Pistons for m20 Stroker

[zaq123]

It's common to use 130mm rods and 84mm crank, don't think there would be any more clearance issues with the OP's idea.

130mm/84mm will be further from the cylinder wall edge than 133/89.6mm. Just picture the crank/rod at 90' angle. One can always grind for some more clearance but 4.8mm of piston skirt down the cylinder could interfere with that idea as well.

[ForcedFirebird]

If the head is near full height, you may get away with the 2mm conventional gasket with that combination.

don't forget about down movement: crank - 2.8mm further down; rods-2mm further down = 4.8 mm at the piston skirt will be further down for the setup. Plus the angle of short rods/larger crank combo: rods might hit the block mid-stroke. Just a thought...

It's common to use 130mm rods and 84mm crank, don't think there would be any more clearance issues with the OP's idea.

[zaq123]

don't forget about down movement: crank - 2.8mm further down; rods-2mm further down = 4.8 mm at the piston skirt will be further down for the setup. Plus the angle of short rods/larger crank combo: rods might hit the block mid-stroke. Just a thought...

I have ordered the Mahle Motorsport pistons because I think the whole concept is better than the alternatives.

But what Im asking me now is wheather its possible to build an 3l with this piston and I think I have found a good way.


The pistons are made to work with 84mm stroke and 135mm Rods and get about 2860ccm.
My idea is to take 133mm Rods, there are available normaly to lower compression for turbo builds and not very expensive.

I would combine them with 89.6mm crank. This crank pushes the piston (5.6mm/2) 2.8mm further out of the block. The rods are 2mm shorter. So I would end up 0.8mm higher than with the old setup. Maybe I could get another 0.4 by reducing the squish to 0.8mm and by using the thicker head gasket another 0.3mm. The last modification would be to skim the chamber and it schould fit with a very tight squish.
The CR would be at about 11:1 to 11.2:1 but with an perfect tight squish and a bigger cam of about 290° is should work perfect.:devil:

Result would be an 3051ccm high comp Stroker and my rhd ITB it schould run awesome:devil:

What do you guys think?

If it gets to tight i could also use thicker MLS gasket;D

[apostate]

For a 290* cam and European high octane fuel you might want to go to 11.5-12:1 CR.
Just use the Cometic gasket to get the CR there and solve the 0.8 mm. issue.

[bmwmaster81]

I have ordered the Mahle Motorsport pistons because I think the whole concept is better than the alternatives.

But what Im asking me now is wheather its possible to build an 3l with this piston and I think I have found a good way.


The pistons are made to work with 84mm stroke and 135mm Rods and get about 2860ccm.
My idea is to take 133mm Rods, there are available normaly to lower compression for turbo builds and not very expensive.

I would combine them with 89.6mm crank. This crank pushes the piston (5.6mm/2) 2.8mm further out of the block. The rods are 2mm shorter. So I would end up 0.8mm higher than with the old setup. Maybe I could get another 0.4 by reducing the squish to 0.8mm and by using the thicker head gasket another 0.3mm. The last modification would be to skim the chamber and it schould fit with a very tight squish.
The CR would be at about 11:1 to 11.2:1 but with an perfect tight squish and a bigger cam of about 290° is should work perfect.:devil:

Result would be an 3051ccm high comp Stroker and my rhd ITB it schould run awesome:devil:

What do you guys think?

If it gets to tight i could also use thicker MLS gasket;D

[apostate]

Thank you for the insight, digger.
I'll stop reading anything else but your posts only. :up:

[digger]

Everything is a compromise, you just need to choose the best compromise for what you want

[apostate]

Relax everyone. Life is shorter than we expect. :D

https://www.youtube.com/watch?v=B9DqykUsqRY

Whatever you chose, your choice is wrong. The only cure is to look into your kid's eyes. There is a whole universe there. And it is larger and vaster than all the pistons in the world.

Cheers.

[apostate]

Sure.
I don't mind a bit, it was just for the folks that are "learning" from you, clever guys. :):)

[digger]

I'm sure I've seen him mention Itva couple years ago atleast, iirc in a thread about the new IE mahle ms Pistons one of the driving reasons behind it. It may have been in his build thread

[apostate]

Fair enough answer. It is just disappointing that you didn't share your "thoughts" earlier on this forum or somewhere else.

Because 30K miles limit is important and it is quite a while that you are not working for IE as I understand.

Active user like you on this forum should have shared his observations to the wide public a bit sooner, don't you think?

Don't get me wrong, but helping a community doesn't contribute much with yours or Digger's earliest posts.

Or may be all of us around here are not at your high level, so we all have to take your posts for granted without explanation whatsoever...

Cheers.

[SkiFree]

@SkiFree - while you are being generous about the 2618 alloy, how come you never mentioned this before (30K miles)? I guess you sold quite a lot of pistons of this alloy while working for IE?

Fair enough question. I went over pros/cons with whomever asked for my input.

Best of luck finding what is right for you.

[digger]

One only needs to use their powers of observation for what works and what doesn't.

[zaq123]

I guess someone with 2618 has to make an input. Cause you guys are only 4032 gathered here. :)

no one here is trying to convince you of anything, 4032, 2618, 4018, 2632, shitcake....whatever floats your boat.

[apostate]

Digger, make up your mind once you write on. It's hard to follow all of your edits.
Cheers.