M998 6.2, 6.5 or 6.5 Turbo Advice wanted

[kfrosty]

I've been searching through a lot of threads on here but wanted my own for opinions.

We picked up a couple of M998's and a few have water in the engines. They have 6.2 engines, but have found some take outs complete 6.5's & 6.5 turbo's.

We'll probably use these mostly for 4x4. My preference would be the 6.5 turbo mated with overdrive transmission. But wanted to check here to see if anybody has experience will all of the above.

The 6.5 turbo engine I can get is missing the actual turbo so I'm not sure how hard that is to find or cost.

I'm mainly looking for info is the 6.5 turbo really a big difference between the 6.5. Especially for mainly off roading.

Will we need a different wiring harness, is there any computer with the 6.5 or 6.5 turbo that the 6.2 didn't have etc we need to consider?

Thanks.

P.S. Any tips on where to find just the turbo's for the 6.5 would be appreciated as well. (Places that sell them or I assume there is a year GM product, from what I read the vans that I could use to find one.)

 

[usmc81301]

I upgraded my from the 6.2 with 3L80 to a 6.5TD with 4L80E. The is a considerable difference in power between those two. I do live quite high up (about 8000ft) and the turbo is much needed at that altitude. Some people have turbo charged the 6.2 but that's up to you. There wasn't a wiring harness change need for just upgrading to the bigger engine. However, if you choose to use the 4L80E, you will have to change the wiring harness and get a controller for it. There are other transmissions you can use with the 6.5 that don't require a controller (such as a 700r4). The turbo isn't hard to find and you could probably find a better one than the stock such as a banks turbo. All of it was a time consuming project, but I have been pleased with the results. Hope this helps.

 

[DanM7890]

What vehicles have the 6.5T that can be swapped over.

 

[usmc81301]

It has to have a rear mounted turbo to fit in the HMMWV. I can't tell you what all vehicles have that. Also if it's not set up for military you would have to make to get 24v items for it unless your HMMWV is 12v.

 

[DanM7890]

I thought it was a side mounted turbo?

 

[usmc81301]

Side mounted won't fit between the frame. It has to be rear mounted.

Also have to get the A2 doghouse to fit over the rear turbo.

 

[DanM7890]

Good info, thanks!

 

[kfrosty]

I upgraded my from the 6.2 with 3L80 to a 6.5TD with 4L80E. The is a considerable difference in power between those two. I do live quite high up (about 8000ft) and the turbo is much needed at that altitude. Some people have turbo charged the 6.2 but that's up to you. There wasn't a wiring harness change need for just upgrading to the bigger engine. However, if you choose to use the 4L80E, you will have to change the wiring harness and get a controller for it. There are other transmissions you can use with the 6.5 that don't require a controller (such as a 700r4). The turbo isn't hard to find and you could probably find a better one than the stock such as a banks turbo. All of it was a time consuming project, but I have been pleased with the results. Hope this helps.

The engines available come mated to the 4L80E. I'm not sure you get the wiring harness or not. But both the 6.5 NA & Turbo come with the 4L80E.

The engines are from Hmmwv's so they would have to have the rear mount turbo. If you go the turbo route, is there a different radiator, were the Hmmwv's with 6.5 TD's built any different etc. From my research, each of these engines from Hmmwv's are all interchangeable. The only caveat is the wiring harness if you from a 3L80 to a 4L80E. Where did you find your wiring harness and controller?

Thanks you for the info.

 

[usmc81301]

If they come with the 4L80E, then I would think they would have the harness to accompany it. It would be a bit rediculous if they took it out but you never know. The engines are interchangeable fairly easily. With my 6.5td, It went in easily and just barely fit under the body (just below the windshield area). If you want to have lots of clearance then you can raise the body an inch if you'd like. I used the radiator I had in already because it was in good shape and I had it flushed. So far, it has done a great job and keeps the truck running right where it should. I have even towed some heavy vehicles up a mountain with it and it worked great. So in my opinion from experience, you don't need to change anything radiator wise. Other than that, it will go right in and be fine. Like I mentioned above, you need the doghouse that fits the turbo. The non turbo doghouse is shaped wrong. I went to kascar to get the harness and the controller. They have a water tight controller that has the water tight connecter that fits the harness. It isn't cheap, but mine have worked great so the quality is good.

 

[kfrosty]

Thank you much. I just got back from Kascar today. Guys are demo'ng Humvees and think it's dictated what you can get.

Course I called them and they said the body, radiator and everything was totally different on the hmmwv's with the 6.5 TD versus the 6.5 & 6.2. I thought they were wrong and thanks for confirming. They have to saw the turbo in half so it can't be reused.

Think I'm going to go with a 6.5 TD unless anybody else post a good reason not too.

Thanks again!

