Compressor Surge, good or bad Options

[Tigawoods]

http://www.youtube.com/watch?v=LZUbo_mNDZM

ive read many debates of whether or not this is good for the turbo.
i first heard it on the ken nomuras blitz skyline and thought it was the blitz bov. i was wrong haha

i love the sound to death

[x_itchy_b_x]

well its bad for the turbo and performance.

slows the turbo down between shifts = more lag
eventually harms the bearings = oil leaks and turbo failure

not really anything good about it other than the sound, thats why higher end turbos are made with anti-surge housings, also to avoid spool up surge where the turbo trys to feed more air into the engine than it can take. pretty much same process as compressor surge just at different time.

[alltracman78]

Yeah, who the hell told you it was good?!!!

It sounds kind of nifty, but that's it.

[jesterwr217]

compressor surge=bent or broken shaft

[lagos]

If loving you is wrong.... I don't want to be right.

[Cuts_the_Pilot]

a little bit is fine, much like those s13's on those vids is bad.

if you have a bov, and want flutter (surge) wind the bov reasonably tight, so it only goes off at say 3 psi and higher, but below that you get combined flutter and bov, you dont wanna sound like the ghey et pulsar and other shi!t little ricer cars that have bov going off every 5 seconds.

This post has been edited by Cuts_the_Pilot: Apr 22, 2008 - 9:58 PM

[Insanity-74]

My car has been making that noise now for two years or more...more so than on that video.....have had no problems with the turbo at all and I`m running 20psi...although I am running the airfilter more or less directly on the turbo which dosnt do anything to deaden the sound.

[x_itchy_b_x]

my bov flutters LONG after the bov goes off. only because the turbo is still spinning for so long and still pushing alot of air sounds like a supra.

[Tigawoods]

i looked it up earlier and there was a debate on the topic. i love the sound

[lagos]

The basic idea is that its bad. Thats why you are supposed to install a blow off valve. In reality, it will take a long time before you do any damage to your turbo because of it.

[Rayme]

I thought about it...

under normal operation, you have the exhaust side of the turbo pushing the turbing, and on the other side, you have the impeller compressing air. That normal condition alone apply a twisting force to the shaft.

During "surge" you have the impeller being slowed down by air, and the exhaust side somewhat spinning freely because of lack of throttle plate opening..that also apply a twisting force to the shaft.

So..is it really that bad? Certainly for performance as it slows the turbo when the throttle plate closes but damage the turbo?
The 5th gen all-trac has no bypass valve, and alot more cars (mostly older ones) and turbos have been around for decades.

Myself I don't think compressor surge is all what it's cracked up to be. All turbos are going to die before the engines itself.

This post has been edited by Rayme: Apr 23, 2008 - 10:09 AM

[x_itchy_b_x]

over time, yes. i don't know the "time" though. kinda like the rapture.
air is thicker than you think.

[mrgt4]

i get massively loud compressor surge when i let off the throttle slowly, not done mine any harm so far... but only been running it as said for around 2k miles

[alltracman78]

I thought about it...

under normal operation, you have the exhaust side of the turbo pushing the turbing, and on the other side, you have the impeller compressing air. That normal condition alone apply a twisting force to the shaft.

During "surge" you have the impeller being slowed down by air, and the exhaust side somewhat spinning freely because of lack of throttle plate opening..that also apply a twisting force to the shaft.

So..is it really that bad? Certainly for performance as it slows the turbo when the throttle plate closes but damage the turbo?
The 5th gen all-trac has no bypass valve, and alot more cars (mostly older ones) and turbos have been around for decades.

Myself I don't think compressor surge is all what it's cracked up to be. All turbos are going to die before the engines itself.

Twisting isn't the big problem, that force is applied in the same direction, which isn't as bad.

You have the compressor spinning at somewhere near 100,000 RPMs [under high boost], when you have surge you have pressurized air shooting back at the compressor blades, trying to force them in the opposite direction.
This fatigues the compressor blades.
It works similar to how rod bolts stretch at higher RPMs, though that is a much more extreme example.

It's not going to break the turbo the first time it happens, or the tenth, or probably the hundredth, but it most definitely will weaken the turbo to some extent. How much depends on how bad the surge is and how often you do it.

It's never a good thing.

[pitcelica]

My car is doing this sound. But I have a Greddy type-RS installed. How can it happen? Can I test my BOV? If yes, how can I do that? Thanks