Well I'm sure im not the only person who's mind this has run through as it's quite a common modification on other turbo marques.

 

For those considering running this setup on a 300zx it's essentially the same as on any other turbo car, use 4xblanking plugs - 2x35mm 2x27mm and get some nice new jub clips and sealant (loctite etc) whilst you're at it! Take off the standard recirc valves, plug in the blanking plugs and then stuff bolts in the redundant vaccum pipes. :thumbup1: (obv you will need a pod filter to hear anything)

 

Now I'm going to tell you it's not worth it on a Z. Possibly due to the turbo size/ piping, or the distance of the airfilter from the cabin, you won't get much of a noise. Yes it's audible when surrounded by walls etc. and makes that nice 'tshh shh shh' sound, but it's not loud enough to be appreciated on stock boost.

 

Driveability wise, it's no different to running an atmos BOV. Occasional lumpyness, and its not as smooth between gear changes as the recircs. So far I havent had my turbo's blow out the side of the wheel arch, or compressor wheels slicing through the car as advised by the nay-sayers :tongue_smilie: I just agree now that it's not a worthwhile mod. Once im running more boost I'll see if its much louder, if not I'll probably revert to the recircs or go for atmos BOV's.

 

Thats my experience so far anyway :biggrin:

Sorry confused.com with this.

The title says going BOV - less, so you remove the stock ones and blank up everything and no noise was heard, which is correct.

Then you mention an atmos BOV so you then fitted aftermarket BOV's?? and heard no noise?

smithy

i think he is trying to achieve the compressor surge noise often mistakenly called wastegate chatter...

is this the noise you are after?

 

[YOUTUBE]LZUbo_mNDZM[/YOUTUBE]

 

i agree the noise does sound pretty tasty... a much more manly sound then a boy racery dump valve :wacko: but i would never subject my tubbies to that sort of punishment...

 

when your turbos are on full boost and merrily forcing induction, all is well, but with insufficient pressure release or recirculation systems (ie blanking the system completely!) when the throttle is released the demand for air into the engine is released but there is still excess pressure in the system... this excess pressure seeks the easiest possible way out, which is back out across the impellers to the intake. this stops the turbos dead and turns them back the other way in milliseconds (surge) causing massive stress on the blades/bearings. the pressure demand from the engine isn't linear and the engine still needs an intake of air, so this surge will 'flutter' causing your turbos to be rapidly changing direction in a series of surges.

 

on a slightly different scale but the same principle is that in my work i often have to ground run modern gas turbine engines which have lots of compressor control systems to stop surging. these systems have only fairly recently become efficient... i remember, on older 737's with lower bypass engines, surges on ground runs that completely detroy the engine spitting bits of blades out the intake... your z32 surge control systems are bovs or recircs. you'd prolly be unlucky if you managed to destroy blades before the bearings go to pot but either way you will decrease your turbo lifespan drasticly.

 

sorry if this is teaching people to suck eggs but that's a quick run through of it for those who might be interested :nuke:

Edited February 8, 201015 yr by Joely P
grammar of an infant

Sorry confused.com with this.

The title says going BOV - less, so you remove the stock ones and blank up everything and no noise was heard, which is correct.

Then you mention an atmos BOV so you then fitted aftermarket BOV's?? and heard no noise?

smithy

 

Blank up everything and tsshh tsh tsh is heard :yes: but on a z32 due to the t25's and piping and distance of air filter you cant hear it very well in the cabin. The tscch scch sound is down to the air going back through the turbo blades as written above - damage is an unknown, though it may well cause an issue in 1k miles, or 80k miles nobody knows - at the end of the day I've had a 200k mile CA18det which had a closed system and the turbo still pulled strongly. The recirc bov is not only there to relieve pressure, it is there to make for a smoother ride and less noise.

 

 

Atmos BOV's are a bit louder as the air escapes the system in a quicker fashion, but it makes a different noise depending on if it has any specialized valves/fins on them. I haven't fit one on the Z32 though I may do so because it will be a bit louder and I'll admit I for one like the noise they make.

 

On some cars, like an S14 or an evo doing the bov-less thing results in a wicked noise which is easily heard even on stock boost :yes:

The recirc bov is not only there to relieve pressure, it is there to make for a smoother ride and less noise.

:

 

Correct in the fact it is to relieve pressure when the butterfly shuts, but in doing so it then stops the tubs from NOT spinning and thus enable them to spin back up to speed again faster, hence it is for the performance of the tubs to get the most out of them especially during acceleration and to try and avoid damage to the tubs from a constant stalling impellor.

 

Atmos BOV's are a bit louder as the air escapes the system in a quicker fashion, :

 

Atmos BOV's are loud simply cos they do release to the atmosphere whereas re-circs send back into the system to reuse that same pressure again.

So as re-circs are actually very quiet, then yep yer right, Atmos BOV's are louder, considerably too not just "a bit"

 

Geez, if i'd known what you were trying to achieve, could have told yer it wouldn't have worked, simply because the length and design of the intake pipes, that is what mainly determines how loud the chatter can be followed by the size of the tubs.

 

Anyway, you tried it now, each to their own an all that but am sure others won't bother now :-)

cheers

smithy

Yeah just glad I gave it a shot as lots of people seem to mention it ... then never go ahead. I mean it is audible, and some people may like it, but it's nowhere near as loud as you'll hear on some other engines - point your peepers to holden VL's or evo's and you'll hear the sound I was hoping to achieve.. but didn't ;)

 

live and learn eh :D

so in a nutshell, you can hear it (reasonably quietly) but you risk damaging the turbos?

