Military 6.2

[Johnny McGhee]

Hey,
Just had a military 6.2 installed in place of my origional 6.5 in a 1995 Chev. 3500 dually. Basically it was installed as a 6.5, all componants were removed from the 6.5 and installed on the 6.2. I'm not noticing any problems yet, actually I'm seeing an impressive boost in overall performance.

My next mods. for this truck will be new 3.5" exhaust system, EGT and boost gauges, then some fuel and boost mods. My question is after reading the articles on potential engine compressions versus boost increases. Not knowing the compression on this engine I'm concerned about what I can actually do to this 6.2 before I destroy it. Or if someone already knows of some pitfalls of this exchange to stop me before I damage something.

This trk. will be used primarly as a towing vehicle. 15K

[cgoffroad]

Your 6.5 Turbo had a compression ratio of 21.3:1 The 6.2 has a compression ratio of 21.5:1 Lowering the Compression ratio will allow you to run higher boost levels safely without the risk of destroying your engine internals. However I would caution running a turbo on the 6.2 especially a military 6.2 with any pressure over 10PSI. I have purchased 3 of these crated 6.2's from a DRMO facility in the past and grenaded each of them within 1000 miles of install. Thats not saying you dont have a good engine just a reminder that the military pulled these for a reason so they should be treated as used unless rebuilt.

How much of the 6.5 parts did you swap over to the 6.2? just heads or heads, Inj pump, Intake manifold. some of your percieved performance gains could be from the heads intake manifold swap. You would be cramming the fuel and Air metered for the 6.5 into a smaller displacment block.

I would encourage you to purchase a boost guage and Pyromoter ASAP. The boost level of the 6.5 could be approacing the upper safe limit of the 6.2 block. THe added heat of the turbo on the 6.2NA block will accellerate any hidden weak links. Did you turn up the fuel, swap injectors or change Inj pumps. THe Injector flow rates are different also from 6.2NA to 6.5TD

Before i did any further upgrades to your truck I would research a set of 18.1:1 Marine Pistons THe lower compression ratio will allow more boost.

I hope that this helps. Good luck and happy haulin.
CGOffroad

[Johnny McGhee]

First, thanks for the great info!!!

the engine came in complete with heads, I added intake, injection pump, turbo, and naturally I had to use the 6.5 front covers for the crank sensors i assume for the electronic injection pump. I did pull the heads for inspection and although I can not swear it is a rebuilt engine, there was no detectable wear no enternal dirt/even dirty oil. However the outside did show mild signs of installation, so feel confident it is not a fresh rebuild.

I have not made any mods. on the injector pump on injectors yet, however that was in the plans.

At the risk of sounding really stupid would a thicker head gasket be an option to reduce compression ratio?

I agree, boost and pyrometer will be first on the list. I guess I could check the boost manually to be sure it it not overwhelming the engine until I can make the guage purchase.

[chestatee]

Where did you buy your engine, I have an interest, Also what model db2 injection pump came on it #????

Michael

[tomtaylor]

I just started a swap project as my factory 6.2 broke a crank and I have had military 6.2 sitting in the steel crate for 2 years waiting until I needed it. I now wish I had torn that spare engine down when I got it just to inspect everything because I now am sitting here with 2 blown engines. the original with a broken crank and the military engine with #1 & 2 spun rod bearings and thrashed rod journals on the crank as well as metal filings throughout the engine of course.

The shame of it is that other than these two spun rod bearings the inside of the engine looks new like it was either almost a zero mile original or just rebuilt. The rest of the crank and the other rods look brand new. even the pushrods and rockers all look new. The inside of the engine including rocker chamber and backside of the valve covers all looks new, there is no oil residue or staining anywhere. Sure is a disappointment given it all looks so new.

When I opened the crate and tore the engine down I found that someone had already torn this engine down once to see what was wrong, of course as you may have guessed I have not got any response back for the seller after attempting to contact them....lol...another life lesson! $$$