Rebuilding M42 (Again!)

[Omi]

Hi folks!

Just bought a 160k engine for rebuild, while I continue running mine into the ground... The rebuild is to be done on a reasonably tight budget, so I'm after some advice on the best way to eke out a few more BHP without blowing the bank manager. (Take that as you will!)

My initial thought is to use M44 pistons, which I'm told are the same pin > deck, and differ only in Bore... Is this right? Adding a few more cubes is always going to be good for power, but I don't have the knowledge, funds or experience to start messing with strange combinations of cranks, rods and pistons.

If the M44 pistons can be used, I'll then be looking at a higher CR because of the increased "squish" area, right? I'm thinking that if the CR isn't too high at this point, a small skim to raise the CR up to about 11:1 would be the best way to release all those ponies.

That's my initial gambit anyway... Tell me what you experts think, and we'll discuss further.

Cheers,

Omi

[Dave_M3]

Use the M44 crank and rods too to increase cc. The iS respond well to a good chipping too thats all I know really so far but really interested to see what peoples advice is cause I'll be hoping to go the same route

[StreetSpec]

why not m44 crank + rods + max. overbore + custom pistons?

Is that pushing the budget?

[Omi]

Custom pistons would screw the budget, but if standard M44 items can be used it would be easier.

I've been informed that the M44/42 cranks are the same in terms of actual throw anyway, so what's the advantage in using the non-forged M44 item over the M42 fully counterbalanced item?

[E30Mark]

I'm sure the M44 stroke is not the same as the M42...

Read this http://www.metricmechanic.com/pdfs/M42_ ... Series.pdf

Stroke between the M42 / M44 is differnt !

[stuartgallafant]

i was certain the throw is different too...

i'll have a look on TIS later