Project 67 GMC custom 6.5 turbo diesel

[mal68ibu]

Its been a while. I don't have any new pics, but I'm bringing the truck in to a local shop to have them make sure the injection pump is timed right. This guy deals with many different makes and models of diesels and has some fancy pulse tool to set the timing. I have a hand fabbed exhaust on it, and a passenger side inner fender in it that I butchered horribly (I have another decent one to chop up using this one as a template). I've installed all the rest of the parts that were missing from the truck. Current issue is crankcase vent to remove as much oil as possible from the system so as not to oil down the intercooler, and a more permanent air filter set up. I should have some time to get some new pics posted up later on this week.

[mal68ibu]

Got a clean bill of health on the truck. Timing is set at 4 degrees. The tech told me to keep track of my mileage for a couple weeks and stop back in. I put the wipers back on the truck but the arms weren't in the park position so I need to fix that before I take some new pics.

[wildwilly4x4]

Cool deal! I used to vent my crankcase to open atmos below the truck, just to keep the oil resid out of my airbox, but I dunno if that is an option for you.

[mal68ibu]

That is what I have going right now, but I found out that I really need to have the stock style set up on this motor, and multiple guys on the dieselplace have mentioned that it will keep seals on the truck, and won't oil down my intercooler. I just need to come up with a suitable air intake and I'll be good.
Adam

[Sub-versive]

Updates and Pics?

[67_C-30]

I finally got mine running today, so hopefully I'll be tooling around in few weeks myself. Can't wait to see the updated pics!

[gm4x4chris]

subscribed im fixing to start an extra cab 4x4 build and plan on using a 6.2 with 6.5 turbo stuff backed by a 4l80e going to using you and 67_c-30 build pages as a refrence

[67_C-30]

Originally Posted by gm4x4chris

subscribed im fixing to start an extra cab 4x4 build and plan on using a 6.2 with 6.5 turbo stuff backed by a 4l80e going to using you and 67_c-30 build pages as a refrence

Sounds like a cool project. I don't know if you know this or not, but 91 - 93 C2500 and C3500 diesel trucks (6.2 non turbo and 6.5TD) came with 4L80E's and had stand alone ECM's just for the tranny. The diesels didn't have computer controlled engines until '94, so that stand alone controller from the 91 - 93's is really nice to retrofit into something older.

[gm4x4chris]

Originally Posted by 67_C-30

Sounds like a cool project. I don't know if you know this or not, but 91 - 93 C2500 and C3500 diesel trucks (6.2 non turbo and 6.5TD) came with 4L80E's and had stand alone ECM's just for the tranny. The diesels didn't have computer controlled engines until '94, so that stand alone controller from the 91 - 93's is really nice to retrofit into something older.

thats good to know thanks for the info i have 3 sweet running ole 6.2s right now and a 4l80e outta 95 3500 hd i know they make a stand alone computer aftermarket for it but maybe i can find one at the bone yard for cheap that would be killer

[woodwright]

Come on man! Weres the updates? I just read the whole thread and am dieing to know how the story ends. What all is upgraded over stock? Got any mileage numbers? I'm interested in doing this swap into my k10.

[67_C-30]

Originally Posted by woodwright

Come on man! Weres the updates? I just read the whole thread and am dieing to know how the story ends. What all is upgraded over stock? Got any mileage numbers? I'm interested in doing this swap into my k10.

I agree!

[Schwinn68]

very cool build! I would love to do this to my truck too. I'd have a manual trans in mine for sure. The fuel mileage would have to be pretty awesome too. I had a 94 half ton longbed chevy with a 6.5/auto and it got around 18 mpg but I drove it hard. It would move pretty well too, I could keep up with my buddy in his Z71 especially when the turbo came on. This would be a screamer in a truck as light as ours are. Can't wait to see the update

[67_C-30]

Originally Posted by Schwinn68

very cool build! I would love to do this to my truck too. I'd have a manual trans in mine for sure. The fuel mileage would have to be pretty awesome too. I had a 94 half ton longbed chevy with a 6.5/auto and it got around 18 mpg but I drove it hard. It would move pretty well too, I could keep up with my buddy in his Z71 especially when the turbo came on. This would be a screamer in a truck as light as ours are. Can't wait to see the update

I used to have a 6.2 truck with a Banks turbo and 4 speed and it really ran well. That's the biggest reason I decided to put a 4 speed in my '67 C-30. I went with a close ratio NP435, so that 1st gear would useable. I'm running a relatively high 3.21 rearend gear, but I broke down the gear ratios on a calculator, and shows that at a 2500 shift the diesel will be in sweet spot the whole time. I would love to have NV4500, but the NP435 was the next best thing I could come up with. Here's how the ratios broke down.

[67_C-30]

When compared to the SM420 that was in truck, you get huge drops in gear ratio causes lugging going into the next gear unless shift a higher shift point than a diesel likes, or unless you run like 4.10 gears.

[mal68ibu]

Originally Posted by 67_C-30

Sounds like a cool project. I don't know if you know this or not, but 91 - 93 C2500 and C3500 diesel trucks (6.2 non turbo and 6.5TD) came with 4L80E's and had stand alone ECM's just for the tranny. The diesels didn't have computer controlled engines until '94, so that stand alone controller from the 91 - 93's is really nice to retrofit into something older.

