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There is a thread started by a new member claiming to have a TT supra running 12's. Anyways were having a little argument on the subject of turbos. I know a lot but not everything about turbos so I like some other opinions.

Heres how the story goes Mr.Supra is driving to work and sees he spots a 2003 Mustang GT picking on a stock looking civic (why i don't know) anyways the Gt is revving at the civic and when the civic revs back he heres the best sounding blow off valve ever.

Now i've riden and driven many turbo'd cars. And to the best of my knowledge when the car is in neutral (or the clutch pedal is depressed) you can rev all you want and no boost will be created because there is no load put on the engine. Now since i haven't riden in or driven a turbo'd D17 civic i am asking the owners to answer this question. Is boost created when you rev the car in neutral???

Heres a link if you'd like to respond on the thread Click Click

 
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ok WANNA KNOW WHY u dont hear the BOV? cause u have a shitty one. honestly... not tryin to sound like a ****.. but its true... i have the Turbo XS one .... u dont hear crap at idle... but if i went out and bought a Turbo XS Type H RFL BOV u would here it all the time... WHY? cause they have horns on them that create crazy PSSSSSSH.. even at IDLE... ur BOV IS blowing off at idle u just cant hear it ... i promise you ... reason why u herd the civic is cause he had a loud BOV. ..

 
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if some one rev's in neutral and is bosting u will hear the BOV.

 
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man..

who told you that when you REV you are NOT loading the engine? THEN WTF are you REVING?

 
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Correction, i don't have a blow off valve. But thats not the point, a blow off valve releases pressurized air (boost) when you let off the gas. Now every turbo'd car ive driven or riden in WILL NOT create boost when you rev in neutral. The vaccuum will decrease but at 0 mm/Hg (no vaccuum but no boost) it stops. It doesn't create boost. There fore no pressurized air can be released through the blow off valve. BTW i was looking at getting a BOV and am torn between the TurboXS Type H and S, whats your opinion of the type-h?

Yes, but if no boost is created then no BOV sound will be made

An engine was made to do work, now when you but the car in neutral and rev no work is being done, the engine is creating power but none of it is being used (actually only a small amount is being used to overcome friction). When a car is moving, doing a burnout or is on a dyno, the engine is moving something other than itself and thus work is being done.

 
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ANYWAY, your are making the engine do exahust gases.. that makes the turbine spin.. no matter if it is moving the tranny or not.

 
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it will spin enough to remove a little vacuum...but not enough to create pressure according to what the fellow above says

 
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I have the Turbo XS that came with the sf kit when i rev in neutral u could hear my bov

 
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hmm maybe its just my setup, hmmmmmm

 
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Driving my friend's GSX, you can floor it for a brief second and it swiftly revs, making 9psi according to his gauge. At WOT and full load he makes 16psi. This is with a K&N Intake, Apexi N1 Exhaust and HKS Super Sequential Blow off valve. You can hear the BOV fine while being in neutral - just not as loud as WOT with a full load.

 
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Yes, if the bov is audible while driving under boost, it can be audible in neutral if you are revving. Think of how a turbo works. Exhaust gases pass through the turbo to make it spool. When it spools, it creates pressure through the intake piping. Once you let off of the throttle, the pressure is released, whether in gear or not. The only place for the pressure to go is through the bov. The higher you rev (higher rpm's equal higher pressure levels) the more boost you can make. That is why boosted vehicles loose traction if you launch in boost. You rev the engine so the turbo creates that pressure then when you hit it, you are already into the boost.

 
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look at it this way......

even though you arent making any "boost" in the manifold, you are still moving a lot of air. So what do you think happens when you all of a sudden close off the passage the air is going to? It increases in pressure.

To test my theory, i hooked up a boost guage to the actual intercooler pipes. I then revved the engine several times to get the turbo spinning. Every time i let off the throttle, the boost guage shot to about 25 psi. That is how much pressure is inside your intercooler pipeswhen you just rev it. When you are actually driving, you can see much much more than that.

AS for the turbo xs-s not going off when just fre revving it, you must not be doing it right. When i installed the 2 kits here at the shop (that used the turbo xs BOV) i would test them by revving them. You cant just rev it to 3000 rpm and let off.... You have to rev it to 5500-6500 and let it go to 4000 then do it again, and again. The turbo has to spin up in order to start moving air. And that wont happen if you only do it once.

I do love my RFL though!!

 
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meaning the turbo has to spool and is in full use like around 4500 thats probably why you didn't hear it.

 
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^^ good point. when most ppl rev they dont rev over say 3000-4000rpm. Just enough to get the point across. And from what ive been reading about the SF kits, they dont make full boost until they hit 4-4.5k RPM. So unless you are really throwing your RPM's up when u rev in neutral the BOV isnt going to be as loud as it would be racing under full boost.

 
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Mine is spooled by 3200 rpm and it's the sf t3/super 60.

 
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but still unless you are throwing your RPM over 3200 you arent gonna be getting a full BOV "release" if you will, as opposed to racing.