No Bov, And Turbo Life-span

[Adriano]

i like what: GTST said above. covered alot of everything in one post ..

Mee too, and i think that BOV's were specifically fitted to improve emissions and fuel comsumption on AFM cars, hence why all modern AFM cars have recirc BOV's and non afm cars dont(although there aren't many of them, some supra's etc.)

[midnight]

I have run no bov with my apex AX53 for almost year now on 16psi. there is zero shaft play either way, and no smoking whatsoever.

if it does do any damage.. its taking a damn long time

Edited August 27, 2007 by midnight

[Cubes]

So having said AAAAALLLLLL this… throttle response and with it boost response will be higher on a car with recirculating bov than a car with no bov.

I say, a turbo spinning at 100,000rpm will slow down MORE with no bov than with a recirc bov between gearchanges.

My reason as stated above is because of the air being forced back through a turbo that is spinning in a direction which is trying to suck air in, compares to a turbo that has nothing trying to go the wrong way, infact has the air that was in the pipes dumped back in front of it.

No force on the back of the COMPRESSOR of a turbo equals less turbo rpm loss between gears.

Has nothing to do with exhaust side of things.

hehe an oooooooold quote.

You really need to not theorise and give it a go. Grab a coke can and cut out a gasket then block off your std bov.

Take it for a drive and you will INSTANTLY notice driving briskly off the lights at part throttle when you grab that next gear the car just picks up and goes; there's no slight delay like there is with the bov connected.

Take it for a brisk spin through the hills; corner exit where your controlling throttle/traction as the road straightens up plant that foot and feel the instant torque.

Having to refill the ic pipes with air in this instance clearly is worse than having the compressor's speed slow slightly.

What you have said sounds like the theory will follow through in practice but it just doesn't.

Really.. Give it a go just so you can go wow, It feels great at part throttle but sh*t I hate that farting, popping and jerking.

I really do like the improved 'response' no bov offers when grabbing that next gear under brisk driving conditions.BUT I just can't stand the popping and farting. I'm having the bov reconnected.

-------

It would be interesting to plumb in a boost gauge to the IC piping to see exactly what boost levels the turbo experiences when jumping off the throttle.

I haven't known of any no bov related failures.

Only tuning related or owner related where they have slipped up with an incorrect toluene mixture that resulted in detonation causing stuffed big ends and ring lands.

[Primordial]

I have run no bov with my apex AX53 for almost year now on 16psi. there is zero shaft play either way, and no smoking whatsoever.

if it does do any damage.. its taking a damn long time

I'm in exactly the same situation - same turbo etc etc.. I havent run a BOV forever and i've got almost zero shaft play too.

You really need to not theorise and give it a go. Grab a coke can and cut out a gasket then block off your std bov.

Take it for a drive and you will INSTANTLY notice driving briskly off the lights at part throttle when you grab that next gear the car just picks up and goes; there's no slight delay like there is with the bov connected.

Take it for a brisk spin through the hills; corner exit where your controlling throttle/traction as the road straightens up plant that foot and feel the instant torque.

I'm in the same boat. I dont care what anyone says, my car has got less response and more lag with the recirc stock BOV (compared to running NO BOV). I've tested extensively, and there is a very noticeable difference. I was worried though about the life of my turbo obviously, and so I decided to check the amount of shaft play after nearly 25,000km of running with no BOV. Almost none.

The theory that you guys have been talking about is utterly logical, and I dont think that there is any disputing that a recirculating BOV SHOULD mean less damage for your turbo, and better response. I think that the reality may be either different to what the theory suggests, or in fact that the effect of running no BOV arent quite as severe as suggested. I'm basing this on the fact that I have tested it, and this is the experience that I've had.

