New M20 Head Gasket Option

[AWDBOB]

Hey R3V-

I know there has been a good bit of discussion on the availability of quality M20 headgaskets now that the Goetze gaskets went away and the Genuine gaskets are supposedly being made by VR now.

A Corteco option popped up recently, and appears to be better than the Elring, more similar to the no longer available Goetze gasket.

I bought a couple and will be assembling a motor with one soon.

I could only find them via FCPEuro.

Hope this helps-

https://www.fcpeuro.com/products/bmw-cylinder-head-gasket-corteco-11121722737-cto-83414628

[It's Soda Not Pop]

I thought the Goetze gaskets were just out of stock everywhere. They quit making them? On a 2002 forum those guys said corteco gasket was a good gasket.

[AWDBOB]

I thought the Goetze gaskets were just out of stock everywhere. They quit making them? On a 2002 forum those guys said corteco gasket was a good gasket.

Goetze M20 head gaskets are long gone. They were also the supplier for the genuine BMW gaskets, and someone else is making them now (supposedly VR according to my dealer source).

Yes, Corteco is the OEM for a lot of BMW stuff, which is why it is exciting to have this option so we're not all relying on Elring anymore.

[McGyver]

This is good to know.

Is the general consensus that a good composite gasket is better than using an MLS? This motor will be NA 9:0 CR, and then will get boosted to 10-15psi.

[AWDBOB]

This is good to know.

Is the general consensus that a good composite gasket is better than using an MLS? This motor will be NA 9:0 CR, and then will get boosted to 10-15psi.

MLS gaskets are tricky, as they requires a specific RA finish on the head and block to seal. Most people that use MLS gaskets don't achieve said finish, so they don't seal well.

If you're not shooting for the moon with boost, I'd say a good stock gasket with ARPs is the way to go. Most of my buddies that do racecar things with their turbo m20s do an oring HG setup, but I don't think thats necessary on a street car.

[McGyver]

Yeah, that was my understanding. Copper spray can help with sealing on an MLS, but a lot of people have issues with sealing. I had the head resurfaced and the block is going to be decked as well, so I might be in the right roughness range. All that being said, low boost with studs was my plan. 300-350whp would probably be excessive for a street car.

When do you think you'll have your motor put together?

[AWDBOB]

Yeah, that was my understanding. Copper spray can help with sealing on an MLS, but a lot of people have issues with sealing. I had the head resurfaced and the block is going to be decked as well, so I might be in the right roughness range. All that being said, low boost with studs was my plan. 300-350whp would probably be excessive for a street car.

When do you think you'll have your motor put together?

In your case it sounds like a good stock style gasket and studs is the ticket.

My new 2.7 is already in the car and running! It's at the fab shop getting a custom header built.

[McGyver]

In your case it sounds like a good stock style gasket and studs is the ticket.

My new 2.7 is already in the car and running! It's at the fab shop getting a custom header built.

What did you do for the 2.7? Does it feel different compared to a stock m20b25?

I have my stuff at a local machine shop. I plan on doing ForcedFirebird's recipe: 84mm block, eta crank and rods, 325i pistons, and 885 head, and deck the block 2mm.

[AWDBOB]

What did you do for the 2.7? Does it feel different compared to a stock m20b25?

I have my stuff at a local machine shop. I plan on doing ForcedFirebird's recipe: 84mm block, eta crank and rods, 325i pistons, and 885 head, and deck the block 2mm.

That is what I do as well. I've done 3 now like that and they rip! My low compression one dyno'd 160/160 on a low reading dyno with stock cam and stock exhaust. The only recommendation I would have is to get the 84.5mm stock mahle pistons (11251714810), as I've found most used i pistons are pretty worn, and it is harder than you'd think to find perfect block that's stock bore and isn't ovaled or distorted.

[E30SPDFRK]

I have used all the commonly available gaskets (Corteco, Victor Reinz, Elring, OEM BMW) and found they all start leaking oil externally after about a year. I've been putting a thin smear of Loctite 518 anaerobic sealant on both sides of the gasket around the oil passages recently and have yet to have a leak pop up. We average around one M20 headgasket a month here at the shop, so this is a pretty big sample size.

