want to build a m20 stroker

[E30 Wagen]

I've got a complete eta block, and i just bought a 325i. The 325i needs a major tune up but i'm interested in seeing what kind of stroker I can build with the engines that I have instead. I've done some research but i'm having a hard time keeping everything straight as far as what I need. I'm willing to bore out the block and buy custom pistons if that will give the best results. I really want to do this right and end up with a nice, fresh engine.

Thanks for any help.

[Sagaris]

want to build a m20 strocker

fixed.

I would suggest being more specific in your what your desires for the engine and questions are.
I haven't done the calculations, but I know that playing with the stroke length brings into play piston velocity which is a huge factor in how quickly the engine may wear out. Would it be for a track toy, or something you want to drive for a long time?

[E30 Wagen]

It would be kind of an everything car, but I definitely plan on tracking it and driving it hard occasionally. I don't imagine it being a long term thing. I also don't plan on going FI.

I just want to know what would be the most optimal bottom end configuration when mated to a 885 head. From what I understand I can just use my eta block with the eta crank, except I don't know what rods and pistons I should use.

No, I won't swap in a s50, even though I could get a complete engine and tranny for $3500.

[nando]

want to build a m20 strocker

fixed.

uhm.. is that sarcasm?

I would suggest being more specific in your what your desires for the engine and questions are.
I haven't done the calculations, but I know that playing with the stroke length brings into play piston velocity which is a huge factor in how quickly the engine may wear out. Would it be for a track toy, or something you want to drive for a long time?

anyway, you aren't going to wear out an engine with any of the cranks that fit into an M20 block, realistically. It's just not worth worrying about.

if you're going to spend the money - go for the 89.6mm crank with 135mm rods and your choice of pistons. You'll pretty much regret anything less, it all costs about the same in the end, the smaller cranks just give you less for about the same $$.

[acolella76]

anyway, you aren't going to wear out an engine with any of the cranks that fit into an M20 block, realistically. It's just not worth worrying about.

if you're going to spend the money - go for the 89.6mm crank with 135mm rods and your choice of pistons. You'll pretty much regret anything less, it all costs about the same in the end, the smaller cranks just give you less for about the same $$.

I agree. If you're gonna already be buying custom pistons, then you might as well go as big as you can since it'll all cost the same in the end. But a 2.8 can be built using all OEM parts which would cost less than custom pistons alone.

[Sagaris]

uhm.. is that sarcasm?

Just a recent inside joke

http://www.r3vlimited.com/board/showthread.php?t=212744

[acolella76]

you know it was hardly funny in that thread, the first few times it was said. imagine how unfunny it is now, in a completely irrelevant thread

[E30 Wagen]

But a 2.8 can be built using all OEM parts which would cost less than custom pistons alone.

What's the parts list for that? I was really looking to build a 2.8. Sorry i'm such a noob.

[nando]

84mm crank ( M52B28 ), 130mm rods, short-skirt I pistons

not bad for the $, but if you have money for aftermarket pistons, going with an 85-86mm bore, 10-11:1 CR, and an 89.6mm crank with 135mm rods is going to be a big difference.