Fabricating stainless wet headers for BBC, need pointers

[Boostedballs]

I'm thinking about building some shorty style headers for a BBC in a jetboat.
I'm going to use some thick-wall stainless all TIG welded together.
These are going to go through the transom. I have tons of room in the engine bay and I'm wondering if the primaries should go up like most of the ones I see or should they point downward?
What size of jets should I use and how should I situate them?

[BrendellaJet]

I would point them up. If you point them down they will have to go up eventually to get out of the transom which could potentially allow a lot of water to rest in the headers while sitting still in the water...Thats just begging to bend parts...

[Unchained]

I seen BBC shorty stainless headers in the Stainless Works catalog that looked pretty good or they have the pieces available in a kit form. You don't need to use a thick wall material though. Stainless is real strong. I used 2" x .060 wall and have 55# turbos hanging on them for the last four seasons.
Aim the primaries up like BrendallaJet said or at least make a U riser out of 4" tubing after the collector to keep the water out.
I've got tubing from Stainless works in Ohio but there are less expensive places.
Look through the www.turbomustang.com site forums. They have a DIY catagory that lists some good suppliers and has some good tips on fabrication. It is a real fabricating challenge.

[Boostedballs]

I do plan on having some sort of barricade so the lake water doesn't come rushing in. I thought I would be better to have the primaries pointing down to avoid sucking water back into the head from the injectors.
I was going to use thick-wall tubing because I plan on hanging a couple of turbos on them without using extra supports. Your headers must be built right to support your monster turbos with thin-wall. Are they custom?

[texas-19]

Am i reading this right,your wanting to inject water before the turbos?

[Boostedballs]

I should have clarified. I'm going to build the engine as a low compression turbo engine but run it the first season without the turbos for easy break-in, cost, etc. I'll do the turbo stuff when I can afford to do it without pinching pennies. With the cost of buying the log type ones for just a short while, I decided to just make the permanent ones now. So, I'll be injecting the water into the headers for now but then plugging the injector holes and moving the injectors to the turbine discharge area once the turbos are in. I can imagine the turbine blades breaking off the shaft at 100,000rpm from thermal shock, I wonder what that would sound like.

[Unchained]

http://www.***boat.com/image_center/data/500/turbosandheaders.jpg
http://www.***boat.com/image_center/data/500/DSC01218.JPG
http://www.***boat.com/image_center/data/500/turboengine10.jpg

[ck7684]

Throw on some used logs on there for now. There a forum member on here that has a BBC set for sale. I was looking at getting them myself, but I had to spend money elsewhere to get my engine running. Then you could build the headers to suit your turbos exactly instead of making compromises now...
http://www.***boat.com/forums/showthread.php?t=158366

[Boostedballs]

Yeah, I decided to get some used logs; they are being shipped right now. That should make things easy for now and I got a good deal on them so I should be able to recoup the shipping charge when I sell them.
Those turbo photos gave me wood. What kind of efi are you running? I just finished building a megasquirt box but I'm not sure if I'm going to run efi on the boat. I have had some good luck with blow-through carbs. The Edelbrock / Carters are very easy to modify for boost.
My engine bay is enclosed, do you guys think it's going to be a real problem with single-wall dry headers in there? I have a bunch of header wrap.
Also, the turbo motor in the bottom pic looks like it has some really small water connections on the front of the block, maybe 3/8"? That seems too small. I think mine are 1/2".

[BrendellaJet]

you will need water jacketed turbo housings to run them under a cover...Take it off. The logs you bought are water jacketed. Any headers you make (if they will be under the cover) must be water jacketed as well.

[Boostedballs]

you will need water jacketed turbo housings to run them under a cover...Take it off. The logs you bought are water jacketed. Any headers you make (if they will be under the cover) must be water jacketed as well.
That's what I was afraid of. It's going to be a pain to build the headers so they won't crack.
I just spent $1100 for the cover last year so I cant really leave it off. Plus without it, my wife will have nowhere to "beach" herself! haha!
This isn't even a race boat, I just like messing with turbos and hauling ass.

[BrendellaJet]

going fast takes money. Lose the turbos and build a bigger motor.

[Unchained]

I've never had a problem with the .060 stainless tubing cracking and I've put hundreds of hours on it.
The dry headers are only for the real serious who want to mount large frame turbos.
No amount of wrap is going to do the job to keep the heat down enough unless your talking about stuff from the space shuttle. :idea:
Aluminum heat shields are mandatory.
Any of the log type manifolds are only going to mount small turbos.
Maybe that would suit your application OK.
I'm using a Haltech E6K and Mikes setup in the bottom picture uses a Big Stuff.
The Megasquirt has some nice features too.

[texas-19]

Also, the turbo motor in the bottom pic looks like it has some really small water connections on the front of the block, maybe 3/8"? That seems too small. I think mine are 1/2".
They are -10 fittings.
My headers are made from .065 wall and have about 20 hours on them with no problems.
If they are welded right cracking should not be a problem.

[Boostedballs]

I've been eyeing the omc water jacketed manifolds but they are heavy as hell.
This may end up being a centrifugal supercharger setup. Those are easy.