Probably will need reboring ¯\_(ツ)_/¯

[flybynite]

Only reason for thinking stroker is that the block has seen 169k miles of action. Probably will need reboring ¯\_(ツ)_/¯

To use 135mm rods standard pistons won't work, you will need special pistons like Alpina used for their 2.7. For an M50/52 crank Alpina pistons will not work (even if you could get them).

If you are boring the block you might as well go to 85mm and go for the I.E street stroker pistons and make it a 2.9 Not the cheapest solution but IMHO the only one that makes an engine rebuild worth while.

https://www.iemotorsport.com/product/2- ... mahle-m20/

otherwise I'd leave it as a high compression B25