Great read on separate wastegate pipes and turbocharged engines exhaust theory.

[Mark Halligan]

http://www.tantrumwerks.com/html/Spl...t%20theory.pdf

Extract from the above link:

"As for the geometry of the exhaust at the turbine discharge, the most optimal configuration would be a gradual increase in diameter from the turbine's exducer to the desired exhaust diameter-- via a straight conical diffuser of 7-12° included angle (to minimize flow separation and skin friction losses) mounted right at the turbine discharge. Many turbochargers found in diesels have this diffuser section cast right into the turbine housing. A hyperbolic increase in diameter (like a trumpet snorkus) is theoretically ideal but I've never seen one in use (and doubt it would be measurably superior to a straight diffuser).

I guess then, that this is why the turbine housing in this GT35R is cast like this.....62.5mm exducer (68mm wheel) flaring out to a 3" outlet, giving a 'gradual increase in diameter'.

I had wondered why...............

[audiman]

Looks like someone has their new turbo then!!

[Mark Halligan]

Looks like someone has their new turbo then!!

LOL had it a while now , but was re-reading that link tonight, and it made me think, that was maybe why Garrett have made the turbine housing like that?

[jeroen]

i cant open the file

but suppose it's giving the pro's off seperate wg exhaust?

and how many bhp would you be running to find a noticable difference?
and has any body got a sound file of what it actually sounds like??

grtz jeroen.

[|Maku|]

Have anyone dynod with and without separate WG pipe? For example if I have ca 400hp RS2 with 3" exhaust system in the end 2.5" silencer and now I would use separate WG pipe, what would I gain?

Separate wastegate pipe issue...