Help, what's the best way to reduce compression?

[Turis]

Hi guys, thinking to fit a turbo on my m50 2.5, what's the best way to reduce the compression? As i heard the best copression ratio is about 8:1, any ideas how can i get that? i don't aim very high, would like to have something around 300-350hp and simillar torque. please let me know all possible ways to do that, thanks

[Highboosted]

Options:

1. Thicker head gasket, won't get you down THAT far, but will help enough to work for your goals.

2. Low comp pistons. The "right" way. Forged low comp pistons are lots stronger than stock to handle "tuning mishaps". negitive is that your doing alot of work to put them in.

[Turis]

Originally Posted by Highboosted

Options:

1. Thicker head gasket, won't get you down THAT far, but will help enough to work for your goals.

2. Low comp pistons. The "right" way. Forged low comp pistons are lots stronger than stock to handle "tuning mishaps". negitive is that your doing alot of work to put them in.

i'm not afraid of doing a lot of work, as the engine is out of the car and striped. i'm changing piston rings and main bearings, that's why i want to know all possibilities how to reduce the compression before i'll collect the engine. pistons sounds good, but i don't think i'll afford them as i presume they cost a lot, am i wrong? do you know where i should look for them if i'll save enough money, i'm not in a rush doing this project, want to know everything what's need doing for that and play with my finances how far can i go with stock internals? how much pressure i can push it to?

[bmwpowere36]

you can make good power with just headgasket and arp studs 500+whp

[Turis]

Originally Posted by bmwpowere36

you can make good power with just headgasket and arp studs 500+whp

how thick the headgasket should be? thanks

[boosted///36M]

.140 mls drops compression on stock 10.5:1 to 8.9:1

Is your engine a M50nv?

[Turis]

Originally Posted by boosted///36M

.140 mls drops compression on stock 10.5:1 to 8.9:1

Is your engine a M50nv?

my engine is m50 single vanos, does it make any difference? as far as i'm aware you can take the vanos off if you want to.

[RacerJames666]

run without rings!
(sorry couldnt resist...ill behave now)

[Highboosted]

Originally Posted by RacerJames666

run without rings!
(sorry couldnt resist...ill behave now)

BWAHAHAH

[rt turbo]

Originally Posted by Turis

i'm not afraid of doing a lot of work, as the engine is out of the car and striped. i'm changing piston rings and main bearings, that's why i want to know all possibilities how to reduce the compression before i'll collect the engine. pistons sounds good, but i don't think i'll afford them as i presume they cost a lot, am i wrong? do you know where i should look for them if i'll save enough money, i'm not in a rush doing this project, want to know everything what's need doing for that and play with my finances how far can i go with stock internals? how much pressure i can push it to?

Wiseco 8.7:1 compression pistons- $570 + $110 ring sets. Thats about the best price new. Needs a very slight overbore. get a MLS .070 head gasket and arp head studs. also, since its apart might as well get eagle esp rods for $485. that a bullet proof combo for not much moola.

[boosted///36M]

Originally Posted by Turis

my engine is m50 single vanos, does it make any difference? as far as i'm aware you can take the vanos off if you want to.

difference is the the nv is ~10:1, not 10.5:1, so a .140 lowers the compression to ~8.4:1

[mattytm3]

If your goal is only 350whp i think that thicker head gasket and arp studs will be efficient for your build especially for street. But cutting ends on a turbo install sometimes can be fatal. Its nice to have the right parts for what you are trying to achieve. Since you already are replacing the rings it would be in your best intrest to go with low Cp pistons, rings, rods and give yourself a solid, reliable platform.

[Turis]

thanks for the info guys, I’ve already ordered wiseco low compression pistons and rings, and arp head studs. will take a long time till I’ll get them as the company in US not shipping parts to UK as we have a "local warehouse" so I meant to buy from them, but the price is double can you imagine that? that's how bad is in the UK. so I asked my friend who lives in US to buy them for me and send to UK. I think the car should be running in couple months. I’ll leave the old rods for the moment as can't afford the new ones, I also have a 328 rods, I think they are slightly lighter(not sure) and shorter, would that be a good idea to use those? as the are shorter, maybe I would get away without thicker head gasket? I’ll let you know if it works and how it works