Turbo pop-off valve??

[StorminN]

I know this isn't really a 6.2L question, but perhaps one of you out there has owned one of these, and besides, you guys have more experience with the non-computerized motors, and you seem more resourceful than the guys on the 6.5 TD forum...

Anyhow, I've got a chance to buy a '94 6.5L TD with low miles, and I'm looking for some advice. This particular engine has been modified a bit and is installed in an '82 Suburban. The previous owner removed the electronic injection pump and replaced it with a mechanical one. He also wired the wastgate closed and installed some sort of pop off valve on the intake manifold. There is an aftermarket boost guage on the dash, but no pyrometer. I took it for a test drive and the boost guage never indicated more than 10lbs, even when really getting on it... I'm told that you can turn the knurled knob on the pop-off valve and change the max boost.
What do you guys think of this "pop off valve" setup?
What other things should I look for on this motor?
What other things were probably modified so it would work in this older truck (wiring harness, lift pump, filters, etc.)
Should I even buy this truck, or am I getting myself into a mess?

I've only ever owned 6.2L NA motors, so I've got no turbo experience...

Thanks,
-N.

[john8662]

Few questions for ya to consider?

The 6.5 that is in the suburban has a factory 6.5 turbo setup? The same setup used on the trucks, or is this a 6.5 engine with an aftermarket turbo on it (aka ats, banks, rayjay)? The factory 6.5 turbo setups for the 90+ 6.5's had interference in the old body-syle trucks (suburbans, blazers, and trucks) that had factory A/C. The turbo and downpipe setup would conflict with the location of the A/C box. So few have used the 6.5 turbo setup in old body style trucks w/o the modification of the A/C box. So, take a look under the hood to determine this. As far as a "pop-off" valve, I am not sure what that is, you could take a picture of the engine compartment and let us have a look see at the setup (entire engine compartment, and then the pop-off valve setup). How cheap is the engine as a whole? What are planning to put it in, the van with 300+k miles on it? Vans and turbo's don't get along at all, considered it myself when I had access to an 83 6.2L DSL van. This was covered in detail what might work in a van chassis in "6.5 turbo on a 6.2? "

http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic;f=2;t=001992

Although, this topic is not exactly a GM van, it is a diesel puller, actually I think there is more room in Eric's rig that there is in the GM vans. some options are discussed. But I suspect the turbo setup that you are looking at if indeed it is the truck/tahoe/suburban turbo on a 6.5 TD that it will certainly NOT work. None of the turbo parts can even be used. But a 6.5 turbo setup off a van or hummer might work, but as mentioned, the heads on these engines are totally different and are others like intake, turbo, exaust, and many other parts..


Conclusion, I would buy the engine for a replacement engine, it would have slightly more power than the 6.2 because of better breathing heads and also get you a 6.5 Naturally aspirated intake and you really have a good running N/A engine.

[Peter J. Bierman]

This pop off valve is a simple solution to limit the max boost pressure, it works but makes no sense in you have a wastegated turbo, there are better ways to control boost.
If the engine was originaly TD the boost can be set higher, but make sure its not an after market kit. (compression ratio )
Anyway,if the engine runs OK and the price is right, why not.

Peter

[StorminN]

I'm not sure if the turbo is a factory turbo or an aftermarket one. I believe I was told that it is a factory one, it came out of a wrecked '94 truck, not sure what kind. I will take some pictures and get back to you guys.

The price is US$2,000 and the engine supposedly has 60,000 miles on it... my thought was also, since it has the mechanical IP, could I pull the turbo off and sell it and convert the motor to a NA 6.5 and put it in my van... I've got a J-code intake that should? fit... they are all the same, no? Would the pump & injectors need to be pulled & recalibrated?

I brought the rig in to get the motor compression checked, but the shop could not find either of their compression testers that day, they think someone must have stolen them... I'm going to try to get it tested next week, I don't want to buy it without having it checked out.

-N.

[britannic]

If that's a 6.5LTD engine, you'll lose a load of power and gain more heat, because they run with a bit less compression and inject about 20cc/min/2000rpm @ WOT more fuel than the N/A 6.2L.

As an option, you could modify the engine to use the OEM turbo in a rear center mount for your van.

