# 99 Chevy 6.5 diesel



## serafii (Nov 29, 2009)

Hey guys. I have a 99 k2500 obs with the 6.5 in it. I'm wondering what are some mods I can do to get a little bit more power under the hood. thanks in advance


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## damian (Jan 29, 2009)

I would not touch it, it has enough trouble staying together stock but if you must you could make sure it has a #9 calibration resistor in the injector driver module connector cavity,this is hard to access and requires removal of the idm to do it unless you already have a remote mount idm,other thing is to put a spring on your turbo wastegate actuator to hold it closed.of couse you may just have a problem with the engine you dont know about,a scan diagnostic would be a good first move make sure timing is correct etc.


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## Philbilly2 (Aug 25, 2007)

you can go to heath diesel. They are the specialest's on 6.5's. I would not recommend it though. as stated above, just leave it stock, they are not happy trucks when you snort them up. For example the stock turbo is only meant to make and hold 7psi. That is not much on an 8,000lb truck. 

These trucks were not built to be powerhouses like the diesel trucks of today. They were built to sip fuel. The 454 Big Block was your power house of the day. Those trucks were great on power but with the fuel economy of a sherman tank, not practical for people pulling constantly.


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## Philbilly2 (Aug 25, 2007)

Here is Heath Diesel's website:

http://heathdiesel.com/


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## Plowtoy (Dec 15, 2001)

damian;1454337 said:


> I would not touch it, it has enough trouble staying together stock but if you must you could make sure it has a #9 calibration resistor in the injector driver module connector cavity,this is hard to access and requires removal of the idm to do it unless you already have a remote mount idm,other thing is to put a spring on your turbo wastegate actuator to hold it closed.of couse you may just have a problem with the engine you dont know about,a scan diagnostic would be a good first move make sure timing is correct etc.


Most importantly, move the idm to a remote location. Keep it out of the heat (that kills them)


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## serafii (Nov 29, 2009)

I'm pretty sure the engine is running fine. I want a little more power because I put a dump insert on it and it will be pulling a 16 foot enclosed trailer about 3 days a week and I don't want it to hesitate too much.


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## NBI Lawn (Oct 15, 2007)

Plowtoy;1454447 said:


> Most importantly, move the idm to a remote location. Keep it out of the heat (that kills them)


I know you need to move the PMD but whats the IMD?


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## mnglocker (Dec 24, 2008)

Go trade it in on a 7.3 ford or a 5.9 cummins dodge if you want to go faster.


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## Plowtoy (Dec 15, 2001)

NBI Lawn;1454560 said:


> I know you need to move the PMD but whats the IMD?


PMD, IDM = same thing only different manufactures. oops:waving:
Pump Mounted Driver (GM 6.5) Injector Driver Module (Ford 7.3)


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## Philbilly2 (Aug 25, 2007)

serafii;1454554 said:


> I'm pretty sure the engine is running fine. I want a little more power because I put a dump insert on it and it will be pulling a 16 foot enclosed trailer about 3 days a week and I don't want it to hesitate too much.


You will need to trade it in and get a duramax or somthing different if you are looking to not hesitate to much. 6.2L's and 6.5L's are and always will be the dogs of Chevy diesels


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## Detroitdan (Aug 15, 2005)

My 97 was definitely not a dog, and it would easily dust a comparable Cummins of the same vintage. It would pull pretty even with a stock Duramax, but there is not enough aftermarket support to do much more than that. So, for a lot less money than a D-max, you can be happy with the truck, regardless of what all the internet experts tell you. 
For what you're asking, just a little more power, all you need to do is put an exhaust on it. Get rid of the factory downpipe, they crush it to make it fit when they install the motor with it on. You can fit a 3 inch downpipe easily, and it will wake the motor up. Moving the PMD is not for power, but longevity. See PMDcable.com for a harness to make it simple. Changing the calibration resistor to a #9, won't hurt it, but it won't really help either, it's going to allow a fraction more fuel through, not noticeable power, that's an old theory. A wastegate actuator like Heaths Turbomaster will help you, DONT do it without a boost and egt gague to monitor. If the wastegate mod doesn't satisfy you, you can replace the turbo with an A-Team upgrade for well under a grand. I did, and it was the best money spent, plus it not only gives you more towing power, it keeps the intake air charge cooler which helps the engine last longer. There are also some computer reflashes available for even more power.

