What happened with the P400 & is it really that good?

[Hummer Guy]

I done some reading last week on the different engines that came in the humvee & saw about the "P400" being the best one of them all which fixed all of the flaws of the original 6.5 & came with a stronger block than the GEP & 6500 Optimizer. From what I read, this engine was better than the 6500 Optimizer & produce 250 hp and 550 ft Ibs of torque. My question is why was this engine discontinued? Seems like this would've been a great engine to use in the armored units.

I see some of these actually were sold, if you have a P400, how do you like it & do you think it's worth it?

 

[Mogman]

The P400 had a girdle to strengthen the lower end and some other mods (some "claimed" mods are on all GEP engines like forged cranks)
If making 250HP (must be electronic, cannot do it with the DB2 IP) instead of 205HP which can be done with the DB2 IP GEP engine is important.
I guess they decided the market was not enough to sustain the extra cost of production.
They would be the pinnacle of the 6.2/6.5L Detroit line for sure, but again that in itself is not saying much, if you want to spend that kind of bucks do a Duramax/Allison conversion, totally different animal.

 

[TOBASH]

The P400 has better rods and pistons and knuckles, better lower end reinforcement, better water jackets, and mildly better nickel content. “Thetruckstop” is a website that can explain it better.

I have one of the last ones crated-up airtight, waiting for an engine to blow.

 

[Retiredwarhorses]

P400 was never a full production motor, as my distributor told me, they don’t even make an OEM oil dipstick for the motor.
They are Mfg discontinued…the issue for any owner will be is if you ever need any parts for the motor that are P400 specific, your SOL.