I could kick myself square in the.........well. I personally chopped up that harness in the 93 3500 I pulled my motor from not having any idea what it was. I've now clocked 4000 miles on my "new" truck and have tweaked the fuel mileage up to 14.5 on the highway. I made a bed extender for it out of one of the factory stainless ford units. Huge difference on the HWY. I also stumbled across a Doug Nash (US Gear) under over drive unit for a TH400 at my local pick N pull so that is how I'm getting my overdrive. Tho a 4L80E would be AWSOME.

[mal68ibu]

Here is a pic of my 71 suburban and the gmc out front. I also added an in the bed spare tire holder to leave room for a blazer tank under the bed. The exhaust is 3 inch pipe to a stainless custom muffler to a 5" tip down. I still do not have the veggie oil stuff on the truck, and I don't have a boost gauge or pyro gauge yet. I have the boost controler turned down to a safe level. BTW the burb is for sale as I'm relativly confident in this trucks ability. I've towed 5 3/4 complete trucks behind the GMC and it flys. I still have some brake issues to work out but nothing more than a day project.

[mal68ibu]

Current under hood pics.

[mal68ibu]

The other issue that I had was alternator related. I found to run one of these alternators the excite wire needs to be run through an idiot light or some other kind of resistor. I blew up the first brand new alt. on the truck but it was under warranty so I just got a new one. The PVC set up is quite important to these motors I found. It sorta keeps the seals in good health, thats why the big red hose. I threw all the original stuff away before I realized I needed it, and thats the best I could come up with on short notice. Its not broken so I'm not fixing it.

[wildwilly4x4]

I had to build the same kinda air cleaner/ crankcase vent on my rig. I ended up blowing all kinds of oil out of the crankcase through that vent canister while doing burnouts..lol Come to find out that lil canister has to have a slight vacuum on it to work properly.

[67_C-30]

Originally Posted by mal68ibu

I could kick myself square in the.........well. I personally chopped up that harness in the 93 3500 I pulled my motor from not having any idea what it was. I've now clocked 4000 miles on my "new" truck and have tweaked the fuel mileage up to 14.5 on the highway. I made a bed extender for it out of one of the factory stainless ford units. Huge difference on the HWY. I also stumbled across a Doug Nash (US Gear) under over drive unit for a TH400 at my local pick N pull so that is how I'm getting my overdrive. Tho a 4L80E would be AWSOME.

No doubt about it, an OD would be nice. I did a little number crunching, and found that my set-up is going to be really close to a 4.10 geared truck with a 4L80 in the higher gears, and a little lower in the first 2 gears, so it should work out great. It's amazing that my 3.21's with the NP435 is going nearly identical to a 4L80E truck with 4.10's on the interstate. I'll be able to run 70 at around 2400RPM, and have plenty of gear getting a load moving in the 1st and 2nd gears. I had a '91 C3500 with a service body that had the 4L80E and 4.10's and it worked out well. Here's the comparison between the 2. The top chart is the NP435 with 3.21's and the bottom is the 4L80E with 4.10's.

[67_C-30]

Originally Posted by mal68ibu

The other issue that I had was alternator related. I found to run one of these alternators the excite wire needs to be run through an idiot light or some other kind of resistor. I blew up the first brand new alt. on the truck but it was under warranty so I just got a new one. The PVC set up is quite important to these motors I found. It sorta keeps the seals in good health, thats why the big red hose. I threw all the original stuff away before I realized I needed it, and thats the best I could come up with on short notice. Its not broken so I'm not fixing it.

Originally Posted by wildwilly4x4

I had to build the same kinda air cleaner/ crankcase vent on my rig. I ended up blowing all kinds of oil out of the crankcase through that vent canister while doing burnouts..lol Come to find out that lil canister has to have a slight vacuum on it to work properly.

I found this out the hard way on the first 6.2 I turbo'd. On this one, I ran the factory 6.5 CDR tube into my custom/homemade/junkyard scavenged cold air tube!

[67_C-30]

BTW, what did you use for the driver's side battery box?

[mal68ibu]

Originally Posted by 67_C-30

BTW, what did you use for the driver's side battery box?

A factory unit that I pulled out of my 71 burb. I figured there was no good reason for it to be there.

[mal68ibu]

Originally Posted by wildwilly4x4

I had to build the same kinda air cleaner/ crankcase vent on my rig. I ended up blowing all kinds of oil out of the crankcase through that vent canister while doing burnouts..lol Come to find out that lil canister has to have a slight vacuum on it to work properly.

I've been trying to lay off the burnouts. The load range E tires aren't cheep. Once I get my boost gauge and pyro gauge and get everything tuned up I'll post some vids with some pick-n-pull tires on the truck for fun.

[wildwilly4x4]

Originally Posted by 67_C-30

BTW, what did you use for the driver's side battery box?

I used a really sweet box that you can buy at circle track/ race fab shops. They cost about $20 and have a really nice battery hold down...the only thing bad is you have to fab your own mount tabs for it if you dont want put a couple of small welds to your core support. I was reluctant to weld mine, but I ended up doing that just to save some time. I will prolly also replace the factory passenger side one the same way. These boxes I am talking about are a much better/ clean looking setup.