double stacked gaskets?

[ah1988ford]

just wondering, i read somewhere you can double stack gaskets on a 6.9 to lower the compression ration. is this a bad idea? i think it would be better than shaving my pistons ?

 

[icanfixall]

Not going to work. Who told you this info??? You may want to get help from someone else too. Please... If you attempt this "idea" post back how it ends up.

 

[Thewespaul]

It’s possible and is actually common in some sled pulling trucks, but you need a plate to sandwich in between the the two gaskets, but I would not recommend it in your 6.9

 

[Clb]

Not going to work. Who told you this info??? You may want to get help from someone else too. Please... If you attempt this "idea" post back how it ends up.

You boob generation
This went on during the stroker pan daze also.
Still does not last.

 

[austin92]

Isn’t Mel working on some kind of decompression gasket?


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[riotwarrior]

Then u have valve geometry problems...longer pushrods required

My thoughts...dont hodge podge it...

 

[Macrobb]

A Guy on FTE experimented with this - 3 layers of steel, 2 of gasket with actual fire rings spanning both sides.
I got a set for a beta-test:
1. My 7.3 hated them. Too little compression when cold. Lots of smoke, and I had to add a lot of timing advance to make it run acceptably.
2. Even with headstuds(and lots of Permatex copper spray) , I ran into leakage after 1,000 miles. (You might be able to prevent this with a re-torque, or maby not. Stock gaskets do not need a retorque)

You do not want to take this much off. You need compression for cold performance.

 

[Hydro-idi]

Lowering compression on a indirect injected diesel is typically not recommended. There’s no need to double stack gaskets on any engine. These engines need lots of compression for them to run well.
And why do you think you need to lower compression? If it’s because your adding a turbo, there’s no need to do that. This is a common misconception that somebody started a while ago and now everyone wants to believe it.
We typically advise that you shave .020 off the piston tops if you plan to run a hot cam.

 

[hesutton]

If you need lower compression height, I'd get a set of reduced compression height pistons rather than milling the crown off. Still have the stock swirl chamber (Ricardo cup) under the prechamber (milling the piston top will obviously change this area of the piston crown). Plus, you have the full thickness of material between the crown and wrist pin. Have seen scorched wrist pins on a few shaved piston IDI's. Barney's twin turbo 6.9 comes to mind.

That's what I used in my 6.9. Didn't want lower compression, but the block decks were machined 0.007 to get them flat again. That was putting my pistons too close to the head/valves with the addition of the typ4 cam. Mahle 0.010 reduced compression height pistons for the 6.9 with rings.. part number 144111WR. I think I paid $550 for a set.

Heath