Solving Boost Spiking On The Gt3540

[SCRIBR]

  DennisRB30 said:

Circumference!  I missed that.  What an odd way to describe the size increase.  I guess if the guy doing the work says the new hole is only 1.9mm wider it sounds pretty pathetic      that's still about a 15% increase in size though.  Mine is like 65% bigger      Its pretty much finished.

http://www.math.com/students/calculators/s...rcle-solver.htm

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is it sad that I read this stuff.. calculated the percentage difference in the port size.. then scrolled down and found this site...

...yes.. yes it is..

[DennisRB30]

  SCRIBR said:

  DennisRB30 said:

Circumference!  I missed that.  What an odd way to describe the size increase.  I guess if the guy doing the work says the new hole is only 1.9mm wider it sounds pretty pathetic      that's still about a 15% increase in size though.  Mine is like 65% bigger      Its pretty much finished.

http://www.math.com/students/calculators/s...rcle-solver.htm

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is it sad that I read this stuff.. calculated the percentage difference in the port size.. then scrolled down and found this site...

...yes.. yes it is..

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That calculator is awesome. I use it all the time.

[velluto]

I realise this information is quite late. I was inspired by the thread that Headsex posted (thanks Mate).I purchased a boost control kit from GCG Turbchargers. It came with a new swing valve and 10lb actuator and connecting rod. I found that it was not useable as shipped (to NZ) as it really needs the new swing valve arm as well. Some people reuse the existing arm. Ideally you should end up with a D-shaped port, the flat edge closer to the arm. This stops the vaqlve getting trapped when it is trying to close again. So, hand porting required including some extra clearance on the inside of the housing to accomodate the larger housing. My original flapper was quite offset to the port so ordinary machining would not have been the answer. A 2mm overlap is sufficient. You will probably need a machine shop to grind the port to recreate the seat for the flapper to sit against after porting. Hope this is useful for someone.