Out and about today and have come across a few other Nissans. What appeared to be an R32 GTR at the Greensborough end of the Ring Road and then a yellow 200 on the way home. In both cases all I could hear were blow off valves. With my TT auto admittedly with it's torque I'm not seeing much more than 3500 or 4000 rpm around town. My auto elec called mine a kettle once (nickname?) but I can't hear it making the same sound as these other Nissans, admittedly both manuals.
Stock 300's, and stock everything I believe, have recirc valves which are pretty much silent. The other BOV's you heard would probably be atmospheric which means they vent their pressure to the atmosphere, making it much louder. Correct me if I'm wrong.
i would correct you sabrewolfe.... but you not wrong..... zeds have recircs,if you want the whoosh sound youve gotta change over to "vents to atmosphere" or tumpeted blow off valve.... not sure if they actually give a performance increase.....ive heard that releasing the air from a blowoff valve instead of recirculating it can cause a car to run a little richer because the air has already been measured by the air flow meter,and then its not getting used caus eit gets vented,so the car runs ever so slightly richer just after changing geras(after blow off)....just something to bear in mind.....
Does yours make any sound? What about when you push it up to around 5000 then let go of the accelerator? The other possibility is you have BOV's but they are seised. That's what mine was like when i firs bought it.
im not sure if your asking a question, but i have noticed since 300s have pretty beastie sounding engines/zorsts that you dont hear their BOV's as much, i got like turbosmart type 2. where as other models, such as silvias, 180s, lancers etc. high rev and have less exhaust/engine sound, making their bov's stand out more. p.s. s15's do come with stock blow off valves, i think maybe s14's do to not 100% sure about them tho. but yeah 90% of bovs u hear are aftermarket atmo ones... my 300 makes a nice sound but your right, due to the torque, you dont really get to make it sing unless your in 1st and maybe a tiny bit in 2nd (mines manual )
you get less boost drop with atmo but you go rich for a second between shifts.. I reckon the hybrid BOV would be the best all round.
Less boost drop? Wouldn't it be more as the air is being lost to atmo and needs to be built up again? I think the main reason for atmo is to protect the turbos
All turbo cars have some sort of BOV to protect the turbo from compressor surge. The ones you can hear are aftermarket ones that vent to atmosphere, the only reason to do this is for the "Look at me I have a turbo" factor. No increase in performance till your pushing 600hp. Most of the time the venting types will cause issues with backfiring, because the engine is expecting the extra air that has just been vented and chucks in extra fuel to compensate. If you have a pod filter you might be able to hear the stock ones working.
Firstly a bov and pov are NOT the same thing, a POV is a pressure release valve which in the case of overboost it releases the pressure and is purely an emergency release valve and nothing more. A BOV is a vacuum controlled valve that vents into the atmosphere to release already pressurized air between the turbo(s) and throttle plate(s) when given vacuum. Secondly compressor surge only becomes a real issue when running large amounts of boost i.e 20psi or more. The only REAL reason for a blow off valve is in high boost situations which will put strain on the turbine shaft when the pressurized air cannot escape, or otherwise known as compressor surge. Most of the people you see with BOVs installed are nothing but loud, obnoxious ricer fools and the only purpose of it for them is to "make a cool sound" which is the sole reason 95% of people install them without knowing the real purpose. If your car is mostly stock, simply put you do NOT need one...
air is lost either way, to the atmosphere or right after your AFM / before the turbo.. the important difference is that at higher boost levels, the stock recircs just don't flow as much as required to evacuate the air from before the closed throttle bodies without slowing the turbos.
No, it's not lost if it's plumbed back in, because it's a closed system after the AFM i.e. no air can enter or exit before the turbo or after the AFM, so the ECU knows exactly how much air it has to play with.
no.. considering I was replying to this: "Less boost drop? Wouldn't it be more as the air is being lost to atmo and needs to be built up again?" It is lost as far as it is no longer pressurised and if it weren't for the turbo still spinning it would be exiting through the pod.
Yes, boost is lost, but the air isn't. If it does exit through the pod the ECU would know about it and compensate to suit. Sometimes you can hear the stock re-circs venting back through the pod.
ok so I should have said boost or compressed air... it shouldn't exit the pod though unless the turbo stops moving completely and if it did the AFM wouldn't know if it was entering or exiting.
That's an interesting point, can the AFM register negaitve values? I suppose that it would be incredibably unlikely for the flow from the recircs to be larger than what's entering the engine. Where's the Guru's when you need them
guru shmuru! the AFM is a hot wire system that just measures temperature drop caused by air passing around it. I can't imagine a situation where you'd get air flowing out the pod unless maybe you had high flow recircs that opened very slow.
^ What he said. A POV is an emergency relief valve only, and only releases air if the set boost level of the valve is reached in an overboost situation. Wtf are you talking about a pod for?
WTF are you talking about POV's for?? There nothing to do with BOV's at all and I don't know whay you keep bringing them up POV's are what you find on Indy cars and the like, and that's just to keep even boost between competitors, not run of the mill street cars.
Yeah that's why all Z31's came with one from the factory aint it? LOL And I brought it up because someone earlier said they're all the same which they arent. Oh it was you, "All turbo cars have some sort of BOV to protect the turbo from compressor surge." Wrong... And it has EVERYTHING to do with BOVs, you replace the POV with a BOV if you plan to run higher boost than what the POV is set to release. This place amazes me sometimes...
