6.5 turbo swap

[Itali83]

Figure I’ll start a slow and long build thread for my new project. I’ve been daily driving my ‘76 K25 for over a year and the fuel mileage is just killing me. 6-8 mpg depending on how much warm up time or plowing in the winter etc. it’s getting old. I know it’s a complete package combination that’s adding up to that terrible mpg. Non lock up th350, full time np203 4.10 gears etc.

I like the economy of my 6.2 in my suburban so pretty early on I was thinking about a 6.2 swap. I’ve got two spare 6.2’s but have been thinking about a turbo just because it’s out and I want one. I know and don’t expect any level of impressive power. Just want a turbo. I came across this 6.5 locally with supposedly a blown head gasket. But it’s complete minus the injection pump(I’ve got two spares) for cheap money. Like what I’ve seen just the turbo manifolds going for so I figured what the hell.

My idea is either check this 6.5 out and if it’s decent, head stud it, gasket it and run it or if it’s too far gone, just swap the turbo stuff on one of my 6.2’s. At the same time, I’m putting one of the good 700r4’s behind it. (Go crazy all you guys want about that. I’ve had good luck with them and know how to make them live happy lives) and also the np208 transfer case to get part time 4 wheel drive to try and get as much mileage as I can while still having a work truck. I don’t tow haul heavy and when I do, I know how to run it.

This will be a slow build as I don’t even have space in the garage for it right now but figured I’d make an actual thread about it.

Ben

 

[Rickf]

In order to use a 6.5TD in a square there may be 2 issues; 1) the down pipe won't fit without a body lift, and 2) the a/c on the firewall, if equipped, may be in the way.
I thought the 6.2 had slightly higher compression than the 6.5 so you need to go easy with how much boost it gets. I could be mistaken, it's been a while since I've messed with either a 6.2 or 6.5.

 

[Itali83]

No a/c on this truck and exhaust fabrication will be no problem.

If the bottom end of the 6.5 is good, I’m going to run that which was originally a turbo motor so should be good. If not, I’ll put the thicker 6.5 head gaskets on the 6.2 to help lower the compression a touch for the added turbo boost.

Ben

 

[Blue Ox]

Compression isn't an issue in these applications. It's not a gas engine.

I ran 10-12 psi on my 6.2. Make sure you run a pyrometer no matter which setup you use. Actually I'd strongly advise against lowering compression in any way. It's detrimental to cold starting and efficiency.

If you're concerned about either 2 or 5 it really depends on the vintage of the engine as to whether the blocks can survive. I broke the crank on my stock NA 6.2 because the blocks are $#it. Some of the 6.5 blocks had issues too.

Negativity aside, I'm looking forward to seeing your work. Good luck and keep us posted.

 

[Itali83]

Compression does matter or make a difference when it comes to how much fuel/boost I want to feed it and how much fuel timing I can run. The old NTC Cummins used to be around 14:1 compression and 220 hp. When they started to turbo them and push for the 350 hp, they had to lover compression to 11-12:1. I know the head gaskets aren’t going to make a world of difference but if I’ve got to do them, I may go that route. This is going to be cheap as possible with the parts that I’ve got. First I need to pull the bottom end and inspect for cracks before getting too far with the 6.5.

I know this won’t even be in the same neighborhood, or county power wise as the 12 valve I used to have, but I just kinda want to do it.

Ben

 

[Blue Ox]

Compression does matter or make a difference when it comes to how much fuel/boost I want to feed it and how much fuel timing I can run. The old NTC Cummins used to be around 14:1 compression and 220 hp. When they started to turbo them and push for the 350 hp, they had to lover compression to 11-12:1. I know the head gaskets aren’t going to make a world of difference but if I’ve got to do them, I may go that route. This is going to be cheap as possible with the parts that I’ve got. First I need to pull the bottom end and inspect for cracks before getting too far with the 6.5.

I know this won’t even be in the same neighborhood, or county power wise as the 12 valve I used to have, but I just kinda want to do it.

Ben

Okay. Have fun.

 

[Strick]

Gotta love those Detroits. I just started on an 82 K10 this week. I have a 6.5 turbo I'm gonna try as well. Good luck in your build.

Strickland

 

[Lowered87]

I have a 6.5turbo in a truck I bought brand new so I know what I am getting. I am putting it in a 73 crewcab dually because I sold the 454 out of it.
I found really good advice on www.dieselplace.com. Once you make inspections and repairs based on their comments, I think most of the problems will be alleviated.
I made PDFs to save for later, see attached. Luckily, I have the entire truck so I have be selling unnecessary parts. I will take the fuel tank, wiring harness, motor, tranny, etc. The motor will think it is still sitting in a 1994 Chevy. Will see how much of the 94 I will use. I will try to spend as little as possible on the swap. Just cleanup the motor. Good luck.