[McGyver]

I've got 12 pistons for the shop to choose from, so I'm hoping there are 6 good ones in there. The block seems so have 2-3 thou of clearance compared to the diameter of a random piston and I believe the limit for a rebuild is 4.7 thou. So I'm hoping I can get away with just a hone and the parts I have.

It's good to know the 84.5mm pistons are available. This would allow me to use the other stuff I already have. However, if I need to buy an oversized piston to make the 2.7 work, wouldn't it make sense to just jump to a 2.9 stroker with an 84mm crank, 85mm pistons, and my stock 135mm rods?

I appreciate the advice E30SPDFRK! I'll definitely put a little 518 on it when I assemble the engine!

[moatilliatta]

I'm starting to think MLS leak from between the multi layers of steel... So a perfect mirror finish will still leak..

This is what happens when people consistently buy the cheaper VR gasket...

[McGyver]

I've heard that MLS should always be taken apart so each layer can be sprayed with copper on both sides to prevent leaks. (based on YouTube car shows)

For the cost of a gasket and the time it takes to change one, it seems like composite is the better choice for most m20 applications. Assuming a quality gasket is used.

[AWDBOB]

I've got 12 pistons for the shop to choose from, so I'm hoping there are 6 good ones in there. The block seems so have 2-3 thou of clearance compared to the diameter of a random piston and I believe the limit for a rebuild is 4.7 thou. So I'm hoping I can get away with just a hone and the parts I have.

It's good to know the 84.5mm pistons are available. This would allow me to use the other stuff I already have. However, if I need to buy an oversized piston to make the 2.7 work, wouldn't it make sense to just jump to a 2.9 stroker with an 84mm crank, 85mm pistons, and my stock 135mm rods?

Awesome, sounds like you'll be fine with what you've got!

Short:

For me, no. For some, yes.

Long: After building my 3.1L and seeing mediocre results I went to the other end of the spectrum and questioned how cheap could I build one of these 2.7s for and what kind of power do they make? The 2.7 so far has felt incredible in the car for the cost difference (and made almost the same power as a buddies similar 3L M20).

So for me, since I have 325e crank/rods for days and an affordable high quality (but slow, can't have all 3 lol) machine shop, doing a 2.9 requires the same change in ingredients as a 3-3.1L, aka changes the entire build. Vs buying $600 pistons is just buying pistons and the build otherwise stays the same and uses all the stuff I already have in bulk on hand.

If you have 0 parts on hand and need to buy a block, crank, rods, etc etc I could definitely see how it would feel similar to do a bigger stroke option. Also $600 pistons vs $1300-1400 pistons is not a small delta. But I definitely see it both ways. For me, the motivation was way less max effort, and way more "how can i use what i have here to put great feeling engines together on the cheap".

It's also worth nothing that we're comparing the 2.7 with proven results to the general varied results of the bigger stroke detonating M20s out there that have invisible dyno sheets. This of course excludes the outliers like Digger, Rama, Grootys R&R, etc. I spent alllll the money on my 3.1 and it made like 190whp. If a 2.7 that costs a 1/10 of the money makes 175whp, I'll take that option all day long! So definitely some bias at play as well.

Also worth noting that ForcedFirebirds highest M20 dyno was on a 2.5 haha, and that was due to baller cylinder head work.

[McGyver]

Thanks AWDBOB, all of that makes a ton of sense to me. It really is a slippery slope.

I originally bought a seta engine with the intent of throwing an 885 head on it and boosting it, but the block wasn't great and at least 1 piston was shot. So then I planned to use the good parts to build a 2.7i stroker. The crank, head, and connecting rods were machined, but then I had to move across country and abandon the block. Now I have a new block (supposedly from the e30 vert that drove down the rocky steps), but I wasn't 100% sure of the block or pistons.

Part of me thinks, "might as well go bigger if I need to buy new pistons." At the same time, the parts I have should feel great off boost and get better at 5-15 psi. Its gonna have a 280/274 cam and I'm going to run it NA for a while, so I'll have Racing Dynamics headers and probably use a custom MarkD chip. Eventually it will run MS2, and then get the turbo.

All in all, it should make really decent power without going to a larger displacement. I'm hoping...