Compressor Surge

[Kevin 1G Drummer]

I found a pretty good video on Youtube of what compressor surge is.

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[JET]

Yours is just BOV flutter, it happens after you let off the gas, so it can't be compressor surge. BOV flutter is normal and should happen when there isn't a ton of air to blow off.

[rocket2g]

maybe u should stop modding dsm's, doesnt seem to be ur forte

[jhaan_dude]

hey rocket, how bout you shut up! hes asking for help, not a flaming!

[lucasoil4u]

the 1g blowoff valve is amazing! sounds like your oil feed line is messed up.

[Tachyon]

So just for the record, the fluttering noise in this video is not compressor surge?


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Reason I ask is because my 14b setup was making that exact same noise as the one in this video (I have a crushed to maximum 1g bov) and I wanted to make sure that the noise I was hearing was not surge.

[Febo]

That half sounds like what my starion was doing before I switched the vac line set up on my bov. I know my sound was alot more turkey gobble like and was a result of my bov not cracking open. Now with my two line vac setup on my bov its just solid woosh. (HKS Racing BOV)

[Shane@DBPerformance]

Real compressor surge happens during spoolup/high boost, not when you let off of the gas. The surge noise in that video is caused by the BOV not letting all the air out in 1 smooth blow. Too tight of a BOV opening and closing over and over might not be the best thing for the turbo, if the air is actually backing up that far, but it isn't real compressor surge and the kind that ported/anit-surge compressor covers are for. People call this noise BOV surge/flutter or "internet surge" because most people on the internet don't know what real compressor surge actually is.

Compressor surge happens when the turbo is flowing A LOT of air and the motor can't actually ingest all that air. A turbo makes boost inside the compressor housing, it isn't like a roots blower/positive displacement blower that works by stacking air in the intake manifold. When air starts stacking up on a turbo car and gets stacked all the way back to the compressor housing, then surge happens. The stacked air starts stopping the spinning compressor wheel or trys to turn it backwards. When you try to stop a compressor wheel going 80,000RPMs, bad things happen.

Compressor surge is common on 2.0l motors with the 61mm turbos. The 2.0l spools the turbo to high boost levels too fast and makes more air than the motor can take in. You can try to get rid of surge by going to a larger exhaust housing/wheel, to make the turbo spool up slower. You can get bigger cams, bigger intake manifold, port the head, to try to be able to take in more air. You can goto a bigger displacement motor that can take in more air each stroke.

A ported shroud/anti-surge cover has passage ways for the backing up air to come back out the front of compressor housing and into your intake pipe to try to avoid reverse flow pressure waves from causing surge.

Basically you can't have your cake and eat it too. If you spool a big turbo too fast you get surge.

[Febo]

So what your saying is, that the people running the 14b's are having bov problems that causes the bov to either not open all the way or not at all, and the air is then stacking on your throttle plate and backing up into the turbo causing a "surge like" symptom, but is really not related to the turbo at all, instead is related to their bov/bpv. Makes sense. Stop crushing your bov on a 14b turbo you cant even really push that much pressure with a 14b to need that.

[iceminion]

Goatblower: Thank you for the proper definition of compressor surge, how about a proper definition for the symptoms I am describing? does BOV surge work? anyone?

This happens, so we have to have established terminology.

And in case anyone is wondering, when the BOV flutters, it does shorten the life of the turbo, I have several examples myself :(