[zertek]

woah... like always there are many variables.... I personally cant decide so i run the turbosmart V port adjustable and run a 50/50 set up

[DjeMz]

question?

i was running a stock rb25 bov and BOTH of them slit in two after running only 17psi...

is that just bad luck? or over tightening of bov?

i want the car to sound really quite, which bov do you recommend? (if the stock one is too weak to hold 17+psi)

[Rolls]

I wonder how hard it would be to find out directly from nissan themselves what the reasons were for fitting a bov instead of sitting here theorising all day, anyone have any good contacts?

Just for the record I've got a HR31 with the original turbo still fitted (no bov from factory), its run ~12 psi for half its life and the turbo hasn't gone pop yet. ~115kms

I do agree blow off vales save compressor wheels. Not so much when you occasionally give it to the car, but at the point where the turbo is glowing hot and relatively mallable, having a ton of air wack up against the turbine blades will bend them back and forth and weaken them till they snap.

That is a load of crap, give one documented example of that happening. Air weighs f**k all, someone worked it out but it was a completely negligible amount, certainly not enough to damage the blades. Put more stress on the bearings/cartridge, yes but how much?

Edited August 27, 2007 by Rolls

[TTT]

hehe an oooooooold quote.

You really need to not theorise and give it a go. Grab a coke can and cut out a gasket then block off your std bov.

Take it for a drive and you will INSTANTLY notice driving briskly off the lights at part throttle when you grab that next gear the car just picks up and goes; there's no slight delay like there is with the bov connected.

Take it for a brisk spin through the hills; corner exit where your controlling throttle/traction as the road straightens up plant that foot and feel the instant torque.

Having to refill the ic pipes with air in this instance clearly is worse than having the compressor's speed slow slightly.

What you have said sounds like the theory will follow through in practice but it just doesn't.

Really.. Give it a go just so you can go wow, It feels great at part throttle but sh*t I hate that farting, popping and jerking.

I really do like the improved 'response' no bov offers when grabbing that next gear under brisk driving conditions.BUT I just can't stand the popping and farting. I'm having the bov reconnected.

-------

It would be interesting to plumb in a boost gauge to the IC piping to see exactly what boost levels the turbo experiences when jumping off the throttle.

I haven't known of any no bov related failures.

Only tuning related or owner related where they have slipped up with an incorrect toluene mixture that resulted in detonation causing stuffed big ends and ring lands.

CUBES you noob.

the 'response' you're refering to can be had with a bov too.

even with the stock bov.

if you block off the little bleed hole on the stock bov which is there to open and shut the valve quicker and the cause of that constant shhh sound at part throttle, you will have the same 'response' on part throttle/through corners etc.

aftermarket bovs don't have the little bleed hole.

so if you get say a GFB plumback bov in place of the stocker, adjust it with the plumback part off so that it is 'just' closed at idle, plumb it all back up and go for a drive, it is exactly like having no bov while part throttle / on and off through corners type throttle, without the poping farting crap as with atmo bov or no bov.

I've tried all kinds of things on my cars.

no bovs, stock bovs, modified stock bovs, 2 bovs, one plumback while other atmo, just atmo etc.

having done all that crap, "FOR ME" the stock bov is the best compromise.

best drivability, cleanest rear bar , no stalling, no attention, no problems.

I was happy to give up the millisecond of increased throttle response for a nicer car to drive.

I think you and I shoudl go in business together.

We could sell "gobble gobble" valves to everyone as endorsed by Nizpro and Coca Cola.

[Cubes]

lol.

Yes I've tried blocking off the hole but it still doesn't offer the same part throttle response as the bov lifts off as soon as it see's some boost.

When I say part throttle Im talking about a part throttle but with a good 6-7psi; so 'brisk' part throttle almost hoon style acceleration.

As with you... I have decided to trade off the noticeable improvement in torque when you grab that next gear because I simply cannot stand the popping and farting. I don't get stalling as I run a 4" inlet pipe between the turbo and afm.

[Gazee]

As with you... I have decided to trade off the noticeable improvement in torque when you grab that next gear because I simply cannot stand the popping and farting.

