Author Topic: Frankenstein m42 built for boost? (Read 2661 times)

Schwarz_Bomber · « **on:** October 20, 2008, 10:44:42 PM »

Ok. so i read the other thread for the 2.0l m42, and i got to thinking, how does one know the displacement a block+bore+stroke will come out to be? i mean, a M44 crank (83.5mm) + S52 pistons (86.4mm) = 1947cc. how much power over stock is that? seeing as its a 151cc gain, and you cant convert CC to HP, im puzzled.

M44 crank (83,5mm) + S52 pistons (86.4mm) = 1947cc
M42 crank (81.0mm) + M42 pistons (84.0mm) = 1796cc - right?

how would i find out what compression ratio i will end up with, and how much HP i will get?

My intentions are: m44 block + m44 crank + whichever conrods are better m42 or m44 + s52 pistons + m44 or m42 head (again, whichever is better) + MLS gasket + m42 intake manifold

**IF ITS POSSIBLE** as i am new to this m42 biznus.

MM claims a worked head for 6% better flow + 6mm valvetrain + Intake cam 272 degrees + exhaust cam 258 degrees + 87mm forged alusil pistons + 87mm moly rings + 138mm ultralite "i" beam rod 475 grams + main bearings 360 degree thrust and oiling groove + m47 88mm forged steel crank gets you 205 HP to the crank with a 11.5:1 compression, which is a no-go for boost correct?

kenika65 · « **Reply #1 on:** October 20, 2008, 10:55:50 PM »

You have a lot of research to do so get to searching.

hesgone2fast · « **Reply #2 on:** October 21, 2008, 03:25:23 AM »

hi there, I use an online engine calculator:
http://home.earthlink.net/~jalby/puter.htm

No one knows exactly how much power over stock will come out, but by increasing the stroke, for sure you will get more torque. By increasing general displacement you will definetely get more power ( about power, there�s no replacement for displacement...).
You can�t know exactly how much power you have until dynoed.

This combo has been done on a few engines, and very good results were achieved. I have finished my project:M42 block, M47 crank, S52 pistons, 2064cc, 11,5:1 CR. I only have 250kms on it since built, therefore I can�t put it on a dyno yet, but I can definetely feel more torque and power from low rpms.
About your project, don�t expect massive gains, since you are basically having a stock engine with bigger pistons, which would give you 1900cc.I guess no more than 15hp correctly tuned...

About MM�s engine, is basically the same as mine. 11,5:1 is too high for boost, but mounting M3 rods (E36 S52)which are 135mm in lenght, and same bearing sizes as the M42, would lower the CR to about 8,5:1, which is perfect for boost.

There are lots of post about this, so do a little research.
Good luck!

nuvolarossa · « **Reply #3 on:** October 21, 2008, 04:42:17 AM »

me prefere this: http://www.not2fast.com/turbo/compression/compression.shtml

all the options and it can calculate the dynamic CR too if you need