Hey i have an R53 worked to the **** but now i need a BOV. Can you add one to a supercharged engine???

 

Short answer?

no.

 

Supercharged motors use what they call bypass valves... BOVs are, from my understanding, strictly used in turbocharged applications, although turbos also have the ability to run a bypass valve depending on the configuration.

GotMINI

 

Sure, just add a turbo kit and there ya go....

 

What was said about the bypass valve, is your blow off valve. I am guessing you want your car to sound like a 1.8T.
How much boost are you running that you actually need more than the BPV to regulate it? If your just looking for the sound, put a whistle in there

 

Actually you can run a BOV on a supercharger but only on centrifugal type superchargers because the are much like a turbo but belt driven. Now bring in the boost building characteristics of a roots and centrifugal. Roots (throttlebody>Roots>motor) is constantly in boost but the amount is dependent on RPM which is where they put a bypass valve and its placement is after the throttle body and to recirculate air when not under load. Centrifugal (SC>BOV>throttle body>Motor) now is layed out much like a turbo in a sense that it uses piping to connect the supercharger to the throttle body which is where the blow off valve is important it is ment to relieve the off throttle/excess pressure so it doesn't damage the throttle body.

 

A good friend of mine has a BOV on his supercharged VW corrado. I looked into setting up a BOV in replace of my bypass... but its to much work for not enough payoff.. just get a DT bypass.

good luck!

what all do you have done?

 

What type of supercharger is it because if its before the throttle body yes it will have a BOV but if its like the roots or twinscrew it will have a bypass valve after the the throttle body. And another thing you can have a BOV recirculate like a BPV or have it do the popular open to atmosphere.

 

Im not sure to be honest. But yeah. you can get BOV to recirculate... but then why replace the BPV? I would just upgrade the BPV...or get a turbo kit! he but maybe thats wishful thinking

 

Total waste of money.

 

Please learn to search, we get this question about once a month....


Jack

 

Good explanation, glad the question was asked...

 

Oh crap after having mine on my 2002 MCS for almost a year I guess I had better take it off if it does not work Now just for the record I did do it for the effect and not ANY performance gains. Although I am not dumping hot pressurized air back through the SC anymore. LOL The only initial problem I had was that my A/F went rich on my for a second. It was an easy fix by adjusting the BOV not to open as quickly.

 

Hey no problem I do my best to help anyone.

 

Like I said in an earlier post somewhere...you can plumb in a Forge or EVOMS diverter valve from a 1.8T...that would be hot. You can change the spring rates...

 

Yes, but that would be completely pointless. The point of a bypass valve in a roots-charged application is to bypass the blower for part-throttle economy! Under boost, or when closing the throttle, the bypass valve will be closed. The idea is that the air does not have to move through the blower under light load, therefore it is just "free wheeling" and not being forced to actually pump air.

 

There... fixed it for ya.

 

actually i am right about the throttle body but it can also do damage to the compressor over time but the throttle body would be the first to go in an instance with no BOV

 

No, you aren't. Have you ever read... Maximum Boost? Or any sort of literature on the topic? Do you have experience with throttle body failure in a turbocharged car? Have you ever owned one? Tell me what your basis for this statement is beyond "I'm right and you're wrong".
'
Here's a good line from Wikipedia... "Blowoff valves are used to prevent compressor surge. Compressor surge is a phenomenon that occurs when lifting off the throttle of a turbocharged car (with a non-existent or faulty bypass valve). When the throttle plate on a turbocharged engine running boost closes, high pressure in the intake system has nowhere to go. It is forced to travel back to the turbocharger in the form of a pressure wave. This results in the wheel rapidly decreasing speed and stalling."

 

Yes that is true for a turbo or centrifugal SC but in a roots SC its impossible to have compressor surge because the location of the bpv and when mid throttle and idle the bypass valve is half to full open which allows the pressure to be relieved and recirculated at the same time so that introduces the fact of impossibility but that is until the bypass fails then you will feel that surge.

 

I want to apologize...I did not want to start a debate or argument between anyone. I am radical when it comes to insane car stuff. Heck I have my own designed Flame system on my MINI. Now that is ridiculous. The BOV was for the effect not function on a performance level.

Don’t you hate when you come up to some Ham bone in his over beefed WRX and he spits his BOV at you? Well I spit right back!

It was a pain in the **** to get it to run right and it makes for a twitchy on/off the gas feeling. I would not recommend anyone but the Fast and Furious effect guys to put one on their MINI.

As I mentioned in an earlier post the only positive benefit is a cooler intake charge. Now I have not actually done a before and after temperature reading yet so I do not know what the difference is. Also my mileage did not go down because of installing it.

But if you ever hear of a MINI that shots a NOS purge though LEDs out the top hood and that has a red oscillating light in the scoop and blows a 6 foot flame out the tail pipe...it be mine. LOL

 

The use of a blow-off valve/bypass valve is never used to prevent compressor surge on a roots blower, assuming the blower is plumbed aft of the throttle body (as in all OEM roots applications). In fact, compressor surge is IMPOSSIBLE in such a roots application, BOV/BPV or not.

Close the throttle and what happens? The blower stops *ingesting* air. It cannot surge if no air is coming in. No pressure spike can exist post-blower in a roots application. That is because nothing changes post-blower regardless of throttle position. Thanks to this fact, bypass valves are absolutely not required on a roots application but are useful to improve fuel mileage on street cars. All it does for us is bypass the blower, requiring less power to spin under light load.

Pressure is never relieved by a bypass valve in our application because pressure is regulated solely by the position of the throttle.

 

I just said that.

 

So when you are at say(example) 6800 RPM 15psi boost and you shut done the throttle plate you go to normal aspiration(N/A) or 0 psi/boost ? My boost gauge does not show this. But it does go from boost to N/A or vacuum when I get off the gas with my BOV. Also if the BPV is defective or not adjusted correctly or the spring is to weak as in the case of the 03 and 04 MCS that YO-YO effect is created other wise known as Blower surge ? I understand what you are trying to say but the monitoring devises do not show this?

 

It's not really blower surge that causes the yoyo, it's boost flutter. If the spring doesn't close all the way it flutters back and forth and you can watch the boost bounce around. Just an annoying aspect of a car with a bypass valve that isn't functioning correctly.

As blitz said above, if the throttle body closes, there's no air for the SC to ingest, therefore it's not pumping any air, so it can't surge. Compressor stall in a SC is similar to in a turbine engine. It also begins to happen when the SC is overspun. It's spun so fast that the leading edge of the rotor actually causes turbulence that disrupts the rest of the airflow.

This is sort of why helicopters have top speeds. Since the main rotor provides both lift and forward speed (Cyclic on the rotor hub controls rotor pitch and allows angled adjustments of the actual chopper), if there is too much forward speed, the blades can no longer provide enough lift on the leading edge, and they stall. The blades then can't provide enough forward speed, and the helicopter begins to sink until speed is reduced.

Not sure what any of this has to do with BOV's, but it sounds like an interesting project to get one to work in a positive displacement blower.

Flames out of the exhaust? That wouldn't last long out here. I'd get pulled over in about 10 minutes.