P400 info

[Dkozi]

Anything anyone can tell me about a p400. What I can expect while installing, running, driving etc.

I'm quite familiar with 6.5s, have roughly 10 of them. (Lost count...)

Thanks

 

[Wreckinball67]

As far as I know they are no longer available from General Engine Products (GEP). If installed in 4x4 truck you have to replace the oil pan since the bottom girdle takes up room. Supposed to be built very strong...wished I had one.

 

[Dkozi]

As far as I know they are no longer available from General Engine Products (GEP). If installed in 4x4 truck you have to replace the oil pan since the bottom girdle takes up room. Supposed to be built very strong...wished I had one.

Here it is, sitting on my forklift

 

[Will L.]

If you are looking for one- good luck.
If you have one - woo hoo.

What are you installing it in becomes a question. A hummer/hmmwv no changes required. In a gmt400 you need a modified oil pan.

Everything else in detail about mega-amazing-ness others here are better at posting links to those threads. I am horrible at searches.

ABSOLUTELY NO WAY I would install it without balancing the lower rotating assembly,
Clean up flashing, and having rings sent to be gapless and having camshaft and main/rod bearings coated.

So hard to get them now, make sure it runs for ever with those simple improvements.

@Twisted Steel Performance here has done extensive work on head flowing, on p400 heads if you are going for performance.

 

[Will L.]

Oh, i forgot to say- that looks horrible and you don’t want it. So just let me know where to come pick it up for you and I will throw it away for you. Hahaha

Please, story time about the lucky rig this goes into?

 

[DieselAmateur]

The P400 is externally the same as every 6.5- same bolt pattern for manifolds, accessories, etc. Except of course, for the bottom girdle, which when installing in a 4x4 truck requires a custom oil pan.

I sourced my oil pan from John @uniquediesel through the company Moroso, based in Connecticut USA. When Chris @Twisted Steel Performance went to install the pan on my engine, he caught some fitment/ clearance issues that I'm pretty sure the average guy wouldn't have caught. John and Chris both worked with Moroso to rectify the issue, and the engine went into my truck perfectly. What the details of the fitment issues were I don't know, perhaps they could chime in here.

Basically saying that if needing a 4x4 pan, contact either of the aforementioned gentlemen to be sure you're getting a good product.

Definitely let us know the plans for your engine. I have a build thread for my p400 project here in progress, will be posting pictures of the internal engine work done too

 

[Dkozi]

If you are looking for one- good luck.
If you have one - woo hoo.

What are you installing it in becomes a question. A hummer/hmmwv no changes required. In a gmt400 you need a modified oil pan.

Everything else in detail about mega-amazing-ness others here are better at posting links to those threads. I am horrible at searches.

ABSOLUTELY NO WAY I would install it without balancing the lower rotating assembly,
Clean up flashing, and having rings sent to be gapless and having camshaft and main/rod bearings coated.

So hard to get them now, make sure it runs for ever with those simple improvements.

@Twisted Steel Performance here has done extensive work on head flowing, on p400 heads if you are going for performance.

Here is another pic, with the truck heads.

Long story, short...

I provide 6.5 parts & service, engine swaps, diagnosis etc. They're my hobby

This engine belongs to a buddy of mine, I've been tasked with installing it in his 99 Tahoe. He's aware of the oil pan issue, says it won't be a problem after the front diff is removed and reinstalled after the 6" lift. I'm skeptical... But we'll see

I'm just curious what they are like, never thought I'd actually see one in person.

 

[Will L.]

So is he selling the hummer p400 heads?

I hope he bought the p400 heads instead of another one. If not have him return them and get the p400 ones!

Buying new head bolts or doing studs?

 

[Dkozi]

So is he selling the hummer p400 heads?

I hope he bought the p400 heads instead of another one. If not have him return them and get the p400 ones!

Buying new head bolts or doing studs?

ARP studs. Eventually I think he wants a super 60 and a quadstar tune. Already have a Gear reduction starter, red silicone hose kit, lift pump relay, 1\0 battery cable kit, and probably more.

Last year I did new gaskets & optimizer heads, FTB, water pump, timing set and 4" Flo pro, still had a compression leak after all that...

 

[Dkozi]

I believe he has the p400 heads sold already.