Running without BOV.

[dencon]

I have been told to take off my blow off valve and plug up. Todays turbo,s are man enough to take it, Any one tried it. It is for competition use only.
Car used on hillclimbs only.

 

[Spikey]

So Nissan spent Millions in R&D and has one fitted from Factory, but then someone tell you to take it off Well i guess he must be right, why not Fit Antilag whilst your at it

Do some Research on what a Bov does and then come Back with your Question...

The Bov Allows the Turbo (well the blades not the Actual Turbo) to keep spinning when you change gear, so the Turbo does not stall and have to spool up again. Its not a Bad thing to have so i would leave it...

 

[geoff pine]

So Nissan spent Millions in R&D and has one fitted from Factory, but then someone tell you to take it off Well i guess he must be right, why not Fit Antilag whilst your at it

Do some Research on what a Bov does and then come Back with your Question...

The Bov Allows the Turbo (well the blades not the Actual Turbo) to keep spinning when you change gear, so the Turbo does not stall and have to spool up again. Its not a Bad thing to have so i would leave it...

Having read a couple of books on engine tuning im looking to go back to a recirculating .

 

[Spikey]

Well im not to keen on Putting Dirty air back into the System and if you have your Maf as a blow through it dont matter if you dump it to atmosphere. Also Recirc is what Factory Cars have

 

[dencon]

I already have launch control and antilag. I think his idea was to flat shift without clutch and not loose pressure ,

So Nissan spent Millions in R&D and has one fitted from Factory, but then someone tell you to take it off Well i guess he must be right, why not Fit Antilag whilst your at it

Do some Research on what a Bov does and then come Back with your Question...

The Bov Allows the Turbo (well the blades not the Actual Turbo) to keep spinning when you change gear, so the Turbo does not stall and have to spool up again. Its not a Bad thing to have so i would leave it...

 

[johnsy]

i was under the impression that after market bov were a waist of time, and it was acceptable to run with out as the effects of not running one were minimal



[h=2]Disadvantages[/h]
In the case where a mass airflow sensor (MAF) is used and is located upstream from the blowoff valve, the engine control unit (ECU) will meter out excess fuel because the atmospherically vented air is not subtracted from the intake charge measurements. The engine then briefly operates with a fuel-rich mixture after each valve actuation.
The rich mixing can lead to hesitation or even stalling of the engine when the throttle is closed, a situation that worsens with higher boost pressures. Occasional events of this type may be only a nuisance, but frequent events can eventually foul the spark plugs and destroy thecatalytic converter, as the inefficiently combusted fuel produces soot (excess carbon) and unburned fuel in the exhaust flow can produce soot in the converter and drive the converter beyond its normal operating temperature range.

 

[Spikey]

i was under the impression that after market bov were a waist of time, and it was acceptable to run with out as the effects of not running one were minimal



[h=2]Disadvantages[/h]
In the case where a mass airflow sensor (MAF) is used and is located upstream from the blowoff valve, the engine control unit (ECU) will meter out excess fuel because the atmospherically vented air is not subtracted from the intake charge measurements. The engine then briefly operates with a fuel-rich mixture after each valve actuation.
The rich mixing can lead to hesitation or even stalling of the engine when the throttle is closed, a situation that worsens with higher boost pressures. Occasional events of this type may be only a nuisance, but frequent events can eventually foul the spark plugs and destroy thecatalytic converter, as the inefficiently combusted fuel produces soot (excess carbon) and unburned fuel in the exhaust flow can produce soot in the converter and drive the converter beyond its normal operating temperature range.

That's why i say Run a blow through Maf as im Doing. Much less hassle and Noticeable Response..

 

[dencon]

Just to add, my car is running a Motec system with map sensor. Den.

 

[red reading]

I run blow thru and it makes a huge differance (still use a dump valve too).........map sensor and standalone is next.

 

[Spikey]

I run blow thru and it makes a huge differance (still use a dump valve too).........map sensor and standalone is next.

Have you got a Pic of your set up? Be Interesting to see how you done it?

 

[red reading]

i made a stainless steel z32

 

[Spikey]

Did you make a flange to bolt in down or just Silicone the top half onto a pipe?

 

[keastygtir]

i have run without one for 5 years now and also before that on my 200sx. i found that they make the car run a bit funny

 

[PobodY]

Sounds like another case of scaremongering and conjecture to me; surely when you come off the throttle the TPS gives a "closed" reading and the ECU ignores what the MAF is saying. The blow-off valve is just getting rid of the air that's hitting the back of the butterflies because they're closed.

 

[geoff pine]

Well im not to keen on Putting Dirty air back into the System and if you have your Maf as a blow through it dont matter if you dump it to atmosphere. Also Recirc is what Factory Cars have

Its not dirty air its metered air :lolwhy is it dirty air) if Nissan recirculated it there must be reasons other than noise why they did this . I have not really found any information on using a blow through maf which has put me off the idea .I did run without a dump valve and now have a knackered turbo (coincident) you must have seen it smoking at the Liverpool meet .Im using a standard turbo at this time with no smoke and a forge atm dump valve and will up grade soon to a disco spud and recirculation valve .

 

[vss irvine]

its not dirty, just pressurised cooler air, most high power motorsport set ups use recirculating systems,

id say you run the risk of slowing or stalling the turbo if you dont get a clear shift den,

billet turbo's should be able to take this but id say life expectancy would be lower, but it will be anyway with the antilag.

Cant win it if your not in it!

 

[danr]

Sounds like another case of scaremongering and conjecture to me; surely when you come off the throttle the TPS gives a "closed" reading and the ECU ignores what the MAF is saying. ...

it doesn't unfortunately. as the turbo is still spinning, it causes maf reading to rise (obviously) and ecu dumps fuel in accordingly. easy example of this is when you come to idle say at traffic lights after boosting and the engine nearly stalls. but it is possible afaik to put maf on intercooler side away from turbo, which should help eliminate overfuelling off boost.

 

[PobodY]

Except it's on closed loop at idle so not paying any attention to the MAF; maybe for a fraction of a second it's still metering the fuel out, but I'm not sure if that makes much difference. - I've had that experience at the trafic lights, but not after giving it any boost. If I've been on the boost it's usually pretty happy; I always assumed this was a vacuum issue (i.e. the servo taking all the vacuum to assist the brakes and the engine stumbling as a result).
I'm happy that the dump valve is there for more than just the turbo; it seems logical to me that it's as much about protecting the throttle mechanism (especially the buterflies) as anything else.

Maybe this is an issue for people running a non-standard ECU/MAF setup?

I should admit that I like the idea of a recirulating valve much better anyway; it makes more sense to me to return the air to the induction pipework... I just don't have one at the moment.

 

[Makaveli_se7en]

"Stall the turbo", "allow it to keep spinning during gear change" :lol:

Stall has nothing to do with turbo speed, its aerodynamic stall i.e. flow separates from the blades creating transient surge (fluttering noise). Unless you're going to run 3bar+ of boost pressure this should kill the turbo excessively quickly, put the BOV in the bin and be done with it.

 

[vss irvine]

ok so stall is the wrong term, but since den runs a fair amount of boost my point was surely it would slow the spool time if gear change wasnt slick?
Since he hillclimbs he's looking for every available 10th.

Since your the turbo boffin then im sure youll know best.
However high end motorsport set ups always seem to use recirculating set ups, and that would only be for a reason