Pros and cons on 6.5 diesel

[aarolar]

These threads scare me every time they come around because I narrowly missed purchasing a 6.5 over my 454...

 

[tanman_2006]

We have owned my 94 since new, it got the rep as only 6.5l in the county that wouldn't stop running as long as you kept spare PMD's. My family has alot of respect for it based on how many yrs of hard labor it was subjected too.

My 95 has also earned respect because it just keeps chugging and rarely has a problem. I paid $5k for it w/ 125k on it. I put 1 pmd and cable on it, one alternator, new rear leafs, upper ball joints, oil cooler lines, LP and relay, vin f, crank pulley and balancer, K 47 intake, and a couple other little things. For putting 175k of pulling 7-8k w/ it and banging it around in pastures I am pretty proud of the truck.

Now my 00 is on its 3rd engine and 2nd rebuilt title. Pretty much the poster child of failed 6.5's.

Source Unknown

 

[great white]

These threads scare me every time they come around because I narrowly missed purchasing a 6.5 over my 454...

Other than MPG, the 454 has it over the 6.5 everywhere.

There's a reason a 6.5 maxes out at an 8500 lb trailer and a 454 maxes out at 10,000. That's the same truck except for the engine. 4l80e, 4:10's.

I can throw 10,000 lbs behind my truck and it will get it going, but that's not hte point ofn the discussion here. I can get anything rolling.

The limiting factor when comparing 454 to 6.5 is the engine, nothing else. A very salient point for the discussion here. GM even knew to limit it because the engine was already overstressed.

Argue that one all you want gents, those numbers are right from the GM documentation....

 

[Conaway7698]

I understand that some can run forever and some only just a few miles.really i don't have the time nor the money to be messing around with a truck that I really wouldn't know anything about,not only to be a first time diesel owner but to own something that would have me (wanting to eat a bullet) and I know a lot of guys love their trucks and I'm sure they do what they want. I have just never really had any hands on experience with a diesel other then just turning the key

 

[454/4X4]

I bought my 1995 K2500 6.5 TD about 5 months ago, 126K miles, very well cared for mechanically, not perfect...but I paid 3500 for it, got it home...did the oil/filter, fuel filter, air filter, Lift pump wasnt working..so i put a new oPS on it, and did the relay mod so it will never need it ever again. I put a boost gauge on it, it had a manual wastegate controller already.

I clay barred it, waxed it, buffed it...put on some SS lower trim after I replaced the cab corners and resprayed the body below the trim, put on some 33" Mud tires, some goodies here and there...like cab lights, rear ID bar, new grille and all new lights, and some Cadillac ACDF horns. New batteries....

As it sits, im in it about eh...4250, give or take...it gets about 20mpg, Ive pulled over 6000lbs with it and it wasnt even trying. im able to push over 14psi of boost and it loves it...previous owner put on a 3" down pipe, 2.5" crossover, and 4" Diamond Eye straight pipe...sounds great, not loud at all.

It always fires right up, even when it was 12* and snowing 2 weeks ago....truck was solid ice..fired as i hit the key agter the GP cycle...not even a hesitation.

Engine bay is dead simple to work in, compared to a Cummins or Power Stroke. 4L80E is a beast, and with the 4.10 gears...well, i think if it could get traction in 4LO...it could move heaven and earth.

Are they perfect? nah. The blocks and cranks CAN break, but generally, this is only seen in punished trucks, with bad balancers, or trucks where people have just neglected them..used ether, etc. Ive seen many many many with well over 300K miles and still going strong, a few a re documented with over 500,000 miles...

The electronics are pretty simple, same level of complication as an era TBI or SMFI gasser...

 

[454/4X4]

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[Jorge6.5]

The biggest problem with these motors other then the pmds are the turbos that came on them. The turbos are way too small and put a lot of exhaust back pressure/ stress on the rotating assembly. With a larger freer flowing turbo and some better ECM tuning, these motors can be very awesome.

When I still had my 6.5 truck, I've towed over 10,000lbs a few times no problem

 

[great white]

The biggest problem with these motors other then the pmds are the turbos that came on them. The turbos are way too small and put a lot of exhaust back pressure/ stress on the rotating assembly. With a larger freer flowing turbo and some better ECM tuning, these motors can be very awesome.

When I still had my 6.5 truck, I've towed over 10,000lbs a few times no problem

Respectfully, nope.

Mine is rolling proof.

That 271/446 in my sig line was with a stock GM8.

It has also hauled a 9000lb travel trailer from the pacific to the atlantic with no egt issues. Sure, I could have pushed it over 1100, but I drive smart. 1100 was more than enough to cross the divide at legal speeds.

That old "GMx turbo is crap" line doesn't hold water if you have the knowledge and spend a little time to figure it out. Drink the kool aid if you want, I don't.

Which is not to say others can't be made to work just as well or a little bit better.

The power limitations in the 6.5 is not the turbo.

That's all I've got to say about that.

 

[Jorge6.5]

Respectfully, nope.

Mine is rolling proof.

That 271/446 in my sig line was with a stock GM8.

It has also hauled a 9000lb travel trailer from the pacific to the atlantic with no egt issues. Sure, I could have pushed it over 1100, but I drive smart. 1100 was more than enough to cross the divide at legal speeds.

That old "GMx turbo is crap" line doesn't hold water if you have the knowledge and spend a little time to figure it out....

You run a gep optimizer right? They are far more stout then the original gm 6.5 and with the right tuning I'm sure a gm turbo is ok if ran respectfully

The main problem is folks run well over 10 psi in turn making lots of drive pressure. Sure it's a good turbo if kept at or below 10psi

 

[great white]

You run a gep optimizer right? They are far more stout then the original gm 6.5 and with the right tuning I'm sure a gm turbo is ok if ran respectfully

The GEP has nothing to do with the turbo performance.

It has very little to due with the power output other than running the proper diamond prechambers and a tick lower compression.