Looking for some input from y'all with more H1 experience than myself.

I was driving the other night and "BOOM", the engine let go.
I knew that sound and exactly what it was, especially after the cabin started filling with smoke.

While waiting on the tow truck I climbed under with a flashlight and there's a pretty good size hole in the oil pan on the driver's side, so obviously something let go and decided to extract itself from the bottom end.

What I'm trying to decide now, is what to do with it.
(I'm not throwing the huge money at it to do a Cummins/Duramax conversion, so that's off the table.)

I'm assuming the top end is OK, but will have to confirm that.
If it is, my original thought was to buy a new short block and get it back together.
Who's a good source for one and what are some reasonable prices to expect to pay for it?

My buddy that will be pulling the engine for me (and has had a couple of H1's) keeps telling me not to waste my money on replacing/rebuilding the 6.5 because it's such a turd and plagued with issues, all the while not making crap for power.
He's trying to steer me towards a fuel injected 502 big block swap.
I have to admit that 500+/500+ with a nice cam lope would be pretty damn awesome, but it's obviously going to run a good bit more money to do.

Does anyone have experience with a big block conversion?
Any good sources to find one?
All I'm finding so far are built, crate engines and they're pretty damn pricey.

It's a 2000 model by the way.

 

I know a few people have gone the big block route but I would have to search the different Hummer forums to find the threads. Most go with the P400. I contacted Predator Motor Sports by San Diego. They do Duramax and Cummins conversations. I bought a complete drive train( 6.5 TD, tranny and transfer case take out) from them for much less than a new short block would cost. Make sure you buy one of the improved blocks when you buy. Most will have more miles on them but mine had 10,000 miles on the takeout motor. If it is a heavy block the miles aren't much of a concern.

 

Yea, I agree. I have a truck over at Predator right now and they are really great folks to work with. I'm sure they can offer some advice or options…

 

Thanks for the input.
I've been completely covered up, but will give them a call next week.

The big block is really intriguing, but it depends on how much more it is than sticking with the 6.5.

Not to sound like an idiot, but what's the P400?
I did quick search, but mostly found discussions where it was mentioned and not what advantages it offers.
Also, I saw a lot of talk about oil pans not fitting certain vehicles and lower compression pistons for the P400.
Any quick insight?

 

GEP P-400. The updated 6.5 motor. Several companies out there sell new short/long blocks. There are also several rebuilders that sell rebuilts.

 

I can do a NEW GEP p400 for under $20k out the door. Predator does not do P 400s. I called predator just to see how much a Duramax conversion is ( which is there bread-and-butter) and laughed! Starts at $50k !!! And all the duramax conversions they very poorly install are used engines they get from scrap yards. I asked how much to get a new duramax and laughed harder. He said they would rebuild it for a additional $14000. I can get a brand new 2016 built GEP p400 long block for less than $13500 delivered. If you are interested in doing a Duramax conversion i would talk to some of predators former customers and see what issues they have had due to their conversion. Im just sayin if your going to drop $50k min ,do your homework about the company your about to wright a check to.

Check out Big Dog Offroad in golden CO. They only service H1 hummers and HMMWV (Real hummers). They do a lot of custom fab stuff. My brother eric with bigdogoffroad.com has been servicing hummers for about 15 years. They have a lot of customers in this small nitch community with a great reputation.

 

I am not a fan of doing the Duramax conversions. There is a lot more to it than dropping a new motor and drive train to do it right. Blocking codes is not the answer. Installing 12.1K half shafts, geared hub gears, brakes, frame rails.......... well you get the pictures. I had a 10,000 mile motor, installed for less than $3,300.00. $2500 for the motor, tranny and tcase,( motor had starter, AC, injection pump, etc all still on it ) Paid Mike S at Tustin to install it, sold the tranny for $900.00 and got a spare T case, starter, injection pump, etc in the deal. I had two Alphas. They are nice, the power is nice but I know too many people that went the Duramax route on the conversion and had nothing but problems. I can't really comment on the 502 conversion. Seems like it would be much simpler and cheaper.

 

I would go with the p400. These trucks are not designed to be 500hp. The p400 is the improved / updated 6.5td block with new parts. The engine cooling system inside the block is improved. It can easily handle up to 350 hp. Its the military and h1 oem replacement engine. All hummer engines military and civilian were made by GEP.

 

Thanks again guys, but one more question.


If looking at a takeout or reman engine/longblock, how can you ensure it's the later block that doesn't have the #8 cyl problem?


I've read that the casting number on the right rear of the block needs to be E99 (May 1999) or later, but have also read that they changed their numbering codes so this doesn't always make sense.
Any other ways to look at the block and know if it's the good one or the time bomb?

 

Just buy a new GEP p400 longblock. I just spoke with our super awesome rep at gep and was quite surprised and happy to hear that they had a long block on the shelf ready to ship out to me monday. They dino test all their engines. Normally the build to ship date is 3 to 4 weeks, but with the holidays I expected it to be quite longer than that. The P 400 is an updated block with better cooling system ability. The time bomb engines not only had a defect in the casting of the block causing a crack on cylinder number eight, but they also did not have coolant going to number four and number eight cylinder which caused to overheat and worsened issue.