Reworked 6.5L pipe dream

[GM Guy]

Man, some of ya'll have been around some abused and neglected 6.5Ls. dead lift pump is why many of them are dogs, but why maintain when you can complain?

The only one I "beat" on is the one in the worst condition, has puffy blowby, has had it for the 50K miles Ive owned it, IDK if its a broke ring or cracked piston, but on a cold morning, that one wont hit for 30 seconds... lol

Yesterday I had to get a little spirited to show a Dodge gas enthusiast these are not quite as bad as the internet says, proud of the old gal, burned tires in 2nd and chirped in 3rd. Will sit on the limiter all day if you wanted it to.
Bone stock 95 C2500 6.5L 5spd 2wd 4.10 gears. being a RCLB and 5spd 2wd, she can get as high as 21.5 mpg, averages 18-19, despite 4.10s.

Now the rest of the fleet the engines dont have blowby, and I trust them much farther distances, so I generally take it pretty easy with them. They are tools for the business (Farming and farm machinery sales) so I try to treat them as such.

Here is a trip I took back in September. Mind you 6.5Ls are rated for 14,500 GCW, From WI to ID and from UT to KS I was over 21,000 GCW. Stock fuel 95 K2500 6.5L 5spd 4wd with 4.10s only "mods" are the 97+ air filter and GM8 turbo, and Leroy Diesel lift pump harness and PMD relocation kit. Past that, just maintenance. Somewhere in eastern Idaho she rolled over 444,444.4 miles. Didnt even have a spare PMD.

I credit alot of my luck with the NV4500, I feel rapping up a cold 6.5L is hard on them, manual lets you ease into it more gently for proper warmup, and with no ATF cooler out front, more air available for the radiator, and what little power is made, more makes it to the ground.

In a drag race I am certain the 350 Vortec would walk all over any of mine, hook up to a loaded gooseneck, stock for stock, the 6.5L would be much more pleasurable to drive, using its low end torque to float up and down hills without shifting.

loaded 16-22,000 GCW, I average 10-12 mpg across the fleet. pretty well all my 6.5Ls are 5spd, some 2wd, some 4wd, all the runners so far are 4.10 geared. empty mpg varies, auto 4wd I can only do 14-15, manual 4wd I do 15-16, and manual 2wd will do 18+

They like their maintenance, and they dont like to be abused. Follow those two rules, and you'll be fine. Make sure and consult 6.5L friendly FB groups and forums to find the good parts (Leroydiesel.com and Quadstartuning.com are the best IMO) and skip crap parts and crap modifications, and it wont cost alot to make noticeable gains.

You must be registered for see images attach

You must be registered for see images attach

September Trip Route

You must be registered for see images attach

Onramp @ Bloomer, headed to ID

You must be registered for see images attach

Loaded at Roosevelt, headed to KS.

You must be registered for see images attach

 

[GM Guy]

All that said, for what the OP wants to do, do a Duramax swap, Cummins swap, or buy something else.

I am a realist, I know they are not perfect and I dont expect miracles. OP is expecting a miracle.

They are 10X better than internet reputation claims them to be. Most 6.5L complaints can be tied to lack of maintenance. Cold start videos, posts about constant starter bolt breakage, overheating, no power, etc. All traced back to people who wont check fuel pressure to see if they have a bad LP, wont wash out the radiator to keep it cool, and wont maintain the starting system so it pops right off versus winding the poor old gal over for 30 seconds while its coughing and bucking and kicking.

 

[CRF450R]

I don't understand why you even ask people for advice, you always just do what you want anyways. We are only trying to save you some pain.

We told you how to fix your 350 (tuning), and you won't do it.

We told you that it is retarded to swap a 6.5 in place of a vortec 350, and you're gonna do it anyways.

I race dirt bikes too, and would like to stress the importance of wearing quality helmets.

