Mls thickness ?

[M3blitkrieg]

I'm building the 328 into a 3.0l stroker just to compare with my s50 which I'm also building for boost right now. Question is what thickness mls gasket is appropriate for the b30. Intend on boost deez nuts off for prez, so thanks in advance for in depth info.

[pbonsalb]

If you want to run high boost on 93 pump gas you need the thickest gasket. If you can afford only an MLS use a 0.140. Ideally, buy a spacer and cut ring gasket from CES. Cost is twice as much but they seal better over time. If running E85 you don’t need to lower compression but a cutring (without spacer) would help handle the added cylinder pressure.

[M3blitkrieg]

I thoaght cut ring gaskets damage the head and block? Secondly, what's considered high boost? It seems every guy in the forum has 20+lbs.

What's the limits of the .140 mls?

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But I need pump gas. 93.

[pbonsalb]

Cutring gaskets do cut into the head a tiny bit but not the block. They hold better than an MLS and last longer. Up to you. If you are actually rebuilding the entire long block I would definitely put the good parts on. If you don’t mind redoing things in a year or 2 or 3 if you are lucky then use the MLS. Either should be with ARPs.

Boost really depends on the turbo - is it a big one or a little one? I ran up to 20 psi from a GT3582R for a few years on an S52 with 0.140 MLS — about 20k miles and it held but my tune was very good and I also ran water/meth and 93 pump. I now use the cutring. Stock rods and pistons may not be reliable much past 500 rwhp and 500 lbs rwtq. People have made more occasionally but it seems like those examples go boom before long. Fully built motors have made 1000 rwhp but that sort of power comes on race gas and with a lot of compromises and traction and driveline reliability are issues. I really think around 500 rwhp is the happy spot — more costs a lot.

[M3blitkrieg]

Yea, our ideas of high boost are different.
I won't be making race car. Just more nuts of a street car. Looking for a stable performance DD. Run pump gas that's not too crazy of a guzzler, and still eat the dueche in a new car.

[spyderg0d]

Bobs more experienced than I. I'm going mls. But I know il be opening the engine up for inspection at least a few times within a couple years.

[pbonsalb]

Why pull the cylinder head a few times to inspect? Lots of work, some money even if your time has little value and totally unnecessary if you do things right to start with. I would run another mls only if I knew I was not doing things right—like I could not afford to have the short block or head I wanted now but believed I could in a year or two and had the rest of the parts to get boosted now.

[spyderg0d]

My reasons are irrelevant and my own.

[pbonsalb]

This is the internet so don’t get too sensitive. If you post something that seems stupid to everyone else but you and don’t offer any explanation, expect some comments. And if your reasons are actually irrelevant, then you did not need to make a post at all about your plans since what you are doing won’t matter to anyone else.

[Butters Stoch]

Bobs more experienced than I. I'm going mls. But I know il be opening the engine up for inspection at least a few times within a couple years.

Heads can only be cut so many times. Using a MLS gasket can be done. I had no problems for many miles. BUT..... The margin of error reduces drastically when using one. The head needs to be prepared properly, the RA finish is very important and also how its sealed. On top of that, the torque process of the cylinder head to block needs to be done precisely, also checked as the MLS gasket will settle over time.
As Pbonsalb mentioned, the cut ring and spacer is a much wiser choice for lowering compression. It holds extremely well, also allows for slight imperfections in the block and head w/o issues. Sure its an extra $250 but having to replace a MLS will cost you $400+. Unless your 1000% confident in your mechanical abilities, have a machine shop that is extremely precise and understands the severity of the finish then go with the Cutring/spacer.


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[M3blitkrieg]

Cut ring it is then.

[M3blitkrieg]

I just tore the engine down last night to see what is really needed. I ordered chain guide rails, arp stud set, knock sensors and everything else was close to 100%. All's I have to do is plastiguage the bearings and gap the new rings and the bottom is good to go.

However I see the copper gasket as my new question. I assume the cut ring doesn't lower compression by much. So would I be assuming correct that I need the copper spacer as well?

[pbonsalb]

If you want to lower compression, yes. If tuning for and using E85 only, no. I would definitely drop CR if running pump gas even if you think you will be happy with modest power. Almost everyone wants more later. This is the time to do it right.

