O-ring my head or MLS HG?

[Guest FrantiC]

Coming across a hurdle in my e30 turbo build.. Need some opinions on what would be better..

I could either:

O-ring the HEAD, Use stock HG and ARP headtuds. Compression of around 9.5-9.6:1

OR

MLS 0.140" (the thickest) HG + ARP headstuds, Thus having a lower CR and being more turbo friendly.

MLS costs more. O-ringing the head was my original plan, Turns out the machine shop my head is at have never done an alloy head before so need alot of info before they attempt to do it. This is where I tryed getting info and was told I am better off to do the block but the block is in the car already and waiting for the head to go back on, Don't really wanna pull it out again (would have to be pulled apart too).. But they can do the head if I get the info like how deep and what wire to use..

So MLS HG, or O-Ring ? Anybody know what sort of CR I would have with the 0.140" MLS?

Edited May 9, 2009 by FrantiC

[tibbs.james 1]

What is the cost in an O-Ring Vs using a MLS HG ?

You could even find that using a Genuine BMW HG + ARP head stud kit is enough.

By the time you are getting to giving the HG a hard time you would be about ready to upgrade to some forged pistons i would think.

At least on Boosted Nissan motors this seems the case.

[Guest FrantiC]

What is the cost in an O-Ring Vs using a MLS HG ?

You could even find that using a Genuine BMW HG + ARP head stud kit is enough.

By the time you are getting to giving the HG a hard time you would be about ready to upgrade to some forged pistons i would think.

At least on Boosted Nissan motors this seems the case.

Nah I wouldn't risk it ae, I hope to run close to 1bar of boost. Would rather do it once and not have to deal with a warped head or something. And the internals of an m20 can be pushed to close to 500hp and be fine, plenty of guys in the U.S with the same setups.

I can get the had done for $300. MLS HG would be around $450.

I am thinking it would probably be my best intrest to have lower compression to be more turbo friendly but yeah..

Edited May 9, 2009 by FrantiC

[CamB 48]

I work out a 0.140" would change c/r by about 1.5 (heaps). 8:1 pretty boost friendly.

Edited May 9, 2009 by CamB

[Guest FrantiC]

That's way lower, What would be a good number ? I imagine 8.1 is quite low so when not in boost it would be pretty poor, right?

VAC Motorsports have either a 0.070", 0.080", 0.980", 0.120" and 0.140". As well as custom.

What would be the right thickness for me ? I would like something like around 8.5 to 8.8 CR.

Take into consideration the head is to be decked, raising compression. Not exactly sure how much they will deck it though. AFAIK, 0.070" is the same as stock HG, If I am not mistaken?

[topcat 11]

talk to the guys at gaskets unlimited.they make anything you want.

cost me 250$.

i used one of their creations (40% thicker over oem standard), installed a set of used headbolts.ran

1 bar,no problems.m30b35

dropping down to 8.something compression is low.really pissy off boost.

i'd be comfortable with running 9's cr and 15psi.

its all up to the tuners,afterall

m

[Guest FrantiC]

I googled, Is it that place that do fridges and cooking equipment gaskets ??

I will be self tuning using MegaSquirt.

[topcat 11]

I googled, Is it that place that do fridges and cooking equipment gaskets ??

I will be self tuning using MegaSquirt.

their based in Kumeu,west auckland

[CamB 48]

You need to measure to properly work out compression ratio, especially if you're getting the head decked:

- measure the amount the pistons are above/below the top of the block

- work out what size the dome is (can find this out online if you know what the pistons are)

- bore, stroke

- measure (cc) the head

- plug details into a spreadsheet with the gasket thickness

I'd have a go at working it out for you, but I'd note that internet research said my 318i M10 head would be 63cc, but it actually measured at 58.5cc - this made a difference of 0.75:1, so I am glad I had it measured... (I suspect the head had been skimmed before).

I found conflicting evidence on the thickness of the stock gasket. I ended up with 0.051" or 1.3mm but don't trust that - measure your gasket you took off.

[Guest FrantiC]

Gasket I took off was a victor reinz one I had put on like 4 months ago when I first put together the 885 head and ETA bottem end.

I will have to wait until I get the head back for the cc measurement of the head.. But yeah I am getting it rebuilt after they test it for cracks etc, new valve guides, valve seats, welded coolant passages around the head for strength. Then I will figure everyuthing out and see what thickness MLS HG to get.