I just read up on a S4 that had a KO3 and a KO4 running in sequence. has any body here done this? maybe you guys should look into it.

 

Where did you read this?
In sequence?? ....and why with two different turbo types??

 

i think that is how set up on Porsches is. sequential. one runs low RPM. other one for high. i would immagine K03 is better for low RPMs cause of lighter weight it will spool up faster, with practically no turbo lag. then K04 would kick in at about 3500-4000 RPM.

 

Whoa! Alex your right on the money. You have my respect, as for you Imolas4 you have my respect too. just not as much as alex does.

 

i think the last Mazda RX-7 did same thing. Nissan 300Z and Toyota Supra and Mitsubishi 3000GT went twin turbo like Audi, one for a set of banks. But you have to remember that those cars are V6 engines, while Porsche is a Boxter engine and RX-7 is rotor. the whole set up is different. I heard some people on Porsche were switching the K03 for a second K04 to get more horses. but those are the people who do tracking and stuff....
doing sequential for Audi probably possible, but considering the setup - it will be more expensive then simply switching the tubos for K04. people with A4 may do that, cause they start from the scratch. S4 is pre-wired for 2 turbos - do not see the need for redoing the whole setup. i doubt u can get more out of the engine that way.

 

Porsche does not and has never used KO3 or the KO4 turbo. they use the K26 and aftermarket K27 turbos.

 

I didnt read your whole message, but now i did. YOu would see a great benifit form doing the Smaller + Larger turbo setup i saw the dyno chart

 

the supra and sklyline r33 and r34 were also sequential

 

well, in the sequential turbo u r running one turbo at any given time... so lets say at 5,000 RPM only the larger of two spins and provides boost. in Audi setup u will have two K04 turbos running full boost at same RPM. i would suspect the Torgue on Audi will be a lot bigger then on sequential setup.

 

Except... how does this apply to the V6 arrangement (the S4 Biturbo layout)?

I'm in agreement with your points (later posts)... the S4 arrangement is plumbed for the turbos to run together. Sequential, in concept, is a great idea, but it would require re-engineering the entire sytem to accomodated the S4 V6.