Don't tell anyone about this, it's better to have the 6.5 be a secret, and let all the people who don't know anything about them keep spouting off about how bad they are. That keeps the prices down.


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## Plowtoy (Dec 15, 2001)

Detroitdan;1464694 said:


> Don't tell anyone about this, it's better to have the 6.0 be a secret, and let all the people who don't know anything about them keep spouting off about how bad they are. That keeps the prices down.


Look, I changed one number on your post and now it should be inserted into the 6.0 good/bad topic:laughing:
The 6.5gm isn't a horrible engine either, its kinda like the 6.0 ford. Everyone wants to comment but doesn't know anything about them. I personally have worked on 6.5s and would rather work on those than a duramax or the 6.0.


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## plowguy43 (Jan 2, 2008)

Detroitdan;1464694 said:


> My 97 was definitely not a dog, and it would easily dust a comparable Cummins of the same vintage. It would pull pretty even with a stock Duramax, but there is not enough aftermarket support to do much more than that. So, for a lot less money than a D-max, you can be happy with the truck, regardless of what all the internet experts tell you.
> For what you're asking, just a little more power, all you need to do is put an exhaust on it. Get rid of the factory downpipe, they crush it to make it fit when they install the motor with it on. You can fit a 3 inch downpipe easily, and it will wake the motor up. Moving the PMD is not for power, but longevity. See PMDcable.com for a harness to make it simple. Changing the calibration resistor to a #9, won't hurt it, but it won't really help either, it's going to allow a fraction more fuel through, not noticeable power, that's an old theory. A wastegate actuator like Heaths Turbomaster will help you, DONT do it without a boost and egt gague to monitor. If the wastegate mod doesn't satisfy you, you can replace the turbo with an A-Team upgrade for well under a grand. I did, and it was the best money spent, plus it not only gives you more towing power, it keeps the intake air charge cooler which helps the engine last longer. There are also some computer reflashes available for even more power.
> 
> Don't tell anyone about this, it's better to have the 6.5 be a secret, and let all the people who don't know anything about them keep spouting off about how bad they are. That keeps the prices down.


I think your on to something, they can be good motors making "ok power". But take a 97 Cummins with internals that will handle nearly 1000HP and you begin to understand why most guys go that route instead. Add in the crazy aftermarket support and.....wesport

by the way my father has a Chevy 1500 2wd 6.5 diesel and its a fun little truck.


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## blazer2plower (Nov 19, 2011)

I had a 95 6.5 1 tone it had all kinds of power it would push a 10' snow plow. Or pull my 18 cornpro all day long. Some Guy stop me
One day and made me an offer that was to good not to pass up. I wish I still had that 6.5 

I love my Z


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## Philbilly2 (Aug 25, 2007)

Detroitdan;1464694 said:


> My 97 was definitely not a dog, and it would easily dust a comparable Cummins of the same vintage. It would pull pretty even with a stock Duramax,


Have you ever had a Duramax? They will walk all over a 6.5L without even trying.

This is *impossible* for me to believe. My 6.5L's that I have had could not keep up with any of my Duramaxs. Not with the 6.5L empty and the Duramax loaded. The duramax will still walk away.

6.5L were not meant to be a power truck. They were built for efficiency. 215HP and 7psi at peak is not much.


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## Detroitdan (Aug 15, 2005)

Philbilly2;1465373 said:


> Have you ever had a Duramax? They will walk all over a 6.5L without even trying.
> 
> This is *impossible* for me to believe. My 6.5L's that I have had could not keep up with any of my Duramaxs. Not with the 6.5L empty and the Duramax loaded. The duramax will still walk away.
> 
> 6.5L were not meant to be a power truck. They were built for efficiency. 215HP and 7psi at peak is not much.


Did I mention my 6.5 wasn't stock? I did just about everything that the aftermarket offered, without getting inside the engine. I even had propane injection on it for a while, that made it pretty sporty but was no good for towing, so I got rid of it. One of the first things I did was lose the restrictive stock exhaust and let it breathe a little, that really woke it up. Eventually I put on a 4 inch open exhaust, it sounded better than any 6 cylinder ever could, and it ran great. The turbomaster on the stock turbo made a big difference, but eventually I put on a new turbo that was 50% larger, flowed way more air while keeping the intake temps down. Another big deal is to improve the ridiculously restrictive fuel supply. By the time it leaves the filter to go to the engine it necks down to a tiny 1/4 inch line, can't give the motor the fuel it can handle. Simple computer reflash to make it demand more fuel.

