Quote:
Originally Posted by JJ's370z
Nice numbers Charles must be a hoot was that on e85? interesting to see how the boost comes in 7psi@2400 - 10psi@4200 - 12psi@5800 - 13.8@7500
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Yes that was e85. The car picked up roughly 100rwhp switching to E85.
Quote:
Originally Posted by JJ's370z
Not what i was expecting thought it would be fully lit from down low.
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One thing to keep in mind about the "boost profile" of a supercharger, which I am sure you are well aware, is that its nothing like a turbo system. While the turbocharger is boost regulated, superchargers are speed controlled and speed is determined by the pulley ratio and engine RPM.
A *flawed* but easier way to look at it, is that superchargers operate at a set airflow vs RPM rather than "target boost". Again, as you already know, the boost generated between the supercharger and intake valves is merely a byproduct of the engines restriction. No matter what the engine thinks of it, that airflow is coming in. When the engine cannot digest it quickly enough, the airflow begins to back up and pressurize. When you reach the point where the increased pressure differential across the intake ports and cylinders becomes high enough to force the engine to digest the air as quickly as the supercharger feeds it into the manifold, this is your boost level. The boost level is how much pressure it took for the engine to reach an airflow equilibrium with the supercharger.
I know that nobody asked for an introduction to boost course, but I am just revisiting this stuff to setup for my point. Where I am going with this, is that the boost curve of a supercharger can be more difficult to predict, particularly on an engine with dynamic valve control systems, until you have a running example to extrapolate from.
There is plenty of room for the boost curve to end up being different on the VQ. It is difficult to know how much of the gradually increasing boost profile in my Coyote is a result of the blowers natural output profile versus a product of the variable valve control system dynamically changing the engines volumetric efficiency. Looking up dyno graphs displaying the boost curve from engines using the same blower, but without variable valve control, will give better insight to the natural output of the blower itself by removing a variable. The supercharger might actually be generating the airflow you desire at those low RPMs, it just might not be measurable as boost... which is often a largely superficial number.
I guess I could have just said that to begin with and spared everyone the essay.
Quote:
Originally Posted by JJ's370z
So going by 0.75 multiplication that would work out to roughly 611whp @13.8psi is that what you meant?
And would torque roughly follow this rule?
If not what would you assume torque would be @500 and 600 wheel respectively?
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Correct that is what I meant. For however accurate this estimate is, torque would follow it just the same since torque and horsepower are directly linked. Horsepower is a product of torque and RPM is its magnitude. A change in HP and Torque, at a specific RPM, will correlate as a percentage.
Rotating Horsepower Calculators - Horsepower, Torque, Speed
Check out this link for an easy place to determine what the torque would be at various HP vs RPM points.