HMMWV Manifolds

[bbtlr3]

I was wondering if anyone has experimented with HMMWV intake and exhaust manifolds. I have heard that the intake will help improve flow. Will the exhaust manifolds help as well. I have an 82 K20 Suburban ya think they would help improve airflow?

[john8662]

Welcome to TDP forums!

Because you already have a K20 you probably already have the HD emissions engine, which is the "J" series 6.2.

There are a few differences that I am aware of for the Hummer 6.2 and the civilian 6.2 in regards to intake and exhaust.

The Hummer 6.2 intake is an open plenum intake in that it is wide open intake to the runners in the head. The problems in using the hummer intake involve the air cleaner housing bolting positions and that there is no casting holes to bolt the factory secondary fuel filter to. The factory 6.2 HD intake (that you probably already have) is a dual plane intake, that just separates 4 of the runners from the others. The dual plane intake is a very good flowing intake manifold, and is wide open as well. The other intake that could be present is the "C" series LD emissions intake, this manifold is restricted because it has an EGR valve present in the middle.

As for the exhaust, I haven't really dealt with Hummer exhaust, but I think they use headers, which could possibly flow better. I think that you're going to run into fitment issues with the headers though.

There are a couple of things that can be done besides swapping out parts. You can construct some kind of air intake tubing into the air cleaner housing that will get more air to the filter. The air filter housing is going to be your largest restrictions if you've already got the HD intake. The hole going into the housing needs to be enlarged and modified, or make a snorkel for it.

Do some searches on the forum and see what pops up. There is a search engine built into the forum that is located to the right of the chevy truck above, and is the second text item.

[bbtlr3]

Thanks for the help. I will look and see if I have the EGR or not. I will look at the air filter housing and see what I can make happen with that. Thanks again

[85-m1028]

you can buy the intake horn or manifold cover from hmmwv supliers they go for about 150-180 dollars, and make an air box for cool air. These manifolds will net you a little more torque I've heard, and can quiet the intake noise! any 88-92 HD intake is single plane but the top is taller so you can fit your stock air box

ps. I cut two big rectangles out of my stock air box in the beginning but it was very loud in the cab