Went Snowoarding over he weekend.... got compressor surge around 3500ft
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"Compressor Surge" doesn't refer to the car itself surging. I'm pretty sure what you experienced was just a change in tuning caused by the change in air density.
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~Justin~ '92 TSi FWD, '93 TSi AWD, '97 Eclipse GS
"Compressor Surge" doesn't refer to the car itself surging. I'm pretty sure what you experienced was just a change in tuning caused by the change in air density.
No this is for sure compressor surge,
it makes that chipmonk sound lol and when the turbo is surging it is causing the car to buck
Compressor surge occurs under boost- NOT under vacuum. The car in that vid simply has too much blow off valve tension for the low (7 psi) boost they are running. What you are hearing is blow off valve flutter- the airflow is trying to force it's way out of the valve, but the high spring tension is not letting it. This is basically rendering the function of the blow off valve to be useless by keeping too much pressure in the piping, and will eventually damage the turbo.
My buddy's Powerstroke Diesel used to surge a lot when he would lug the engine down in a higher gear. The turbo would be making full boost (somewhere around 28-30psi) at an RPM where the engine couldn't make use of the airflow the turbo is producing. The pressurized air would back up in the piping, and you would hear a sound through the intake that sounded much like the blow off valve on the car in that video, only it would happen under boost, like this:
...and this vid, of a Skyline with horrible surge:
If what you're hearing is blow off valve flutter, your valve's tension is simply too strong for your boost level.
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~Justin~ '92 TSi FWD, '93 TSi AWD, '97 Eclipse GS
What did your boost gauge do when you left off the gas? Anything out of the normal as in where the needle drops to?
A lot of the time, comp surge like that is from the BOV spring being too stiff. Seeing as it's a 1G BOV, it could be just a little too stiff since it is crushed. Please, do try using an uncrushed BOV next time and see what happens. If it was a Greddy or a HKS there shouldn't be any kind of problem because the Greddy can be adjusted for spring stiffness and the HKS is a different setup.
My question: Can someone do a quick explanation on why an altitude change, as well as a idle Vac change, would effect spring stiffness. I can grasp the gist of it but not in terms that would make sense to other people .
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Project Workhorse: New Turbo in the Works
It is compressor surge. Without the valve opening you are getting 0 flow at high pressure levels, which is always past the surge line. Surge can, and does, occur under vacuum.
Even with it being crushed somewhat, it shouldn't do that. What boost levels did you try it at?
BoostFrenzy, it's that the amount of vacuum trying to overcome the spring tension is less, so less spring tension is needed to get a decent blow off point.
When I had C.S, I took of my 1g BOV and check if something was blocking it. I found some electrical tape that covered 3/4 of the flange hole.
Check and see if you have something blocking it or even check the vacuum line from your intake manifold to your BOV is still there or if its kinked and what not.
P.S: In one of your vids, I hear all that remains in the background..keekee!
well it happened most of the time when i was in 5th gear, i would build a little boost to keep speed up hill and then when i let off it would surge,
i just bought a uncrushed 1g bov so we will see if that helps i am hoping it does.
Quote:
Originally Posted by meliketoball
When I had C.S, I took of my 1g BOV and check if something was blocking it. I found some electrical tape that covered 3/4 of the flange hole.
Check and see if you have something blocking it or even check the vacuum line from your intake manifold to your BOV is still there or if its kinked and what not.
P.S: In one of your vids, I hear all that remains in the background..keekee!
I agree with the other member, the video of the car suppossedly "compressor surging" with the hood off, was indeed not "compressor surge". That was blow of valve flutter, many people confuse the two. Easy way to tell the difference......BOV flutter occurs when letting off of the throttle, which lets the valve let off and you hear the noise. Compressor surge occurs under load, such as open throttle and accelerating.
I agree with the other member, the video of the car suppossedly "compressor surging" with the hood off, was indeed not "compressor surge". That was blow of valve flutter, many people confuse the two. Easy way to tell the difference......BOV flutter occurs when letting off of the throttle, which lets the valve let off and you hear the noise. Compressor surge occurs under load, such as open throttle and accelerating.
