Yeah, Another Bov Thread.

[CEF33Y]

So, I currently do not run a bov of any kind.

My setup, RB20, hypergear op6 highflow, usual supporting mods. Nistune.

240rwkw. With a fair smack of lag, lol.

In past non-bov equiped cars, i've had the zu tututu/ compressor chop/ dose noise. When fitted with a bov, obviously the noise goes away, but difference in performance, or boost drop off between gears felt negligible. (as what most things I've read/searched)

Current setup however, feels a bit different.

If I get it on boost (>12psi) then lift to change gears, I dont tend to get the compressor chop, just one big choof, almost like an atmo bov. Also notice a fair drop off between gears.

So afaik, the 'dose' noise is intake air coming out though the turbo, afm, etc slowing the turbo down (but not completely stopping it)

One big choof would potentially mean the turbo is stopping?(or slowing down much more)

Also, being a standard size core style turbo, would assume inertia would be rather low, compared to a much larger turbo.

Do you guys, in this instance think a bov would assist in getting it back on boost after a gearchange?

Cheers

[Ben C34]

Yes.

[Dose Pipe Sutututu]

a turbo will NEVER stop spinning.. it's not possible, the motor would stall

[GTSBoy]

a turbo will NEVER stop spinning.. it's not possible, the motor would stall

That's not true. There is no requirement for the impeller or turbine to be spinning for gas to flow through them.

[zebra]

That's not true. There is no requirement for the impeller or turbine to be spinning for gas to flow through them.

Yep

Can hold my TD06 still with the car running and noting changes

[KiwiRS4T]

So, I currently do not run a bov of any kind.

My setup, RB20, hypergear op6 highflow, usual supporting mods. Nistune.

240rwkw. With a fair smack of lag, lol.

In past non-bov equiped cars, i've had the zu tututu/ compressor chop/ dose noise. When fitted with a bov, obviously the noise goes away, but difference in performance, or boost drop off between gears felt negligible. (as what most things I've read/searched)

Current setup however, feels a bit different.

If I get it on boost (>12psi) then lift to change gears, I dont tend to get the compressor chop, just one big choof, almost like an atmo bov. Also notice a fair drop off between gears.

So afaik, the 'dose' noise is intake air coming out though the turbo, afm, etc slowing the turbo down (but not completely stopping it)

One big choof would potentially mean the turbo is stopping?(or slowing down much more)

Also, being a standard size core style turbo, would assume inertia would be rather low, compared to a much larger turbo.

Do you guys, in this instance think a bov would assist in getting it back on boost after a gearchange?

Cheers

That's what BOVs are for. AFAIK the only commercial bovless setups are for low boost applications.

[CEF33Y]

Thanks guys, will source a stocker bov, give it a go.

Oh and FYI cefiro's were bov less from factory, but yeah, 10psi is low boost i guess

Edited July 30, 2014 by CEF33Y

[Dose Pipe Sutututu]

Yep

Can hold my TD06 still with the car running and noting changes

Maybe not on a large turbo I'm confident a stock turbo if you were to grab the shaft whilst the engine is running it would stall as there's not enough exhaust gases being relieved as the rear wheel is so small

[GTSBoy]

Maybe not on a large turbo I'm confident a stock turbo if you were to grab the shaft whilst the engine is running it would stall as there's not enough exhaust gases being relieved as the rear wheel is so small

How does the rotation of the wheel change the % open area it has in the turbine exducer?

[zebra]

Maybe not on a large turbo I'm confident a stock turbo if you were to grab the shaft whilst the engine is running it would stall as there's not enough exhaust gases being relieved as the rear wheel is so small

Did it to both of the standard CT12a's

Don't get much smaller than that.

[Dose Pipe Sutututu]

logically, if you're halting exhaust flow from a motor.. it would stall right?

[GTSBoy]

logically, if you're halting exhaust flow from a motor.. it would stall right?

But you're not. There are great big open gaps between the fins of the turbine. They are always there, regardless of whether the turbine is spinning or not. You could spin it backwards, forwards, keep it stopped, plug half of them up with putty, and it wouldn't stall the motor.

[Ben C34]

Block the exhaust with your shoe sole next time your car is idling.

Doesn't stall.

[GTSBoy]

Block the exhaust with your shoe sole next time your car is idling.

Doesn't stall.

Actually that usually says more about how many leaks there are in the exhaust than what happens if you completely block the exhaust!

[WMDC35]

That's what BOVs are for. AFAIK the only commercial bovless setups are for low boost applications.

The 20s in the A31 & C33 had no BOV for some reason

Edit- woops as it says above!

Edited July 30, 2014 by WMDC35

[Ben C34]

Vl turbos also had no bov. And were low boost.

Edited July 30, 2014 by Ben C34

[Blackkers]

A fuel injected engine will keep running under huge amounts of extra exhaust pressure so long as it can get fresh intake air

Stopping the turbo from spinning doesn't seal anything. People have seized turbos from lack of oil or w/e and still been able to drive home from the strip haha