Originally Posted by homemade wrx

yes, a single scroll is more efficient as it doesn't lose velocity because of skin friction from the added material/surface area...hence why I said the top end loss is worth the gain of area under the curve.
the single scroll also has less thermal transfer but I'm really curius at how negligable the thermal loss is.

Originally Posted by ill-luzion

Quote:
Originally Posted by ill-luzion
Hey, would you need to run a 4inch Turbo back if you went with a built 2.4 93oct/meth on the GT4094R? or is a 3inch fine?

3" is fine. There are turbo'd V8's that don't have 4" exh.

Thanks

Originally Posted by robertrinaustin

What do you mean by "more effecient"?

Originally Posted by High_PSI

They also have 2 3.0 pipes, one for each side. So 6.0 of flow.

Originally Posted by homemade wrx

thinking about a twinscroll with the same a/r as a single entry...the twin has more surface area = lower velocity fromt surface friction and more heat loss...wonder how that would affect the top end as normally the top end issue is choking and thus causing reversion...

Originally Posted by Drifto

The ability of a twin scroll to utilize the pulsing, unsteady flow of the exhaust exiting the engine gives it a huge bump in "apparent" efficiency, and ultimately spools up the turbine that much sooner. Twinscrolls also isolate the cylinders' blowdown events much better than a non-divided housing, preventing the exhausting cylinder's very high PEAK exhaust manifold pressures from finding their way into the other cylinder on its overlap period. "

Originally Posted by THUB

Looks to me like he's disagreeing, while legitimizing your point. theoretically a single scroll on the flow bench where air flow is truly constant would e more effective. but engines let out exhaust gasses in unsteady pulses, and make for unpredictable results that a twin scroll could be better able to cope with.

Originally Posted by homemade wrx

yes, a single scroll is more efficient as it doesn't lose velocity because of skin friction from the added material/surface area...hence why I said the top end loss is worth the gain of area under the curve.
the single scroll also has less thermal transfer but I'm really curius at how negligable the thermal loss is.

Originally Posted by PVD04

It doesn't really work that way. 2 3.0 pipes flow about the same as 1 4.0 pipe.

-Paul

Originally Posted by sonicnofadz

I don't see what all the arguing is about, twin scroll is obviously better suited for circuit duty. It will lose top end, there is no doubt about that. If your car is all top end, it will only be good in a straight line. To properly conquer a race track, you need power and torque ALL over the RPM range (to properly accelerate into, around, and out of turns with minimal shifting). This is why the twin scroll has an advantage. However the twin scroll is not the end all solution for better midrange power. More displacement, playing games with the intake/exhaust manifolds, mivec, cam timing, porting the cylinder head, and the turbine housing all are huge factors. A good example is the AMS time attack Evo, which doesn't use a twin scroll setup, and yet it manages to scorch down lap times comparable to that of an open wheel formula 1 race car.

Originally Posted by High_PSI

In a V Formation? Each bank of 4 cylinders (assuming a true dual Exhaust) would have it's own 3.0 exhaust pipe. How would it flow as well as 1 4.0 pipe?

Originally Posted by Full-Race Geoff

i would say that single scroll has less FRICTION, less efficient depends entirely on what "efficiency" you are referring to. There should be no top end loss to correlate the newfound area under the curve if the system is working optimally. the heat transfer is negligable, especially with Spark Ignition

Originally Posted by homemade wrx

so with spec manifold runner length, radius, diameter and collector volume with a spec cam, I would imagine the single scroll of the single a/r to still out perform the tiwnscroll in the top end for the afformentioned reasons. Are you saying the identical set up twinscroll can make the same as a single? Of course the twinscroll should smoke it for the rest of the power band.