Centrifugal superchargers built boost linearly to redline correct? If your s2000 (or any car) has a pulley for 12psi at redline (9000 for now), then the supercharger is likely making 6psi around 4500rpm correct? So what if you're cruising down the highway? Are you always boosting or is the boost being dumped via a BOV or BPV into the intake or atmosphere until you go WOT?

I imagine if you didn't have a BOV/BPV then you would always be boosting?

 

the BOV would always be venting until there is sufficent pressure/vaccume in the manifold to do otherwise.

With my setup of 10 psi @ 8600 rpms i make about 5 psi @ 4500. different blowers have different efficencies and gear ratios so power/boost delivery under the curve may not always be the same.

 

And your setup has a BOV right? And if you were cruising down the highway at 4000rpm it would be venting? Can you hear that? lol

 

I have a recir valve. Which is basically a BOV which vents back into the intake path of the blower.

I do get part throttle boost. So long as the throttle plate is open enough i'll start to get boost.

My setup is very quiet. So the only time i really hear the BOV is when i left off the throttle and it initially makes a *HUFF* sound.

I have disconnected the recirc hose and vented straight to atmosphere and it will vent constantly and sound like a continuous WOOOOSSH until i get on the throttle a little and you easily hear when i get full boost because it goes totally silent.

my recir valve does nothing to shape the sound so it was annoying without the recirc hose, but if you have a nice BOV it can sound like a continuous whistle. on an s2000 with a good sounding exhaust its like an orchestra you control with you right foot.

 

So will you get boost just being pretty easy on the gas around town?

 

You'll get boost while driving. If you don't want to make boost while on freeway get a turbo

 

Yes, partial throttle, half the boost goes out the bov and you get a continuous whistle.

 

Nice. So how much boost do you get partial throttle really?
Having boost partial throttle is nice so you don't have to floor it to get going nice.

 

Incorrect. The blower is ALWAYS pushing air, but unless you have the throttle past a certain percentage you will not have a positive pressure enter the intake manifold. The boost pressure will push the valve in the diverter shut so the air is forced into the engine.

 

How much do you have to be on it for it to build boost up? Does it have to be practically wot or what?