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:

LOL at this thread!!

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!

 

thank you thats what i wa trying to explain..

thank you thats what i wa trying to explain..

 

You were trying to say the opposite?! lol

make yer mind up Mikael, lol. do you think BOVs will make a car go faster or slower!! :1eye:

 

EDIT: ^ ditto

My 2 pence worth.....

 

.....I don't care! I may have missed the point of the original thread but here's my opinion. I don't care for "chavtastic" loud BOVs - no point! I'm 40 in a few days, not 18 so I don't need to announce my turbo charged presence with a Tisssssh sound.....

 

Secondly Nissan spent time and money developing the engine set-up and, for most people, the recircs work just fine. I reckon I'll keep them and if they ever go wrong, I'll just replace them like for like.

 

Richard:cool3:

sorry gents .. faster - slower .. what i experienced is that when no bovs car accelerates through gear change bit faster then with them ..

..

Edited February 8, 201015 yr by mikael jackson

You were trying to say the opposite?! lol

 

:rofl: :rofl: :rofl:

sorry gents .. faster - slower .. what i experienced is that when no bovs car accelerates bit faster then with them ..

..

 

LOL! what timing gear did you use for this as the tests I have seen had a recorded difference in favour of using recircs!

 

Or did it just "feel" quicker. A bit like the lad at my work who fitted a max power air filter to his fiesta?! :whistling:

LOL! what timing gear did you use for this as the tests I have seen had a recorded difference in favour of using recircs!

 

Or did it just "feel" quicker. A bit like the lad at my work who fitted a max power air filter to his fiesta?! :whistling:

 

will prove my point soon )) leave it with me pls ..

...yawn... No one cares!

:death:

Hope this helps people to understand what BOV's and re-circulating valve's do.

 

Should I get blow-off valves or not? Do they really help?

 

The Great Blow Off Valve Debate:

First of all to understand the functionality and benefits of a blow off valve you have to have a complete understanding of how a turbocharger works. If you don't understand the basic mechanics of a turbocharger you can forget about trying to understand the benefits of a blow off valve. If you do understand the mechanics of a turbocharger, read on...

 

An Explanation of Compressor Surge:

 

The turbine in a turbocharger in its ideal mode is spinning at a very high rate and therefore generating lots of pressurized air that is fed into the OPEN (wide open throttle) intake manifold which translates into more power, but what happens when you take your foot off the gas when shifting between gears? The turbine in the turbo is still spinning at a high rate but now you've taken your foot off the gas and the intake manifold is CLOSED. Now the turbine spinning at a high rate and is trying to push out all this compressed air but since the manifold is closed, that compressed air has nowhere to go. What happens next is that the turbine slows down because of this pressure build-up between the compressor and the intake manifold. Since the pressurized air can't go forward into the engine it heads the wrong way back towards the turbo where it slows the turbine down (compressor surge). After you shift gears and you step on the gas again you want to have the turbine spinning fast so that its producing boost but since you took your foot off the gas and caused compressor surge, it slowed down, so you have to wait for the turbine to "spool up" (spin fast) again. This delay waiting for turbines to spool up is what causes some of the performance degradation that were trying to avoid.

 

The Blow off Valve:

 

What if we could figure out a way of eliminating compressor surge? Then the turbine in our turbo would have a much easier time keeping its speed up and we wouldn't get the lag in power waiting for the turbine to spool up between shifts. Enter the Blow off valve. At that moment in time between shifts when compressor surge is slowing the turbine down we'll just poke a hole in the tube running between the turbo and the intake manifold and let all that air leak out somewhere. The turbine can keep spinning fast & we'll have lots of boost when we step on the gas again. We'll also want to plug up that hole we made because we have a purpose for that pressurized air now, where as when we let off the gas we did not. The blow off valve is a gizmo that's constantly opening and closing giving you that cool sneeze sound when it "pokes" that hole in the intake manifold tube to keep the turbine spinning fast. We've eliminated compressor surge but we did confuse the engine just a bit since the ECU already told the injectors to issue fuel to be used for the air that we've now thrown out. Other than that sounds like a good idea right? so what if were running a bit rich for a moment, no big deal. Before you place your order read on...

