Header bending and assembly questions
 

Hey guys few questions to the metal workers and welders on this site.

with the Offshore headers, the tube inside a tube, are they bent at the same time with a mandrel bender or are they bent separately and then some how assembled and welded to the flange and the collector or collar?

Anyone have any information on this at all?
basically in a nut shell, how to they make these things?

Thanks
Jason

I think both. Some tubes are bent separately and then inserted into each other and others are bent together-- fill the two tubes with packed sand and then bend them together.

Sand?
That is the secret?
SAND?

are there like metal fingers or fins if you will on the inside tube to the outside tube?
How do you keep the inside tube from touching the outside tube on this deal?

Thanks CM

Jason

Yea, put one tube inside the other and then fill the inside and the area between the tubes with sand and keep the inner tube centered, pack it in and then bend and then shake it out. Weld the ends at the flanges and they stay separate, not touching.

It sounds to me that the process of using sand can make for some mistakes here and there. What if the tubes touch in the bend somewhere? Wouldn't that cause a bad hotspot and possible crack in the pipe? I guess that the manufactureres would say that they have this procedure perfected but mistakes can happen.

Actually, both methods are used. The material between the tubes is a low melting point metal alloy. Cerrobend rings a bell. It melts well below the boiling point of water. CMI pieces their headers together with nuclear quality welds. Hot spots are a concern with either method. Even though they might be concentric when cold the pipes move a lot when they warm up.

Would a coil spring be a better buffer between the pipes and then just pull it out when your done?
Do these companies use TIG or MIG welding techniques for their
stuff?
I see CMI has this cool collar thing at the base that the one pipe is welded to the inner pipe after it comes off the block flange and starts its sweep up, Do all companies do this or is it just CMI that
allows that about 1-2 inches of bare metal be heated and rest is cooled by the water jacket?

Just interested in how these things are made and produced and why the hell they are 3500 a pair is all

Saw monster garage last night so Now I feel I can make a pair
Tim Allen Oh yeah yeah yeah RRRRRRRRRRRRRRR

Jason

Jay I think this would be a good challange for you over the winter sence some one else will be fix'in your motors:D Charlie

Well the thought had crossed my mind about making headers for the boat but also as a business more or less.
Start up capital is what is going to probably kill this whole idea since pipe benders (mandrel benders to be more specific) are very costly and welding supplies and office and work space and storage space to hold the completed ones type of thing will cost a small fortune)
But ya never know.
My dry exhaust setup that I built worked out flawlessly for the little time I was out on the water with the baja.
That is incentive to produce some cool stuff I would think.
Maybe a CNC machine and make my own custom risers would be an idea too but just as a thought.
(dont know how long aluminum would hold up)
but be assured, if it comes from me, Ill warranty the damn things for 10 years and I wont chop your nuts off with price either.
Stellings 3500 a pair
Yeah you wait until I get some of this market
your going DOWN!
Jason

Jay I new you had dry pipes but did not know you made them yourself tell us about them lets see a picture.
I think aluminum would hold up ok sence that is what the hp manifolds are made out of and Stainless Marine's entry leval risers are aluminum.

Hey Rag, I thought everyone always read my posts LOL

What I did was bought a set of stainless steel risers from some place out in California they were take offs from some dealer
they had been run but like half a season

What I did was bought myself a pipe cutter tool, and an expander tool
From there I got some stainless steel welding rods and borrowed a friends torch.
I got some pipe (galvanized cause I could not find stainless anywhere near me in a short period of time.)

I made a PVC template of the pipe I needed and grinded and sanded it down to match the inside of the outlet of the riser
Then I slipped this PVC pipe into the galvanized pipe I got and
basically formed it to match the PVC that was inside it (flat on the one side of the pipe at the top cause riser elbows outlets are not perfectally round)

From there basically took a mallet and smacked them in the riser about 3 inches, each time I smacked it in about 1/2 inch I used some real high temp exhaust gasket goop just to have something to sort of seal it (granted that wont last too long but it will hold for a while)
Then after I got the pipes in and used a template that told me when the angle was perfect I started stick welding the pipes to the risers at the outlet
My cams have 7 degrees of overlap on a 110 LSA so they would tend to suck water right in and up there.
So with these riser extensions now there is no chance of that at all.
To worry about asthetics as well I took all that rubber foam stuff exhaust tubing stuff out of the boat and used 4 inch chrome pipes that I got from a MACK truck Parts distributor and cut the lengths I needed (about 16 inches)
I reused the rubber coupler from the origional exhaust and the silent choice I used to have to couple it from the riser to the tramsom
So now if you look In my engine compartment, You have the stock merc exhaust manifolds and risers but then chrome pipes out to the back of the inside of the transom.
small rubber coupler on each end of the chrome pipe.
Looks very good but the sneaky part is if you look at the back of the boat and lift up the rubber flappers about 3 inches up you see the inner pipe where the exhaust flows and then the outer pipe where the water flows
so basically it is a pipe in a pipe setup to create a dry exhaust setup that cost me in materials including the chrome pipes and stuff about 70 dollars for both engines.
Hows that for exhaust solutions to big cams when you cant afford 3500 per pair stellings headers and pipes!!!

Give me a challenge I will come up with a solution.
Put me in Jesse James' Monster garage, Ill wow them too

I dont have pics of my exhaust but I can get them when I go get the stuff from Ike's (he has all my exhaust there)
Ill snap a few shots for you
Jason

Oh and Rag one more thing
I wanted her LOUD

I like the fact that engine can scavenge exhaust from the manifold since it is one huge chamber and the dry pipes make it perfect
Now if I could only get it even louder than it already is Id be happy
Jason