Stroker build.

[slo325i]

looks fun

[Danny]

Danny... no machine work is need on the pistons? Just drop-in?

Well they are stock afterall ;) But there may need to be little reliefs cut in the skirts along with the bobbing of the crank.

Anyone know anything about VAC high performance valve springs?

[Slangbox]

Sooo... Maybe I missed another thread from you where you explained this already, but how exactly is this 2.8 coming together? The "spacer" you mentioned must be referring to a spacer between the head and the block? Is that correct?

[Danny]

No it fits over the crank and fills the hole in between the oil seal and where the M20 crank's "snout" I guess, used to be.

[Slangbox]

Okay, so then I'm confused. I could have sworn I calculated that with the m52 stroke, the eta rods, and the I pistons, the piston deck height was either 1.5 or 3mm too tall. Am I crazy, or have you found a way around this?

[Danny]

Its the same deck height as stock I pistons, you must have calculated wrong somewhere.

[Slangbox]

Damn. That's frustrating.

[Slangbox]

Okay I figured it out. I was off, but I was partly right. The m52 2.8 crank has a stroke of 84mm, compared to the m20b25 stroke of 75mm, meaning the crank-center-to-tdc difference is 4.5 mm. The eta rods, however, are 5mm shorter than the I rods (130mm compared to 135), leaving you .5mm short. Which, obviously, is not the same as .5mm too tall. I must have mixed this up with one of my other prospective combos. But so is that .5mm small enough that you're just not worried about it?

[Danny]

.5mm shorter than stock deck height?

[Slangbox]

Yyeah...

[Danny]

The increased stroke puts the comp ratio back up to where it belongs, yes the stroke:rod ratio isn't ideal, but it works.

[Slangbox]

Okay cool. That's what i was wondering. Thanks man.

[Danny]

Okay cool. That's what i was wondering. Thanks man.

:up:

[Miasma]

Cool project, Very interested in your results. Gonna pick up one of those spacers when he make more.

[Danny]

Crank spacer arrived today.

On the crank:



How it fits over the crank and between the oil seal.





And the spacer itself.