 

My GTi-R used to do it and I played on it alot because I liked the noise lol. :tt2:

any chance of a recording of it?? :p would be nice to see how it compares to the 200s

Have you got round to measuring the performance decrease yet?! :lol::tongue_smilie:

Have you got round to measuring the performance decrease yet?! :lol::tongue_smilie:

 

There's none, a recirc valve cannot increase performance over not running a bov. :yes:

There's none, a recirc valve cannot increase performance over not running a bov. :yes:

 

Hmm a pair of turbo's operating with no type of BOV = impellor stall = lag

 

ANY type of BOV = none or reduced impellor stall = quicker spooling turbo's

:tt2:

smithy

i would never deliberately do this to the Z tho if im running on full chat with the windows down sometimes I can hear a faint t-t-t-t- of the compressor surge straight after my BOVs dump but i guess the springs are not set quite correctly.

Hmm a pair of turbo's operating with no type of BOV = impellor stall = lag

 

ANY type of BOV = none or reduced impellor stall = quicker spooling turbo's

:tt2:

smithy

 

Exactly!!! :smartass:

Roll on what next a cherry bomb

Hmm a pair of turbo's operating with no type of BOV = impellor stall = lag

 

ANY type of BOV = none or reduced impellor stall = quicker spooling turbo's

:tt2:

smithy

 

LOL nothing more than internet heresay, if .. and I say if, it is the case it makes a difference for a fraction of a second and is not noticeable. I'd be happy to dyno it to prove it if somebody was willing to spend the money.

 

I'll agree there may be a risk to the turbo's, but it's slight. Again, I've had turbo cars with no bov's recirc or otherwise fitted since the factory run huge mileage. Me taking off a blow off valve isn't going to sh*t a turbo in less than 10k miles unless it was going to sh*t it by then anyway due to mileage. :)

 

I'm quite sure Baz will agree with me here if he ran this setup on his GTiR, the difference in performance is negligible. I've been in plenty cars with this setup as well which were run very hard - nobody's reported any issues with it.

 

As for it being chavvy - it's no worse than an atmos BOV, and is a damned sight less money wasted, with the advantage being it wont leak at higher boost levels which factory nissan recircs are reasonably prone to doing. But it won't be as smooth during gearchanges or easing off the throttle.

 

No need to pounce on me guys, I was just testing it out :helpsmilie:

Hmm a pair of turbo's operating with no type of BOV = impellor stall = lag

 

ANY type of BOV = none or reduced impellor stall = quicker spooling turbo's

:tt2:

smithy

 

 

iam sorry gentelmen but you are WRONG .

no bovs means that the pressure cant escape to atmosphere thus decreasing lag quite vastly .. when i do drag race i usually disconect my bovs . and yes chaterring sound is achieved and can be heard very well ..

Ok, so foot on throttle and car accelerating = butterfly open and air being sucked in, engine needs cool dense air and a lot of it, foot of throttle = butterfly shut. what happens to all that air/pressure build up in the intake system, where does it go?

 

Mikael, we're talking either BOV or no BOV at all, forgetting for a moment if it's atmosphere or re circulating.

smithy

Edited February 8, 201015 yr by Smithy

will this help your reply

http://en.wikipedia.org/wiki/Blowoff_valve

 

Theres absolutely nothing about internet hearsay, it is also common sense.

 

Notice very early turbo production cars didn't have BOV's, certainly mid 80's many didn't.

Nissan wise, the S12 didn't however engineers realised this was happening and fitted BOV's in Nissan's there after the S12.

 

Knowing the tish sound was not everyones cup of tea and by putting the prssure back in the system later may help, we end up with re-circs fitted as standard on every Nissan after the S12 that i know off, hmm i wonder why!

smithy

The 1.8t s13? the 2.0 6-cyle turbo Laurels, cefiro's? none of them had bov's into the 90's.

The 1.8t s13? the 2.0 6-cyle turbo Laurels, cefiro's? none of them had bov's into the 90's.

 

yep.

car can accelerate faster and spools faster with no bov or rec bov ..

thats my opinion and experience with turbod cars ..

I'm pretty sure the Bluebird SR20 SSS's didn't have them either. The recirc valve will lengthen the lifespan of a turbo marginally yes - that doesn't mean that not running one will suddenly limit your turbo to 2k miles. It may last 80-90k instead of 100k before needing servicing. But as for performance issues - poppycock :D

Dam some tw*t fitted a re-circ to my S13 when they had it before me, dohh

should have said mainly "performance" cars as to what they were fitted to.

Certainly though, once they started a wee bit later on, all Performance Nissan cars were that i know off. around 93ish?

 

Like said before, each to their own, you can either believe what manufacturers of BOV's and designers of the cars say or yerself, cos it's your car at the end of the day.

cheers

smithy

This looks like another "whats the best colour" thread ;)

This looks like another "whats the best colour" thread ;)

 

nah cuz that's clear cut.. white, midnight purple, bayside blue and yellow all have even grounding.. the others are crap :lol:

LOL at this thread!!

 

A dyno will prove nothing at all as the BOV or recirc valve will not come into play until after you lift off the throttle!!

 

Why do you think they fit them then?!

 

I have an article somewhere where they tested a car with BOV's, Recircs & no BOV - the recirc fitted car came out on top.

 

Now this is only by a small margin but that is the same with most mods - an induction kit will make a small improvement, so will a lightweight flywheel, as too with an underdrive pulley etc. Add them all up & so the differences add up.

 

Facts are a BOV will reduce compressor stall allowing the turbo to build pressure quicker when you hit the throttle again on a gearchange. As small as it may be it will still improve performance!