hi guys can you hear your after market dump valve /bov when you just revving the engine I cant hear any thing from my blitz valve just wondered if that's normal also if I rev the engine between 3000-4000 rpm I get pop n bang sound from the driver side exhaust only is that a misfire or sum thing on driver of engine .

this is phutumsch engine bay pic lets hope he can shed some light on the matter

 

I will shed some light for you..............they work perfectly where they are, sound is not ott, wouldn't swap them and i've never had any sort of problem.

 

And btw that is a slightly dated pic and having no fan shroud makes no difference at all, apart from being a finger protector that is.

I will shed some light for you..............they work perfectly where they are, sound is not ott, wouldn't swap them and i've never had any sort of problem.

 

And btw that is a slightly dated pic and having no fan shroud makes no difference at all, apart from being a finger protector that is.

 

no stalling ? no issues when it was mapped

I had the ssqvs on my 95 slicktop and they done my head in.

Indeed, a fan shroud has no real bearing on the coolant temps. My own car idled at 81° regardless if the shroud was fitted or not, and with an FMIC fitted.... or not.

 

Regarding BOVs, it's a simple concept. The 300ZX TT has an inordinate amount of intake piping between MAF exit and throttle intake, plus long runners to the combustion chamber due to intake design. In short, a huge volume of already-metered air in a closed system. Too much for the combnination of Z32 hot-wire MAF & BOVs.

 

I love BOVs as much as the next guy (I have a GFB RFL fitted to my WRX which has approximately 1/100th of the intake pipework of a Zed) but on the Zed they are simply not suitable. Unless running a blow-through MAF. Which I do. And still I run no pressure relief valves whatsoever....

 

End of the day, it's a compromise. If you like the sound/aesthetics and want to run them, do. If the correct running of your Zed is more important, don't. Regardless, make sure they aren't leaking on boost, and expect to overfuel a lot at high RPM, low/medium load when they are on the cusp of dumping all that lovely intake air. And keep those revs up when coming to a junction if you set your BOVs to dump the moment they see more than 1psi :laugh:

Edited February 23, 20169 yr by Noz

Indeed, a fan shroud has no real bearing on the coolant temps. My own car idled at 81° regardless if the shroud was fitted or not, and with an FMIC fitted.... or not.

 

Regarding BOVs, it's a simple concept. The 300ZX TT has an inordinate amount of intake piping between MAF exit and throttle intake, plus long runners to the combustion chamber due to intake design. In short, a huge volume of already-metered air in a closed system. Too much for the combnination of Z32 hot-wire MAF & BOVs.

 

I love BOVs as much as the next guy (I have a GFB RFL fitted to my WRX which has approximately 1/100th of the intake pipework of a Zed) but on the Zed they are simply not suitable. Unless running a blow-through MAF. Which I do. And still I run no pressure relief valves whatsoever....

 

End of the day, it's a compromise. If you like the sound/aesthetics and want to run them, do. If the correct running of your Zed is more important, don't. Regardless, make sure they aren't leaking on boost, and expect to overfuel a lot at high RPM, low/medium load when they are on the cusp of dumping all that lovely intake air. And keep those revs up when coming to a junction if you set your BOVs to dump the moment it sees more than 1psi :laugh:

 

am sold mine are coming off to day to re fit the stock ones

I don't doubt that 100xs was an exaggeration but think about it. Without a shroud the fan moves air, well from all around, with it its forced to pull air through the rad.

Where talking logic here, path of least resistance.

No, we're talking about log files & empirical data. If running a shroud was required, I would have had mine fitted and suggest people do the same. It made no discernible difference to the temps at idle, so as far as I have seen on countless Zeds on both the dyno and the road, at standstill and at 145mph after a top speed run at TOTB, it doesn't matter if the shroud is fitted or not :)

 

The reference to the intake pipework lengths of a WRX and a Zed was totally unrelated to the efficiency of the fan shroud on a Zed, though :confused1:

Edited February 23, 20169 yr by Noz

who said anything about a WRX?

 

The only logical out come to your findings then is that the radiator is efficient enough to not require that help. Ie the fan has no return value of efficiency. Your a knowledgeable guy Noel, it's illogical to suggest that cooling efficiency of the fan is not effected by the shroud. Can you think of a car on the market that does not encorperate a shroud? As a side point at 145mph I suspect that cooling would be more efficient without the shroud, due to a less restrictive pathway. What I'm stating is that at in a hot idle scenario a fan shroud will improve the radiators ability for thermal exchange. Simply because a larger, more focused percentage of the total amount of air pulled by the fan is actually drawn through the radiator.

 

The reality may be as you suggest that the exchange is good enough than the gain from the shroud is immeasurable. I'd be surprised about that though. The bottom line is though, it's a fact that more air will pass through the heater core at hot idle with a shroud than without, as a result the efficiency of that thermal exchange would be maximumised.

who said anything about a WRX?

