What are the best plenum gaskets?

[MuRCieLaGo]

Hi,

'91 ZR-1.

There's 4 different plenum gaskets available for the ZR-1. 4... I'm a bit lost now. Which gaskets are THE BEST?

[Gunny]

Poll notwithstanding ... why don't you contact Jerry directly? He is one of the most stand-up guys in the entire ZR-1 community, is a ZR-1 owner, and, recognizing the need for quality parts for our cars, has stepped in and developed those very parts.

I'm sure if you ask Jerry the differences of the plenum gaskets listed in your poll as well as any other gaskets that might be available, you will get a straight answer so that you can make a decision on what's best for your needs.

[MuRCieLaGo]

I didn't want to bug him that's why, and I thought the information would be useful for ZR-1 owners, we will all need plenum gaskets at some point...

[Karl]

The thicker gasket with extra material is "suppose to" help block heat transfer to the upper plenum, especially with the coolant bypass.

Anyone know if they make those a/o engineering or who ever it was, upper plenum spacers?

[A26B]

Plenum Gasket Comparison

OEM:
Good choice if the plenum & injector housings have not been ported. If the engine is ported, gaskets will require extensive hand cutting to enlarge & match to ports.
Value is not so good as evidenced by eBay listings today:
1 single gasket @ $59.99,
Set of 2 gaskets @ $189.96
1 single gasket @ $97.81

Jerrys Gaskets 1/32" $23.50/set http://www.jerrysgaskets.com/gasket-...32-90-95-11d2/

This is our basic plenum gasket which can be used on both stock, un-ported engines and also on ported engines up to 37.5mm. Precision die-cut tooling, dimensioned from actual engine drawings, not copied from a gasket.

This is our highest selling plenum gasket

Jerrys Gaskets 3/64" "50%Thicker" $28.50/set http://www.jerrysgaskets.com/gasket-...64-90-95-11d3/

Cut with the same tooling and gasket material as the standard 1/32" gasket, just thicker. The reason behind this plenum gasket was aid in sealing the plenum/injector housing interface on engines having some degree off damage to the surfaces, such as warpage or stray tool marks from porting. The gasket material has 12~20% compressibility.

Essentially, this means the gasket will conform to mating surface irregularities up to 20% of the gaskets un-compressed thickness. So, for the 1/32" gasket, that is 20% x 0.03125" = .006". For the "50% Thicker" gasket, it's directly proportional to thickness @ .009,"

While we do not recommend re-using gaskets, many of our customers do so successfully. Being 50% thicker, makes it more resistant to tearing.

The "Thicker" gasket continues to gain in popularity and is not far behind the standard plenum gasket.

Both 1/32" Standard & 50% thicker
Gasket Material: The material we use has a nitrile-butadeine (rubber) binder has very good recovery @ 45% min, meaning it will expand back to much of it's original thickness. Cheap, silicone treated paper gaskets will not do this and do not have a high coefficient of friction to stay in place like our gaskets do.

Early Color Gaskets $28.00/set http://www.jerrysgaskets.com/gasket-...or-90-95-11b3/
We have a number of customers who have their ZR-1's judged by NCRS. Some incurred scoring deductions for the dark gray plenum gasket, so we had plenum gaskets produced from a different material which matched the color of the "Early" engines. I don't know where the cutoff actually ocurred, but probably in the 90~92 models.

The material used is good material and up to the task, but not as good as our primary choice for LT5 gaskets.


General Information

Myth: Thicker is better! Not necessarily. Gaskets seal differential pressure. Leakage will occur from high pressure to low pressure. The force(F) against the gasket is directly proportional to the surface area(A) exposed to the differential pressure(P). F = P x A. A simple comparison to a hydraulic press. Given the same pressure of 100psi against a hydraulic ram with a piston size of 2" vs 3", the force exerted by the press is 314 lbs vs 707 lbs. Both the 1/32" standard gasket & the 50% thicker gasket are made from the same gasket material and have the same friction coefficient & clamping force applied. The thinner gasket will be less likely to be forced out of position by differential pressure.

What about gasket sealants? We get this question frequently and as you would expect, there are points, counterpoints, personal preference and we have our own.

1. Most important: Mating surfaces should be carefully cleaned of all old gasket material and then wiped down with a no-residue cleaner. We recommend cheap, spray brake cleaner. Spray it on a rag & wipe the surfaces clean before installing the gasket. This makes for better retention of the gasket.

2. Sealants: In the vast majority of applications, I do not recommend the use of sealants with our gaskets. If the surfaces are undamaged, properly cleaned, and the components properly assembled, our gaskets do not need sealants. The nitrile butadiene (rubber) binder will hold it in place.

There is one exception, and that is for ported engines at the injector housing/cylinder head interface, around the cooling port between the front two cylinders on both banks. There is very little left of the surface between the cooling port & intake runners. At operating conditions the differential pressure is very high (16psi coolant + up to 20" vacuum intake port). As added insurance, the use of an adhesive/sealant like Permatex is recommended. Apply only a very thin film, just around the coolant port, to both sides of the gasket.

I hope this answers most of your questions. Ask away if questions remain.

[efnfast]

Nice write up Jerry. Great info.

[Dynomite]

Jerry......... Did you say Permatex?

[A26B]

Originally Posted by Dynomite

Jerry......... Did you say Permatex?

I'm still choking on that a little. Wouldn't you know Mr Permatex hisself would notice that! Don't you dip chips in the stuff?

[GOLDCYLON]

Jerry's thicker gaskets 3/64th as you can reuse em. End of debate. GC

[MuRCieLaGo]

Thanks a lot for the complete answer Jerry! I'll try the 3/64'' for now. Will order soon.