Bov close to turbo

[deaf_rattle]

Any problems with running a plumb back bov close to the turbo?
thinking maybe having it mounting on the outlet of turbo, then plumbing back into intake pipe (between afm and turbo)

yay or nay?

[79rolla]

shuldint be an issue, my mate has his 180sx setup like that, no issues except his cheep turbo just killed itself but dont thinks its related to bov.

having bov like that could reduce intercooler heat soak (in thery) and reduce lag by not having as mutch of a vacuum in the inlet

[strx7]

it will be the laggiest set up possible after changing gears because when the BOV opens all the pressurised air between it and the throttle body back feeds to vent out the BOV. when the BOV closes you then need to pressurise up all the volume between the bov and the throttle body before you are back into boost

[deaf_rattle]

ok, looks like ill need to run a hose/tube from the t/b side of the engine bay over to the intake! doh!

[fivebob]

Should be fine, that's the stock SW20 set up and there are no issues with it even when using much larger turbos

[fivebob]

it will be the laggiest set up possible after changing gears because when the BOV opens all the pressurised air between it and the throttle body back feeds to vent out the BOV. when the BOV closes you then need to pressurise up all the volume between the bov and the throttle body before you are back into boost

That doesn't make sense:?

Location makes no difference to the volume of air that the valve vents, and that is the air the will have to be "replaced" when the valve closes again, therefore there should be no detectable difference in lag.

[sergei]

Also GT4 has BOV before intercooler.

[deaf_rattle]

Should be fine, that's the stock SW20 set up and there are no issues with it even when using much larger turbos

do you have any pics of this set up?

the bov im running is nothing special, (bosch bov as used on porsche, saab etc) and not worth "showing off" so maybe hiding it away under the intake would be quite good.

[sergei]

It plumbs where the yellow plug is, right next to inlet on the intercooler.

[FLAWLES]

std vvti 1jzgte factory bov is straight after the turbo ( well on that big stupid manifold )
back feeds into the plenum type set up

and thats where my new aftermarket one will be going

[loudstealthGT-Four]

Read somewhere that the closer the bov is to the throttle body the better the response and the closer it is to the turbo the louder it is? True or BS

[escortman]

std vvti 1jzgte factory bov is straight after the turbo ( well on that big stupid manifold )
back feeds into the plenum type set up

and thats where my new aftermarket one will be going

on my mates chaser he found it would struggle to run when that factory bov is unplugged

[Coke]

std vvti 1jzgte factory bov is straight after the turbo ( well on that big stupid manifold )
back feeds into the plenum type set up

and thats where my new aftermarket one will be going

Will it be a plumb back? I hear they run like shite if using a bov that vents because of the afm....ive got a vvti 1jzgte and thought about going aftermarket.

[matt dunn]

Read somewhere that the closer the bov is to the throttle body the better the response and the closer it is to the turbo the louder it is? True or BS

Makes sense so I'd believe that,

but 1/2 the people that are worth listening too say close to the turbo and the other 1/2 say close to the throttle.

I go close to the Throttle body,
as if it's pre-intercooler, the airflow through the intercooler is reversed when it's venting the pressure out, and then has to change direction again to re-pressurize.

I dont think it makes much if any difference either way though.

[strx7]

it will be the laggiest set up possible after changing gears because when the BOV opens all the pressurised air between it and the throttle body back feeds to vent out the BOV. when the BOV closes you then need to pressurise up all the volume between the bov and the throttle body before you are back into boost

That doesn't make sense:?

Location makes no difference to the volume of air that the valve vents, and that is the air the will have to be "replaced" when the valve closes again, therefore there should be no detectable difference in lag.

I'm pretty sure that it actually does make a different to the volume of air, it certainly makes a difference to the pressure of charge at the BOV

With the BOV by the turbo, the intake charge is like a wave at the beach, back and fowards, with it by the throttle body, its like a stream. the intake charge keeps flowing in the right direction

I'm sure there would be some data somewhere which supports having it by the TB

where do WRC cars have it????

[fivebob]

With the BOV by the turbo, the intake charge is like a wave at the beach, back and fowards, with it by the throttle body, its like a stream. the intake charge keeps flowing in the right direction

Which makes it even more strange as by definition pressure waves move at the local acoustic velocity, which given the temperature and density of the air in the intake track is around 350m/sec. So in the time it takes the valve to open and close the pressure waves have travelled backwards and forwards a thousand times.

Sometimes using ones perception of how things should work leads to a misunderstanding of the realities of the physical world. Air does need to be flowing in any particular direction for pressure waves to move in that direction. A perfect example of this phenomena is exhaust systems, in particular two stroke expansion chambers, and despite the vast amout of research we still don't fully understand all the parameters that make them work.

Please note I'm not saying that BOV position has no effect, just that most likely the effect won't be measurable by the average seat of the pants dyno.

[iOnic]

Both Fivebob and strx7 are correct. "In theory" it's better to have the BOV closer to the throttle body so as to keep all the air mass flowing in the one direction. In practice......everything happens so quickly that you'll never notice the difference anyway.

[FLAWLES]

std vvti 1jzgte factory bov is straight after the turbo ( well on that big stupid manifold )
back feeds into the plenum type set up

and thats where my new aftermarket one will be going

Will it be a plumb back? I hear they run like shite if using a bov that vents because of the afm....ive got a vvti 1jzgte and thought about going aftermarket.

no not the kit that i am getting, ( sard r2d2 full jzx100 kit blocks off oem bov and moves the sard one away from the manifold )
read this it will help you alot
http://www.jzx100.com/forum/index.php?showtopic=1521

[Malcolm]

jeez I love hearing people claiming that "in theory" this is the case, when the theories that define the physical behaviour of many systems are highly complex and you can't easily draw conclusions as specific as "your BOV should be close to the throttle body" from them. As fivebob says, some physical phenomena can't be explained simply by what you think should happen, especially for fun things like fluid dynamics. The only real way to answer these questions is either through an assload of simulation and modelling (which may or may not be accurate), or better, physical testing and experimentation.

[sergei]

BOVs are there to not make more power, but to save turbo. In this case in my opinion it should be as close to turbo as possible. Reasoning behind this - it will drain where it needs to drain.
But if you think the speed of sound and sound waves, the BOV opening will take thousands of times slower anyway.