Can this popping and farting can't be tuned out?

[TTT]

there are devices that can tune the stalling issue out so I'm you're the excess fuel on throttle off can be 'tuned' out.

I've found the best device to tune out the popping, farting, stalling, jerky transition between throttle on and off is a stock bov.

I'm sure there are more expensive stuff out there if you're that way inclined.

[Cubes]

Can this popping and farting can't be tuned out?

It can't be tuned out as such; well not if running an AFM.

I believe the HKS EIDS helps considerably. But not 100% as I haven't tried it.

[Kaido_RR]

talk about bring back an old topic lol

[BAMR33]

Don't know whether anyone has quoted this yet but straight from Garrett FTW

The Blow-Off valve (BOV) is a pressure relief device on the intake tract to prevent the turbo’s compressor from going into surge. The BOV should be installed between the compressor discharge and the throttle body, preferably downstream of the charge air cooler (if equipped). When the throttle is closed rapidly, the airflow is quickly reduced, causing flow instability and pressure fluctuations. These rapidly cycling pressure fluctuations are the audible evidence of surge. Surge can eventually lead to thrust bearing failure due to the high loads associated with it.

Blow-Off valves use a combination of manifold pressure signal and spring force to detect when the throttle is closed. When the throttle is closed rapidly, the BOV vents boost in the intake tract to atmosphere to relieve the pressure; helping to eliminate the phenomenon of surge.

[Gazee]

there are devices that can tune the stalling issue out so I'm you're the excess fuel on throttle off can be 'tuned' out.

I've found the best device to tune out the popping, farting, stalling, jerky transition between throttle on and off is a stock bov.

I'm sure there are more expensive stuff out there if you're that way inclined.

at what psi would the stock bov leak on a larger turbo like a GT30 for example?

[TTT]

stock bov or all bovs for that matter... work by boost and vacuum.

when you have the vacuum line connected to the top of the bov it can't leak.

when you are boosting and your boost gauge sees 20 psi (example obviously), you have 20 psi of air being rammed in to the motor.

so there is 20psi of air in the intercooler pipes.

so there is 20 psi of air on the bottom of the bov piston pushing against it.

however, if your boost gauge is showing 20psi, that means the vacuum line on top of the bov ALSO has 20 psi of pressure in it as it gets it's vacuum source from same place the boost gauge does (in the plenum side of the throttle body).

therefore, 20 psi on top and 20 psi on the bottom = 0 pressure.

if there is 0 pressure, then the bov is not going to open.

so wether you have a stock 7 psi or some monster 30 psi, the bov will not leak.

the only reason to change the bov is that at massive PSI and power, the amount of air that is to be "blown off" on gear changes is too much for the stock bov, that you get some flutter.

so a bov with a larger diameter piston and venting capability is required.

but as Cubes and I were discussing earlier, some change the bov for that little bit of extra throttle response in on/off throttle instances like racing.

the stock bov has that tiny leak hole to make the transition on to boost smoother and to allow the bov to open and close rapidly as required.

See what user "the Maffia" has to say about GT30, stock bov and 300rwkw.

Edited August 28, 2007 by GTST

[DjeMz]

Ok so which BOV would you recommend?

Im after something nice and quite (and cheap lol)

[R31Nismoid]

Stock or GTR

Simple as that

[GOR33]

lol, i ran no bov for over a year on my stock turbo. didnt do a thing to it, ran at 14psi for liek 3 yrs, and i took it off and sold it, had almost no shaft play

man when a turbine is spinning at whatever it does at full boost, do u really think having no bov is gona be enough to slow down the wheel and f**k up the turbo? i doubt it.

well i aint no turbo expert but im definatly living proof. i made 300rwhp on stock trubo with no bov for over a year and it was fine, i think theres way too much hype about this issue

[Kaido_RR]

Stock or GTR

Simple as that

lol...