I don't have a BMW but I use Wiesco forged pistons in both my drag cars (434 CI SBC). Both of these engies make around 14:1 compression. After initial running of the motors I have found some excessive crankcase pressures. Most of this is due to the low tension, 1/16 in compression rings and seating time. However, I installed electric vacuum pumps on both cars, running it into a valve cover where the PCV valve would normally be and blocked the other valve cover. This pump pulls about 8lbs of vacuum in and pulls the excess compression out of the crankcase. it fixed the problem I was having. Not sure if it is the same issue you are having but it sounds similar. After about 15 passes at the track I noticed an increase in vaccum telling me the rings were completely sealed. This also increased my ETs by eliminating any pressure in the crankcase.
© 1997 -
2009
Jump Internet Inc. All rights reserved.