Well I'm starting to think about this stupid black bear tune thing everyone keeps telling me to do I personally think it will be a waste of money and time but I'm really getting sick of how gutless my 5.7 vortec is and I'm sick of this 15 mpg highway thats Imperial mpg so more like 12 US gallons. I've done a fuel pump Acdelco new fuel filter new fuel pressure regulator new cap plugs and wires and dual exhaust no cats with a double H pipe and this ***** still only gets 15 mpg highway and still a gutless slug. This f***in 5.7 struggles to pass a slow poke on the highway it's frickin embarrassing how gutless this thing is and I always get a engine light while on a extended Highway trip it's claiming 02 sensors I've also replaced all 02 sensors I'm thinking now it's cause I got rid of the cats and I'm told black bear can fix that. But this thing even at -5c will not start unless the block heater is pluged in it just cranks all most starts then floods it self I replaced that temp sensor by the thermostat and didn't fix nothing I'm very fusterated with this 98 it's bin very unreliable my 94 Silverado was a dam good truck I definitely got a lemon here. Not sure if the hard start when cold has something to do with the piss poor mpg and sluggish power or not but I'm starting to think about this black bear tune what is involved what the hell do I have to do? I need my truck I cant have it parked for weeks on end while someone tunes the computer.

 

[BNielsen]

You can buy a PCM from Blackbear already tuned. It's a little more expensive but in terms of truck downtime it's not terrible.

 

[CRF450R]

You can buy a PCM from Blackbear already tuned. It's a little more expensive but in terms of truck downtime it's not terrible.

Oka

 

[letitsnow]

^^^I did that, and keep the stock one with the truck on long trips just in case... I am still used to my dodge diesel where I had to bring 2 of everything on trips so the POS didn't wreck my trip.

 

[RDF1]

My dad has a buddy who bought a K3500 with the 6.5 back when they first came out. He destroyed two brand new engines in something like 10K miles. I don't remember the details of the transactions but I believe the GM dealership ended up buying it back and he went and bought a Ford which he ran until the Duramax trucks came out. He runs a concrete business and does a ton of heavy towing so he definitely used them hard, but that story pretty much cemented my opinion of the 6.5s.

I think in the right application with an owner who doesn't beat on them regularly (and knows their weaknesses) they're probably fine, and I still want a HMMWV so I can't say I'd never own one... But I think a 6.5 would be pretty much dead last on my list of engines I'd spend time and money swapping into one of these trucks.

Have you ever driven a HMMWV? DId a 4L80E swap in my buddys and the only good thing was instead of only being able to go 55 barely comfortable with the TH400, you could go 75 even more uncomfortable with the 4L80E but the same RPMs. We had plans on LS swap it with a turbo but that is in the future.

Had to use a sharpie to mark 70 on the speedo for him.

Id never want one. Tell my buddy all the time he is crazy to like this thing so much.

You must be registered for see images attach

You must be registered for see images attach

 

[Sparkysikes]

Well I'm keeping the 6.5. Throwing in some 18:1 Pistons and keeping her going. I'll let you guys know how it goes

 

[df2x4]

Have you ever driven a HMMWV? DId a 4L80E swap in my buddys and the only good thing was instead of only being able to go 55 barely comfortable with the TH400, you could go 75 even more uncomfortable with the 4L80E but the same RPMs. We had plans on LS swap it with a turbo but that is in the future.

Had to use a sharpie to mark 70 on the speedo for him.

Id never want one. Tell my buddy all the time he is crazy to like this thing so much.

You must be registered for see images attach

You must be registered for see images attach

Well he didn't get the more aerodynamic slant-back body style, that's why it sucks.

Seriously though I have not driven one, and everyone I know who has says pretty much the same thing that you did. Don't care, still want one.

 

[Sparkysikes]

You buy a hummer for 1 of 2 reasons.

When SHTF you can go where ever when ever or you just like crazy off road.

Reason 2 status symbol and than you don't deserve a real hummer. Get a H2!

On a YouTube channel they built up one and put on 40 or 42" tires and I thought it made a decent truck.

The 6.5 with a good turbo can move one decent. But it's not a LML duramax making 1000hp!