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Appears I need another bov...have incurable compressor surge/flutter
I have an AA kit with the turbosmart bov. I have battled this surge since the beginning, but the car has been in surgery for some time, as I'm fabbing over fenders for the car. In preparation to be back on the street, I recalled this surging issue. At light to mid throttle the bov works cleanly...no flutter, but at higher rpm/boost it flutters hard (or should I say my supercharger is fluttering/getting its *** beat). Being this bov is shipped with the kit, I'd imagine it flows enough CFM to work with the setup, so I was in denial that the bov could be the issue.
I've removed it, reduced spring tension, checked function, ensured the vac line isn't collapsing and its all fine. It simply appears the bov doesn't bypass enough air. Also, having limited access on the cold side, I've considered installing a hot side bov location to shorten the vacuum line run.
Has anyone else experienced this with the AA kits? I have an 02Z, 580whp running about 8psi with longtubes. I see some other kits come with the Tial Q, which is a monster by comparison to this turbosmart. Just curious because I hear supercharged Corvettes on Youtube all fluttering like mad, but the owners appear to not know any better.
I assume Tial makes a supercharger bov that opens at part throttle or very low vacuum? Anyone offer me a deal or have one for sale with the alum flange so I can TIG that puppy on?
I don't have any experience with those kits, but I've always ran 2 knockoff TiAL BOVs in my setups just to be safe. At $100 shipped for 2, it's still cheaper than 1 real BOV, and they work awesome. Lots of my friends run them too. PM me if you want a link.
I have an AA kit with the turbosmart bov. I have battled this surge since the beginning, but the car has been in surgery for some time, as I'm fabbing over fenders for the car. In preparation to be back on the street, I recalled this surging issue. At light to mid throttle the bov works cleanly...no flutter, but at higher rpm/boost it flutters hard (or should I say my supercharger is fluttering/getting its *** beat). Being this bov is shipped with the kit, I'd imagine it flows enough CFM to work with the setup, so I was in denial that the bov could be the issue.
I've removed it, reduced spring tension, checked function, ensured the vac line isn't collapsing and its all fine. It simply appears the bov doesn't bypass enough air. Also, having limited access on the cold side, I've considered installing a hot side bov location to shorten the vacuum line run.
Has anyone else experienced this with the AA kits? I have an 02Z, 580whp running about 8psi with longtubes. I see some other kits come with the Tial Q, which is a monster by comparison to this turbosmart. Just curious because I hear supercharged Corvettes on Youtube all fluttering like mad, but the owners appear to not know any better.
I assume Tial makes a supercharger bov that opens at part throttle or very low vacuum? Anyone offer me a deal or have one for sale with the alum flange so I can TIG that puppy on?
Your post is a little unclear.
Are you saying the fluttering occurs at high rpm/boost when your foot is on the throttle, or when you lift off ?
I don't have any experience with those kits, but I've always ran 2 knockoff TiAL BOVs in my setups just to be safe. At $100 shipped for 2, it's still cheaper than 1 real BOV, and they work awesome. Lots of my friends run them too. PM me if you want a link.
Interesting...lol. Can't get surge with that setup...lol
Originally Posted by jimbos'ss
I run a synapse synchronic bov. It has the fastest reaction to vacuum and is open during vacuum to prevent surge.
I've had mixed feelings about synapse products. I was with them from the beginning when they won best new product awards at SEMA. I've run every product they have. I pushed a lot of the wastegates out of my shop in the 2007/8 era (iirc the years). I like their stuff but I always had a hard time leaving Tial which was simply proven. Plus the Synapse and Tial guys got in a tussle in the beginning...kind of turned a lot of us off. I can legitimately say their push pull stuff is definitely worth looking at...and who doesn't like an adjustable wastegate with no spring changes but...ehhh...idk.
Originally Posted by stevieturbo
Your post is a little unclear.
Are you saying the fluttering occurs at high rpm/boost when your foot is on the throttle, or when you lift off ?
Are you 100% sure it is opening fully ?
Where is the BOV located ?
Off throttle...throttle shut...ch ch ch ch ch ch ch ch....surge. At part throttle let offs and blow offs below like 5psi it blows clean...above that is ch ch ch chas. Just wonder why I hear so many setups doing this but it doesn't get much attention is all.
BOV location is in the wheel well like all AA kits...as I said...I'm not a fan. The AA setup is nice, but the piping, location of the bov and some of the quirks are garbage. I am going to redesign most of the kit's piping/intercooling solution soon. As stated, I'd like to blow off the hot side instead of cold...but that's wishful thinking that leads to remote location. I might just do the twins in the cold pipe right at the tb...why not.
Yeah, as I said...I had arrived at that conclusion, I guess I was just more curious as to why it seems I've heard so many AA cars fluttering like mad online. I suppose it'll really come down to a compressor map for this head unit and some cfm capability info on the turbosmart valve but...I'm surprised it can't handle the cfm.
