88GMCtruck's never ending 88 GMC build thread

[Sampuppy1]

in my opinion the mechanical injected 6.5's are far superior. The 6.5 in general can be pesky but when they're running right they're solid.

The random PMD failures are a nightmare on the equipped trucks. Even when relocated with massive heat sinks they still fry. Coupled with the stock block issues they can get expensive in a hurry. The optimizer would be the way to go if you wanted a drop in and go setup but in the world of mods you have three options. Cheap, quick, reliable. And you get to pick two.

Lol in that type of light duty application it would be fun

If you can get your hands on an optimizer.

Make this your first upgrade. http://www.aaawa.com/membership/membership_types.asp . I wasn't always against the 6.5, I even thought hat it had a bad rap for awhile. Nope, it really is a polished t*rd.

Agreed. I mean do what you like but I always take into account what great white went through and westmimudder. I hung out with him quite a bit and that 6.5 always had him on his toes. Aside from that he had it wheeling with me a few times and it really didn't perform like he wanted. And he had some decent upgrades on it. You actually use yours off road and I'm not exactly sure what type of wheeling you do mostly but the 6.5 is not gonna suit you well in mud or sand. I've seen it personally and it was anything but impressive. And that was the PMD equipped version. Mechanical injection may be more reliable but it lacks power and efficiency. Not that the latter would mean anything in a truck used primarily off road with a SAS.

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[88GMCtruck]

in my opinion the mechanical injected 6.5's are far superior. The 6.5 in general can be pesky but when they're running right they're solid.

Seems like most people point out the bad form them and less of the good.

The random PMD failures are a nightmare on the equipped trucks. Even when relocated with massive heat sinks they still fry. Coupled with the stock block issues they can get expensive in a hurry. The optimizer would be the way to go if you wanted a drop in and go setup but in the world of mods you have three options. Cheap, quick, reliable. And you get to pick two.

Well, PMD is it's own issue. I've dealt with 2 PMD equipped trucks, one was my 99. A lot of the issues with PMDs can be fixed with clean wiring connections and a good heatsink. Extends the life. But they still fail. Always carry a spare... no issue then.

If you can get your hands on an optimizer.

Not the hardest of things to get, with the $$$.

Agreed. I mean do what you like but I always take into account what great white went through and westmimudder. I hung out with him quite a bit and that 6.5 always had him on his toes. Aside from that he had it wheeling with me a few times and it really didn't perform like he wanted. And he had some decent upgrades on it. You actually use yours off road and I'm not exactly sure what type of wheeling you do mostly but the 6.5 is not gonna suit you well in mud or sand. I've seen it personally and it was anything but impressive. And that was the PMD equipped version. Mechanical injection may be more reliable but it lacks power and efficiency. Not that the latter would mean anything in a truck used primarily off road with a SAS.

I'm very aware with GW had done to his truck, what happened over Snoqualmie pass (an hour from me), and what he has since done to his truck. They can be a piece of work.

I really don't do much for mud at all. Some technical stuff and sand. And let me tell you a turbo diesel does great in sand. Truth be told this truck will be getting turned into more of a weekend driver post selling the yellow truck. Cleaned up and looking nice.

 

[Sampuppy1]

Jeramy had his on the dunes with me and he had nothing but trouble. He fried a PMD and got hot pretty often. He couldn't climb hills either. The fact that the 400 weighs so much and the lack of power on tap from the 6.5 just seems to do nothing but work against the driver while off road. If you still want to do it you're more than welcome and I'm 100% positive you have done more research than I have. And being that you have already owned a few and read up on more I think you know more than I do as well. Respectfully I hope that, regardless of your decisions, it all works out in your favor.

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[ChevyDave]

I would have a hard time putting a cummins in my truck because it's a non GM motor into a GM truck. I'm a weird purist. It's the same reason my front axle is a passenger drop Chevy Dana 44 and not a Ford driverside drop. If I get a duramax for anything, it would be going in the dually hands down.


Don't forget I did own one for 2 years..... After I worked the bugs out of it I didn't have problems. Only sold it because I wasn't using it much and needed the money.

I think I would try going mechanical 6.5L if I were to swap one in.

I know what you are saying but duramax isn't a chevy engine even though they are in gm's.

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[88GMCtruck]

Jeramy had his on the dunes with me and he had nothing but trouble. He fried a PMD and got hot pretty often. He couldn't climb hills either. The fact that the 400 weighs so much and the lack of power on tap from the 6.5 just seems to do nothing but work against the driver while off road. If you still want to do it you're more than welcome and I'm 100% positive you have done more research than I have. And being that you have already owned a few and read up on more I think you know more than I do as well. Respectfully I hope that, regardless of your decisions, it all works out in your favor.

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I don't fully know what his setup is either, but my 99 did fantastic in the sand. There are a lot of factors out there so it's impossible to tell if he was running something I would or not in the sand. Or if your sand is the same as our sand. Keep in mind I'm dragging 16k truck camper trailer out in the sand now in the dually.... It goes just fine. Obviously not climbing Hills but yeah.

I know what you are saying but duramax isn't a chevy engine even though they are in gm's.

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Now you are splitting hairs. It was made for gm in gm vehicles. Cummins weren't made for gm

 

[Sampuppy1]

I don't fully know what his setup is either, but my 99 did fantastic in the sand. There are a lot of factors out there so it's impossible to tell if he was running something I would or not in the sand. Or if your sand is the same as our sand. Keep in mind I'm dragging 16k truck camper trailer out in the sand now in the dually.... It goes just fine. Obviously not climbing Hills but yeah.



Now you are splitting hairs. It was made for gm in gm vehicles. Cummins weren't made for gm

Oh yeah the variables list could go on forever. From altitude to fuel variations in pressure, temperature, quality etc.

I know what you are saying but duramax isn't a chevy engine even though they are in gm's.

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Well you can't say that either. Duramax is a joint venture between Chevy and Isuzu. They both worked on development.

If you want some options don't rule out the old cat engines from the 400 based Kodiak's of the generation. Hell some of the later (99-02) 400hd platforms came with the Big block 8.1. And there are GM chassis step vans that came equipped with 4bt (3.9) cummins engines. Even bolt right up to a 60/80e. Just so you guys know. Cheers!

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[MYT HI]

I think 88gmctruck has his 6.5s down! I'll be watching to see if you do it and how you do it

 

[skylark]

I agree 100% that the Optimizer is the way to go. Honestly, I never had electrical issues. I never fried a pmd and mine isn't on a huge heat sink but it is in my air box. The injection pump never had a problem. I thought that the turbo was weak but it turns out that my truck was dealing with emphysema due to crap for compression and the turbo wasn't spooling due to a lack of drive pressure. I lost #5 exhaust valve at 104k and it just simply isn't worth it for me to continue down the rabbit hole. This is my #2 of 4 6.5 vehicles that I have owned and the second one with a low miles valve failure. I have had heating problems and I have all of the upgrades. I do believe that some of the heating problems may be due to over fueling from the turbo not spooling properly.
I wish that I could say that my problems were due to driver errors but with gauges to monitor egt and boost I just can't buy into that. All of my 6.5 complaints are due to an inferior - in my opinion - design with poor metal.

 

[thz71]

Even GW Said he knly did the optimizer becaude he was in a bind. He also said many times he would never do it again.

 

[Sampuppy1]

We don't want to deter you from fulfilling a dream build but we also don't want to see a dream build spiral into a nightmare.

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