1988 crewcab, 96 6.5 military takeout. took the whole thing to a diesel mechanic to put together. He is going to start with a compression test and overall inspection of the engine. He is familiar with 6.x engines.
So, what I have so far. High output Water pump upgrade. The banks turbo setup. Geared timing set. I need some injectors and a pump. Mechanical of course.
Planning on keeping it for a long time, I would go fluidampr balancer, gapless rings. Leroy gets them. Also the injectors and a pump. Stock pump or bumped up a bit? make sure hardened internals for ulsd.
You still have v belt 4 bolt pump I take it? If so, the hmmwv fan clutch for 100% lockup and control to engage it whenever you want- like bottom of a big hill when towing. Also can have it engage when the a/c is on if you want for colder a/c in stop and go traffic.
96 military take out=GM block not optimizer from GEP. rethink that imo. if he pulls it apart and the block is perfect then ok. But not if it has the slightest of problems. double check 2 rear cylinder specs real close, main webs, and heads.
You running a serpentine belt? Reverse rotation HO water pump upgrades don't work with V belts or the V belt water pump backing plate.
I wouldn't spend 10cents on the GM cast 6.2/6.5 engine for machine work. New cam bearings yes. High Volume oil pump, yes. Anything else the risk of cracks before it's time would have me start over with a improved casting take out Optimizer. I would suggest you don't touch the crankshaft bolts - the stresses are already there and settled in. A re-torque is new stresses. That's my theory and I am sticking too it. Rod bearings will indicate if you need to look at the crankshaft bearings.
Compression test is a waste of time and money. Just pop the pistons out and put in new rings. Gapless rings. Deglaze the walls with the crankshaft in place. You likely will have blowby with the military rings from abuse (getting hot) or not seating well. It's not worth the money to go 0.x over on GM cast blocks. Deglaze, ignore everything but show stopper condition of cylinders otherwise, new rings and off you go.
Money is best spent looking for cracks in the heads, main webs, and cylinders.
Head studs are another good option since you are there.
No matter what brand you choose, top post not side post.
As for brand, I am a optima fan. A bunch of stuff came out when they closed the US plant saying all the made in Mexico ones are junk. But I got over a decade on set from Mexico. The fleet I worked in that went to optimas for semi to pickups got massive years from them.
Search battery in the search section and you will find a few threads on it.
If you go with AGM it is worthwhile to relocate them out of the engine heat. You get them for less corrosion.
In hot weather like we get combined with higher underhood temps of an IDI diesel the Optima red tops can't take it. I returned all I could and gave the last two away. The lifetime in gas rigs is also low in our heat but longer than diesels.
Spill proof is not leak proof. I have had Coroded cables and battery pan from side post leaking. Several cracked and leaked around top posts.
Even without the heat when I lived in normal climates like Colorado the luck I have had with them isn't as good as they used to be as far as longer life.
Deka agm's are worse in the heat. Swelling the case and failing open internally. Didn't last a year.
Thanks for input all. I do have head studs and serpentine belt setup. Would there be any reason to not run 1988 6.2 heads on a 1996 6.5 block? Will check on the precup style. Also I have a couple turbos. Banks and a tf07. Or I could sell and get something else
I would change the pre cups to diamond's for sure... and with the 88 6.2 heads I'm almost sure you would want 6.2 head gaskets NOT 6.5's.... I can't remember right now but older 6.2 heads have a different end water port and require a different gasket.... research before purchase to make sure the right gasket is used or you will end up with a leak...
I have been running 6.5 head gaskets on 1985 6.2 repowers without issue. 6.5 gaskets have been recommended for turbo 6.2's forever. Maybe you are thinking of the one off 1982?
Precups from NA engines limit your fuel with turbos. They are restrictive and spin the fuel air so fast that they centrifugally separate turning into smoke. This is Not an issue with GMx asthma attack turbos. Go bigger and precups hold you back.
6.2 heads have a different injector angle. This angle causes the injectors to hit the turbo manifold. Use two manifold gaskets to clear. Wrap manifold to keep heat down.
There was discussion of 6.2 precups having a different diameter than 6.5 precups so its not a drop in solution.
End of the day on a budget use 6.2 heads. Want power and big turbo the 6.2 heads are a problem esp. with precups. Good luck machining them, 6.2 NA, larger.
You can machine the precups to work, but have to call around to shops that grind inconel. More and more shops can do it now with better machinery becoming more affordable and almost everything cnc.
I was thinking there was 6.2 head that used different size precup than the other 6.2s - same size as the 6.5, but can’t remember details.
Plan on maching work. Imo, definitely do the better precups.
Many people accredited the smaller precups in n/a 6.2 heads to the higher mpg’s of old. The testing we did at the fuel company proved this incorrect. It was the old fuel that is no longer produced. We had a 100,000 gallon batch produced for testing. My 99 pickup went up 4.5 hiway mpg from just the fuel alone. But of course it killed 8.4 million penguins and raised Earths temperature 18 degrees doing so. Ok, so I bumped the numbers a little- it was 4.47 or 4.48 - close enough. Haha.
Hoping one of the turbo gurus could tell you something about your turbos there. Especially @Twisted Steel Performance or @WarWagon as they are usually outspoken quite well on thier favorite turbos in this platform. I just feel GM’s suck as much as they blow.