What to do with this 6.5?

[RumRunner742]

Gents,

I'm posting this in the cucv forum because you guys have daily experience with the N/A 6.2s and 6.5s. I bought a 6.5 from a guy who did a LS swap on his humvee and didn't need the engine any more. The engine is low miles (13K) and I have video of is running prior to removal. I'm confident in its condition, but after running the block numbers its a 2000 GM 6.5.

The block is a 506 and the production stamp is C010, so March 1st 2000 if I understand the process correctly. I was planning to put this in a 89 K30 to replace the tired 454, but after reading the specs I'm not sure that I can safely get it to the torque I would like without it having a come-apart under load. From what I've gathered about the 6.5 2000 was right at the end of the GM run and it's better than the 90s gens, but still nowhere near as capable as a GEP.

My goal was to get as close to 450-500 lbs of tq without sacrificing durability, but I don't think it's possible with this engine. Should I sell it and search for a GEP or is there a way to safely get this engine close to where I want it? I know I could toss a 12v in my truck, but I'm trying to stay GM and I the weight is a major issue. Open to options for the Gurus.

Thanks!

 

[NDT]

Is the 6.5 NA or turbocharged? You put the gas engine pic in the thread.

 

[Barrman]

I am not sure how to reply.

I don’t really pay attention to horsepower and torque number claims. But, I don’t think any side mount turbo 6.5 be it GM or GEP will put out 500 foot pounds for more than a very short burst. If then.

Having put 6.2, 6.5 and 12 valve engines where they replaced gas engines in trucks. The little things are going to drive you nuts. Do you have dual fuel tanks on that truck? You will need a new fuel transfer valve that includes the return lines. Return lines will need to be run no matter the number of fuel tanks. Manual transmission? The 6.5 will need a 6.5 specific bell housing to clear the starter motor. The turbo needs a boost gauge and EGT gauge. 2 batteries means another battery tray will have to be found and fitted. Plus wired. A GM turbo downpipe won’t fit between the body and the frame without a body lift. The cross over pipe will hit your front drive shaft with the GM turbo. Oh, the GM turbo will sit about where your A/C accumulator and evaporator live right now.

Basically I don’t think any 6.? Will fit your 500 foot pounds need without different pistons, an intercooler that will be custom made and a huge amount of changes to just about everything. Refreshing your 454 will be loads cheaper and easier.

A 6BT sounds so easy. Those things are massive and very, very heavy. Think new cross member, new front springs with a lift, probably a body lift and at the minimum a transmission meant to go behind one. Again, rebuilding your 454 will be cheaper and easier.

Now, if you just want a project. Go for it! The water pump on that 2000 6.5 should have the massive fixed stud fan mount on it instead of the 4 bolt fan mount older engines had. It should also have the dual thermostat cross over pipe. Those two things will keep your coolant where it should be. You will have to make a throttle cable bracket though because all the dual thermostat engines were drive by wire.

 

[RumRunner742]

Thanks Barrman. The truck is a 89 TBI 454, so it has the return lines to the tanks. I didn't realize the turbo plumbing would be that much of a PITA. After reading your response I think I'll just rebuild the 454 and roll. I'm willing to sell for what I paid it if anyone had a truck hard down and needs a engine. I'd rather see a member get their truck up and going than try to find something around here to stick it in just because I have it.

 

[Skinny]

Personally if the 454 runs fine I wouldn't go out of my way to swap in a Detroit flavor. I like the 6.2 in my truck. If it blows I would actually consider an Optimizer to replace it.

But if you want those power numbers I hate to say it I would just start with something that can make that without coming apart or being stressed hard.

Even then do you want to spend $10k+ on that platform to make those numbers? I don't think there is a right answer just setting the budget and expectation. Like if your cool with that then take that engine, do your mods, run it. If it blows you buy a long block to move your stuff over to it and repeat. If your not don't commit swapping in a 6.2 only to blow it up and be committed to that platform.

I'm rambling now...that sucks though that your Hummer donor didn't have a GEP in it already.

 

[sbgarage]

I'm in favor of the 454 revival.

What did you pay for the 6.5 if you don't mind my asking?

 

[Barrman]

I was thinking civilian 2000 6.5 engine when I wrote the above. Thanks for the pictures. That is a HMMWV normally aspirated 6.5 that is supposed to have the same power rating as a 6.2. You do have the nice serpentine belt set up.

That engine will happily live just about forever propelling your squarebody down the road at 62-68 mph, starting in less than a second every morning and probably getting you 15-20 mpg depending on your gears. Of course normal maintenance and glow plugs will be needed.

All of the diesel conversion things I wrote about before still apply. As does the fact that it will on just about every drive make you want for more power if you are thinking “454” every time you turn the key. I installed a 6.2 in my M715 to replace a 396 big block that replaced the stock engine. It took just a few drives before I realized normal driving power and usable everyday torque was actually better with the 6.2. I adjusted my driving from 4,000 rpm or higher “ROAR, ROAR” shifts to 2,500 rpm “Chug, chug” shifts. That was 13 years ago and I can’t imagine going back to a big block on that truck.

 

[MarkM]

I am not sure how to reply.

I don’t really pay attention to horsepower and torque number claims. But, I don’t think any side mount turbo 6.5 be it GM or GEP will put out 500 foot pounds for more than a very short burst. If then.

