Why is it not possible to up the boost of the Vortech SC by putting on a smaller pulley, and then protect the engine by blowing off the excess boost at higher revs using some sort of calibrated BOV?

In my opinion this would achieve much better early / mid range power with only slightly more parasitic loss due to driving a smaller SC pulley.

Am I missing something?

Has anyone experimented with this?

 

I upped the boost but I don't let it out. It does increase the torque/hp in the lower normal driving range.

 

I think your thinking of a wastegate. A BOV only relieves excess pressure after the throttle has been closed, it does not control boost in anyway. If you put a smaller pulley on it would produce more boost on the low end and the high end.

 

^More boost on the low end is what he is looking for but with a centrifugal SC it will not be peak boost. I would think there is a way to bleed boost pressure through the use of a wastegate type device. You can do anything if you bring enough $$.

 

The only way you could do it would be via a pressure relief valve on the outlet side of the blower Kevin. It would have to be so precisely sized though, as you would have to have a calibrated spring that released at the 7 psi you require, to stop it overboosting at higher revs.

It would also have to dump a sufficient amount of air, but not so much that you lost all boost - so the sizing would be key. Can be done, as I deal relief valves for the plant at work.

Tricky without going down the wastegate route! Turbo is the only way if you want real low down grunt, but for me, that spoils the spirit of the car.

MB

 

This topic has been done to death. When we think of a wastegate most of us think of the turbo application. That is, a pressure controlled relief valve that diverts the exhaust away from the turbine. SCs are crank drive so this doesn't apply.

I guess the idea is to drive the SC harder (smaller pulley) to create adequate boost down low (say 6lbs at 3500) but then release the excess airflow up top so that the boost at 9000 rpm doesn't exceed 8lbs (or whatever). You could do this with a mechanical or electronically controlled release valve but the questions are response time and accuracy. Our engine accelerates from 3000 rpm to 9000 rpm in about 5 seconds in first gear. And can drop from 9 to 6 almost instantaneously during a gear change. Can a valve react quickly enough and maintain an accurate enough pressure or will is spike at every change.

But the real question is why? Why go to so much trouble to make this work badly when the problem has already been solved with a turbo? I expect if you sold the SC and bought a turbo kit the change over cost would be less than the development costs of a system like this. And although you need much better engine management with a turbo you'll need the same with this system.

I guess that is the reason no one has done it.

 

And also the reason I upgraded to a turbo.

 

THe best thing is to install a shorter final ratio i.e. 4.44


Do not play with boost, things are more complicated in this side of the ocean than in US/Canada/Australia

 

Aus, a spring relief valve would do it but as I said, the accuracy of the spring would be critical. Should be ok on this service as it will be regularly exercised and there is no corrosive medium to bond the seat / face. it would probably cope fiarly well, but as no one has done it, you would have to engineer it.

I also think the gains would be minimal and not worth the bother.

MB

 

Do you have any idea how annoying the sound will be?