Off Throttel Surge

Is there any cure for it other then running a second blow off vaulve? It can not be good for the turbo? Just wondering what every one else is doing?

I cut 4 coils off my spring to lower the cracking pressure on the BOV. Now it pops with just the slightest difference in throttle position (it is still closed at idle). I am using the Turbo XS BOV. My brother put a two stage BOV on his APEX and it works well stock, but it cost 4 times the money.

this is the bov i went to only use one on my vector up to 17-18 pounds boost have no throttle chop at all as soon as you get out of the throttle just a tiny bit you can here it blowing off no matter how much you get out of the throttle.it cost less than half of what the hks cost & the guys at street import said its built in the same factory.its got a funny blow off sound but works great for me.http://cgi.ebay.com/ebaymotors/Monza-SS ... 5080QQrdZ1 oh how do you like your holz suspention so far rip.

sled

How did you mount the blow off valve? do you have a pic?Rip sold his holtz he is going for a m10

I have issue with my SCApex at 1/8-1/4 throttle... It surges/flutters like crazy because it is building 4-12lbs boost (measured at intercooler) in those partial throttle high-rpm positions... The engine is not using all the boost created so it's forced back out the compressor wheel... Very annoying !!! and very hard on equipment I imagine...

I recently bought a TurboXS Type S BOV trying to resolve this issue... Had a piece of 1" OD piping welded to the intercooler and plumbed it in as purchased... Problem is it will only blow-off excess pressure after a hard WFO run and letting the throttle plates slam closed (all the way off throttle)... It did nothing at the part throttle positions (stays closed)... After reading woodsriders post above yesterday I went out and cut 4-coils off the spring (thanks by the way woodsrider)... Further testing will be required for my application... At this point it just starts to crack open (relieve pressure) at 4000rpm (2lbs showing on boost gauge measured at intercooler)... I'll either be cutting off more coils or calling TurboXS for a new spring to replace the one I'm hacking up...(hehehe)

The theory goes something like this:

Vacuum on one side & Pressure on the other = Valve Open
Pressure on both sides = Valve Closed

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http://www.gofastbits.com.au/index.php?parentid=tech_info&option=tech_info

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Typical Automotive = MAF mass airflow sensor (closed loop)

CBV (compressor bypass valve vented back into the intake track after MAF sensor) Being a closed loop system, any loss of air (venting to atmosphere) for which fuel has already been metered by the movement of the airflow sensor plate, will result in an over-rich condition.

Yamaha Apex = MAP manifold absolute pressure sensor (open Loop)

BOV (blow off valve vented to atmosphere) This is most common in an open loop EFI system that uses a MAP sensor. As the MAP sensors source is inside the inlet manifold's plenum chamber, relieving air to atmosphere will not affect fuel metering or engine operation.

thats the great thing about the hks is that it can handle unlimited boost & it will blow off at any throttle poisition do to the 2 diff chambers it has one to handle high boost & one for low boost where as most bov are high boost or lower depending on spring pressure.if iam climbing a hill & get out of the throttle just a little you can here it releasing exesse pressure or if you are at 1/4 or 1/2 throttle & back off it strats releasing pressure. it also has a ajustment screw for spring pressure .i attached pics of the 2 adapters you can use with this bov.just go to ebay & do a search for hks bov & you will find all this stuff.