2.7 Rebuild info

[Borat]

Gus, did you miss the bit in that article about the 325i pistons and e rods sitting down too low? They will sit 1.5mm too low in the block.

[madjurgen]

I want more torque, but I love the way the 2.5 runs from 4k+.

This is exactly how I feel. So you plan on using the M52B28 crank with e rods and custom pistons? Sorry to sound stupid but whats r/s? What cr do you plan on having?

So even a stock e36 M3 has a rod ratio of 1.51-1.56. Seems pretty low.

[nando]

This is exactly how I feel. So you plan on using the M52B28 crank with e rods and custom pistons? Sorry to sound stupid but whats r/s? What cr do you plan on having?

So even a stock e36 M3 has a rod ratio of 1.51-1.56. Seems pretty low.

no, I'll either do the 2.7 eta crank or M52B28 with i rods (e are 130mm vs the 135mm for the i). as far as compression, I'm not sure yet, but no higher than 9.5:1 (we only get 92 octane around here).

as far as the M3 engine, remember that professional BMW engineers designed it to do what it does, I don't exactly have millions in R&D budget so I try to stick to the basics. :)

[Jordan]

Also, food for thought.

S54B32: (8,000 rpm limiter)

Stroke 91 mm
Rod length 139mm

Rod ratio 1.53

[Gus]

i did read the part in the article about the pistons sitting low in the bores...i also read the part about machining that height off the top of the block and having an adjustable cam pulley to compensate the timing

sorry, but i fail to see why using the 325i pistons is a bad thing...they would match the head, and have a high(ish) compression ratio. is there something obvious i am missing?

[Jordan]

Decking the block 1.5mm is a really bad idea.

[PeaveyBassist]

Why is that Jordan?

Will

[Gus]

as above...strength/cooling issues?

[nando]

Why is that Jordan?

Will

cam timing will be quite a bit off, among other possible issues. you could get a custom cam sprocket made to fix that but ehh.. may as well just spend the extra dough on forged pistons at that point.

[SpecM]

cam timing will be quite a bit off,

-But you can just adjust the factory cam gear to compensate, right?

[nando]

-But you can just adjust the factory cam gear to compensate, right?

if you mean moving the belt one tooth at a time, sure, but that's not going to give you the range of adjustment neccesary to set cam timing correctly.

[e30bimmerdude]

why not just save yourself some time and money.....and go F/I with a eta bottom, 731 head..325i ecu, T/B, and intake mani.....good power at only 6-8psi and a boat load of torque... not to mention the 7.9:1 comp which is a bit low, but maited with a good sized turbo= alot o fun!

[MR 325]

Budget strokers are teh suck.

This is me calling your bluff

Mine is far from teh suck

[Jordan]

It has a big old snail connected to it, as such it is disqualified.

[Gus]

well i cant see any reason not to deck block...an adjustable cam gear would surely be far less expensive than forged pistons...anyway anyone got any answers to my original questions? how many bits need to be replaced? more of a general rebuild question than a stroker one.

on another tangent, how well would a eta bottom end and 885 (325i) head handle boost?

if i did want forged pistons, could i just order oversized enough to make a 2.8 and then just replace the eta pistons and whack my 325i head on? how would i communicate the piston shape to the piston builder?