[john8662]

StorminN,

Yes, you could buy the engine and use it in one of your vans as a NA engine. The 6.2 and the 6.5 are direct bolt ins. You can use a 6.2 J code dual or single plane intake manifold on the 6.5 for use as NA in your van. The J code intake will fit in your van just as the C code one did, the van intakes are not different from the 80's truck intakes, same intake not taller or shorter (although shorter ones made for 6.2 hummers will cause problems, they are LOW profile). The injection pump and injectors will work, The injection pump will NEED to be turned down on the fuel calibration as it won't be able to burn the same amount of fuel that it would if it were turbo'ed. The injectors should work as is, and being that they are stock 6.5 injectors they are probably the "short-body" injectors which the vans require anyways because of clearance. You can also use your 6.2 injection pump, but you will have to use the 6.5 injection lines because of the angle that the injectors are installed in the heads of the 6.5.

Also, for cost considerations, 2k for a used 6.5 is a fair deal complete, But I would also consider looking at a used 6.2, lots of people sell them on ebay, like 6.2's pulled from military trucks that were only purchased for the axles (aka, Dana 60 front Gm Coporate 14 bolt 10.5") and didn't want the low mileage 6.2 and turbo 400 trans.. Just a thought... Usually go for about 1k or less but you pay shipping...

[ 07-31-2003, 12:52 PM: Message edited by: john8662 ]

[StorminN]

Thanks guys for all the input...

Brittanic, I'm confused about the turbo options... are you saying I might be able to take this same OEM turbo and install it in a center position? If so, what is involved? Just mainfolds and pipes, or heads too? Is it available in a bolt-on configuration, or does it involve custom pipes, etc?
I'm sorry to say I've never paid much attention to the turbo stuff, (I thought vans and turbos were mutually exclusive) and I've been away from the forum for a bit, but I recently read some info and saw some pictures of center mount turbos, but the price of $5,800 scared me off... I don't need the power that bad, these are just conversion vans, and I don't tow more than the occasional 3,500lb boat and trailer... no need for real turbo power... at least not $6,000 worth of it...

John, I should have clarified that the $2,000 price includes the '82 Suburban that this motor is currently installed in... it's a 2WD 3/4 ton, but it's got heavy-duty axles, eight lug wheels and a 14-bolt rear end that just had $1,300 worth of work done to it... pretty straight body and only one rusty spot... I know, I know, I should just buy it, but I've currently got a "stationary vehicle surplus", and I just want to get a compression test and coolant pressure test done before I spend my money... I don't need another rig with problems.

Thanks again, guys...

-N.

[john8662]

StorminN,

The whole vehicle, sounds like a winner to me, I would just buy it and drive it (use it as your heavy hauler like I do my 95 6.5). I understand the "vehicle surplus" thing, I am starting to look like a car collector myself (3 driveable units one parts truck.. so... 4).

As far as what britannic was saying about the adaptation of a turbo on a van. he is referring to the centermount turbos used in 95+ Vans and hummers with the 6.5TD. The heads used on the 6.5's in the vans are totally different from the stock truck engines. The heads have different angle bolt holes for the intake manifolds to bolt to as well as the exaust. These engines are only for vans and hummers. What some have considered though is taking the heads off one of these hummer-van engines and installing them onto an existing 6.2 or 6.5 block (because the hummer-van block is almost the same as the truck block, but with the different heads). To do this, one would have to purchase two heads, the special intakes, the special exaust manifolds, the special turbo. I would imagine all could be had for about 1.5 to 2k. But I am sure someone out there already has the parts as junk off a crate engine or something. Also with the turbo being in the center you would have to ditch your gear driven vacuum pump for a belt driven unit or convert your vacuum to use an electric vacuum pump of some sort, also have to install a "blank" gear in the spot where the vacumm pump came out. These can be had out of any 6.5TD pickup. To give you a look at these engines I have posted some pics on the web of two engines that were from hummers or vans w/ stuff mounted on them.

http://members.cox.net/acmdsl/vanturbo/

Its ALOT of work to find the parts, then ALOT of work to swap heads for a van, then you would have to do some custom exaust work, insulation to protect the doghouse (maybee modify the doghouse to clear turbo). Its all in the air, no one that I know of has admitted to getting the project completed in an 80's van.

good luck with your decision..


John