240hoke Posted January 21, 2003 Share Posted January 21, 2003 Somebody helps me understand how this device works, I purchased a Vortec Maxflow BOV and it lets air out at idle and any time there is vaccum. If it stays halfway open until boost where it shuts, how do you build boost? Quote Link to comment Share on other sites More sharing options...
Sparky Posted January 21, 2003 Share Posted January 21, 2003 have you tried adjusting the spring tension? it sounds as though is adjusted all the way out...(so its very loose) so at idle (vacuum...its actually able to pull the gate open..then at boost the pressure in the line forces the gate closed. and where do you have the vacuum source hooked up too(should be off the intake manifold). i would tighten the adjustment nut down while at idle until it closes....then hit the throttle a couple of times...the valve should open slightly when you let off the throttle....when it does this tighten the adjustment down 1/4 turn and thats your lowest setting. if that doesnt help that i dont know what will. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted January 21, 2003 Share Posted January 21, 2003 Yap, I think the BOV is too loose Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted January 21, 2003 Share Posted January 21, 2003 Is the vacume connected to the top of the valve? Your likely to have a problem with a factory fuel computer and a BOV. Alex Quote Link to comment Share on other sites More sharing options...
yo2001 Posted January 21, 2003 Share Posted January 21, 2003 what kind of BOV do you have? Well, if if leaks, you can always plumb it back in front of th turbo. Quote Link to comment Share on other sites More sharing options...
Guest MegaShaft_2000 Posted January 21, 2003 Share Posted January 21, 2003 Originally posted by 240hoke:I have tried adjusting it all the way and it still vents at idle, i have even called the manufacturer and they said this is what it suppossed to do, it always vents unless under boost, but i still dont understand how you get boost with a big hole They aren't supposed to vent at idle. That would surely hurt your spoolup when you're trying to give it gas and the turbo is throwing some of it's boost right into the atmosphere instead of using that air to make more power and exhaust. I have Apexi BOV's, and there's a set screw on the front of them that you adjust to the pressure differential you want them to release at. Like another poster said, you have to have the vacuum line hooked up to the front of them. Quote Link to comment Share on other sites More sharing options...
DAW Posted January 21, 2003 Share Posted January 21, 2003 It should be venting at high manifold vacuum (like idle). That's how it works, when throttle plate snaps closed that is when you want to get rid of the column of pressurized air between throttle plate and compressor wheel. There is no significant boost developed at idle...once the throttle plate is cracked open, however, the highest manifold vacuum drops and the BOV should close and this occurs before boost can develop anyway. DAW Quote Link to comment Share on other sites More sharing options...
Sparky Posted January 22, 2003 Share Posted January 22, 2003 is this BOV meant the dump into the atmosphere? maybe thats whats going on....if its meant to be plumbed back into the incomming stream of air...than it would matter if it was open or not. somebody correct me if im wrong. the problem with saying that its supose to vent to atmosphere while not under boost causes some big bells to go off in my head. that is a HUGE vacuuum leak right there....unless of course.. after looking at the picture of this BOV it seems as though it is designed to be plumbed back..and not vent outside. this would certainly explain a good bit if this was true. I just know how mine works...and i assume thats how they all are supose to work. anywho... anyone....anyone?.......bueller? Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 22, 2003 Author Share Posted January 22, 2003 Okay i called the company up again to confirm that its supposed to be open during vaccum, and i got he same reply, they also said and i quote " all bovs are open during vaccum they only **** under boost" I still dont under stand how i can make boost, ive hooked it back up and im gonna go for a ride tomarrow to see if it is possibly closing when i put my foot down and just leaking at idle. Heres a pic of how ive got it hooked up: http://www.geocities.com/datsun260zt/BOV.html Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 22, 2003 Author Share Posted January 22, 2003 DAWS that makes sense, and is probably what is happening, now that ive tightened it, i'll give it a try. Im new to turbos, and engines for that matter, just trying to learn all i can. Quote Link to comment Share on other sites More sharing options...
CU Zcar Posted January 22, 2003 Share Posted January 22, 2003 You seem to see what DAW and your BOV company is saying, but if you're still not clear this may help: http://wwwrsphysse.anu.edu.au/~amh110/Technical_pages/blow_off_valve.htm Yours sounds like the "Compressor Bypass Valve" type of BOV. Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 22, 2003 Author Share Posted January 22, 2003 I have tried adjusting it all the way and it still vents at idle, i have even called the manufacturer and they said this is what it suppossed to do, it always vents unless under boost, but i still dont understand how you get boost with a big hole Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 24, 2003 Share Posted January 24, 2003 Thats a clean Z engine. I like the manifold. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted January 24, 2003 Share Posted January 24, 2003 Originally posted by 240hoke:Okay i called the company up again to confirm that its supposed to be open during vaccum, and i got he same reply, they also said and i quote " all bovs are open during vaccum they only **** under boost" I still dont under stand how i can make boost, ive hooked it back up and im gonna go for a ride tomarrow to see if it is possibly closing when i put my foot down and just leaking at idle. Heres a pic of how ive got it hooked up: http://www.geocities.com/datsun260zt/BOV.html I would say that is essentially correct. The only way you are going to make the BOV work on an EFI using an airflow meter (or MAF) is if your idle vacuum is less than vacuum when you lift the throttle at a good rpm. Then you may be able to adjust the BOV to open at the higher vacuum level. Otherwise, use a compressor bypass. The ECU needs the system to be closed, then it doesn't matter if the valve leaks at idle. As soon as you push the throttle, your vacuum drops and the valve closes. Boost should build. This will also happen with a BOV, but your idle will suck. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.