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copbait73 copbait73 is offline
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Join Date: Nov 2003
Location: Chesterfield IN
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Originally Posted by Quicksilver77 View Post
Craig: you know I love you Andial hatred!!!
Thank you for the reading! I am very much considering the BL WUR.

RarlyL8: Yeah, no **** on the boost levels...
As far as the engine build goes;

3.4L Mahle P&C 7.0-7.5:1 CR (the shop could not remember which compression ratio)
SC cams
Stock bottom end
K27 7200 Turbo
Kokeln IC
Stock waste-gate (1bar spring)

It is throwing me for a loop, my best guess is that I am experiencing higher boost levels than the WG spring is set for because of the GHL headers? Much like the Tail WG's are experiencing with the same headers???
356-930, and I have also been corresponding and he brought up a good point and question: shouldn't the boost peak just above the WG spring pressure, and then hold steady at that WG's spring rate, instead of tapering off, as shown in my boost chart?

I really appreciate the time fellows!
Sean, you are right to show concern regarding the boost level because the W/G should control what you set. First check your W/G for proper function. Much of the A/F ratio problem is your uncontrolled manifold pressure and excess air.
After checking your W/G have you relocated the W/G pressure tap from it's stock location? Assuming the W/G is functioning properly, when I see a boost curve like yours it has been modified by electrics (modern) or relocation (old school) of the pressure tap controlling the W/G.
Next, but of lesser importance, your comment about the GHL headers may be contributing to the boost curve shape as their 90 degree branch off pipe from the base of the turbine inlet is widely known to be less than ideal for proper exhaust flow to a W/G. Basically, you are dealing with turbulant flow because of this improper design and stange things happen in turbulant flows.
Once you have control of the manifold pressure a slight boost overshoot is generally considered desirable for "response"....but not at 1.35bar.
Old 03-31-2008, 07:31 AM
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