Jump to content
SAU Community

Recommended Posts

  • Replies 62
  • Created
  • Last Reply

Top Posters In This Topic

ive been told you should not run an after market bov on skylines becouse it is not good for the engine, it requires the pump back system to run at full potential, unless you have done the work on the engine and the car has a new ecu to change fuel mapping, is this true.......

Stock or aftermarket, as long as you are runing one. GTRman1992 i hear what you are saying about not running a BOV, but dont agree.

Whats creates boost is the turbo spinning at rpm, and whilst not running a BOV will not stall the turbo, or force it to spin backwards, it will help slow the rpm. As the inlet tract is of fixed volume, the combination of dropping exhaust gasses and trying to pressurise a fixed volume, the turbine wheel will not have enough axial force to continue spining the compresor wheel whereby maintaining any positive pressure in the inlet tract.

After all the turbo does not represent an air tight seal so air can escape the'open' system back thru the airfilter.

BOVs by way of venting air either to atmosphere (my preference) or recycled back to the inlet tract, will lessen the rpm lost by the turbo, meaning when you crack the throttle and the exhasut gasses start to flow, there is less accelaration of the turbo required to get back to boost producing rpm.

I am at the minute not running a BOV because im redoing all my pipework, and i sure as hell notice poor response from the turbo after gear changes. (Its a fair whack bigger then std turbo) My new pipework is going to run 2xBOVs to ensure that they can vent the cfm that my turbo can produce.

Everyone has an opinion on BOVs

Placing one that will vent to atmosphere next to the throttle body, about 4" actually from the throttle body, and then the other is going after the turbo outlet (just before the pipe shoots thru the inner guard, and is being plumbed back to the inlet.

Im still umming and arrring over plumbing back the BOV on the turbo outlet, compressed air from the turbo will be hotter then inlet air thru the filter, and as it will not be passing thru the intercooler, will only be recirculated back to be compressed/heated again... i may just atmo vent both of them, as i dont want a return line running accross the rocker cover from the throttle body. :P

But then there is the whole stalling thing so will have to wait and see how it goes... may need to chase down a HKS EIS (piggyback idle thingy)...plans need to be flexible :P

GTST - Yes I have no BOV at all. The factory ones are blocked off.

Roy. I agree when you say everyone has an opinion on the subject. BOV is almost like having a religeous discussion. Soon I will be setting up a pressure sensor with high speed logger in front of the turbo outlet. This will measure both the pressure wave some claim and the back on boost response time. I will do it on a GTR that have BOV's so we can shut them off and get a true final answer on the subject.

Roy, On your loss between gear changes, I think it is the bigger turbo. As I said earlier I spin the wheels from 1st to 2nd and 2nd to 3rd, so I cannot understand the powerloss arguement. Will see soon anyway.

The factory nissan BOV is very good. They leak a little insignificant amount of air back to allow for a nicer throttle response just off boost. You can easily block the bleed hole if this is a problem for you. It has no effect on performance at all.

For the most part people who claim that the factory ones leak are usually 'hearing' the leak and not seeing it on the boost guage. OR are blaming the BOV for boost drop caused by something else. If you do have a leaking factory BOV the replacement will cost you less than $50. These factory BOV's can be further modified to allow for operation at 40psi or so if you are concerned that there is some substance behind the myth that they don't work at higher boost pressures. And you can atmo vent them (provided you block off the other pipe no longer used) if you are concerned about a small amount of slightly warmer air.

Gson plumb back are better as the air going into the engine is measured by the AFM's, so if you vent it to atmosphere your car will run rich on gear changes as the ECU thinks that air is still in the system. There are ways to fix this but its all too hard only for the swissssss noise that will get you a defect.

GTRman1992 - If the psshht noise is a defect, how come I hear so many cars with them, the dep of trans and police would be instantly attracted to them?!? I can only see how a BOV would change emmission levels, but that's the only thing I could possible see that would make it a defect, and even then it would be hard to prove, right? Please be gentle, I am a noob to this :-)

I just have bought a stock R33 and want to have that beautiful sound, and after reading up and talking to several different mechanics about BOV's I have decided to get one, but not if it'll get me defected here in QLD, that's just a waste of money!

Ska

Yeah, atmo venting BOV's are defectable because of the change to emissions etc....

The only reason you hear so many is because they havn't been caught yet... there are tricks to driving to make your BOV quieter when needed....

EG:

* Slowly back off the accelorator for gear changes instead of just lifting your foot off

* Tune the BOV so it "flutters" under certain RPM

*Drive around cops with low or no boost so that the BOV doesn't go off...

etc etc....

Then the only thing you have to worry about is getting pulled over for an RBT and getting defected.... :)

I have been pulled over for many RBT's and not once have the cops asked to pop my bonnet. I could have been lucky all this time, but I'm just saying it's not a 100% dead certainty that you will get defected just because you are at an RBT. They have a drink-driving quota to fill while there, so they are more interested in getting you in and out as quickly as possible.

If the cops *did* pop my bonnet, they would most likely not find my bov anyway. It is pretty well hidden and you'd need some tools to disassemble bits of the engine bay to find it :)

Interesting, I am contacting QLD transport to try to get clarification on this matter with them, it would be so good it they aren't. But I really do not see why they should be, the emission from them is only compressed air right, so it's not like they are adding any pollution and hang on a sec bov's would have to be legal, because my stock 93 R33 has a bov right? If so then it would have had to pass when it got the compliance plate when it was imported, and it did pass the roadworthy before I bought it?

