Stu --- M42/44 Question Here!!

[Low Level E30]

What would be the advantage of running an M44 block w/ an M42 head?

A club racer nearby is apparently doing this, and achieving an 8500rpm redline. Surely he can't be using the stock crank pulley (harmonic balancer) to do this?

[demlotcrew]

this is not possible hes talking out of his ass, the M42 and M44 are totaly different engines, first of all the oil/water channels dont line up! the Oil pumps are different and then the bottom crank pulley not the same, the list goes on!

[Bryson]

he's probably using the forged internals from the m44 in the m42 block

[///M42 sport]

I though the m42 was forged?
________
Side effects from wellbutrin

[Rob]

bryson has it backwards I guess....

[m42technic]

he's probably using the forged internals from the m44 in the m42 block

Other way around. ;)

[Stu]

yea, thats a lousy way to do a stroker. The 1.9 crank isn't forged or fully counterweighted. Only way to properly stroke is to use Schnitzer/Aplina parts (cha-ching), and have 2+ litres.

[Low Level E30]

yea, thats a lousy way to do a stroker. The 1.9 crank isn't forged or fully counterweighted. Only way to properly stroke is to use Schnitzer/Aplina parts (cha-ching), and have 2+ litres.

I've been pokin' around on this for a li'l while now, Stu. I'm interested to hear what you have to say...

To achieve a 1.9L (w/ an M42 as a starting point), all you need is the M44 crank, correct? You will be slightly less displacement than the M44 since the bore of the M42 is 84mm vs the 85mm on the M44. To climb to a 2.0L M42, it needs to be bored out. Either S50 (86mm) or S52 (86.4mm) pistons are reported to work, though I have no idea if the cylinder walls have enough thickness to allow an extra 2.4mm to be taken out - do you?

E36 M3 US 3.2L pistons (86.5mm) along with a M44 crank (83.5mm) should put the displacement to slightly under 2.0L. However, for a stronger bottom end, the forged M42 crank over the longer stroke cast M44 crank would be better, I would think?

Of course, forged lightweight pistons would be the choice to reduce stress on the rods and crank. Any idea how tough the M42 or M44 rods are?

As far as cast M44 crank failures, I haven't read or heard of any, so far - maybe because it really is a short crank, not like that of a straight-six. Another difference to note between the M42 and M44 crank are the counterweights (M42 = 8 weights, M44 = 4 weights). Is that what you mean when you say the M44 crank isn't "fully counterweighted" - that it doesn't have those extra four? That racer I mentioned - yes, turns out its an M44 crank in an M42 block, that he turns 8500rpm on. I haven't spoken to him, just heard through a secondary source that knows the guy.

I have heard that Jim C. said the M42's harmonic balancer fails at 7200rpm.

Further poking around lead me to a company called GT-Technic --- in order to rev higher, they prepare their race motors with a solid billet pulley which eliminates the balancer. However, I would think that M42s running on the stock management system can't do this, since the crank position sensor reads the position of the stock pulley, so would this require a standalone setup?

Thanks for your help, Stu.

[e9nine]

ok AJ what are you up to now .... should I be concerned of my car's safety..?? (walks to see if car is still in lot...)

[Low Level E30]

ok AJ what are you up to now .... should I be concerned of my car's safety..?? (walks to see if car is still in lot...)

Nothing, nothing at all 8) - you know me!!