I was wondering if its a good idea to put a blow off on a supercharger? I am going to be getting one within the next few months and i was telling my friend about it. He started telling me to put a blow off on it. Now, i know its possible to put one on, but my question is, wouldnt it eventually hurt the supercharger. The bypass is letting of all the pressure at idle, but if you put on a blow off, it wont let the pressure out and it would just recirculate, am i right? Now i am not an expert, and i dont know extreme amounts about this stuff, but i really want to learn, so any input would be great.
a blowoff valve is used when the butterfly of the throttle body closes but there is still compressed air coming from the turbo or s/c that is before the TB.
if you're thinking about a roots style s/c, it wont work because normally the air goes through the tb first and then to the s/c and then to the engine.
if you're thinking about a centrifugal s/c (like a turbo but driven off a belt), it'll work but it'll be MUCH less effective and not very loud, seeing as the s/c is belt driven
if you're thinking turbo, it'll definitely work, and it is the most common application to have it.
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- Sold my beloved J in April 2010 -
If you're getting a centrifugal charger you'll need a BOV. If you have a roots blower you wont be able to, nor need to run one.
ps - the reason cars have blow off valves is because of this reason:
exhaust leaving engine enters turbo, spins wheel, exits car
wheel spins other wheel, causing incoming outside air to compress, and go towards the throttle body. if the throttle body is closed (aka you get off the gas after flooring it) the air has no where to go, and so the blow off valve will release that pressure.
normally, the turbo and centrifugal s/c will be in between the air intake filter, and the throttle body.
on roots style s/c (the long silver ones you see on the cavalier, cobalt, etcs), the compressing rotors are after the throttle body and into the intake manifold, so there's no pressure spikes to worry about.
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- Sold my beloved J in April 2010 -
Quote:
if you're thinking about a centrifugal s/c (like a turbo but driven off a belt), it'll work but it'll be MUCH less effective and not very loud, seeing as the s/c is belt driven
i dont know about sum kits, but i love my vortec bov, and its quite loud.
Doesn't a roots type charger still have a type of BOV.... but it's a recirculator valve.......... it's the black thingy on the s/c right after the tb ...... it almost looks like a wastegate... has a vac line attached to it .......................looks plastic though .....
it releases pressure when you let off the gas I thought .........
I may be wrong.... I'm still trying to learn about the roots type chargers myself......
Lee
JDM Civic Hatch
Status: Parting Out Turbo Kit....
14.224 @ 102.01MPH @ 5.5psi.... 2.3 60'
Next: Civic JDM B16a2 w/GSR LSD Turbo - Goal 300whp 1400lbs...
its not a recirculator valve, its a bypass valve.
when not in boost, you dont wanna waste gas, so the air goes around the charger rotors and straight into the engine, as if there was no charger there (via the bypass valve). when you get on the gas, that plastic thing is a vaccuum regulator that pulls closed the valve (like a tb butterfly) and the air goes through the rotors to create boost. but the rotors are placed after the tb, so theres no need for a blow off valve.
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- Sold my beloved J in April 2010 -
I'm going to have a BOV (kinda sorta) to regulate the boost pressure. That way I can run the supercharger at 5psi (just a made up number) while still using a pulley that will allow 10 or 15 psi.
I may even be able to adjust the boost on the fly or even "shut off" (open valve until switched closed) the supercharger, something that's not too easy to do with a Roots Supercharger most of the time.
What I'm going to try to have set up is the valve will vent the pressure to the inlet side of the supercharger, possibly in front of the TB (not sure yet on this, might be behind the TB) so that when the set psi is reached, it sets the supercharger to "free spin" and only feeds the motor what I allow it to.
I could try to explain further, but I'm not to good at that kind of thing. communicating my thoughts, just ask my wife
^ yea, i totally dont see the logic in that.
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- Sold my beloved J in April 2010 -
black03coupe wrote:Quote:
if you're thinking about a centrifugal s/c (like a turbo but driven off a belt), it'll work but it'll be MUCH less effective and not very loud, seeing as the s/c is belt driven
i dont know about sum kits, but i love my vortec bov, and its quite loud.
Ditto. My little brother has teh RSM kit and it sounds sweet.
-Chris
lemme rephrase what i said as it seems to be the popular quote
Viper98912 wrote:if you're thinking about a centrifugal s/c (like a turbo but driven off a belt), it'll work but it'll be less effective and not as loud, seeing as the s/c is belt driven. it will also be much less effective if you have an automatic.
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- Sold my beloved J in April 2010 -
it will work as a wastegate controller in a way, I'll be able to turn the boost up or down. Then I can set the boost to whatever without changing pullies. The pulley will set the MAX boost the supercharger will deliver, and the "BOV" will set the boost at a preference level.
does that make more sense?
why dont u just use less pedal? i foresee horrible tuning problems with that, trying to get the fuel right at least.
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- Sold my beloved J in April 2010 -
hotbug1776 wrote:it will work as a wastegate controller in a way, I'll be able to turn the boost up or down. Then I can set the boost to whatever without changing pullies. The pulley will set the MAX boost the supercharger will deliver, and the "BOV" will set the boost at a preference level.
does that make more sense?
I just flat-out have no idea what you're talking about.
Are you working with a GM M45 kit here?
You mentioned managing the boost before the TB and then just letting the blower spin freely when you get to your desired level. This would require a turbo (or centrifugal blower) to be installed before the TB which will essentially negate your M45.
If you're talking about twin charging, then this will start making sense to me. As it is though, if you're just looking to put a smaller pulley on and then bleed off the extra boost, you're wasting your time. Once you've tuned the engine for higher boost, you'll want to stick with that higher boost and just use the go pedal to regulate it. If you haven't yet tuned for the higher boost then you're taking a big step backwards in spinning the blower any faster than you have to as you'll just generate heat and cavitation.
