These turbos work simultaniously so having different sized turbos would not work in this situation. If they were set up like a Supra, for example, I believe you can run different sized turbos since they are boosting at different rpm levels. I am no turbo expert but I know twin turbo setups like on the 996tt, need to be matched. I am assuming and could be wrong on the Supra scenario.

 

Craig,

Thanks for the input...experience is the best teacher. And you been through a good amount of setups. The theory seemed suspect to me as well but I didn't come up with the question out of thin air. I was told that the different sized turbos on each side is a possibility. Just wanted to double check that with some of the more knowledgable members...

BTW... I have the K16/24 hybrids already, but interesting read about them

 

I think we're discussing the difference between parallel turbos (a la 996TT), and sequential turbos (a la 959).

In a 996 TT, one turbo feeds one cylinder bank, and the the other feeds the other, so it would be undesireable in the extreme to destroy the symmetry of the two turbos working in parallel.

In the 959, a smaller turbo spools quickly at low RPM, building enough boost to spool the larger turbo at higher RPM (i.e. sequentially). So, in that case, the answer to the question is yes, and Porsche did it in the 1980's.

 

I was going to say the sequential turbos would only work on a straight six or such deu to the single exauhst manifold being used ergo, two turbos useing the same flow source to spool unlike the 996TT where one manifold each three cylinders supplies its own supply of air each




the 3000Gt and other cars have used the sequential idea before.

but no it would not work on a 996TT

 

I would consider these 3 choices as best of the bunch... not in any particular order... "proto" was todd knighton- the protomotive k24/18g and I also recommend it highly.
if u want 600 plus HP u need to choose any of these.... everything else is marginal and not worth the upgrade... go for it all the way b4 u need to get into the fuel rails and pumps and be done. after these three u have 700 HP crank set ups and u need alot more money, alot more to acheive those results.
markski

 

So I guess the better question would be " Is it possible to have a sequential setup on the 996?" And I guess the answer is no. Once again I was told it was possible!

 

I suppose with enough money anything is possible...just why would you do it? Many other "better" options out there (as some have already posted).

 

Exactamundo

 

the moral of the story is that k16 based turbos do not offer any significant power... u need a k24 based hybrid. so u go with a k24 housing... or someone like Kevin takes the k16s and c&cs the internals and bumps up the specs to a k24 housing...

 

wow.. i'm suprised no one got his question.. he's basically asking if he can run two different size turbos.. a k16 to boost his low end because of the quick spool and a k24 for straight top end power.. lots of people have experimented with this on other cars like supras and such.. but it hasnt been proven to be beneficial over the straight dual big turbos.. it works in theory but in reality it doesnt work

 

You obviously did not read all of the posts!

 

This is sort of what the 959 was running, the smaller turbo spools up to 3500RPMs or so (from memory) and then the other turbo picks it up from there up to redline, these are sequential turbo setups which reduce lag. Works good, but complicated (expensive) and has now been overcome by more efficient turbos that reduce lag, so there is no real need for it, this is what hybrids do.

Markski, great input, the only thing I would correct here is that stock (X50, GT2) K24 turbos cannot give you more than 530-540HP on a 996 due to the relationship between compressor size and engine maximum specific airflow. No matter what boost you run or what the dyno tells you.

 

What about a K16/24 on one side and a K24 on the other? I don't think you would have to mess with the programming?

 

Man, it is very simple. You cannot have different flows between the two turbos because there is only one ecu to command the turbos and you need to feed both sides of the engine, left and right side, with the same amount of fuel and air. For a sequencial system it would be needed that the two headers converged into one pipe, and only then you can have a small turbo and after a bigger one. (Mercedes made a SLK diesel with sequencial tri-turbos ). With money nothing is impossible but with your idea it is like having two independent engines in one car. Not the best route for performance and money wise.