Brainstorming Manifold Ideas

[guitaraholic]

After a bit of research, on manifolds, I've found that the stock manifold ported (honed) out is best for those who plan on using the stock T25/T28 setup. I am guessing that a LOG style is good for low end, and an equal length will give you a bit more top end, at the cost of some a slightly delayed spool. Here is what I am thinking. What if you...............


Use an equal length manifold and use a 2-3" tube (maybe longer) that separates the manifold from the turbo, this would allow time for the exhaust impulses to "merge" together and you don't get the side to side interference that is only overcome with a twin scroll. If it works as planned, you could get some awesome spool (like almost that of a twin scroll) without the cost, and you would get some awesome spool time and upper end with something like a gt2871r.

I've also am thinking about going with an external WG setup, because you don't get the back pressure at high RPM that causes you to loose boost near redline

[godsmack]

interesting thought. i see the logic with the tube. the only problem i can think of with it would be possibly clearence with the hood and also if you'd go bottom mount with the motor mount.

[guitaraholic]

Well, the issues "could" be resolved with a custom manifold that would normally mount the turbo a little higher (bottom mount), maybe a slight up bend before going down on the manifold. I believe that would resolve the clearance issues.

[godsmack]

well if you have the power of doing a custom manifold why not just add some straight piping on the end instead of having another gasket in there. but in that sense then yes do it up should work.

[ZakS13]

i think the best would be a custom made manifold that is "similar" to the stock RB series LOG manifolds.

[guitaraholic]

Just looking at it visually, I don't see how flow would be very good on a log style manifold. With an equal length tubular manifold, exhaust pulses will exit the manifold at exactly 180 degrees apart from each other. With a log style, I can see the pulses getting "bunched up"

Does anyone know how much "room" there is to play with in mounting the turbo say 3-4" lower than where it is stock. Basically, it would be putting a 4" pipe extension between the manifold and the turbo. You would need a different down-pipe as well.

[ZakS13]

[ Parts Test | TOMEI POWERED SR20DET EXPREME EXHAUST MANIFOLD ] J.D.M. OPTION INTERNATIONAL

heres some numbers on LOG vs Tomei manifold.

[guitaraholic]

Originally Posted by ZakS13

[ Parts Test | TOMEI POWERED SR20DET EXPREME EXHAUST MANIFOLD ] J.D.M. OPTION INTERNATIONAL

heres some numbers on LOG vs Tomei manifold.

Nice find. So according to Tomei, the shorter the pipe, the more torque you get, and less lag (good thing). So..it begs the question. Would putting an extension make the turbo more efficient(no side to side pulses), or would it cause more lag, negating the effects of the "shorter the better"?

[godsmack]

well i think that what they were saying is they had the tubes going into the flange so that the gases wouldn't interact wrong and keep flowing smoothly instead of hitting bends and having the pressures push eachother and pulse sideways.

[guitaraholic]

Originally Posted by godsmack

well i think that what they were saying is they had the tubes going into the flange so that the gases wouldn't interact wrong and keep flowing smoothly instead of hitting bends and having the pressures push eachother and pulse sideways.

I didn't see anywhere in the article that said that the design stopped the side to side pulses. Where did you find it at?

[godsmack]

under the graphs they have pictures and that's what i was understanding from them. yes from the discription itself it pretty much said the shorter the better but then in the pictures it says this "The inside of the manifold is split up. The 1st and 4th tubes come in junction with the 2nd and 3rd tubes to make up a 4-2-1 design. The gases are designed to cross in a pattern of cylinder 1, 3, 4, and 2 into the turbine, according to the ignition."

Which i believe relieves some of the side to side pulses by keeping the air flowing by the cylinder relief pressures not interacting with eachother but working together. I could be wrong but that's what i think.

[Monooxide]

A big part of the reason why Twin Scroll(Fully Divided) is effective is because they help keep the heat and velocity up since there is less volume in the collector therefore the exhaust velocities and temps are higher giving you more exhaust energy to the exhaust wheel.

Good luck with 2~3" runners and it being equal length and the convergence angles be correct as that is going to be impossible.

[guitaraholic]

Originally Posted by Monooxide

A big part of the reason why Twin Scroll(Fully Divided) is effective is because they help keep the heat and velocity up since there is less volume in the collector therefore the exhaust velocities and temps are higher giving you more exhaust energy to the exhaust wheel.

Good luck with 2~3" runners and it being equal length and the convergence angles be correct as that is going to be impossible.

Actually, looking at the dyno results from the Tomei design, I might go that route. True, you loose a little bit of top end, but more than make up for it with response and mid-range torque. I'm just wondering how well this manifold will do with 400whp goal with a GT2871r.