My boss bought a Hummer H1 a few weeks back. About a week after he bought it, he was ready for more power. He came to me to see where and what to buy to make a diesel run.

I suggested a few vendors that I thought would be able to help him out. I was mistaken.

Why is it that there is only a few modifications that you can do to the 6.5 Chevy diesel?

The only things that I found were intake, exhaust and box that only added something like 35 horse. I did find a replacement intercooler that added another 30 horse or so, but it was crazy money.

I am pretty new to the world of diesels, and what I do know is about Dodges not Chevys. I did hear that the 6.2 Chevy was once a gas motor that GM converted to diesel, and that it did not hold up well.

Why is the 6.5 Chevy the red headed step child of diesel motors?

 

Hopefully not stepping on any toes, the engine is underpowered, lacks durability, poor economy.... and so on. They have an injection pump that generally has to be changed before 100,000. The owners usually don't like them.

Ok all that being said, there is a Chevy truck net that has some diehard 6.5 owners and could guide him to some upgrades. I don't remember the site, but just search for Chevy truck on Google.

 

There are 2 Chevy dually's around here that used to have the 6.5 in them but are now sportin' 12v CTD's

 

The 6.2 and 6.5 litre engines are not bad if left stock.
The 6.5's with the mechanical injection pump were the most reliable. When GM replaced the mechanical pump with a computer controled pump, reliablity started to decrease.

Also, both the 6.2's and the 6.5's were not built to be heavy pullers. They were more for daily driving and built for economy purposes.

You wont find much out there in the way of performance for these engines (there are some, but not like what can be found for the PowerStroke or the Cummins).
This is becuase the 6.5's just were not designed to handle big power.
From the heads, to the main bearings, the 6.2's and 6.5's just are not up to making big power... by design.

Take a look here to help see why:
https://www.dieseltruckresource.com/...threadid=50908

I had a GMC with the 6.2L diesel and the engine had 402,000 miles on it when I traded it in.
They are good engines... IF LEFT STOCK and taken care of, but they are not power makers.

Rich

 

I used to own a 94 GMC 2500 with the 6.5 and I looked all over for mods. I found a place in Grandville, Michingan that rebuilds the 6.5 for marine uses. They were willing to rebuild my engine for $$$$$$. I would have had 300+ horsepower, but it would have involved a great deal of work, new injectors, pump, etc. I don't remember the name, but if your boss is interested, I could try to look it up. PM me if you want more information.

 

As others have mentioned, the 6.5 isn't an engine that anyone likes to work on, due to reliability concerns. You can safely add another 10-20 HP MAX before you start having crank problems.

Rod

 

'Cause it's a modified Pontiac big block. The old 6.2's would run forever stock, but the 6.5 turbo ones (as others have said) can't stand up to much more power than they make stock. Any diesel that has a dummy distributor to drive the oil pump wasn't intended to be a diesel in the first place.

 

My dad had a 6.5 in his old truck. We replaced the IP and injectors at 70K miles. Only reason we knew there was a problem was because it would hic-cup occasionaly. The milage wasn't the best, but then again, it was a 4x4 crew cab long bed with 33" tires and 4.10 gears in an auto. It pulled our 10K horse trailer with no problem. Slow, yes. Even with a gutted cat and duals. Call up banks and see what they have to offer. It's gonna cost some money, but they are the best by far in upgrading the 6.5 IMO. I really enjoyed driving that truck and I miss it a whole bunch. I want to track it down and possibly buy it back from the people who bought it from us. It was a great truck. I ragged the carp out of it and other than the above mentioned problems, we never had a problem with it. Dang I miss that truck. I almost cried when we sold it. I learned to drive on that truck. It meant as much to me as my CTD did. But we won't go there. Tell your boss to call up banks and get some stuff from them.

 

I owned a 95 Chevy 2500 with the 6.5turbo. I put 320k with the original inj pump. I had the banks stinger+ kit on and it was quite respectable. I'd bought another but they opt for the "Jap" motor so that left me out.

 

I have a '82 GMC Jimmy 6.2 with 286K on it (the engine was rebuilt at 245K, right before I bought it). It ran pretty good, a solid 18 mpg, no problems (sorta slow to start when it was below 30 deg., though); I put the Banks Sidewinder Turbo kit on it at the recommendation of a friend who had mod'ed his 6.2 truck - and had put over 100K on it. With the Sidewinder, the Jimmy REALLY rocked, and the mileage actually went over 19 combined (when I wasn't stomping the Go Pedal too much) - it can smoke my '99 CTD, no problem..

I cannot attest to the 6.5's ability to stand up to the extra oomph, but the Sidewinder set up on the 6.2 made a HUGE difference.

Note: The 350-turned-diesel engine was a 5.5 or 5.7 - somewhere in that range - and didn't last for SQUAT....

 

[QUOTE]Originally posted by Rauschbo
[B]I it can smoke my '99 CTD, no problem..

You must have a slow '99

 

....nope, just a fast Jimmy!

(No jokes on that, please!)

 

I had a 95 6.5 for 178,000 miles with a few lessons learned. The 6.5 & 6.2 are not converted gas engines, they are Detroit Diesel blocks built under license by GM. The majority of there troubles are related to the electronic pump mounted driver that controls the injector pump. It's mounted on the pump in the V of the motor Where all the heat is. With GM not being a big diesel player the mechanics would replace the pumps at any sign of trouble as they had so little expierence with them. The motor is a high compression motor running at 22 to 1 where our Cummins are at 17 to 1. This makes them good starters but unable to run boost pressures safley over 10 lbs. They tend to blow head gaskets and stretch head bolts at that level plus put undue stress on the crank. Remember that it was 2000 dollars less then Dodges diesel option and with a superior transmission in the 4L80 behind it.You could easily take them to 250 rear wheel hp but above that you were asking for trouble.They responded well to exhaust mods as the down pipe from the turbo looked like it had been run over. GM's design was intended as a fuel miser in half ton trucks so you can see where the light duty label comes from.

 

I had a 1998 GMC 2500 4x4 and liked it. It pulled pretty well I never tried to bomb it. All in all I liked the truck and 6.5.

 

My dad had two of the 6.5's. 93 and a 95, he seamed to favor the 93 with the mech. injection pump it had a bit more power then the 95. IMO the 95 ran alot better pulling the the 97 ford he traded it for. None of us liked the powerstroke. The 6.5 might have been slower taking off but the powerstroke would just fall on its face on a hill that was very long at all. Only problems with either was the 95 had some transmission problems but was replaced under warnenty.