Do I Run A Bov Or Not?

[joeyjoejoejuniorshabadoo]

some cars have them stock, and some dont...

millions of people run without one, and i have NEVER heard of a turbo dying because of a no BOV situation...

you'll be fine deano...

[BAMR33]

I found that my car lost some mid range response when changing gears, as this is my daily drive it was reason enough to put the bov back on.

[bozodos]

Nobody's mentioned the sick dose factor yet...

Don't they improve fuel economy as well? (That would be the reason if I were to get one).

[R31Nismoid]

Running a AFM setup Nissan style, likely to hurt economy if anything. Certainly wont help it

[Taso84]

Ok, here's the thing:

Compressor surge (commonly known as dose) is bad for your turbo. There is no real dispute about this. Whats in dispute is how bad it actually is, ie the simile mentioned before was a tennis ball against a brick wall.

What you got to remember is that if any given turbo has a life of 120K kms then compressor surge isn't gonna do you any favours in regards to life expectancy. From my experiences so far compressor surge is not going to have any affect (other than increased lag b/w gears) in the short term, but if ur looking to keep ur car for a few years and/or have an old turbo on there, I would def be putting on a BOV.

P.S., Ive got a blitz one for sale if u need it

[Munkyb0y]

how about a bov wound down fairly tight? tight enough to clearly hear compressor surge. when there is enough pressure, it releases back into recirc, but otherwise it doesnt.

thats how mine is, and i dont see any fuel economy issues, or added lag between changes.

a bit off topic, but still in the ballpark

Edited April 22, 2009 by Munkyb0y

[PM-R33]

Nobody's mentioned the sick dose factor yet...

My dose on 20psi sounds SICK!

There, i said it.

[Munkyb0y]

hahahaha, feel better now you got it out? do ya? huh?

[Munkyb0y]

This is what Corky Bell has to say about it. But with a name like that, i'm not sure what to believe

Compressor surge is the rapid fluctuation of turbine speed caused by the throttle's being closed under boost. Rapidly spinning air compressors (turbos) can go unstable briefly when this occurs. The fluctuating speed can be damaging to the turbo and the accompanying noise is obnoxious. The condition can be alleviated with a compressor bypass valve that opens as the throttle closes and allows air exiting the turbo to vent back to the front This keeps the flow up. Many modern turbo cars are equipped with such valving, but seldom are they big enough to handle high-flow, high-boost systems, A useful fringe benefit to these valves is that they reduce lag and perceptibly increase fuel economy.

[PM-R33]

Compressor surge is the rapid fluctuation of turbine speed caused by the throttle's being closed under boost. Rapidly spinning air compressors (turbos) can go unstable briefly when this occurs. The fluctuating speed can be damaging to the turbo and the accompanying noise is obnoxious. The condition can be alleviated with a compressor bypass valve that opens as the throttle closes and allows air exiting the turbo to vent back to the front This keeps the flow up. Many modern turbo cars are equipped with such valving, but seldom are they big enough to handle high-flow, high-boost systems, A useful fringe benefit to these valves is that they reduce lag and perceptibly increase fuel economy.

Obnoxious my ass!!

Edited April 22, 2009 by PM-R33

[bozodos]

Hehe. TBQH I'm kinda over the whole dosing thing now, was curious as to whether there would be much of an improvement using a GTR BOV with a MAP sensor ECU.

[IanB]

My mate put a turbo on a MX5 BOV'less and it lasted about 5 months before the shaft play was quite bad. No shaft play to begin with.

He has another one of the exact same turbo (he baught my old turbos, R34 standards) and is running it with a BOV and it is fine and has lasted already longer then the last one. In that mind that does it for me.

[krzysiu]

Running a AFM setup Nissan style, likely to hurt economy if anything. Certainly wont help it

Hmm i guess it depends on the car. Running no bov or an atmo bov should have the same effect on fuel economy. I run an atmo bov and still manage about 480km to a tank before the fuel light comes on. (Standard ECU)

[raZ1911]

If u were running 20 PSI id say rock one, or if it was a crap turbo id run one as well.

[joeyjoejoejuniorshabadoo]

its a 2540, so its not china crap

[R31 POWER]

I found with one (gtr bov) fitted it doesn't have that boggy feeling on gear changes and wont stall when clutching it. Compared to having none fitted. To me thats win win.

[Kinks]

My thoughts: Red top RB20DET + FMIC never had a BOV factory, wound it up to 14psi ran it for 3+ years pulled the turbo off and it was exactly the same as you'd expect a 120,000km turbo to be. A little bit of oil but nothing out of the ordinary, it still boosted hard. Car drove great. Put an R33 turbo on and continued running with no BOV, zero problems.

RB25DET S2, blocked the BOV off and the car ran like shit (I still have the factory SMIC). I think the newer ECUs are far more sensitive with their mapping and the airflow changes upset it.

I would have no qualms whatsoever running without a BOV, providing the ECU could handle it.

there is always shaft play.

Did a turbo swap on a mate's RB25, the brand new HKS we put on had about 3x the shaft play of his stock item. Excessive shaft play is a problem, minimal is not.

blades are spinning at several thousend rpm, them coming to a complete stop when air is pushed back through? it has 2 do sumthing

No. Do you think compressor wheels are made of paper mache? They have to be strong enough to compress air while being hot and spinning at a hundred thousand RPM. Do you think a little bit of chuffing noise is going to upset them? Doubt it.

What you got to remember is that if any given turbo has a life of 120K kms then compressor surge isn't gonna do you any favours in regards to life expectancy.

Most turbos last longer than that, but say 120k with a BOV and 115k or 110k without. Who cares?

My mate put a turbo on a MX5 BOV'less and it lasted about 5 months before the shaft play was quite bad. No shaft play to begin with.

Too many variables, or just bad luck. He was probably more careful with the second turbo as well.

[R31Nismoid]

Hmm i guess it depends on the car. Running no bov or an atmo bov should have the same effect on fuel economy. I run an atmo bov and still manage about 480km to a tank before the fuel light comes on. (Standard ECU)

logically speaking it wont have the same effect...

but every car/driver is different... i said it wouldnt help.

[sneakey pete]

Too many variables, or just bad luck. He was probably more careful with the second turbo as well.

I'd say that because he was more careful he put the BoV on....

[Turbz RB-25]

Here's a simple test.

First, obtain a tennis ball in the opposite hand that you throw with.

Subsequently, go outside your house, find a nice spacious brick wall, and through it at the wall.

Then, inspect the wall to see if there is any damage...

Same principle applies to air hitting the turbo fins....