Single vs Twin Scroll
Discussion
I'm trying to wrap my head around turbocharging and all this kind of stuff, and despite reading up on this from multiple sites I still have questions.
I know that the idea of twin scroll is to split the cylinders of the engine in two lots of "balanced" cylinders, like 1,2,3 and 4,5,6 on a 2JZ. Sending them through different paths of a turbo you can direct them at different parts of the turbine blades and the inner one can give lower level boost, while the outer can give more boost high up the rev range once exhaust speeds increase (please excuse terminology or understanding if I'm wrong here).
My main question is, if you had a properly set up equal length manifold, with all runners meeting at the turbo at the right time, would a twin scroll still be of any benefit? Would splitting the pulses still give a benefit over just 6 evenly spaced pulses?
I've heard differing things about equal length turbo manifolds. Some people say it's not worth it as it doesn't make much difference on a turbo engine, but in my head what's best for power NA should be best for power turbocharged too. Evenly spaced and "forced" pulses of exhaust gas hitting a turbo must be a benefit, right? While yes it works on NA, is there any scavenging effect on a turbo engine manifold? Maybe from the turbo turbine itself?
One thing I definitely am not questioning is sound. Just as with NA, equal length turbo manifolds sound so much cooler to me. Personal preference, I know, but I like it. PHR Street Torque "log" vs PHR equal length tubular.
On that topic, though, I do wonder if there'd be a difference between single and twin scroll exhaust notes on the equal length kit. I suspect not, but there's always doubt.
I know that the idea of twin scroll is to split the cylinders of the engine in two lots of "balanced" cylinders, like 1,2,3 and 4,5,6 on a 2JZ. Sending them through different paths of a turbo you can direct them at different parts of the turbine blades and the inner one can give lower level boost, while the outer can give more boost high up the rev range once exhaust speeds increase (please excuse terminology or understanding if I'm wrong here).
My main question is, if you had a properly set up equal length manifold, with all runners meeting at the turbo at the right time, would a twin scroll still be of any benefit? Would splitting the pulses still give a benefit over just 6 evenly spaced pulses?
I've heard differing things about equal length turbo manifolds. Some people say it's not worth it as it doesn't make much difference on a turbo engine, but in my head what's best for power NA should be best for power turbocharged too. Evenly spaced and "forced" pulses of exhaust gas hitting a turbo must be a benefit, right? While yes it works on NA, is there any scavenging effect on a turbo engine manifold? Maybe from the turbo turbine itself?
One thing I definitely am not questioning is sound. Just as with NA, equal length turbo manifolds sound so much cooler to me. Personal preference, I know, but I like it. PHR Street Torque "log" vs PHR equal length tubular.
On that topic, though, I do wonder if there'd be a difference between single and twin scroll exhaust notes on the equal length kit. I suspect not, but there's always doubt.
Crudeoink said:
And also https://www.youtube.com/watch?v=T7JTRRlSEYI
In reality ? Will what is being built really benefit ? Maybe not. Even more so when simple v-band turbine housings are becoming more popular, so not really twin scroll friendly
If genuinely optimising everything, best manifold, best turbo, suitable cams ( bigger cams may see more benefit from twin scroll due to somewhat isolating exhaust valve events from others ), then maybe twin scroll is worth worrying about.
I'd sooner build something with a nice cast Artec manifold and v-band, than a fabricated manifold.
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