It is gasket crush, not bolt stretch into the plastic range on a 928 that requires a retorque with MLS gaskets.

 

Yes. My point exactly.

 

I'm not "Carl-bashing"....you are way too good at doing that, on your own.

Your product failures and warranty policies have certainly scared away almost anyone that can read, on this Forum....without any help from anyone else.

I'm strickly pointing out how utterly futile it is to stick an entire engine in an "oven" and think that heating it up a couple of times is going to make it "properly heat cycled". What an absolute crock of crap!

That's absolutely ignorant suggestion....and I'd tell anyone that suggested this, the same thing.

The block and the heads, in an oven, are going to heat up at the same rate. There is not going to be enough heat differentlial between the two pieces to do anything to the head gasket.

In a "real" break-in situation, the block is actually much cooler than the heads, which get water after it is run through the block (thus is much hotter) and has the heat of combustion transfered into them.

This is the temperature differential that makes torque values "change".

Seriously....you could get almost the exact same temperature differential that you are getting in your "oven" during a Wisconsin Winter storm...without the cost of the electricity. Save yourself some money and leave the engine out one cold night and bring it back into the shop....same thing!

BTW...I'm actually really confused by some of your statements. I thought you "invented" your own head gaskets (the ones that sit crooked on the locating dowels) so that you didn't need to use MLS gaskets? Now you are saying that you "cook" your engines in an oven....but only because of the MLS gaskets. Are you saying you don't use your own head gaskets on your own engines??? Earlier in this thread, you suggested that Ducman could/should use "your" head gaskets. So what do you suggest? MLS and "cooking" or "your" head gasket? Can you clarify this?

 

Greg, I disagree with your assessment.

The laws of physics still apply, even in SoCal.

If you heat the aluminum block and heads to operating temperature, they will expand, and they do add the additional crush to the MLS head gasket that we are looking for.

I do agree it is not the same as the heat sources and heat localization that occurs when the engine is running, as I have already said. But, for purposes of re-torquing the heads, it works well and I have the results with MLS head gaskets to prove it.

I would not have mentioned it if I had not already done it myself and it works. We have not had to retorque a MLS head gasket since we started doing this, and we have had zero MLS head gasket failures or leaks. We run 17 psi of boost, produce 950 HP, and run 21 psi of water pressure in the cooling system on our own race car.

None of my customers with MLS head gaskets have had a leak either.

 

If you read about the 3 head gaskets we offer for the 928 here:
www.928engine.com

they have very specific applications. I did create the Graphite-composite steel and the Silicone-coated Copper gaskets for the 928. Of course I did not invent the Cometic MLS head gasket.

I do use my GCS head gaskets on my supercharged 1991 928 GT with 506 HP. They work well.

I did recommend the GCS head gasket for the application Ducman stated. They would be a good choice. They do not require perfect head or deck surfaces (as the MLS head gaskets do) and have greater substrate strength than the Victor-Reinz paper gaskets. When the water-resistant coating on a paper gasket is penetrated, they turn to mush and loose all their strength. The Graphite-composite steel gaskets do not do that.

I do not recommend the use of MLS gaskets without taking a skim cut on the block deck and decking the heads to assure absolute flatness. You really have to have a reason to need MLS gaskets, and at high temp and high boost, my Bonneville motor has that reason.

Again: each of the 3 gaskets have unique properties. Spend a moment reading instead of criticizing and you would know that.

 

Yeah. Reading comprehension has always been one of my big downfalls.

I now understand my confusion and appreciate you taking the time to explain it to me, slowly.

There for a minute, I thought Ducman was asking for a head gasket that would work with boost and you suggested using "your custom made gasket".

Now I completely see your point.

You personally use a different gasket than your custom gasket, with your own engine that makes boost, but it should be fine for Ducman.

Makes perfect sense, now.

 

There are low-boost and high boost applications.

The GCS gasket works fine for low-boost applications, as it was designed to do.

I use both gasket models in my cars. The GCS gasket in my supercharged 1991, the MLS gasket in my supercharged race car.

 

To summarize and get back to the original post, I would say we have covered most of the requirements.

-You can use a stock gasket but detonation will kill it and as Greg said it is better to catch it early by having the correct size of fuse (stock gasket) in there.

-The stock gasket has been proven to handle high boost.

-The head tightening procedure and! Bolt/Stud are a critical part when it comes to their yield, stretch and rate of expansion.

Did I miss anything

Brad

 

The "fuse" concept is an opinion, not a fact. Opinions on that theory vary. I dont agree with the "fuse" opinion for this reason:

Detonation will kill ALL head gaskets, and break piston ring lands, and possibly crack the rings, and possibly crack the cylinder walls. Detonation is so severe an impact to the parts involved that it is beyond any head gasket or our rotating assemblies. In other words - detonation is beyond any head gasket or head gasket discussion. It simply cannot be allowed no matter which gasket is used.

IMHO - by the time the stock head gasket fails due to detonation, other parts are likely already damaged -especially if we are talking about the relatively weak stock cast Mahle pistons. (Very good cast pistons, to be sure, but not as strong as forged pistons none-the-less)

So, if you are really concerned about detonation for some reason (presumably engine mods), you should have in place a better/faster detonation preventative or discovery indicator than using the blown head gasket as your first sign of trouble.

 

I had my cylinder towers welded to the head before i put the bottom half of the block on...no head gasket. So there!