6.5 Diesel Questions

[West Mi Mudder]

Honestly Ty...if you take your time to search for a nice decent condition 6.5 powered truck you will prob not want to swap it to Cummins. As for the updates to the cooling system they can be added to the older engines as well. In fact im giving some serious thought to the idea of updating to the newer serpentine set up to allow me to run dual alts on Vegas.

Good luck finding the bracket for the second alt. Thats what im looking for

 

[bow61509]

They get trashed way more than they deserve. I think that's because they are lacking in the "vroom-vroom" department, however as you said that isn't what they are designed for. You can't compare them to a Cummins or International. That's like comparing a 4.3 to a 454...different design, different purpose, different performance.

Personally I'd probably go for a mechanical one or an old 6.2 (I also would take a TBI over a Vortec any day of the week, call me crazy if you want). I like simple engines that are easy to fix.

your not crazy I like my tbi over the vortec I had

Sent from my static android

 

[88GMCtruck]

Yup, most people try to stack them up against the cummins or powerstroke of that era. That just isn't realistic. The motor was designed for economy and GM decided to put it in something it rightfully shouldn't have been (IE 3/4ton and 1-ton trucks) but they needed a diesel to compete with all the others. There is a reason you find 1/2ton 6.5L pickups and Yukon/Tahoe/Blazers, but not 1/2ton dodge or fords.

My 6.5L got about 14 towing my trailer, 17 in town and 22 on the highway. It had 3.73s and a 5-speed though.

FWIW it towed my trailer better than my 88 when it had the 350, but the 454 WAY outperforms it in every way except mileage.

I also like TBI considerably over the vortec GMT400 motors. The LS motors are nice though.

 

[96-1500]

but the 454 WAY outperforms it in every way except mileage.

^ That basically sums up a 6.5 description. Economy is the 6.5s strong point.

I also like TBI considerably over the vortec GMT400 motors. The LS motors are nice though.

Vortecs have a little better power stock as we all know, but are so much more complex and expensive to maintain/upgrade. They did a lot of work redesigning that motor to get a little.

 

[outalne94z71]

The later model the better! The 99.5-2000 has all of the factory cooling upgrades including the spin on fan clutch, HO water pump, dual thermostats and the 9 blade fan. The 96ish-98ish has issues with the metal and are prone to cracking in the webs. Relocate the PMD off of the engine, alot of guys locate theirs in the grill/bumper area. Ours is in the airbox. Get rid of every piece of the factory exhaust and the turbo. Diamond eye exhaust and a holset or knock off work well. The 6.5 isn't a power house. We have pulled 18.3-18.7mpg @ 62mph but that goes in the toilet at any faster speed. We do have 4.10's though. Truthfully, when the 6.5 dies a cummins will go in its place but as long as you aren't planning on drag racing it then you will do ok.

all turbo 506 gm blocks were prone to cracking from the piston squirters to the water jacket, all 6.2 and 6.5 were terrible for cracking in the web around the crank itself, i had a 6.2 599 block that the crack actually matched the radius of the crank, was kind of crazy looking, the 506 blocks were also prone to breaking the #2 main cap, 97+ all were the upgraded cooling just that the 99+ changed to spin on clutch, i had my exhaust break about 3 ft from the down pipe so it was not really restricted and i got a whole lot more boost but my fuel mileage was terrible vs having stock exhaust, i have a 99 n/a non squirter 506 with a gm-8 and have gotten 28.8 mpg with it if i run at 60 but average 24 with 4:10 and the oddball 215/85/16, the n/a heads get better mileage but you lose power.

the biggest issue with the 97+ was gm built the blocks too fast with no cure time so they developed stress risers and were the highest in failure in 97.

personally i would get a 93 and if the 599 block dies then get a optimizer 6500 and update the cooling or find a 98+ manual trans truck and put in a optimizer with a db2 mechanical injection

 

[97PROSHOZ71]

Interesting reading guys, you have provided a lot of good information, I know when I can get one I will be looking probably for a later model. Is the mileage on a dually very different from a SRW 6.5? I'd really like a reg cab dually with the diesel.

 

[outalne94z71]

Interesting reading guys, you have provided a lot of good information, I know when I can get one I will be looking probably for a later model. Is the mileage on a dually very different from a SRW 6.5? I'd really like a reg cab dually with the diesel.

the dually will have 4:10 gears which the sweet spot for mileage seems to be at 60, if you find one with the oddball 215/85/16 like i have they seem to get a little better as the tires are narrower, i have range E tires on mine and crank up the pressure, it wears tire centers faster riding empty but i do a lot of highway driving so i prefer the less rolling resistance, a 2wd with that tire size would be even better.

personally i wouldnt go with anything smaller than the club cab, reg cabs ride rougher and just dont have much room, my mud truck never would even had been a reg cab had i not gotten it for free

 

[97PROSHOZ71]

You know what makes me want a Reg. Cab dually?

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I LOVE this truck.

 

[92GMC]

I love that truck! If I could find one with a 350 tbi it would be in the driveway. I've never been impressed with a 454 in any kind of way. Power or economy.

 

[88GMCtruck]

personally i wouldnt go with anything smaller than the club cab, reg cabs ride rougher and just dont have much room, my mud truck never would even had been a reg cab had i not gotten it for free

I can agree, Regular Cabs are just difficult. No space for anything inside. I'm constantly fighting to find storage. And I own 2 regular cabs..... and sold the excab.

You know what makes me want a Reg. Cab dually?

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I LOVE this truck.

Yuuuuuuuuuuuup.

I love that truck! If I could find one with a 350 tbi it would be in the driveway. I've never been impressed with a 454 in any kind of way. Power or economy.

Stock TBI 454s are just dogs. Good torque but that is about it. I'm glad I built my 454 up, it's really got good power and decent economy for a big block. I'm sitting at approx 385HP/500FTLB and get 8-9 towing and 13-14 highway unloaded.