6.2 heads

[gsimpson]

Will 6.2 heads fit on a 6.5 engine, and can 6.5 precups be installed on 6.2 heads?

[sctrailrider]

Yes & Yes....

What year 6.2 heads??? I ask because you may need to use 6.2 head gaskets...

[gsimpson]

The heads are off an 1986 military 6.2 engine, I am wanting to put them on a 1995 6.5L Chevy.
I know they will fit and will lose HP without changing the precups.

I am in NC by the way SCtrailrider

[Yukon6.2]

I wouldn't worry about losing power over the precups.Just make sure they are the same on both heads.
Even if you has access to a dyno,you wouldn't know the difference in power.

[gsimpson]

So Yukon, you have a 6.2 that is turbo charged what turbo did you use and why? Dis you change pistons to reduce the compression ratio? I am looking at rebuilding the 6.2 engine and making it like new by boring it out for 6.5 pistons and adding a holset turbo with studs instead of head bolts.

Any info you could give me would be greatly appreciated.

[DmaxMaverick]

So Yukon, you have a 6.2 that is turbo charged what turbo did you use and why? Dis you change pistons to reduce the compression ratio? I am looking at rebuilding the 6.2 engine and making it like new by boring it out for 6.5 pistons and adding a holset turbo with studs instead of head bolts.

Any info you could give me would be greatly appreciated.

You can't (successfully) bore a pre-1990? 6.2L block to fit 6.5L pistons. You'll need the later block (599), which is the same for 6.2L and 6.5L, except for the bore dia. (the cylinders have the same outer dia.). The rest of your build plan sounds fairly common.

[Yukon6.2]

So Yukon, you have a 6.2 that is turbo charged what turbo did you use and why? Dis you change pistons to reduce the compression ratio? I am looking at rebuilding the 6.2 engine and making it like new by boring it out for 6.5 pistons and adding a holset turbo with studs instead of head bolts.

Any info you could give me would be greatly appreciated.

When i got my truck i didn't know much about diesels especially light duty diesels.I was allways around big diesels in our equipment.
Then i found this site and spent lots of time reading up on the 6.2/6.5.
After months of reading i started to gather up parts for my 6.2 turbo build... most of the stuff is still in my shop on a mock up engine.Life got busy and i have just been using the truck NA.The engine had an issue when i was fixing it and it still runs good,but in the meantime i have acquired a 6.5 that was a crate engine that will be going in the truck with all the turbo, after cooler,ect.
I chose to go with the Mitsubishi TE 06E? it was the one that Banks had used for their Ford kit.I have modified a 90's Dodge after cooler to fit in my Rad support,modified the top hat that came with the Banks stuff i found and built an air cleaner housing to keep the hot air from the engine compartment out of the air intake.
I am running the gear drive and griddle ,dual t stats on the 6.2 which will go on the 6.5.

[gsimpson]

You can't (successfully) bore a pre-1990? 6.2L block to fit 6.5L pistons. You'll need the later block (599), which is the same for 6.2L and 6.5L, except for the bore dia. (the cylinders have the same outer dia.). The rest of your build plan sounds fairly common.

Hey Dmax

The 6.2 pistons are sized 3.82" isn't that correct?

and 6.5 pistons are 4.02 isn't that correct?

So if you bore out a 6.2 .030 over you are at 3.85? Right?

[DmaxMaverick]

Hey Dmax

The 6.2 pistons are sized 3.82" isn't that correct?

and 6.5 pistons are 4.02 isn't that correct?

So if you bore out a 6.2 .030 over you are at 3.85? Right?

The bore difference is more narrow than that, and the numbers appear to add up and sound reasonable. However, Boring greater than 0.020" over introduces the possibility of cylinder wall cavitation and erosion (a common issue with Navistar 6.9/7.3 IDI engines), but much depends on the actual condition and original state of your specific block. I know of successful bores to .040"+ over, but that doesn't mean it's advisable. Can do and should do are not the same. The general rule is, a (pre-599) 6.2L block can/should not be bored to fit 6.5L pistons. That doesn't mean you can't do it.

[arveetek]

About 10 years ago I bored a 1982 6.2L block .040" over with no issues, and it was turbocharged as well.

Back in 2001, Benny and Jamie Avant had an older Suburban at the Rendezvous in Ohio that had a 6.2L they bored to fit 6.5L pistons. I can't remember if it was a 599 block or not, though.

Casey

[john8662]

That Avant engine was a '660 regular cast block bored to 6.5 pistons (4.055"). Not sure I'd recommend doing that but from the cuttings I've taken from blocks the wall thickness is there but due to core shift may work on some and not others.

[More Power]

The heads are off an 1986 military 6.2 engine, I am wanting to put them on a 1995 6.5L Chevy.
I know they will fit and will lose HP without changing the precups.

I am in NC by the way SCtrailrider

The pre-1991 model year cylinder heads won't work on a 6.5TD because of injector angles. GM changed the injector angles to be more upright for the 1991 model year in preparation for the introduction of the 6.5TD in 1992. The injectors needed to be more upright to better clear the passenger side exhaust manifold made for the side-mounted turbocharger.

Along with the different injector angles, the steel fuel injector lines were also re-designed to fit the new injector orientation. So.... pre-1991 heads need 6.2L fuel injector lines and 1991+ need 6.5 lines, whether or not there's a turbocharger involved.

At least in 1994, the 6.5TD got the small port precups in the light-duty applications. The 1994 Blazer I have is one example...

Jim