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Discussion Starter #261
Last night I decided to start on the firewall. First I needed to remove the front clip then I made the top piece by cutting some 14 gauge. I used my method of cutting 1/2" way through the metal to make a bend. I didn't have the cojones to weld it in yet. The middle of this new panel will be clearanced later when I get more things in the engine bay in place.

In another thread in the general section I have talked about making a exhaust manifold so I can position the turbo lower for hood clearance out of stainless. I think the last pic will basically give you the idea of what I'm thinking. In the other thread a couple of guys think that it should be thicker than 1/8" thick. Let me know what you think.







 

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Discussion Starter #263
The custom manifold idea is awesome! I'd have to agree and say maybe a bit thicker too for sure. 3/16" . Why not a tube style manifold/header thing?
As of right now I have not found 304 stainless in 1.75". The ports on the exhaust are 1.25"wide by 1.75" tall.
 

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Discussion Starter #264 (Edited)
Got all of my exhaust parts last week. Started working of the flanges for the new manifold I'm building. They're made from 304 1/2" stainless. Transfer punches make finding the hole pattern so simple to copy. I can't stress enough if you need make parts bolt together and have an existing part to go off of, transfer punches are the best. The first piece when trying to cut the port holes out I tried to connect the 4 corner holes with my plasma cutter. IT DIDN'T WORK. The cuts didn't go straight down so it left almost no material at the edges. The other 3 I drilled the 4 corner holes and my machinist friend connected then with an end mill.

After that I mocked up where I want the exhaust to go. Hehehe













In the past I have always used the exhaust clamps that are basically U bolts and they deform the exhaust tubing causing the exhaust from ever coming apart. This time I am using a band style clamp. I'm pretty pleased with the fit up with these clamps and they use some 7/16" bolts. Ultra beefy so they hopefully don't break when I need to take them off later after they have been through a few hot and cold cycles.

 

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On thing. The openings in your flanges should be slightly larger than the head ports for good scavenging. Some people port the heads to match the exhaust manifold and you lose a bit of velocity by doing that. A little mismatch seems to increase the flow speed. It may not be huge, but it would tend to give a faster turbo spool.
 

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Discussion Starter #268 (Edited)
On thing. The openings in your flanges should be slightly larger than the head ports for good scavenging. Some people port the heads to match the exhaust manifold and you lose a bit of velocity by doing that. A little mismatch seems to increase the flow speed. It may not be huge, but it would tend to give a faster turbo spool.
Right now they're about 1/16"ish over all around the size of the port now. Do you think they should be more than that?
 

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No, that sounds about right. 1/16" is a good border and should work fine. In my younger days I had a performance engine shop next door and learned how to port from those guys. Not sure we followed the same rules on gas engines as I've found on turbo diesels. Sometimes we see guys open up the manifold port that feeds the turbo. That would be a mistake. You'd want that one slightly smaller than the one entering the turbo to keep the velocity.
 

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Discussion Starter #270
OK that's what I thought on the exhaust port side of the manifold. I have thought about smoothing of the surface of the exhaust ports on the head for a little better flow but i really doubt I'm actually going to do it just because I don't think I'll notice any benefit.

The turbo side of the manifold I was planning on keeping it the same size as the turbo port but that makes sense because there is only one cylinder of exhaust going into the turbo at a time.
 

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Discussion Starter #271 (Edited)
I was able to layout and get my first piece cut for the runners on the manifold last night. I used dykem at first and realized that it was kinda of silly becuse its not like the tolarences are going to be that tight for the plasma cutter. :rolleyes:

I think it came out nice, now I got to make another one for the top side.



 

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Just read through the thread and it looks really good. My friend completely redid a 69 Bronco and had a helluva time getting the body panels to line up and fit. I believe that they had a 1/4" of tolerance allowed from the factory.
 

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Discussion Starter #273
Just read through the thread and it looks really good. My friend completely redid a 69 Bronco and had a helluva time getting the body panels to line up and fit. I believe that they had a 1/4" of tolerance allowed from the factory.
Yeah I have definitely had a hard time getting stuff lined up
 

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Discussion Starter #280
I think it would be best to keep it bolted to the head for as much welding as possible.

Ed
My plan is to bolt it down to some thicker piece of angle iron and weld as much as can. I really can't TIG weld the manifold a lot on the engine. (Or I'm just not that skilled) I am using pulsed TIG which is supposed to help with distortion. I'm pretty sure it will have to be milled flat after welding, but will we see.
 
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