The big ding on fuel efficiency with the Ford engines has mostly to do with two things: One is that the larger displacement contributes to "pumping losses" and friction losses unless run at lower rpm. This is somewhat exacerbated by the roller cam/lifter that ford uses. Since it flows better for more power, unless you keep the engine loaded by low rpm it's pumping air that is not needed for efficient combustion.

Having said that, if you can keep the rpm under control you have an advantage until you run out of gears. Here is where the 6.9 really shines since a diesel-durable overdrive transmission is readily available cheap (zf5 series) as a stoopid simple bolt-in where one is NOT readily available or cheap for the GM engine (nv4500). Once you have overdrive and tall gears, and know how to drive, the benefits of the GM engine evaporate completely.

I was recently in the same situation and very nearly bought an 89 GM with a drop-in 6.5 turbo, and am very glad I did not since upgradeability of the transmission would have been impractical. Every time I have gone to the local pick n pull there has been a zf available for $150ish. A comparable GM nv4500 five speed would be close to a grand.

That roller cam (and modest displacement bump) plays a big role in the *grunt* you get from the 6.9. But the last thing to consider is parts availability into the future. The 6.9 and 7.3 are abundant even today considering how old they are. GM sold nowhere near as many 6.2's and 6.5's.

 

Absolutely agree. Between that and the 5.7, GM nearly killed automotive diesels in the US. I had an 85 Suburban with the 6.2 and 700r4, it sucked about every way it could. No power, crappy mileage, failing emissions equipment, and in the end the tiny oil capacity killed it. What kind of self respecting engineer specs a 6qt capacity for a diesel truck? They knew they screwed up, too, since it had a 2500miles OCI.

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Majority of crank failures are due to bad balancers. The heads crack from heat not age

Both if which can be fixed easily but a fluid damper balancer and a reverse rotation water pump and a seven blade fan or if you want to do it right use the duramax fan

6.2 6.5 is to gm/Detroit as 6.0 is to ford/ international

Everyone knew or had one that was beat and hated it

Now use 6.2 heads and injection on a 6.5 block with steam holes copper head gaskets studs and a ats turbo or gm 8 with studs on the bottom with a girdle fly cut the pistons to lower compression to take the boost stick 20 lbs boost intercooler external glow plug controller and your rollin!!!

That is a max of 3600 rpm but in the future I'm thinking of pushing that to 4200 rpm and ease the boost up to 30 lbs and see how that goes

Also the statement above pertains to a running set up using the ats turbo setup at this time not some dyno baby either it was in a dd first then a mud runner and in the excursion forum I brought up swapping it into an EX

 

Holy buckets this is déjà vu for us

 

One thing I forgot is the oil pan mod it to get 10 quarts in is a huge help

 

Ive heard of guys putting 6.9/7.3 into superdutys, but a 6.2? If a 6.9/7.3 is a step backwards, a 6.2 would be the equivelent of falling all the way down mt. everest. Like you say above, that would be like swapping a 6.0 in.... well anything really lmao.

 

Just a thought to, the 6.2 shares bell housing with every other 90* block, so the bells out of late 90s camaros and s10s with world class t5s bolt up and allow the use of any Ford pattern manual.

 

If you want fuel economy, stay away from the CUCV. It's got 4.56 gears and a turbo 400 trans (no over drive). They go about 55 with the engine standing on the red-line. They also have a rather ghetto 24V system. GM placed a huge resistor in parallel to the entire engine compartment. It's a heck of a thing if you have electrical issues (which you will on those trucks). They have 24V starters that are nigh impossible to get quality replacements for.

The 6.2 is cheap because it's basically a throw away engine for the military. They go about 50K and junk the vehicle or engine swap it. You can buy complete running 6.2 replacement engines cheap as heck on military surplus though. So maybe that's a selling point.

I'm not advocating one platform over the other, just telling what I know about the 6.2 and CUCV (which I'll admit, are really cool and I'd love to own one!).

 

yeah, but what does that get you? 250, maybe 300hp? Put the same amount of work and money into a 6.9 or 7.3, and you'll be running some very nice numbers with a much more reliable base to begin with. The 7.3 may have a rep for cavitation, but run a modern coolant and that issue is gone. No matter what you do to a later 6.2 or 6.5, they still want to crack the rear cylinder due to head bolt stresses.
There's a reason GM went begging to Isuzu for diesel help, too bad they used them up and threw away the carcass.

 

that much money? about 5500 bucks with machine work,

 

For that much you can have a very stout fuel system, turbo on custom piping, studs and possibly an o-ringed block if you don't count the other rebuild costs, to go along with the cut pistons and have yourself one absolute hell of an engine.
I'm not saying the GM diesels don't have a place, plenty of boats out there need anchors-

 

HAHHAHAHAH

 

6.2's are not a POS, I have had two 6.2's and both of them ran great. They were daily drivers in 4x4 suburbans. I maintained them well and both of them went well over 200,000 miles and ran as good when I sold them as they did when I bought them. However, maintenance is a nightmare. Such a job to get the injector pump off and to get at the injectors was tough too. I wouldn't want another one for that reason alone! But they did get great mileage. But, I've achieved 22mpg with my 5 speed 4x4 7.3 when it was not turbo'd.

V-465