 

[usmc81301]

I know what they're saying because they're referring to the ECV HMMWV which is an A2 with beefed up cooling and new body style, but I have an A0 with the old body style and certainly isn't an ECV and it took the 6.5td easily. The harness was the only major thing I had to change. Just to help put your mind at rest a little more. Shame about the turbo. I would look at a banks as it is better in the higher rpm's (less restrictive) than the stock gm turbo. That being said, the gm one will be cheaper and if your a purist, is technically correct. I've thought of changing mine but don't want to do the work as the gm does good enough for me. Good luck, glad to help.

 

[kfrosty]

Another thing I thought of, the guy at Kascar said if you go with a Turbo, you had to change out the drive shafts, is that correct? Also, don't you have to have an inner cooler for a turbo to work correctly?

 

[usmc81301]

No HMMWVs have intercoolers but there is a kit out there to put one on. I only had to change the drives shafts so they fit the 4L80E to transfer case (which I have the NP242) and the output from the transfer case. Since yours already has those components I don't see any reason why the drive shafts you have wouldn't work. Since I upgraded my drivetrain from an A0 to an A2 basically, it's hard for me to say what you would need since yours comes with what I put in mine. Hence why I think you're fine.

 

[gimpyrobb]

To use the center mount turbo, the heads and intake are different from most other 6.5TDs. The only thing that is the same is the van 6.5TDs.

 

[patracy]

To use the center mount turbo, the heads and intake are different from most other 6.5TDs. The only thing that is the same is the van 6.5TDs.

Yup, and that's due to the intake bolt angle. I've been gathering parts, but I plan on using a 6.5 turbo from a civy truck on my 6.2. I'm going to use the stock HMMWV passenger manifold to create a log manifold with a turbo flange. Then put the turbo in that pocket that's open on the front passenger side of the engine. The oil drain would be easy there too. Just need to swap the lift pump to an electric. Then use a civy intake manifold to plumb the output of the turbo. Hopeful to reuse the stock airbox too with some plumbing. The problem is going to be the downpipe. I need to take some more measurements to see if that'd prevent my idea from working.

I'm wanting a 4L80e too. 700R4 would be easier though. I'd probably swap to a civy t-case if I used a 700r4 for a 2wd mode.

 

[kfrosty]

Finally got my 6.5 turbos today. Now I'm looking for turbos. Searching right now but what GM van year/models have rear mount turbos that will work on the Hmmwv 6.5 TD?

Also, any recommendations to places to purchase such as rebuild shops etc?

Thanks

 

[86sa]

I think transmission mount and cross member is different with 4l80e

 

[Texas187]

Didn't read all the above posts but on the fence myself over this. My recent research led into to going with a Whipple Supercharger...instant gratification over the turbo.

Just google "whipple charger 6.5L HMMWV"

Awaiting EUC approval on my HMMWV 6.5L

Please keep an update on your findings/result.

 

[racing4funn]

Instead of making a new thread let me get some clarifying here. Im needing a front Dana 60 for different project and a diesel motor swap for a HMMWV. I dont care as much what diesel motor I end up with because Ive had them all and can be happy with any as long as its turboed. So Im going to buy a complete salvage truck to kill both birds. A front Dana 60 and a turbo diesel motor (and hope to use the trans and transfer case)

My question is: So as posted above the GM truck 6.5 TD motor wont fit between the humvee's rails but a top turbo mount motor will (GM van? what years?). What about the Ford 7.3? Its top mount. I know people are doing the Cummins swaps and older trucks have a Dana60. Ford, GM, and Dodge all have had some good turbo diesels and certain years the front axle I need.

Suggestions please

 

[Texas187]

Instead of making a new thread let me get some clarifying here. Im needing a front Dana 60 for different project and a diesel motor swap for a HMMWV. I dont care as much what diesel motor I end up with because Ive had them all and can be happy with any as long as its turboed. So Im going to buy a complete salvage truck to kill both birds. A front Dana 60 and a turbo diesel motor (and hope to use the trans and transfer case)

My question is: So as posted above the GM truck 6.5 TD motor wont fit between the humvee's rails but a top turbo mount motor will (GM van? what years?). What about the Ford 7.3? Its top mount. I know people are doing the Cummins swaps and older trucks have a Dana60. Ford, GM, and Dodge all have had some good turbo diesels and certain years the front axle I need.

Suggestions please

Have to pull the dimensions, but that 7.3 is a biggy and heavy. Dont give me wrong, is a strong hard long lasting diesel and can handle power...had a 99' F-250 w/~300k when I sold it and ran like new. Can pull one from a salvaged school bus. Personally I would do a Cummins, say 6.7L or less, they weight around 1K. then matched to an Alison tranny. If I can get a deal on one im going that route vs. whipple...Just my personal opinion.