No, you are not going to see 1000 hp out of a 6.5. It was designed simply as a light duty pickup engine, while Ford and Dodge were stealing engines from truck makers because they are too lame to try to build their own. Not to mention, the 6.5s were being built before this big diesel performance craze caught on, so it just happened that they weren't as over-built internally as a medium duty truck engine. There are plenty of 300 hp 6.5 trucks out there, and while you aren't going to do much drag racing or tractor pulling, 300hp makes for a fun daily driver and competent work truck. There is nothing a 1 ton truck cant do with 300 hp, that you would ask of it, outside of drag racing. I regularly towed 10k with mine, and pushed a ten foot plow every winter. And I did it for a whole lot less than buying a stock Duramax truck. Dont forget, those hp mods that are so widely available arent cheap.

It doesnt bother me much if you dont believe me. I know a lot of people were surprised by my truck when they rode in it. I knew a kid with an 04 Dmax that was stock when he got it, we used to play around a little on the farm road, he was NO faster than me, even though I had 33 inch tires. He started doing mods and was able to pull me, but just barely. From what I understand he's got a lot of power now, my truck wouldn't even hang with it anymore. I would love to find another one, wish I hadnt sold the 97, I had it set up just the way I wanted, lifted, airbags, everything. Not that I wouldn't like a duramax, Ive driven them and they are sweet, plus all that aftermarket power is a big temptation. But like I said, it doesnt come cheap.

Another friend had a 97 Dodge that was identical configuration to my Chevy, all stock he hated it, it struggled to pull his horse trailer in the mountains, and there was so little available for simple aftermarket upgrades. Yes, you can build them, but you really need to tear into it to do it. The newer 24vs are much simpler to bump up, imo.

Lastly, for now, what most of us already know is that hp numbers are meaningless, torque numbers are the important thing, that's where the work gets done. Stock, with just exhaust my 6.5 made 356lbft torque. Not bad for a little old pickup truck. After turbo and computer it was in the neighborhood of 500. That's plenty for me. And at the end of the day, did you buy it to work and drive it, or to race it? If you really want to go fast, forget about towing and plowing and get a little turbo four cylinder car, that's what's fast nowadays.


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## NICHOLS LANDSCA (Sep 15, 2007)

Detroitdan;1465435 said:


> Did I mention my 6.5 wasn't stock? I did just about everything that the aftermarket offered, without getting inside the engine. I even had propane injection on it for a while, that made it pretty sporty but was no good for towing, so I got rid of it. One of the first things I did was lose the restrictive stock exhaust and let it breathe a little, that really woke it up. Eventually I put on a 4 inch open exhaust, it sounded better than any 6 cylinder ever could, and it ran great. The turbomaster on the stock turbo made a big difference, but eventually I put on a new turbo that was 50% larger, flowed way more air while keeping the intake temps down. Another big deal is to improve the ridiculously restrictive fuel supply. By the time it leaves the filter to go to the engine it necks down to a tiny 1/4 inch line, can't give the motor the fuel it can handle. Simple computer reflash to make it demand more fuel.
> 
> No, you are not going to see 1000 hp out of a 6.5. It was designed simply as a light duty pickup engine, while Ford and Dodge were stealing engines from truck makers because they are too lame to try to build their own. Not to mention, the 6.5s were being built before this big diesel performance craze caught on, so it just happened that they weren't as over-built internally as a medium duty truck engine. There are plenty of 300 hp 6.5 trucks out there, and while you aren't going to do much drag racing or tractor pulling, 300hp makes for a fun daily driver and competent work truck. There is nothing a 1 ton truck cant do with 300 hp, that you would ask of it, outside of drag racing. I regularly towed 10k with mine, and pushed a ten foot plow every winter. And I did it for a whole lot less than buying a stock Duramax truck. Dont forget, those hp mods that are so widely available arent cheap.
> 
> ...


You were making 500ft lbs to the wheels with a 6.5? Hmm I'd like to see the dyno sheet


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