To begin with when I got my bov (turbosmart supersonic) it came with the, low vac 22inHG, high vac 20inHG, yellow spring. This seemed accurate for our cars but when I put it on it sounded like a supra with the super loud compressor chopping air sound, then it would open like way late. Flutter dump. So I put the red spring, low vac 17inHG, high vac 14inHG spring in. It works great now, except it's always open at idle and may most likely be open all the time under vacuum. I never thought this was a problem till I noticed that when I drive my car when it's really cold outside (winter here in MN) that when the bov sticks shut, that my car accelerates with what feels like allot more torque. I have a feeling when I get on it under normal circumstances that it's open until I build boost then it closes and I feel the power. Is this a real thing or am I just crazy?
If its open at idle its too soft of a spring.
It should be easy to open at idle but it should be closed.
where is the vac source for it?
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Source is from the manifold, no tees, the line is as short as possible and it's the bigger vac line not the little stuff. Should I had shims to the soft spring or start cutting down the heavy spring? Does it being open at idle affect anything?
I'd see what turbo smart recommends. I ran 3 different bovs and ended with a tial because it just seemed to work the best.
I imagine being open at idle doesn't effect anything on our cars but it doesn't seem to be set properly which will probably cause issues with boost etc
I'm sure there's a fix for it. I believe my tial was using a spring that's comparable to the first one you mentioned. My car pulled around -20 at idle. It was always closed and snapped open effortlessly when needed
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Maybe I will slowly cut a 1/4 of the coil and keep going if needed and see if that works, the springs are cheap so I don't mind ruining one. Ultimately though would this contribute to a sluggish feeling car off boost?
Yea cause any air from the compressor is bleeding off.
Even out of "boost" I'm pretty sure there is positive pressure in the intake at certain loads with a turbo on the car (relative to outside the piping anyhow) This would be because the motor Is pulling air through it at a rate that doesn't show boost on the gauge. My setup used to blow off at anywhere from 0 to -5in depending on load. Sometimes lower than that but loading the turbo that hard with low rpm would cause it to surge pretty bad. I could be off base on my theory but I do know that an open bov will rob power down low
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
That's what I thought too because when I'm crushing at highway speeds I might only be at 2500-2800 rpm but I'm usually up around atmospheric pressure on the boost gauge. Thanks for the input hopefully I can figure it out. I should have just bought tial!