Um the very first video is compressor surge. Its caused by the BOV being to tight and not letting all the compressed air and and forcing it back into the housing.
Either way both are bad for Turbos.
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91 tsi 60k on the clock.
Um the very first video is compressor surge. Its caused by the BOV being to tight and not letting all the compressed air and and forcing it back into the housing.
Either way both are bad for Turbos.
Very true, my bad on that one. I just recently learned that the can be two different types of compressor surge. But the only difference is the bov fluttering and doing what you said causes one. And your engine not being able to use all the air the turbo it putting out, so it backs up into the housing would be the other one. That definitely helped though, thanks. Plus I agree 100% on it being bad for a turbo
I personally don't consider it "surge" unless it's happening under load, although a poorly-functioning BOV will cause air to back up in the piping under vacuum in a way similar to surge happening under load....there's just nothing continually driving the compressor wheel when it happens under vacuum.
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~Justin~ '92 TSi FWD, '93 TSi AWD, '97 Eclipse GS
I'm trying to fine tune my bov I'm afraid of getting compressor surge. I have a cheap ebay turboxs knock off. It has a weak spring in it so it has 6 washers in it...If i take all washers out the car will die after i let off the gas after full throttle. But I'm afraid if I have to many in it I will get compressor surge. As it is right now with 6 washers in it it holds all 15 psi I have, when im at a low rpm like 1500rpm's at wot and i let off the gas it will still flutter at that low of an rpm. Can someone guide me through this?
Sure...scrap the knockoff RFL and get a 1G valve, then hook it up to recirculate as it's intended. No tuning required, no need to worry about the car stalling between shifts or surging at low boost.
You own a knockoff of the RFL which, even in Genuine form, is probably the worst BOV on the planet. It's designed for Honda guys who are running 6psi to make some noise so they think their car is fast.
Using a BOV that is held in place by three set screws is asking for trouble.
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~Justin~ '92 TSi FWD, '93 TSi AWD, '97 Eclipse GS
Sure...scrap the knockoff RFL and get a 1G valve, then hook it up to recirculate as it's intended. No tuning required, no need to worry about the car stalling between shifts or surging at low boost.
You own a knockoff of the RFL which, even in Genuine form, is probably the worst BOV on the planet. It's designed for Honda guys who are running 6psi to make some noise so they think their car is fast.
Using a BOV that is held in place by three set screws is asking for trouble.
Compressor surge occurs under boost- NOT under vacuum. The car in that vid simply has too much blow off valve tension for the low (7 psi) boost they are running. What you are hearing is blow off valve flutter- the airflow is trying to force it's way out of the valve, but the high spring tension is not letting it. This is basically rendering the function of the blow off valve to be useless by keeping too much pressure in the piping, and will eventually damage the turbo.
My buddy's Powerstroke Diesel used to surge a lot when he would lug the engine down in a higher gear. The turbo would be making full boost (somewhere around 28-30psi) at an RPM where the engine couldn't make use of the airflow the turbo is producing. The pressurized air would back up in the piping, and you would hear a sound through the intake that sounded much like the blow off valve on the car in that video, only it would happen under boost, like this:
...and this vid, of a Skyline with horrible surge:
If what you're hearing is blow off valve flutter, your valve's tension is simply too strong for your boost level.
my car sounds just like that SR20 if I boost less than 5psi, and if your listening under the hood and rev the car up, the flutter sound is coming from the intake pipe and air filter area, not from the UIC pipe, so wouldnt that mean the air is blowing back through the turbo, wich is generally not good? and isn't that a form of compressor surge? BOV is not recuirc'd either and there is no sound from there at all when it happens. Anything over 5 psi functions as normal, so basicaly reving in nuetral does the flutter best.
Isn't the video with the skyline Turbo Stall? Turbo stall usually is an imbalance of psi between compressor side and turbine side and when when the force in turbine side isnt strong enough to drive the comp side, it stalls out making a "surging" sound
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----------Gary, a proud owner of 97 GS-T
Yeah that's turbo stall, the sr20 was a case of the bov not working and the "ts ts ts ts" sound was air going back out of the turbo fins while moving in an opposite direction.
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