pizzai69

Hi,

I already made researches and I still have to understand something.
I will try to ask that very precisely because I know that this subject is complex.

Context:
With the same engine (let's say f20c), with same intake (oem TB and intake manifold), same exhaust (let's say oem also for the example), same fuel, and same type of FI (centrifugal supercharger), and same level of boost (let's say 10psi at the map sensor)...

Question:
What would be the reasons for one make/model of supercharger kit to make more power than another one?? (I think about Paxton Vs rotrex as I saw lots of different results)

Obviously there could be the tune of course. But assuming that both would be "well" tuned.

We know that output power directly depends of the quantity of air that the engine burns. With the same engine setup as said, and with the same pressure of boost, I can't see a reason why the air mass flow would be different.

Where am I wrong?
Is the temperature/density of air the only thing that can be different in that case?

flanders

Rotrex for example is more efficient than Paxton, less parasitic losses will make more total power output.

Charper732

Different design/size of impeller blades and efficiency.

Chuck S

10psi is 10psi no matter how it's produced. But the power required to produce that pressure will affect the power at the wheels. More efficient supercharger will put more power to the wheels.

-- Chuck

pizzai69

Of course ! Thanks for your answers.
I still think that the power results at the same psi level can be very différents from what I saw. But in those cases, there must have been more differences between the setups...

flanders

Differences between dynos and also engines is usually a lot.
Unless it's the same car on the same dyno with two different SC setups I wouldn't bother to much about it

riceball777

The size of the supercharger / turbo will make a big difference in power output. With everything being 100% the same other than the supercharger or turbo the s2000 with the bigger or better supercharger will make more power. At 10 psi a novi 1200 will make more power than a novi 1220 supercharger at 10 psi. A novi 1220at 10 psi will make a hell of a lot more power than a novi 1000 at 10 psi. Same goes with turbos. With everything being the same a turbo s2000 with a greedy turbo will make a lot less power at 10psi vs the same car with a new top of the line Garrett ball bearing billet compressor wheel gtx3076r turbo at 10 psi.

i have gone through many different turbo setups. I remember years ago I ran a old Garrett t3 50 trim turbo and my s2000 make about 390whp at 13 psi on 91 octane. I swapped that turbo out for a Garrett gtx3576r and the car made 450whp on 91 octane at the same 13psi. There is many reasons for the gain in power. Main one is the gtx3576r is bigger so it’s more efficient and make more power for each pound of boost. The gtx3676r has newer and better turbo technology that makes it more efficient like a better turbine wheel design and a better billet compressor wheel design and it’s ball bearing.

with turbo cars the turbo manifolds can make a huge difference as well. One of my first turbo setups for the s2000 I ran a cheep log manifold and made 330whp at 11 psi on 91 octane. Then I only changed the manifold to a tubular manifold with a proper 4-1 merge collector and the same turbo same 11psi of boost same 91octane and same dyno and same everything else it made close to 400whp. Your talking 70+whp gain on 91octane with just a different turbo manifold.

Charper732

[QUOTE=riceball777;24624534]The size of the supercharger / turbo will make a big difference in power output. With everything being 100% the same other than the supercharger or turbo the s2000 with the bigger or better supercharger will make more power. At 10 psi a novi 1200 will make more power than a novi 1220 supercharger at 10 psi. Same goes with turbos. /QUOTE]

I preach the same thing but for whatever reason someone always comes the 10 psi is 10 psi argument...always someone that is N/A. haha. It's pressure + VOLUME. not pressure alone.

riceball777

Not true at all. With everything else being the same 10 psi on a smaller supercharger/turbo vs 10 psi on a bigger supercharger/turbo will yield vastly different results.

Every 10 psi with the same turbo setup and the same turbo with the only difference being a log manifold vs a tubular manifold manifold can yield 70+whp difference.

pizzai69

I have a problem with this concept.
For me, 10 psi is 10 psi actually.
You say it is "pressure + volume", but for me, the volume, or in fact the flow, is directly dependant of the engine (intake, exhaust etc).

I can't understand why 2 superchargers could have different flows at the same pressure on the same engine
(I say supercharger, because it could be the case on turbos due to the turbine on the exhaust which modifies the engine flow rate)