Twin wastegates to keep the manifold fully divided- Worth it?
 

As title. Compared to a divided manifold with a shared wastegate. I mostly care about spool, but power of course if its significant.

Has anyone got any firm evidence that two wastegates is better to keep it totally divided? In theory it certainly is, but has anyone got any firm data?

I guess the other option is 1 wastegate with a divide right up to the valve, but I may as well run two smaller gates for the cost and effort that would be! :)

Ive only ever had a divided manifold that ran 1 gate with the pipes joining about 2in from the wastegate, but my new setup I could run either, depending how I welded it. But obv 2 more $$$ and more space...

Thanks.

I will have a twin waste gate fully divided manifold fs soon. Its for an fd though.

I'd think that as long as the flow of the exhaust was divided it would be enough to keep the velocity up. i'd think the difference between a twin WG manifold and a well designed single would be minimal.

depending on the size you go 2 WG could be cheaper and not take up anymore room. would just take more creativity to plumb

Arghx had posted a great thread about this from Mazda's engineering dept. It was basically open flange type vs. fully divided (S5 stock turbo). This is small scale, but it showed very obvious results, look it up. But, you could technically achieve the same thing with a single wastegate but divided entry into it, Turblown has been doing that I believe.

Build the rest of the car right and it won't matter.

Here is a comparison between a 1.06 GT35R( BB) vs a P trim 1.15 GT35R( journal). The BB has a twin scroll manifold the other has a undivided tubular manifold. Identical spool. Don't mind the difference in peak pressure, just different w/g springs.

wow great info !!

Going by most of the information on this forum, the BB, twin scroll input and a smaller exhaust housing should of seen a significant increase in spool.

Was this done on the same engine ?

would of been nice to see a tail VS as well :)

Not sure that's a fair comparison, P-Trim turbos are supposed to spool better than the 35R turbines due to the less exhaust restriction on our engines. That's what it seemed like in Sean's 3574 thread when it first came out. Have you tested open vs twin scroll on the same turbo, turbine wheel, A/R?

That dyno sheet does not tell you what happens on a throttle event. For example what is the difference in rise time (measured in mSec) between the two turbos from a 2800rpm 5% cruise to both 30% opening and 100% opening. You would then measure rise time to 67% or 90% of final manifold pressure and compare the results.

That is where the smaller turbine wheel (and ball bearings) should pay off. It will come back to more acceleration G forces quicker on throttle tip ins at RPM's below the full boost threshold RPM.