As stated, I have removed it, taken the filter off, disassembled it, tested it...it works. I've built custom forced induction systems for about 10+ years, and tuned EMS via my in house chassis dyno up until 2010. I'm not unfamiliar with FI by any means. Lots of guys who'd buy the Ebay bov's...they'd ship with dual springs and wouldnt' even open...so they'd surge hard. I've seen poorly machines valves, bad vacuum lines collapsiing under vacuum, etc. I guess I just found it hard to believe this has never really come up as an issue. I trusted the kits design, so I repeatedly convinced myself it must be a defective valve, but I've found no evidence of that.
In the end...yes, I'm going to replace it. Just kind of surprised I suppose you could say.
My A&A v3 si w/3.6 pulley does the same thing you're describing. Anyone come up with something other than I need a bigger blow off valve? I'd be a little disappointed if I had to blow money on a new BOV when this one is supplied in a kit that should just work.
If its a turbosmart raceport BOV it should be more than big enough. One thing to check is the vacuum line. Make sure it is big enough and as short a routing as possible. I was getting fluttering and found my line was damaged. A new line fixed it up.
The line has to go to the complete opposite corner of the engine bay, front passenger under the headlight clear over to the brake booster. That was my understanding as per the AA instructions, even had to cut some off the hose they sent. I'll have to check if any of the cables ties I used are too tight. I also have the cap on the BOV backed out to the black line.
Is there somewhere else I should be pulling vacuum other than the brake booster line?
The line has to go to the complete opposite corner of the engine bay, front passenger under the headlight clear over to the brake booster. That was my understanding as per the AA instructions, even had to cut some off the hose they sent. I'll have to check if any of the cables ties I used are too tight. I also have the cap on the BOV backed out to the black line.
Is there somewhere else I should be pulling vacuum other than the brake booster line?
It should be good from the brake booster. Just make sure its not pinched or kinked anywhere. That's what I found even though I thought I was careful running it.
Yeah, as I said...I had arrived at that conclusion, I guess I was just more curious as to why it seems I've heard so many AA cars fluttering like mad online. I suppose it'll really come down to a compressor map for this head unit and some cfm capability info on the turbosmart valve but...I'm surprised it can't handle the cfm.
As stated, I have removed it, taken the filter off, disassembled it, tested it...it works. I've built custom forced induction systems for about 10+ years, and tuned EMS via my in house chassis dyno up until 2010. I'm not unfamiliar with FI by any means. Lots of guys who'd buy the Ebay bov's...they'd ship with dual springs and wouldnt' even open...so they'd surge hard. I've seen poorly machines valves, bad vacuum lines collapsiing under vacuum, etc. I guess I just found it hard to believe this has never really come up as an issue. I trusted the kits design, so I repeatedly convinced myself it must be a defective valve, but I've found no evidence of that.
In the end...yes, I'm going to replace it. Just kind of surprised I suppose you could say.
Check the block where your vacuum line is hooked up, if its sharing with anything it will not function correctly. I moved mine to its own port and no issues after that. That was with the stock bov at 700+. I run a tial q now.
The line has to go to the complete opposite corner of the engine bay, front passenger under the headlight clear over to the brake booster. That was my understanding as per the AA instructions, even had to cut some off the hose they sent. I'll have to check if any of the cables ties I used are too tight. I also have the cap on the BOV backed out to the black line.
Is there somewhere else I should be pulling vacuum other than the brake booster line?
Try running a 3/8 line from behind the passenger side throttle body directly to your BOV.
I've seen issues where when letting off the throttle, there's a surge and then it goes away after a second, due to a delayed response. Shortening the line and dedicating it to the BOV solved the issue each time in those cases. If after you've done that, you've still got an issue, I would have to conclude it's too small.
Try running a 3/8 line from behind the passenger side throttle body directly to your BOV.
I've seen issues where when letting off the throttle, there's a surge and then it goes away after a second, due to a delayed response. Shortening the line and dedicating it to the BOV solved the issue each time in those cases. If after you've done that, you've still got an issue, I would have to conclude it's too small.
I agree. Easiest way to check if its the line.... short direct new hose.
I just Tee'd into the brake booster like as per the A&A instructions. The car is otherwise stock so there shouldn't be anything sharing it but I'll make sure.
I also Tee'd into the line running to the BOV to run my boost gauge line. Could this be causing my issues? I'll disconnect it when I get home later tonight and see if it helps.
Try running a 3/8 line from behind the passenger side throttle body directly to your BOV.
I've seen issues where when letting off the throttle, there's a surge and then it goes away after a second, due to a delayed response. Shortening the line and dedicating it to the BOV solved the issue each time in those cases. If after you've done that, you've still got an issue, I would have to conclude it's too small.
I'll have to give this a try when I get home as well. Thanks for the replies guys.
So i decided to just take a video of the valve in action after cleaning and oiling it to no avail. Also removed the boost gauge from the equation with no positive results.
Looks to me like the valve is operating how it should. Completely open and still getting surge. Talked to Andy and he recommended trying a bigger valve. Hes gonna send one out for the difference. Ill post up the results when it gets here.
Last edited by StripedZebra; 02-26-2015 at 08:34 PM.
02-15-2015, 01:24 PM
Appears I need another bov...have incurable compressor surge/flutter
nice work 