Having put 6.2, 6.5 and 12 valve engines where they replaced gas engines in trucks. The little things are going to drive you nuts. Do you have dual fuel tanks on that truck? You will need a new fuel transfer valve that includes the return lines. Return lines will need to be run no matter the number of fuel tanks. Manual transmission? The 6.5 will need a 6.5 specific bell housing to clear the starter motor. The turbo needs a boost gauge and EGT gauge. 2 batteries means another battery tray will have to be found and fitted. Plus wired. A GM turbo downpipe won’t fit between the body and the frame without a body lift. The cross over pipe will hit your front drive shaft with the GM turbo. Oh, the GM turbo will sit about where your A/C accumulator and evaporator live right now.

Basically I don’t think any 6.? Will fit your 500 foot pounds need without different pistons, an intercooler that will be custom made and a huge amount of changes to just about everything. Refreshing your 454 will be loads cheaper and easier.

A 6BT sounds so easy. Those things are massive and very, very heavy. Think new cross member, new front springs with a lift, probably a body lift and at the minimum a transmission meant to go behind one. Again, rebuilding your 454 will be cheaper and easier.

Now, if you just want a project. Go for it! The water pump on that 2000 6.5 should have the massive fixed stud fan mount on it instead of the 4 bolt fan mount older engines had. It should also have the dual thermostat cross over pipe. Those two things will keep your coolant where it should be. You will have to make a throttle cable bracket though because all the dual thermostat engines were drive by wire.

What about a built cummins 4BT or there abouts? Easily outpower the stock 6.5 turbo and in a tiny lightweight package with excellent fuel milage and durability. If my 6.5N/A ever let's go I'm going with a 4 cylinder Cummins with an appropriate Turbo.

Mark

 

[Skinny]

I will throw a complete wrench into this entire thing...ready?

Your truck is already set up for a big block. An L18 8.1 will literally bolt in. You will now enter into a realm of existence where a pickup truck drives like a very nice old school muscle car. Gobs of torque, scare the children, rip some tires...

All joking aside if you want power and you already have a big block this is the route I went on my square Suburban. With good headers and a bit of tuning the numbers are amazing for a stock engine. If you really want to messa around you can only go up as far as your Raylar dollars limit you.

Plus there is always the PSI 8.8L if you just need to say hey I've got the biggest production V8 in a light truck.

If you ever think of this you want to secure a van accessory drive bracket before doing anything if you want AC. You also want to make sure the fuel rails on the engine you buy are not rusted out.

 

[patracy]

The only thing I can add is the fact a gen 5 454 was weak sauce from the factory. 230hp new and 385ft-lbs. The 6.5 in question is only 160-170/290-300ft-lbs NA. But if you added a 6.5 turbo setup to it, you'd get closer to the 454's factory power at 190-200hp/380-400ft-lbs. And you'd be able to pass a gas station.

Now that said, your Gen 5 isn't all gloom and doom. If you're going to rebuild it, it'd do wonderfully with a set of flat tops to get the CR up from the 8:1 it has. That and a cam and ditching the TBI with a good intake would get you over 300hp out of it and still be reliable.

@Skinny mentioned the PSI 8.8L. I'm building one right now for my car. I will say though, you're going to have to go at it without the stronger following of the Gen 6, Gen 5, and Mk IV big blocks. The PSI 8.8 uses the 8.1 design heavily. (Even then, there's a sprinkling of the older Gen 6 and below BBC side of things with a mix of metric and SAE hardware) I've got a set 8.8 rods and pistons I'll never do anything with if anyone wants them. PSI made these engines for industrial low RPM use. So they have a odd arrangement of pistons with offsets. The 8.8 heads also have a small port runner design to them. Hank Slockum is the man to talk to if you're wanting to soop up a 8.8. He CNC's the 8.8 heads to get some decent numbers out of them. If you want to rebuild the rotating assembly in a 8.8, I used a 6.7 rod along with a Icon forged piston off the shelf on my build. I'm using a set of Raylar aluminum heads from a 8.1 on my build though. And building a custom intake for it.


Another thing to note with the 8.1/8.8 path. They use a different accessory drive and water pump setup. So you'll need to contend with that as well. (I'm using a 8.1 van accessory drive setup for my build) Also note, the 8.1/8.8 are designed to run via EFI. There's a crank reluctor and cam reluctor on them. If you're going to run a GM ECU, you'll need to shop around and find one from a 8.1 truck to utilize the setup. Otherwise you'll have to run the 4bbl intake and a tall deck distributor with a adjustable collar to run a carb/distributor. Even then, the 8.8 uses a inverted 54x reluctor and special crank position sensor that is wired differently. If you're running a holley, no biggie. If you're running a GM ECU, you'll need to swap the 54x reluctor on the 8.8 for a 24x from a 8.1.

 

[Skinny]

What a monster, do you have a link to a build anywhere on this?

I do miss my 8.1, kind of makes me want to go find a grandpa 2wd big block pickup. Shorten the wheelbase, slap some Superduty axles under it, and just converting gas to noise!

 

[patracy]

Don't mean to hijack this thread. But I've only shared about it on my facebook page. I might spin something up here in the mess hall if anyone is interested. Cliff notes: 8.8 big block that will make 1K hp+ on pump gas with low boost under 6K rpm. I'm even going to have AC and all the creature comforts. It also could have a "party tune" with a smaller pulley to make around 1800.