Quote Originally Posted by KaiserBill View Post
For all we know the Ripp unit could be flowing twice as much air into the cylinder head as his Prodigy's Garrett turbo does at 1800rpm which could result in a 40% increase in power at that rpm range over the stock engine.
No.

Each cylinder has a capacity: 3.6L / 6 = 0.6L

The cylinder fills with 0.6L of air at close to the manifold pressure. Yes, it's more complex than that due to valve overlap, timing, etc., etc., that can affect how efficiently the cylinder fills, but let's simplify it and just say it fills with 0.6L of air at the same pressure as the manifold pressure. It doesn't matter for the sake of this discussion because we are not comparing different engines with different cylinder fill efficiencies.

If the manifold pressure is 15.7 psia (1 psi boost above atmospheric pressure at sea level), then the cylinder will fill with 0.6L of air at 15.7 psia. It is 100% irrelevant what the supercharger/turbo is *capable* of flowing. If it is producing 1 psi boost, then there is 0.6L of air at 15.7 psia going into the cylinder. The only difference is going to be the efficiency of the turbo/supercharger and the intercooler, leading to differences in air temperature, which will affect the actual amount of air molecules in the cylinder. I can assure you that intake temps at full throttle at low RPMs with the turbo are pretty close to ambient temperature. There's no way that the RIPP could have intake temps at that RPM so much cooler that it could explain a much larger gain.

At 1800 rpm, the RIPP is making about 0.6 psi. So at sea level, standard temp, pressure, etc, that would be about 14.7 + 0.6 = 15.3 psi.
At 1800 rpm, the Prodigy is making about 0.3 psi, so same conditions, that's about 14.7 + 0.3 = 15.0 psi.

Ideal gas law, PV = nRT. Given the same volume (1 cylinder), temperature (already established IATs must be very close) and type of gas (atmosphere), pressure is DIRECTLY PROPORTIONAL to number of molecules of gas. That means that at 1800 rpm, the RIPP is only putting about 100 x (15.3 - 15.0) / 15.0 = 2% more air into the cylinder than the Prodigy.

The RIPP also only puts 100 x (15.3 - 14.7) / 14.7 = 4% more air in than stock. Add to that that the RIPP is DIRECTLY driven by the engine itself, it just does not make sense at all that the RIPP supercharger itself could be responsible for a 40% gain in net power output at that RPM.

Exhaust back pressure with the turbo would not explain a much smaller gain from the turbo compared to RIPP at the same RPM where boost is very similar. The exhaust pressure is much more indirect than the RIPP being powered by the crankshaft. That exhaust pressure is what is driving the turbo. I also happen to know that the exhaust:boost pressure ratio with the Prodigy setup is less than 1:1. That means the boost filling the cylinder is stronger than the exhaust back-pressure during valve overlap, so there won't be an issue of exhaust back pressure causing some exhaust to remain in the cylinder. The boost will actually help push the exhaust out of the cylinder.

It has to be either a much improved calibration over stock that favors power rather than whatever Chrysler sacrificed power for at that RPM (emissions? fuel efficiency? dumbing down power for "driveability"?), or the 40% gain claim is B.S., or a mix of both.

If such a large gain in power is possible at 1800 rpm with the RIPP, then a respectable gain should also be possible with the turbo down in that rpm range if tuned similarly. A 40% gain from RIPP vs a perceived zero gain from Prodigy at the same RPM (we unfortunately do not have any good stock vs Prodigy dyno charts yet to see for sure) simply cannot be primarily explained by differences between the supercharger and turbo themselves.

Quote Originally Posted by KaiserBill View Post
Well, actually Turbos tend actually rob you of power when they aren't producing boost.
The turbo is producing boost in the situation being discussed here.