I am looking forward to seeing what QLD Transport have to say!

your skyline has a bov that vents back to the air inlet, therefore keeping the air:fuel mixtures right.

vent externally on the standard AFM system and during the gear shift or back off from throttle, your car over fuels causing your car to run rich during that time, causing richer exhaust fumes...

THAT is one defect, the other here in NSW (depending on if the cop wants to be a jerk) is NOISE.

It is apparently UNDUE noise pollution.

Interesting, I am contacting QLD transport to try to get clarification on this matter with them, it would be so good it they aren't.  But I really do not see why they should be, the emission from them is only compressed air right, so it's not like they are adding any pollution and hang on a sec bov's would have to be legal, because my stock 93 R33 has a bov right? If so then it would have had to pass when it got the compliance plate when it was imported, and it did pass the roadworthy before I bought it?

I am looking forward to seeing what QLD Transport have to say!

It's not the the fact that compressed air is venting that is the issue. But the fact that on AFM equiped cars with venting BOV the A/F mixtures go very rich while the BOV is venting air. This is where some people have problems with back firing and stalling.

So it's not the air that's coming out of the BOV that is of concern, but the super rich exhaust fumes.

J

So it's not the air that's coming out of the BOV that is of concern, but the super rich exhaust fumes.

OH ok now I get it, bugger still it will be very interesting to see what responce I get, I have already contacted them re air pods, because I saw some not too happy ppl in NSW posting that it is illegal for them to have air pods, and QLD Transport said:

Generally, the fitting and use of vehicle accessories (air pod) do not

require specific approval from Queensland Transport. As such, Queensland

Transport does not approve or disapprove the use of vehicle accessories.

However, Queensland Transport requires that vehicles continue to comply

with the standards set from when the vehicle is first supplied to the

market. Accordingly, the use of any aftermarket devices must not result in

deterioration of vehicle compliance with the applicable Australian Design

Rules.

The only regulation relating to air filters is contained in Queensland

Transport's Approved Inspection Station (AIS) Code Of Practice which states

that, "air cleaners must be fitted".

It is the responsibility of the driver of the vehicle to ensure that

emmisions levels are maintained.

It may be necessary to supply proof that the vehicle maintains the original

emmision levels.

So I guess that answers the BOV question too, fitting an aftermarket BOV would most probably change the emmision level's because of the motor running rich during release of the air.

Still I'll wait to see what they say specifically about BOV's and hope :Bang:

In vic you are only allowed one air intake modified

modifications are: intercooler, pod filter

So you can only have one or the other, however most skylines (if not all) come stock with an intercooler, so any skyline with a pod is defectable (in vic), however Ive been pulled over before, they ask if you have any mods, i say yes, an aftermarket air filter, they pop the bonnet look around and go your free to drive off

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • The 296mm rotors are the R33 turbo brakes. The 310mm rotors are the R34 turbo brakes. The calipers are nearly the same, but not. They're the same caliper but the R34 caliper has longer legs so that it sits out far enough to go over the rotor. The pads are the same for both. When you say, "I bough tsome EBC"....did you just mean pads? Or rotors? 310mm rotors fit under 17" wheels. There may be some wheels without enough clearance though. I can't fit my fingers between the barrel of my wheel and the "corners" of my R34 calipers, but there is plenty of room behind the spokes. This is on Enkei RPF1. You can fit 324mm rotors inside a 17" wheel, but I'd be willing to bet that it would be close to impossible with the Nissan/Sumitomo caliper (using an adapter, of course), because the Sumitomo caliper is fatter than the Brembo caliper that is supposed to go on the 324mm rotors.
    • Hi. Can someone tell me what brakes(and mainly WHERE) can i buy brakes on R34 GTT? I bought some EBC which SHOULD go on my car(i have GT but it has GTT brakes) but it does not fit, Brakes are "too" small(296mm) Are 310mm be good or? I have 17 inch wheel so no "big boys" but for me driving i just need one that fits and i can get here in EU/Czech.
    • Since winter isn't that harsh anymore in Poland, i will definetely drive it 365 days a year 😉. But if the snow hits i will try it for sure and let U know. Only swap i am planning to do is of course R34 GTR front 😍.
    • Hey. Very valuable information about pitwork, I will pay attention when buying any consumable parts 🙏 As for the carpets - I got a handful of information from nengun, from which it appears that indeed the carpets for the driver's side are OEM. They are not able to show me any pictures due to the long chain of different sales entities but after I place the order, as soon as the goods arrive at the nengun warehouse from which they will send the shipment to me they can send me photos and if my purchase differs from OEM I can immediately return it / cancel the purchase. I think I will give it a try 😉. Of course i'll let you know what's what as soon as i get them P.s. I know the topic is not relevant to the thread, but both nengun and amayama have these SICK 😍 trunk room lamps available. Do you know anyone who ordered them? I need to have one in my car
    • I've managed to find this: Nissan_Stagea_AutechVersion260RS (1).pdf
×
×
  • Create New...