 

The Re-circulating Valve... a better idea:

 

How about instead of poking a hole in the turbo to intake manifold tube and just letting the air leak out wherever it wants to, we could direct that pressurized air somewhere else where we could hold on to it until we need it again? The intake side of the compressor housing (between the intercooler and the turbo) would be a good place wouldn't it? that way we wouldn't slow the turbine down and we would have that pressurized air that would have otherwise been thrown out, ready in a really good place when we need it. On top of that eve got still got the correct air/fuel ratio going since we're not throwing and air out, just moving it from one place to another within the intake system. Instead of having to suck in air for the turbo to pressurize, we've got some pressurized air with the correct fuel amount already waiting. Now we've got all the benefits of a blow off valve and then some. That's a re-circulating valve. Let's all order re-circulating valves then and skip the blow off valves completely. They're probably gonna cost a bit more than the blow off valves since they work a little better right? Now the big surprise... Re-circulating valves were engineered into the design of your 90+ twin turbo z on the drawing board... you've already got them...

 

In conclusion: You could always disconnect your stock re-circulating valves (which you have to do to install blow off valves) and spend 500-600 bucks for blow off valves and what will you get? better performance? No, basically you do get the cool sneeze sound though you aren't going to be any faster than you were before (but you might sound like you are). If by chance you are running boost levels that exceed the airflow capacity of the re-circulating valves (~600+ hp?) then you've probably spent enough money and have enough experience and knowledge to know where the benefit reverses. For the rest of you who weren't in the know, I hope I've helped you save some time and money...

 

Paul

will prove my point soon )) leave it with me pls ..

 

In mikael's defence i did read an artical in a chav/max power type of mag which conducted 0-60 tests on stock recirc, atmospheric bov, and just blanking it off and with nothing fitted(blanked off) the fastest 0-60 time was recorded, but then again it was only a slight fraction faster not enough to make me want to do that to a vg30dett.

In mikael's defence i did read an artical in a chav/max power type of mag which conducted 0-60 tests on stock recirc, atmospheric bov, and just blanking it off and with nothing fitted(blanked off) the fastest 0-60 time was recorded, but then again it was only a slight fraction faster not enough to make me want to do that to a vg30dett.

 

iam still using bovs on daily basis but not when out racing ..

Well I've probs done about 1500-2000 miles with a good dose of hard driving since I performed the modification... not one single problem yet, and I don't get any of the pops/bangs out the exhaust associated with running atmospherics :) Also it sounds sweet!

oh edit- before anyone comes back, I didn't do it for any performance gain (as that would be pretty ridiculous), I did it for the noise - exactly the same reason people use atmos jobs :)

My 2 pence worth.....

 

.....I don't care! I may have missed the point of the original thread but here's my opinion. I don't care for "chavtastic" loud BOVs - no point! I'm 40 in a few days, not 18 so I don't need to announce my turbo charged presence with a Tisssssh sound.....

 

Secondly Nissan spent time and money developing the engine set-up and, for most people, the recircs work just fine. I reckon I'll keep them and if they ever go wrong, I'll just replace them like for like.

 

Richard:cool3:

 

:bow:

:asshole:No BOV or Recirc = eventual Turbo BOOOOOOOOM! :asshole: Richard Smith said it all.

lol mate, turbo's dont last forever anyway they are a stressed piece of equipment - they would be due a refurb at 100k or so, if having cool sounds only results in 10k less before rebuild it's of no fuss to me :) I'll pop up a vid of the sound it makes in a few days!

ps. running bovless is NO worse than running atmos bov's, one shags cats, one shags turbos.. they are both done for the noise regardless of how many hundreds of pounds one spends on jdm tyte valves. Also having had cars with atmos bov's, this drives smoother and better than having the pressure dumped. What's the big deal? If you're happy running recircs then thats brill - I sadly need simple things to amuse me and I love tinkering :p - what I did find hilarious though was proclamations that the VG engine was completely different to any other turbo engine and shouldnt be tarred with the same brush, utter cobswobble. :)

:asshole:No BOV or Recirc = eventual Turbo BOOOOOOOOM! :asshole: Richard Smith said it all.

 

non sense!

You can hear the sound at the beginning of this vid of what flutterdump/bovless sounds like!

Edited April 13, 201015 yr by ck300z
link removed as not showing correctly

lol what you cannot embed vids here? ok

 

http://www.youtube.com/watch?v=v2EIDyWExgI&hl=en_US&fs=1&