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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
There is no threshold adjustment for boost retard on the MSD 6-BTM so it always starts retarding the timing at 2psi. Thats earlier than needed on a 930.
A 2psi boost retard threshold is probably a good average for a motor with higher static compression than a 930 like most of todays supercharged and turbocharged cars.

If you use the MSD 8762 boost retard box with a CDI you can adjust the retard threshold so it doesn't start retarding timing until 5 psi.
That gives you more useful timing control when under boost, and with the low compression of the 930 you get a little more low speed engine torque before boost arrives and while it first starts building by keeping the timing advanced a little longer with the 8762 retard threshold set to 5psi.

Anotherwords, in my opinion a 930 running around 15psi total boost with the static ignition timing advanced to around 12 degrees before top dead center at idle, and with the origonal vacuum advance/retard lines hooked up to the distributor and a properly adjusted MSD 8762 boost retard module set to 5psi threshold and 2 degrees of ignition retard per pound of boost along with the MSD 6 AL CDI... it is capable of giving a little better off boost torque than the MSD 6-BTM.
Old 02-08-2010, 10:18 AM
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