6.5L Turbodiesel variants (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Eagle Scout

Eagle Scout

Joined
Jan 29, 2010
Threads
4
Messages
43
Location
Flagstaff, AZ
The downside of self-education: how do you know if your facts are correct?

Am I correct to conclude that the Optimizer 6500 was an upgraded version of the earlier GM 6.5L TD - specifically with Caterpillar injectors and strengthened block, and the P400 has even better, yet somehow a little mysterious, improvements over the Optimizer 6500 design?

Poked around on this site and didn't find alot of answers to my question. I've also been poking around reading about 6.5L engine #8 cracks and injector issues and relocation kits for better cooling, etc. Seems the P400 reviews list it as a resolution to all previous issues ?

Thanks - any references/links appreciated. Thinking it might be a good repower over the next few months for 97 LX450 with 180K on the stocker.
 
I have ben spending alot of time over the past 1.5 years on three sites that deal with the 6.2/6.5 diesels, along with other diesels that are found here in the USA. The sites are,--- thetruckstop.us --- dieselplace.com --- thedieselpageforums,com --- these all cover the 6.2/6.5, Powerstroke, and Cummins.

I'm far from a diesel guru, but I have never heard of Cat injectors in the Optimizer. If my memory can be trusted, the Optimizer is a strengthened block and the P400 is a completely re-engineered block. The pics of the P400 that I remember seeing showed a complete block girdle as part of the casting.

The 6.5 has cooling issues, but there are mods that seem to take care of them. I have a 94 K2500 6.5TD pickup that I have done some of the mods to. I used the 2000 model year High Output Balanced Flow water pump along with an 02 DMax 9 blade fan and Heath's low temp turn on fan clutch. There are other mods for the 6.2/6.5 that can really wake them up. Heath's tunes, Kojo's tune, Kennedy's tune, the ATT turbo, etc. I'd have to write a book to explain them so I'd reccommend you spend some time on the forums I listed. I listed them in the order that I prefer them/apparent quality of info I have found there.

I am hoping to be able to put either a 6.2 or 6.5 into my 40 someday.

Don
 
caterpillar

Thanks for the links and information - appreciated.

The info on the Caterpillar parts came Diesel Garage, from this thread (WFS) that has this quote:


You are probably thionking of the all new P400 6.5L they came out with just a few years back. It is a 6.5L diesel engine, but that is about where the simliaritys end. It is factory rated at 250-275HP and was built for the new up armorred HUMVEE. It uses a new injection system with a CATERPILLAR comtroller for the engine, basically an all new animal. The OPTIMIZER is a revised 6.5L engine based off of the old GM 6.5L. It has the newer re-inforced blocks with the redesigned webbing in the bottom end, corrections for the #8 cylinder cracking, and many other improvements. The heads also bear the INTERNATIONAL diamonds as I have seen sets with them cast into them. GEP does all of the assembly of them for the military, and they also build the engines that PENINSULAR sells, and some of the other 6.5L marine engines. They build them in 2 varietes, a 20.3:1 version for N/A and turbo'd in the trucks, and an 18:1 version for marine use either turbo'd or supercharged.

The Caterpillar controller, not injector, is supposedly used. I have inadvertently made my point about proliferation of information and misinformation on the web, it seems.
 
My tow rig is a '93 Chevy crewcab tdi dually that we bought new (500 mi). It has never had any issues with cooling. I replaced the radiator with an expensive factory replacement a couple years ago. The '93 has mechanical FI. Ours has a Banks exhaust, waste gate mod a water-to-air intercooler that I cobbled together from ebay parts.

It runs great, but by turning up the FI pump it smokes a bit, especially when towing at altitude.

I think the 6.5 with mechanical FI would make a great motor for an fj40 with an nv4500 and an Orion or an Atlas. Mine is probably about 200hp and 350 ft lbs?

attachment.php
 
Last edited:
I also read about some massive (as a %) improvements in fuel economy with either the optimiser or the p400.
 
Dougal said:
I also read about some massive (as a %) improvements in fuel economy with either the optimiser or the p400.
Click to expand...

Had not read anything about significant mpg improvements with the P400 or optimizer. Would appreciate the link on that.
 
Standard 6.5 vs Optimizer vs P400

Found this information at this link poking around tonight - may have answered my original question. Had not searched on key term "GEP P400" until now. Posting here for the benefit of the collective

There are a few differences between the GEP 6.5TD, Optimizer 6.5, and P400.
First GEP is just the name AMG gave the facility after buying it from GM. Aside from the block being cast to eliminate the #8 issue the GM and GEP is pretty much the same engine.

The Optimizer is built by GEP as well. The biggest difference between the standard 6.5 and the Optimizer is it uses Caterpillar engine management. There are are a few other differences as well such as the intake manifold.

The P400 is marketed as the 6.5TD with all the weaknesses and problem areas worked out. It's very stout and looking at the block it is very beefy.

Us Hummer owners are always concerned with the #8, PMD, and head gaskets on the late 90's 6.5TD. However reading other diesel forums, it seems the guys with the same model year engine in pickups, dually, work trucks etc. Had more issues with the block cracking at or near the main bearing caps, the web, the girdle etc. The P400 fixes all of the block failures.
 
another p400 article with pics

The "new AMG engine" named in this 2007 article seems to be the P400 as it is mentioned as an update to the Optimizer 6500. AMG and GEP seem to be used interchangeably, but I get the impression they are different plants, or GEP is newer designation for AMG. Both terms seem to be mentioned as a source of Hummer engines as I read different articles.

From The Diesel Page, click here to link.
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)

Share this page

Back
Top Bottom