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Twin scroll versus "normal" turbosystem?

Jussi Alanko

Member
Joined
Jun 5, 2020
Location
Finland
Has anybody tested a twin-scroll system back to back test at one scroll system?

How much earlier twin scroll turbosystem wakes up versus normal system with same size turbo?

My guess is something between 500-1000rpm when exhaust manifold is good.

Example, b21 with hx40 twin scroll made boost somewhere about 3000rpm, and max boost is somewhere about 4000rpm.

With normal 60mm turbo b21 made boost somewhere about 3500-4000rpm and max boost is at 4500rpm.

Has anyone tested this in practise, or does someone made this kind of test with any engine, or do i find this kind of test at youtube?

How much earlier turbo wakes up with a twin scroll system???
 
I found this text at borg-warner turbosystems:

Twin scroll technology produces results similar to twin-turbo applications, but in a smaller package with lower weight
and cost. In turbochargers of this type, the channels between the exhaust manifold and turbocharger of the first
and fourth as well as the second and third cylinders are separated from each other. The exhaust gas streams are
directed into so-called scrolls (spirals) and then reunited again directly at the turbine wheel. Separating the
streams in this way offers improved performance. With this type of charging, spontaneous boost pressure
can be built up 1000 RPMs earlier, which significantly improves response in the low rev band.


So borg-warner says that twin-scroll design can build boost 1000rpm earlier versus single scroll.

This is quite a lot!
 
Now i make contact with a guy who makes exhaust manifold to me, he send me some pictures.

This is what my future exhaust manifold looks like:



When i get this manifold before end of this month, i had to replace wastegate pipe and go with a divided pipe to the wastegate, then this manifold acts like a true twin scroll manifold.

With this setup i had the scavenging effect at low speed rpm:s, this broadens powerband and enhances low rpm torque output, in other words it acts like a long tube header whichs enhances torque output at any given engine speed.

I coat this with Vht:s flameproof coating, it is used in aerospace industries and automotive solutions.
 
I'll reroute the wastegate pipings so that they'll be divided from each other to the wastegate valve, then exhaust pulses will not gonna be mixed.
 
Hello,

This is a manifold I built for my b21 that I put a super hx40 on https://drive.google.com/folderview?id=1qINeoQjm3cO9ujESwavir5Rh-J94j31h

Later on I combined the wastegate pipes in a Y seperated all the way to the wastegate valve.

This motor is a monster with hx40, k cam, 531 head, big intercooler, 970cc injectors and 25 psi of boost :D

The turbo starts building boost at 2000 rpm and is at full boost at 4000 in a 3 gear pull using 98RON with octane booster.

These injectors are actually maxed out at 25 psi
 
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