Im going to get my 6.2 rebuilt, Im going to put a 6.5 turbo set up onit, its a offroad truck, mud/rock crawler.. what brand and compression ratio should I get?? Thanks

18:1 Pistons would be ideal but I don't know where you get those.

No low compression 6.2 pistons available, reason I scrapped my 6.2 to 6.5 project engine and am going with 18:1 6.5 complete.

Penninsular at one time sold 19:1 6.2 pistons, they did not have any when I checked last fall you might check into that.

What yr 6.2 block or cast # block do you have, there was a period of transition where the 6.2 & 6.5 had the same block but just underbored for the 6.2, so if you had one of those you could punch out to 6.5 18:1 specs

Actually, I think pretty much any 6.2 can be bored to be the same as the 6.5. That would make things simple... Just find some 6.5 pistons.

As I recall there are also "marine" pistons for the 6.2 that are available and those are lower compression.

the motor is a, 1983 can I bore it enough to put (new) 6.5 pistons init, also I found a good deal on a good 6.5 crank and rods should I put those in the motor also, will thay work?? THANKS Doug

No not enough meat in a 83 6.2 to 6.5 bore, or I would have done that as well with mine, AFIK if there were low CR marine pistons they are not available or at least not at any of the guys like Peninsular who should know. Crank & rods I believe are interchangeable. I believe the "punchable 6.2-6.5 was 95/96 whatever the last yrs of GM 6.2 production was , I'm not sure when that transiton was

The interchangeable 6.2 blocks had a one piece rear main seal, same as the 6.5. These are the only cranks that are interchangeable due to the seal set up. Also, the late 6.2 blocks don't have a casting on the front of the engine that says 6.2D, it is just blank. Most of those blocks will be a 599 casting made around 1992 to 94.

It can be done. Not sure of reliability. There is a place i think called diesel depot in georgia. I talked with him and they use the older blocks with the two piece and leave the crank from the 6.2. Then they bore it to a 6.5. Don't know about reliability but it can be done. I thought about doing this but still in limbo. Hope this helps a little.

It can be done. Not sure of reliability. There is a place i think called diesel depot in georgia. I talked with him and they use the older blocks with the two piece and leave the crank from the 6.2. Then they bore it to a 6.5. Don't know about reliability but it can be done. I thought about doing this but still in limbo. Hope this helps a little.


Jamie, at Diesel Depot, will also cut down a set of 6.2 pistons for you to any reasonable compression ration and then ceramic coat them. They are very well respected in the Hummer H1 community. I'm having him do a set for me at the moment since I've got my heads off anyway to put in studs.

ph# to non site sponsor removed

Tell him I sent you. They are good ole' boys and not exactly internet hip, so you have to do it the old fashioned way and actually talk to them person to person!

FWIW, :rolleyes: I have no connection other connection with them except as a customer.

Also found on web as Avant Salvage, Sandersville GA, while not saying they are bad, sometimes their work requires re-do, have heard some folks swear by them & others swear at em, communication with them is the most frustrating part. Communication with customer seems to be a weak link also

Spindrift once a frequent 6.5er here had a engine done by them which required a lot of owner & his management to bring the project to a close, broke down test ride home GA to NJ, overlooked plumbing issue during rush to finish but there was enough time in the project that it should not have had to be a rush job.

Then the engine crapped out for the preacher Spin sold it to, but Diesel Depot did stand by the job so ultimately even though the engine warranty was with Spin it was a good outcome. Message I've heard about Diesel Depot if held to the fire they do good work, but requires close intervention on your part to make it happen.