[M3blitkrieg]

I just noticed the copper gasket deal doubles the price. $500 for the cut ring and the spacer! Wouldn't a copper spacer refute the idea of the cut ring as 1 side would only contact the copper? I feel like that's kinda much compared to the $60 oem gasket and the $200 mls that's already thicker.

But just for the sake of understanding. I see stock gaskets require 30 to 60 ra. So chances are a cleaned head is already good for an mls.
But I don't understand why the longevity of the mls is so limited? I doubt such a distinguished name brand would be notorious for faulty or ill made products. What's the give?

[pbonsalb]

The block is cast iron. Clamping force against it is enough. The cutring seals to the head. Yes, it costs twice as much as an MLS to lower compression. If you don’t mind doing the job twice, try the MLS. There are many of us who have been there and done that 5 or 10 year ago or more and we are running cutring now because it works better and lasts longer. And yes, we resurfaced our heads properly and used ARP studs. I had one 0.140MLS last 20k miles — that was pretty good and it was still good when I pulled it to build the motor. You might well be fixing something in a year or two that requires the head to come off — these cars are all 20 years old. But I run the cutring.

[spyderg0d]

See.. Didn't even have to say it.
Go the cheaper route first, then when you want to go big, $500 will be squat compared to the turbo and other stuff. Sometimes baby steps help you learn more in hand than by reading the book

[pbonsalb]

I started with the cheap route because it was all I could afford at the time, but I spent a lot more in the long run than if I had done it right from the start.

[jakermac]

If you decide to go .140" MLS, I have a brand new in the package Cometic for 84.5mm bore for a decent savings off the current going rate. PM me if interested.

[M3blitkrieg]

I have read up ALOT on mls and copper gaskets the past day or 2. I think the mls is a better solution. I'm confident I can make it work. Mostly, I'm sure I can learn to tune well enough before I go big boost that I won't run into something I can't handle to make a mls fail prematurely. The cons of a copper gasket on our engines is just as bad as an mls. Except its twice the price because its paired with the cut ring. It looks like there is no way around having to re-gasket the head eventually anyway. I'm absolutely posative that I will be able to make an mls last as long as I need.

[spyderg0d]

My only thing that I just realised and I never considered. How will the .140mls be while on the stock ecu and stroked? The ecu probably will be off from the displacement, but then the little drop in compression while still unboosted in the break in time might confuse it... Or would it run better because it will be closer to stock compression before you install the fi?

[pbonsalb]

I would not be concerned about the compression drop, but maybe the displacement increase would put the ECU out of its range.

[spyderg0d]

I know a 413 dme will handle it. But I haven't ever worked with the siemens on a stroke build. I think mister m52 said he ran 6lbs on a stock m52 dme. So that should be a bit more volume than a .2l displacement increase.

[spyderg0d]

I just found this thread pertaining to supercharged engines and headgasket. It look's like I will be set on a stock gasket until around 400hp. So I will just wait that time to invest in the mls instead of wasting the year of the mls run time on low boost.
http://www.bimmerforums.com/forum/sh...imits-on-a-S52
It sums up that supercharged engines do not have such a high peak of cylinder pressure as a turbo and hence the stock gasket will handle when accompanied with good tune.
At an online price of about $40 a head gasket, I won't have to worry about some stupid mistakes while learning to tune and blowing a head gasket! There's $200 saved for about a years time!

[M3blitkrieg]

You ROCK! I already bought the MLS. But I would rather do what you got planned. That takes a lot of stress off my shoulders worrying about screwing up the mls on install and throwing another $250 in the tiolet! At least il have 1 head job notch on my belt before I get crazy!

[pbonsalb]

I just found this thread pertaining to supercharged engines and headgasket. It look's like I will be set on a stock gasket until around 400hp. So I will just wait that time to invest in the mls instead of wasting the year of the mls run time on low boost.
http://www.bimmerforums.com/forum/sh...imits-on-a-S52
It sums up that supercharged engines do not have such a high peak of cylinder pressure as a turbo and hence the stock gasket will handle when accompanied with good tune.
At an online price of about $40 a head gasket, I won't have to worry about some stupid mistakes while learning to tune and blowing a head gasket! There's $200 saved for about a years time!

Centrifugal superchargers raise cylinder pressure less than positive displacement ones or turbos because centrifugals do not produce peak boost until redline.