Re: ? for the engine gurus............. (archive)

creative thinking once again,...in the past i've built several very high output v-8s using basic hotrod technology...ie, pocket porting,unshrouding the valves, increased valve size,.increased cam lift and duration...compression etc....
point being.........i've picked up a spare 3.5 head that i'm currently doing valve pocket cleanup on,..2mm larger valves on intake and exhaust,..e34 535 cam,gasket matching intake ports....
on the v-8s it was common to surface the head, along with new pistons for increased compression. if memory serves me right....for every 10 thousands removed from the heads surface there was almost a 1/2 point increase in compression.
if.......i were to mill a sufficient amount of material from the head to bring compression up to say 9/9.5 to 1....would it be possible to regain the proper cam relationship (timing) by use of an adjustable cam sprocket..?
input from the gurus would be greatly appreciated...!!!!!

Yes, with an adjustable cam sprocket you can "re-time" the cam and put it into proper cam timing.

As for miling .010 off head for 1/2 point compression increase.... seems to me more like .030 would be 1/2 pt increase for the std BMW 6.

Make sure you flow the head after any intake grinding mods... BMW heads are already well designed and need little if any flow work. The larger valves and cam (lift and duration) you are installing will help to increase airflow, but don't expect huge increases in power output (20-35hp) is about average these types of mods.

Follow Ups:

[ Follow Ups ] [ 5-series (E28) Message Board ] [ Msg. Board FAQ ]

Questions, comments, or problems, please visit the Roadfly help desk.