Phat Korean

Compound Turbo



Found this to be interesting and got to wondering about application to the Genesis. Thoughts.

Whatnot

In the works..... kind of.....



http://www.gencoupe.com/2-0t/35714-t...ld-thread.html

wheel_of_steel

Seems pretty heavy.





I'd want someone with a big R&D budget to do it correctly. Think of how hard it would be to avoid a mid range dip in power under all atmospheric conditions, and to get it all switching correctly, what happens when one compressor stalls, what happens when the throttle is suddenly closed, etc etc.



It obviously can be done, but I think the price difference between that and an ordinary turbo kit could be well compensated with nitrous and still be cheaper.

red97tib

The nice advantage to this setup is that you don't get the sudden surge in power which tends to cause broken drive line components. I think it would be a great setup if your looking for insane psi numbers and have awd or rwd to support them. On a fwd platform I think tire smoke is all you will see.

tibbytib

I believe Dave had a twin fi setup on his Tib for a little bit. Supercharger and turbo. Same concept. Reduced lag. I believe he said that tuning it was a complete nightmare. Sure makes you wonder the possibilities tho.....

red97tib

There have been a couple of super/turbo combos on the Beta long ago. They produced instant boost but after a short time the supercharger is basically fighting the turbo.



I think these setups are great idea for built motor cars. The one in the video is almost a track built car if I remember correctly. By that I mean the engine bay supports no air con or other creature comforts. I don't even remember if he had power steering. There was a DSM guy who did this a couple of years back and did a full build thread dedicated to it.



It was funny because a member told him the power output from the beginning but no one would listen to the fact that you have to drastically increase the size of you larger turbo. In the end of that build he produced the power stated by the outcasted member. For this to work to the degree people want you have to put a monster turbo on there.

Phat Korean

Im interested in seeing more of this concept put to practice. I think the idea is so simple its complex and i can only imagine how hard it would be to tune

Random

BTW, these are properly called "sequential" turbos, not "compound" turbos. The Toyota Supra TT's were sequential turbos(most people dumped them for 2 equal size turbo's or one big turbo). The new BMW diesels use this kind of setup, but they use 2 small turbos feeding one larger turbo.



It's brilliant and simple in concept. It's very difficult in reality to get it working right, tuned right, etc when doing it yourself. If you notice the plumbing on his setup is a convoluted mess of tubing/wastegates-valves, etc It's probably works great, flows well and fits into the limited space available in his engine compartment. I'm not knocking it. I'm just pointing to it to give you an idea how hard it's going to be to duplicate. Then you need the 2 turbos to be properly sized to complement each other, but not push the other into stall/surge. Not impossible, just difficult.



Everything has it's pros/cons. But I would recommend you look @ yourself in the mirror and ask yourself this question.

Are you really up to the technical tasks, and do you have the skills required to get a sequential turbo up and running and tuned properly?

red97tib

There is a difference between "compound" and "sequential" turbo setups. The main difference being the routing of piping after the first turbo to the second and the location of the air intake.



In Sequential setups the first turbo usually feeds the second turbo through the cold side intake along with outside air. This does spool quicker than traditional single setups but not nearly as quick as a compound set up. On lots of OEM setups you can feel air come out of the intake for the larger turbo when you release throttle due to pressure densities inside.





In Compound setups the second turbo is solely fed by the first turbo in a closed loop system. This allows the the boost to grow at a much quicker rate. Example: if the first turbo is set at 7 psi and the second is at lets say 20 psi. When the first turbo hits 3 psi the second turbo compounds the boost (hence the name) to something like 9 psi due to both turbos compounding the air before it goes back into the motor.





This is a very crude example. I've attached pictures to try to help. Hopefully they come through, I rarely post pics. Both pics are pretty simple.

Whatnot

^^WHSthis is extremly common in large turbine engines, they have mulitle stages that compound the compression before it gets ignited, but detonation isn't an issue so it can have insanely high inatke temps. I think intake temps are more of an issue on compound setups. They are more common and IMO make much more sense in a diesel or an aircraft than a gas engine on a car. Just my opinion, but I would say the order goes sequential, one large one, twin, then compound.