Custom Exhaust Manifold Q's

[91PlymouthLaser]

Ok, well I've read a few posts but I havn't really found the answer I was looking for in them so I figured I'd just make my own post and see what I can find out. I have to have a project for this semester in Ag Metals. I figured I would just make me a custom exhaust manifold and so now that I got the go-ahead on it from my teacher I was hoping I could find some ideas on what would be the best way to build it. I've been welding for about 8 years now so I'm not worried about the welding on it so don't worry about intracacy of it. Just looking for some tips and hints. All the help is greatly appreciated, Chris.

 

[Loewen21]

Equal length is the way to go. Meaning each cylinder should have the same length of pipe until the flange. Measure twice cut once shouldn't be too bad

 

[propeine]

Nice to make the firing order go in a circular direction as well. Old tip for NA cars but it can't hurt. Personally if I were making a manifold I'd make it divided in T3 or T4 just in case you ever wanted to run a divided setup. Of course the circular direction thing doesn't matter so much then.

 

[91PlymouthLaser]

what do you mean by divided? you got pics you can show me to explain?

 

[Supa Dexta]

Divided housing helps with spool, team up the pulses, so that it keeps the wheel spinning in a more constant manner.. I can't remember which cylinders are connected off hand though.

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[Locke]

Pair 1-4 and 2-3 for divided flange.

 

[BoredDSM]

Route the tubing that some what goes up and back down so that it forces the exhaust towards the blades of the turbine.

 

[propeine]

Divided housings can have a smaller AR for a given cylinder. For example the holsets are 12cm^2 divided T3 housings for the HX35. Each half of the volute is only 6cm^2 though.

Each pulse/cylinder sees only one part of the housing and each part of the housing only sees half the exhaust flow. Therefore you have half the AR but you have twice as long for each "pulse" to flow through. Each volute sees only one pulse per 360 degrees of crankshaft rotation. In a undivided setup the volute sees a pulse every 180 degrees of crankshaft rotation. If properly setup, the same AR for a given turbo will spool faster with a divided housing than a nondivided.

 

[91PlymouthLaser]

Route the tubing that some what goes up and back down so that it forces the exhaust towards the blades of the turbine.

so do you mean in the sense of like a ram-horn header?

 

[BoredDSM]

so do you mean in the sense of like a ram-horn header?

In a way yes. Make sure the exhaust flows out and pushes down dowards the exhaust manifold instead of jsut striking the blades on the side.

Visual Frequently Answered Questions - Home Page

Theres a comparison between the 1g and 2g manifold. As vfaq states the 2g manifold runners go a little higher and point downwards towards the blades.

 

[mitsu-luver]

-dont make the header too short!
now im not sayin do some straight john shep shizz unless your straight drag racing

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-although the welding on this is awsome, dont do this, it will heat up very fast and will cause problems (like cracking)

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-dont be scared to make the manifold a little longer and lose spool because in the end
it will last longer and make more power.
-also use symmetry when integrating the wastegate flange, dont just make it straight 90% off the header
heres a great example on symmetry, this is a gorgeous header by kansai service
(a branch of hks)

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-dont make the wastegate flange too close to the header. the cooler the wastegate is the better it will respond and function.
-weld on the inside ______ where possible and do like a dotted line on the outside ---
thats my 2 cents

 

[kahl23]

Sounds like an awesome class! Personally I would look to see what the best fabricators are doing and go from there. These guys really know what they're doing and have the results to prove it. Also note that for proper boost control with a divided manifold you need two wastegates, one for each pair of cylinders. You can go with one wastegate, but it isn't ideal.

::ShearerFabrications.com - Products::

Full-Race Motorsports

 

[johnboy1065]

some awesome info in this thread. I've been wanting to make a manifold for a long time.

One question though.

what is the Ideal runner length and runner diameter for a 600 HP setup?

I've been thinking about doing 1.5 inches in diameter for the runners. But don't have a clue on the ideal runner length.


thanks,
John