M37B3 Project

[k8icu]

Spring is on it's way so hopefully I will be able to get back into the garage and get more done on the truck!

One thing I'm struggling with is how to run the down pipe for the turbo. I thought of going up the side of the cowl ala M35A2 style, but I'm not a big fan of that and IMHO it takes away the lines of the truck.

I've decided I'm going to run 3 inch exhaust pipe instead of 4 inch for the 6.5l diesel and I was thinking of mocking it up with PVC pipe first before I start cutting and hacking expensive exhaust pipe. I know that PVC pipe is measure ID and exhaust pipe is OD but I would think using 2.5 PVC would give me the closes to the 3 inch OD of the exhaust pipe where as 3 inch PVC would be to fat for clearances?

Anyone have a thought about this?

[Cal_Gary]

Hi Joe!
I can't say for sure. What I do know is that some engines run better with some back-pressure in the exhaust. With a turbo though you'd initially get a pretty free-flow exhaust from being so close to the manifold and ahead of your muffler. You just want to avoid a choke-point with too much exhaust trying to pass down a small exhaust pipe.
Gary

[k8icu]

Hey Gary,

On a stock 6.5l GM diesel the exhaust is 3 inch so I was going to go to 4 inch which is a standard mod on a chevy or gmc truck, but 4 inch just wont fit on a m37. So, I think 3 inch will work fine. The problem is working around the limited room to fit the exhaust on the truck. My first attempt would have had the exhaust flowing into the path of the passenger side front tire which I think would have been a bad thing... I figured out how to make a mock up for the pipe. I've cut some 2 x 4s and with some glue and screws put them into a + at three inches all around so that will allow me to figure cuts and bends then once the mock up is made then I can cut tubing and put it together.

[Cal_Gary]

Sounds like a good plan! You could also mock it up with some PVC I suppose-wouldn't be too expensive.
Gary

[k8icu]

Wood is cheaper, I have a lot of it from many other honey due projects, and I can get the exact size. Where as PVC is either bigger or smaller. Exhaust pipe is measured in OD and PVC pipe is measured in ID.

[RCrombie]

I think you will find 3inch works just fine, and unless you’re planning to be making some serious power, there’s not going to be any performance difference between 3 or 4 inch piping.
Whatever you use for mock-up, it’s mainly for getting the routing and the angles just right. When you start cutting and welding the pipe, you will find that you will have to make adjustments anyway, so as long as you know you have the space to run the pipe I wouldn’t worry too much. One tip I have found helpful for fabricating exhaust is to first mock up everything, and then fully weld each piece before moving onto the next. This way you can test fit in between, and correct for any warping as the metal heats and cools. Otherwise you may find that due to the length of the pipe, the warping can cause a pretty significant shift!
Also, whatever route you choose with the pipe, I would keep it behind the cab as there’s nothing more annoying than breathing exhaust fumes every time you stop.
Hope that helps
Rob

[k8icu]

Thanks Rob, that does help. To be honest I with the M37s frame didn't close in on the front like it does and was straight front to back. I could use a little more room up front. LOL. I'm not an engineer, but I do play one in the garage.

[k8icu]

Here is an update on some things I've gotten done.

I made a down pipe and rejected it. I moved the front shock mounts and made new ones in order to make a better down pipe and exhaust system. Made a mockup exhaust out of wood. Then made the new down pipe and exhaust. Also did some repair work on the fenders and the corner of the cab.

I've got it all here if you want to see it. http://leathernaturally.com/m37b3-page-3/

Enjoy my ramblings...

[m-11]

I remember when you made the deal for this truck. It was about the same time I got my truck and was finishing up on restoring my A2. Anyway, do you know whatever happen to your A-1? The folks that got it seem to have dropped out of sight shortly after getting it.

[k8icu]

I remember when you made the deal for this truck. It was about the same time I got my truck and was finishing up on restoring my A2. Anyway, do you know whatever happen to your A-1? The folks that got it seem to have dropped out of sight shortly after getting it.

No my beloved m151a1 has disappeared as far as I can tell, but then again with my only MV still in a thousand pieces I haven't been active in the MV scene here in Ohio. Don't go to many events cause I don't have a ride to take, plus the rest of my life has gotten in the way from me being able to go to events like I use to, so they may still be around, who knows.

I've decided to set some goals for this project in order to get it done. The long term goal is to drive it to the Armed Forces Day event in Findley Ohio in 2024. The short term goal is to get the cab, front clip and frame to the sandblasters by the end of October. I've got like three things to get done to make that happen this year. Sometimes I take one step forward and two backwards on this project, but hey that's have the fun of working on this project.

[k8icu]

Just a quick update note. The rolling frame and front sheet metal including cab went to the sandblasters last week Oct. 25th to be blasted and primed. With the weather going south here in Ohio quickly I didn't want bare metal waiting around all winter till it got warm enough to paint so I'm having them prime it to keep it from rerusting. The blaster guy said about 4 weeks to get it all done so now I'm waiting. I will post some pics of it when I get it back home. I made my first short term goal. Now to start my second short term goal list.

[John Mc]

The long term goal is to drive it to the Armed Forces Day event in Findley Ohio in 2024.

I grew up about 20 minutes from Findlay, in Fostoria, Ohio. I've moved away and come back a few times, somehow, I was unaware of that event going on. (These days, I'm in VT, so not a whole lot of chance I'll make it out there.)

[Cal_Gary]

Hey Joe,
Thanks for providing an update! Glad to hear you're still fiddling around with an HMV! Now if our Browns will figure things out, we'll have some real fun!
Gary

[k8icu]

@John Mc Yeah they have been doing the Armed Forces Day gig at the Hancock County Fair grounds since I think the late 80s or early 90s. I attended the first one they had in the town square with about 10 other vehicles and then I went for the next like 10 years. Then life got in the way and well... I don't make them as much as I should.
@Cal_Gary Well one game at a time. LOL!

[k8icu]

I finally got my truck back from the sandblasters a couple weeks ago. The body did not develop any new holes. Seems I did a good job fixing all the rust in the cab. The frame on the other had has a few spots that opened up. Once I can get back into the garage this spring I'll be doing some grinding and welding to fix those few spots up. Once I get back into the garage I'll take some pics and post them up for everyone. Right now the truck is tucked safely in the garage for it's winter nap.