• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Snake Oil?

Interesting. I know the dimples help air flow better in the manifold and head ports. One guy dimpled his exh manifold & up pipes and saw improvements.
Guessing someone tried pistons because- why not, and it works.
Would be a good business decision for the military if all of a sudden the HMMVW started getting better mileage. Not that uncle sam demonstrates that saving money means much.

Think of all the extra funding that would become available for other things like... ...take your pick.
Yeah, Rubber duck bought parts and is having some components made so they can complete the last of the p400s to be sold as complete assemblies. Idk if there is any expected parts left over. I was really hoping to get a set of heads. I’m quite sure I can’t get an engine $$$

He is also the one who got those wazoo ds4. I was told they were using only db2 for testing, but they had some oddball ds4 that required a different computer and program iirc. This was different than the cat computer that was used in the 2004 hummers that went away from the normal ecm used in all other ds4 6.5.

There has been talk of a different engine for hmmwvs for some time. They also spent a lot of time at gep working on di heads and fuel system, not sure that came through or not.

Really sad that as soon as the 6.5 issues are understood and the p400 corrected most of it, they get pushed aside because the assembly line had quality control like a 1930’s assembly line allowing flashing everywhere and unbalanced components worse than any v8 gas engine ever made. SMH
Last edited:
You would think that since newer hmmwvs will get transferred to NG and reserve units as the Army replaces them, that GEP would continue building them to keep those units running until they are all phased out. The techs in those units know the 6.5 in and out and wouldn't have to be retrained in the most tense of times.