premo-s12 Posted September 2, 2006 Share Posted September 2, 2006 so im doing a custom install w/an eaton M90 on my 87' SE 200sx/s12 (vg30e) . i have the complete unit sitting, i have all my adapter plates, brackets, etc, etc made, but i have one last thing to do...thats the bypass valve. now its gonna be a complete pain in the ass to plumb and i was wondering if its kosher to run a BOV on a blower? sorry, this might be a dumb question, but im a turbo guy and blowers are fairly new to me. anyhow, i have a BOV sitting on the shelf and this would WAY simplifiy my install. would it just be constantly making a 'blowing off' sound as the engine would be turning the blower? could i just put the TB after the blower? any info would be greatly appreciated!! thanks in advance Quote Link to comment Share on other sites More sharing options...
Blackbob Posted September 2, 2006 Share Posted September 2, 2006 so im doing a custom install w/an eaton M90 on my 87' SE 200sx/s12 (vg30e) . i have the complete unit sitting, i have all my adapter plates, brackets, etc, etc made, but i have one last thing to do...thats the bypass valve. now its gonna be a complete pain in the ass to plumb and i was wondering if its kosher to run a BOV on a blower? sorry, this might be a dumb question, but im a turbo guy and blowers are fairly new to me. anyhow, i have a BOV sitting on the shelf and this would WAY simplifiy my install. would it just be constantly making a 'blowing off' sound as the engine would be turning the blower? could i just put the TB after the blower? any info would be greatly appreciated!! thanks in advance Yes, it will work,you mount it the same way you would on a turbo application. Quote Link to comment Share on other sites More sharing options...
Guest Jason84NA-T Posted September 3, 2006 Share Posted September 3, 2006 You don't really need one for a roots type blower because there's no compressor surge to deal with. I thought most M90's already have a sort of bypass valve and actuator built on to the housing... at least mine does. Quote Link to comment Share on other sites More sharing options...
premo-s12 Posted September 3, 2006 Author Share Posted September 3, 2006 it does have a bypass, but it'd be ALOT easy to plumb in a BOV then that bypass.. there will be a surge of vacuum or build of pressure of some sort depending on weather the TB is before or after teh blower the second i close teh throttle plate..hence there being a bypass valve. im just curious if its cool to run a BOV Quote Link to comment Share on other sites More sharing options...
Guest ZFury Posted September 3, 2006 Share Posted September 3, 2006 I would put the TB after the blower. That small surge is a plus. Quote Link to comment Share on other sites More sharing options...
premo-s12 Posted September 3, 2006 Author Share Posted September 3, 2006 yes, but what about the MAF? would i be losing metered air if i put it before the blower? Quote Link to comment Share on other sites More sharing options...
Guest ZFury Posted September 3, 2006 Share Posted September 3, 2006 You should have the MAF set up so the air is being pulled through. That little pressure build up should not do much but prevent lag. Quote Link to comment Share on other sites More sharing options...
premo-s12 Posted September 3, 2006 Author Share Posted September 3, 2006 thats what i was thinking. im just really curious i guess if its gonna be a detriment in performance to run a BOV as opposed to a bypass hey, what body kit is that on ur Z? damn, i want one for my 85!! Quote Link to comment Share on other sites More sharing options...
mtcookson Posted September 4, 2006 Share Posted September 4, 2006 I'd use a recirculation valve because releasing metered air will cause air/fuel ratio problems. On top of that, you'll need to be able to adjust the spring a bit to where the valve will be constantly open under vacuum. I believe the biggest reason they use a recirculation valve is to simply increase efficiency under part throttle/vacuum. Spooling characteristics won't change at all due to it being spun directly by the engine, unless the valve stays open then you'll see some issues. I though most Eaton setups had an internal bypass setup... basically to where all recirculation is done internally where no plumbing is needed. Is this one not the case? On the throttle body, I believe for the positive displacement s/c's to run properly, the throttle body should be before the s/c (i.e. throttle body, supercharger, manifold/engine) Quote Link to comment Share on other sites More sharing options...
premo-s12 Posted September 4, 2006 Author Share Posted September 4, 2006 gotcha. no, its an external bypass, but built onto the side of the blower if that makes any sence. ill see about getting some pics later...for now im off to a bbq! Quote Link to comment Share on other sites More sharing options...
280zedx Posted September 8, 2006 Share Posted September 8, 2006 Everything depends on where you place your throttle body. If you put the TB before the S/C like most are factory designed then there is no need for a BOV. The internal bypass mechanism that mounts to the side of the SC will control the boost by "sealing" the chamber when you go off vacuum (hard on the gas) and open when you go under vacuum (cruise and idle). This will work perfect with the MAF as well. If the TB is located after the supercharger then you have to have a BOV between the 2 in order to vent the pressure when the throttle plate slams shut (letting off of the gas). If not this pressure will back up into the SC because it has no place to go (even though the SC bypass is now open and thus not making more boost) and apparently they really don't like that! The tradeoff is the fact that the closer the TB is to the intake the better for throttle response. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted September 8, 2006 Share Posted September 8, 2006 Mike is spot on. What will happen if you place the T/B after the supercharger without a BOV is you will break the belts that drive it, or worse. Dave Quote Link to comment Share on other sites More sharing options...
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