Hi folks! I wonder what are the benefit of a blow off valve on a 10 psi setup supercharged? Do I need one at this boost pressure?

I will gain some performance of not at all?
Which one would you recommend and why?

Thank you!

 

No

 

I would say YES you should use one. It will prevent compressor surge and premature failure of your blower.

You will not see any performance benefit from a BOV.

What kind of supercharger do you have?

 

In the case of any supercharger the role of the BOV is not quite the same as in the turbo system. In the case of a supercharger A Bov is a Diverter valve. A lighter spring is used and its role is to releive boost pressure durring decell due to a superchargers ability to produce boost not by needing load but by its drive speed. so when ur cruising in 6th gear and downshift in traffic and decell a turbo wont make boost but a supercharger will still be spinning and making boost due to engine rpm. A diverter valve will evacuate the boost pressure not to prevent surge cause surge can not be produced because the blower is physicaly spun via belt but rather reduce strain on the engine. When the throttle is closed a wall is created and since the supercharger can not back spin the excesive pressure will cause strain which in turn places strain on the blowers drive belt which in turn places strain on the engine itself. In the case of sone vehicles this build up in pressure will bend throttle plates as well.

Hopefully this explains your question.

 

Which kit do you have? Comptech comes with a bypass valve and so does SOS I believe. Vortech comes stock with a bov. I changed out my bov on my vortech since I got one as a gift. I'm sure it did no difference however. Direct plug and play on the vortech aftercooler for a greddy bov I think.

 

comptech and sos use a standard bosch recirculating bov installed backwards. this oe type of bov is very weak in the spring department and often leak like a sive on a turbo set up. By installing it back wards the boost pressure is not pressing up on the piston but on its side not forcing it to prematurely open. the weak spring and engine vacume will cause i to open upon decel. backward instalation will effect flow of the valve though.

 

I have a comptech sc with a novi 1000 blower. I will soon go with a 10 psi pulley.

Should I get this one or what they state is pure BS?

http://www.youtube.com/watch?v=MU5Y6...feature=relmfu

 

The valve should be shut at idle. If its open then you are sucking in unfiltered air and in the case of cars with a MAF this is a vacume leak.

 

It's not BS. The theory behind it does make sense.
I'm using the Synapse bov right now and I'm pretty happy with it.
It's not perfect but it's better than anything else I've tried.
While crusing at partial throttle, it seems like it can't decide if it wants to be open or closed so you get this slight rattling noise.
I haven't figured out how to tighten the resistance (not sure if that's possible)
or attempted to use 1 port at a time (this may fix it).

 

Not quite. The valve is open during high vacuum situations (idle, decel, cruise) because the SC is supplying more air than the engine needs. The valve is open to reduce the workload on the SC. With the valve open, the SC isn't compressing any air and therefore creates less heat and less parasitic drag on the engine. The valve is relieving pressure from the spinning SC at idle so the engine will not be sucking in air from the open valve. If the SC was spinning so slowly that it's delivering less air than the engine is inhaling with a closed or nearly closed throttle plate, then it could suck air through the BOV but I've never seen that circumstance. My valve is blowing massive amounts of air out during idle.

Using a BOV or diverter valve/bypass valve (same thing except one vents to atmosphere and one vents back into the pre-compressor intake) will improve engine efficiency at less than WOT and will reduce the wear and stress on the compressor. Similar to a turbo, when the throttle is shut, a large pressure wave is created that loads the compressor and can cause damage or excess wear unless it is vented via BOV.