Exhaust Manifold Design

[s2d4]

I wouldn't trust a guy who can't plumb an air flow meter correctly

I hope you are saying that as a joke... otherwise you just haven't seen all of those setups back then.

[s2d4]

It really depends on your goal but I prefer smaller diameter runners, 6-2-1 with less merge area to keep the gas speed up. This may restrict your top end capabilities a little, but most don't need 800+kw of flow anyway.

Don't forget, the wastegate path is just as important as the turbo, the incorrect angle off the merge may see you struggling to control boost without a 60mm gate, and perhaps limit your top end flow unnecessarily.

Thanks for your input scotty.

Yes the wastegates will be angled correctly, even more so than most of the setups that tends to be at 90 degrees and are for sale these days.

[Piggaz]

I hope you are saying that as a joke... otherwise you just haven't seen all of those setups back then.

I think Ben was talking about this.

Something looks out of place here

[KiwiRS4T]

Would love some manifold fabricators/vendors to chime in.

This the guy who made mine - have a look through his gallery:

http://www.sincocustoms.co.nz/gallery/Custom%20Fabrication/2

[niZmO_Man]

I think Ben was talking about this.

Something looks out of place here

Nothing looks out of place here Mr. Scrutineer. The airflow meter is attached to the intake as per regulations .

[sneakey pete]

Some bloke name Fred Gibson ran a HR31 Skyline during the Group A era. He made his own manifold.

You can also ask R31House for one.

Both of these seem to be internal gate, for what it's worth.

[s2d4]

I think Ben was talking about this.

Something looks out of place here

Lol, I know, It's weird as f.

I was just saying that if you have a look at photos of those r31 race cars from back then, they were all like that.

[s2d4]

This the guy who made mine - have a look through his gallery:

http://www.sincocustoms.co.nz/gallery/Custom%20Fabrication/2

I had a look, none of those are 6-2 to the flange.

And sorry to trouble you scotty, do you have any photos of your 6-2-1 top mount setups?

[bigmikespec]

This is my collector effort so far... the T4 flange part is billet machined to get the transition from circle to rectangle spot on.

[Piggaz]

Are you making you're own manifold, Mike?

[CEF33Y]

I would legit sell a kidney for one of those r31 house manifolds, far out they look good.

[bigmikespec]

Are you making you're own manifold, Mike?

Yes, definitely slow and steady though...

What I wanted to be able to do is have a compact billet collector, makes it as cheap as possible. But also so that you can build a 3-1 tube merge and weld it straight on.

[Blackkers]

can someone please explain the location of the AFM in that R31? It's doing my head in

[GTSBoy]

Had to be fitted to the car and connected to the intake system. Creative rule interpretation led to what you see in the photo. Was not outside the rules. Was not inside the intent of the rules. Gibson at his greatest.

[s2d4]

This is my collector effort so far... the T4 flange part is billet machined to get the transition from circle to rectangle spot on.

Good stuff! That T4 flange part is exactly what I wanted as well as a T6 variant.

The 3-1 section off the back half of the cylinders for me would be further away so just a schedule 10 2.5 inch crossing over with the wastegate off that.

The front 3-1 section would be roughly the same or slightly lower with the wastegates being about 60 degrees from vertical, as the power steering/AC will be relocated elsewhere.

Edited February 26, 2016 by s2d4

[AngryRB]

why not merge them earlier to create more merge points for extra venturi effects and group each two that will fire close together? above collective looks alot like the usual twin scroll ..

Edited February 26, 2016 by AngryRB

[s2d4]

why not merge them earlier to create more merge points for extra venturi effects and group each two that will fire close together? above collective looks alot like the usual twin scroll ..

The merge earlier part is exactly what I said 1 post above yours.

Not sure what you are on about for the "extra venturi effects and group each two that will fire close together" part though.

[bigmikespec]

Good stuff! That T4 flange part is exactly what I wanted as well as a T6 variant.

The 3-1 section off the back half of the cylinders for me would be further away so just a schedule 10 2.5 inch crossing over with the wastegate off that.

The front 3-1 section would be roughly the same or slightly lower with the wastegates being about 60 degrees from vertical, as the power steering/AC will be relocated elsewhere.

I can get the flanges made with what ever primary size going into it and a T6 one too... send me a PM.

A more progressive merge and a waste gate port that is more in line with the merge instead of 90° is a lot better but I want to keep it compact and I am using twin 44mm gates so boost control should be ok.

[AngryRB]

The merge earlier part is exactly what I said 1 post above yours.

Not sure what you are on about for the "extra venturi effects and group each two that will fire close together" part though.

I was on about merging 1+5, 3+6 and 2+4 so you have 3 merge points then they merge into the final collector, when cyl1 fires then number 5 that fires next will have a vacuum in its runner ( venturi effect)

Each merge ( 3 pairs + 1 final merge) would step up in pipe size to encourage flow , maybe start off with a small diameter pipe and get larger at each collector like a set of TRI-Y extractors on a V8

http://www.ifs.tohoku.ac.jp/edge/library/020609ppsn(kanazaki).pdf

Edited February 29, 2016 by AngryRB

[s2d4]

I was on about merging 1+5, 3+6 and 2+4 so you have 3 merge points then they merge into the final collector, when cyl1 fires then number 5 that fires next will have a vacuum in its runner ( venturi effect)

Each merge ( 3 pairs + 1 final merge) would step up in pipe size to encourage flow , maybe start off with a small diameter pipe and get larger at each collector like a set of TRI-Y extractors on a V8

http://www.ifs.tohoku.ac.jp/edge/library/020609ppsn(kanazaki).pdf

Not sure how that would work for a twin scroll setup?