If you're looking at twin charging, then you'd want to rig up the bypass valve to be open at vacuum... then close up to your set amount of boost, and then open again above that since the turbo would be providing the boost at that point.
Wild Weasel wrote:hotbug1776 wrote:it will work as a wastegate controller in a way, I'll be able to turn the boost up or down. Then I can set the boost to whatever without changing pullies. The pulley will set the MAX boost the supercharger will deliver, and the "BOV" will set the boost at a preference level.
does that make more sense?
I just flat-out have no idea what you're talking about.
Are you working with a GM M45 kit here?
You mentioned managing the boost before the TB and then just letting the blower spin freely when you get to your desired level. This would require a turbo (or centrifugal blower) to be installed before the TB which will essentially negate your M45.
If you're talking about twin charging, then this will start making sense to me. As it is though, if you're just looking to put a smaller pulley on and then bleed off the extra boost, you're wasting your time. Once you've tuned the engine for higher boost, you'll want to stick with that higher boost and just use the go pedal to regulate it. If you haven't yet tuned for the higher boost then you're taking a big step backwards in spinning the blower any faster than you have to as you'll just generate heat and cavitation.
If you're looking at twin charging, then you'd want to rig up the bypass valve to be open at vacuum... then close up to your set amount of boost, and then open again above that since the turbo would be providing the boost at that point.
i'm pretty sure he's not referring to the GMPP roots blower but a centrifugal one. i understand completely what he wants to do. he wants to set it up like a turbo system capable of say 12 psi but using a BOV and a boost controler to regulate the amount of boost. he can pudder around at 6psi around town then turn it up to 10psi when passing cars on the hgwy kinda thing.
which if thats the case, just dont push the accelerator pedal as far. gonna be horrible for tuning im tellin ya
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- Sold my beloved J in April 2010 -
i agree that the gas pedal is the best form of boost control but tuning it for 12psi and running around on 6 is no big deal either.
try this boys, it's a M-90.
The valve goes on the pressure side of the supercharger, and vents to the inlet side. thus the supercharger just recirculates the air its moving, not building up pressure over a certain point. almost like the bypass on a 3800 SC
to quote Magnuson:
Why do you need a bypass valve? The best kept secret in forced induction is the little known bypass valve.
This small valve, when properly installed between the supercharger and the air throttle body, allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. Our M90 supercharger uses less than 1/3 of 1 HP at 60 MPH cruising. The bypass is operated by a vacuum actuator control unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required (accelerating) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system.
I'm doing this, but instead of it equalizing at vacuum, it will release the pressure at a preset level. I wont have a "bypass valve", since my supercharger is off a Super Coupe (the bypass valve on those mount to the intake pipes) so the valve I am going to use will be to control the psi. especially since it pushes twice the displacement and CFM of the M45.
And no it wont blow the motor, it's been done and is being done right now on several other cars with the same motor. I'm not the only one doing this, theres another guy doing the same thing. Can I also make it a true Bypass valve, yes, without much hassle.
correction before someone makes a complaint--- I meant to say twice the displacement and 240 more CFM at the same PSI.
i think it sounds coo. let us know how it works.
hotbug, i think you read that a little incorrectly.
they should rephrase that quote to be "between the ROTORS and the throttle body" which is just what a bypass valve does. most superchargers today have internal bypass valves.
If you think about the flow of air, it will go: filter ---> intake --> TB --> -->bypass ---> manifold --> engine. there's no where where the air will go backwards through the bypass (even though hypothetically it could, the vaccuum the engine would create would force it in through the hole first rather than back up through the hole).
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- Sold my beloved J in April 2010 -
I dont know, that's the exact quote from them. I guess someone should tell them that then LOL
I'm just going to use it like a wastegate, mounted in the manifold, and dump it between the filter and the intake, it might sound like a jet, it might not. I need to experiment with placement and what not.
If I dump it between the throttle body and the supercharger, it wont hiss, and it SHOULD just recirculate the pressurized air.
Either way, it should do it's job, and keep the psi down to where I want it.
it's going to be one hell of a ride any way I look at it.
Viper98912 wrote:its not a recirculator valve, its a bypass valve.
when not in boost, you dont wanna waste gas, so the air goes around the charger rotors and straight into the engine, as if there was no charger there (via the bypass valve). when you get on the gas, that plastic thing is a vaccuum regulator that pulls closed the valve (like a tb butterfly) and the air goes through the rotors to create boost. but the rotors are placed after the tb, so theres no need for a blow off valve.
Hey,
I have a gm s/c for a 04 cav ecotec and was trying to learn more about the bypass valve. I've done some researching on the org and think I have a pretty decent idea about how it works. But my question is about adjusting it. I noticed there's a bolt that is near the "lever?" that opens and closes the valve, and the bolt has an alan head adjustment on the opposite end. It looks as if you could turn it so that it touched the lever, even pushing the lever in. So I guess my question is, if you turned the bolt so that it pushed the lever some to close the valve partially, would that have any effect, and if so what would it be? Or should the bolt even touch the lever at all? Thanks
doesn't your charger have a sticker on it that says DO NOT ADJUST THIS? please do not adjust the valve acutator thing, it is done by the factory. doing so could cause you major problems in the future.
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- Sold my beloved J in April 2010 -
Viper98912 wrote:doesn't your charger have a sticker on it that says DO NOT ADJUST THIS? please do not adjust the valve acutator thing, it is done by the factory. doing so could cause you major problems in the future.
i hear you can get some more boost outta it though
