e30 low conpression turbo engine

Post Fri Apr 17, 2009 8:56 pm

can anyone help with info on low conpression my m20 2.7 e30 as its turbo'd. with out spending loads of money thanx for help

Post Fri Apr 17, 2009 10:48 pm

Cheapest way And the wrong way is a extra thick head gasket and a adjustable cam pully for the timeing. Won't handle as much boost as you think.

The right way cost's and you have no choice, which is low comp pistons from j&r or another rep company...

Post Fri Apr 17, 2009 10:56 pm

hiya mark i stil dont understand wiy u cant use the standad blok with out ase much of the 2mm skimed of. I ges the pistons wood stil be the beter optshon if thay are desind for terbo

Post Sat Apr 18, 2009 1:41 am

you can also get a de-compression plate if you want to drop thr c/r

Post Sat Apr 18, 2009 9:47 am

cliff_costa wrote:hiya mark i stil dont understand wiy u cant use the standad blok with out ase much of the 2mm skimed of. I ges the pistons wood stil be the beter optshon if thay are desind for terbo

Ki passa Cliff.

It's weather you want your engine to run a sencible amount of boost and last. Or S**t it self after a while.

Post Sat Apr 18, 2009 8:07 pm

so its 81mm crank with 84 mm bores @ the stock 206mm deck height ? ( crowns 2mm down bore )

with a stock H/G thats around 7.9:1 on that capacity, plenty low for some serius boost ( 1 Bar +++ )

Turbo size is the key on these, what are you running ? how much boost ?

*post moved to FI BTW*

Post Fri Apr 24, 2009 1:23 pm

hiya ant so its the pistons for sereos bust then . By the way my 2.7 is in and runing chers for all the help and the chips working fine cant wate to run it in and chek the power

Post Sat Apr 25, 2009 9:21 pm

I just came back from a trip back home where I mapped a few different turbo e30 325i´s.

#1. 8.8 compression, oem headgasket + ARP bolts, HX35 , results - 1.5bar boost no problem
#2. 9.7 compression pistons + 0.140 MLS gasket(8.0:1 compression ratio), ARP bolts, T4 , results - 1.5bar boost no problem

Both totally easy to drive and go like mad stink when floored.,
Component selection is vital key to a successfull turbo system.
An even more vital key is the tuning. You can have the best parts in the world and bad tuning will kill them no matter how much they cost.

#1 is always have a HP goal to aim at. These guys where aiming at 400hp+
and both of these solutions worked out. When you have selected a HP target then it´s easier to ask what current compression ratio you have an work from there.

I have also noticed that decompression plates make almost fukk all difference to how good or bad a turbo engine breathes or how they behave. Sure it´s a big deal when you have no extra pressure trying to push in but overall, It´s totally fine to run without a 100% exact cam timing.