 

The only logical out come to your findings then is that the radiator is efficient enough to not require that help. Ie the fan has no return value of efficiency. Your a knowledgeable guy Noel, it's illogical to suggest that cooling efficiency of the fan is not effected by the shroud. Can you think of a car on the market that does not encorperate a shroud? As a side point at 145mph I suspect that cooling would be more efficient without the shroud, due to a less restrictive pathway. What I'm stating is that at in a hot idle scenario a fan shroud will improve the radiators ability for thermal exchange. Simply because a larger, more focused percentage of the total amount of air pulled by the fan is actually drawn through the radiator.

 

The reality may be as you suggest that the exchange is good enough than the gain from the shroud is immeasurable. I'd be surprised about that though. The bottom line is though, it's a fact that more air will pass through the heater core at hot idle with a shroud than without, as a result the efficiency of that thermal exchange would be maximumised.

 

I did. Read back through. Crossed wires.

 

I'm not discussing cooling efficiency or thermodynamics here. I'm simply stating that the fan shroud isn't required due to empirical findings. Every Zed I have worked with I have been monitoring temps in a "hot idle scenario". It doesn't matter if the shroud is fitted or not. And when I say "monitoring temps", I don't mean checking to see if the needle moves, I mean fully monitoring sensor outputs via Nistune.

 

Regardless of what should be and will be happening regarding airflow, the reality is that the fan shroud doesn't need to be fitted. It's as simple as that.

True my temps a lower with no shroud

Mine's staying on! lol. Doesn't look any better with it off and I wouldn't wanna risk getting ****ted by a blade if I had to go into the engine bay with it running. I'm stupid like that you see! :lol:

The trick is to both undo & retighten all the CAS bolts with the engine running. Level 5 skillZ.

The trick is to both undo & retighten all the CAS bolts with the engine running. Level 5 skillZ.

Tighten the CAS he said....... engine running he said....... lol

:laugh:

Sharpened steel blades on that fan? Damn! :-P I've been hit a couple of times by fans but no worse than some cursing and swearing though... That pic also reminds me of the guy who thought it was a good idea to turn on the engine and put it in gear to clean his motorcycle chain :-o

 

Sent fra min C6903 via Tapatalk

Noz, how come having bov's would cause overfueling at high rpm?

Noz, how come having bov's would cause overfueling at high rpm?

 

It's the inherent design of pressure relief valves. Hold it at high RPMs and low/medium load on a responsive car (as opposed to a car fitted with a monstrous turbo) and you can hear the BOVs venting, especially ones with weak springs.

So a large turbo'd car would benefit from them?

So a large turbo'd car would benefit from them?

 

Have a read of this from Greg@SZ

 

http://www.twinturbo.net/nissan/300zx/forums/general/view/2421113/I-do-not-recommend-blow-off-valves-on-the-Z.html

So a large turbo'd car would benefit from them?

 

Not exactly. I meant something like a 2L car rocking a Holset HX35W :)

 

If you have a 300zx with a draw-through (stock) MAF, you want a closed-system due to the pipework length.

 

On the other end of the scale is the Subaru Impreza. MAF -> 50cm(?) of pipe -> turbo compressor inlet -> turbo compressor outlet -> Y-Pipe -> TMIC -> Throttle body. No BOV or recirc valve and the car drives like crap due to reversed flow hitting the MAF and making it run pig-rich on gear changes. VTA BOV works great, still dumps at high RPM & medium load, but there is hardly any metered air in the system, so drivability is mostly unaffected. Hence I run the loudest most obnoxious BOV I can on mine :wack:

Good read Andrew cheers, and thanks for the reply noz. It's good to have someone who knows, explain it.i didn't fit them, but both my cars have them, looks like I'll be on hunt for some stock recircs in the near future after reading up on this!

Good read Andrew cheers, and thanks for the reply noz. It's good to have someone who knows, explain it.i didn't fit them, but both my cars have them, looks like I'll be on hunt for some stock recircs in the near future after reading up on this!

 

Seconded. Knew about this before, however great that the extremley busy 'techies' on this forum always find the time to explain things...sometimes, time and time again.

 

Imagine if Noz, Jeff, Jimmer and a few others (in the know, not the guess) got their heads together and wrote a book; it would be at the top of my christmas list!!! (As long as I could do the photography and art!!lol)

 

Well done guys

fixed bov/dump valve they were stuck in closed position

[video=youtube;E-LLQFmE-Wc]

Awesome.

Seconded. Knew about this before, however great that the extremley busy 'techies' on this forum always find the time to explain things...sometimes, time and time again.

 

Imagine if Noz, Jeff, Jimmer and a few others (in the know, not the guess) got their heads together and wrote a book; it would be at the top of my christmas list!!! (As long as I could do the photography and art!!lol)

 

Well done guys

 

I'd buy it but I probably wouldn't have a clue what Noel was on about most of the time lol.