Re: "Performance" Exhausts... A Must Read... (archive)

According to SEVERAL people I have spoken to, including a man who built F1 motors in France, a free flow exhaust will HARM the performance of an e24, and could actually hurt the motor as well. The 3.5l motor was designed FOR backpressure, and a FREEFLOW system is NOT worth the money. The Euro M6 and US M6 should only be used WITH FACTORY MOTORSPORT EXHAUSTS!!! The Us 635csi is a bit more marginal, but you should STILL steer clear of the Free Flow!!!
Food for thought.
BTW, we dynoed my M635csi w/ w/out the free flow B&B, and I LOST 4HP from 2500-4500 RPM, and I lost over 10 horses at 5000!!! The torque only suffered a bit, 4-6 foot lbs. throughout the entire powerband. Needless to say, I sent my exhaust back to Billy... The "quieted" version of the B&B actually HAS backpressure, and is almost to BMW spec...
Joe ///M

Joe ///M

I have some imput...I spoke with B & B triflow and a german BMW tuner about free flow and was told that the cars especially euro models, perform better the free flow does have a little back pressure, and is good but a personal choice. I have a 80 635CSi and 85 M6 euro after running a 3" pipe to the freeflow muffler the cars perform
better, and that deep german accent comes out clearly...i also run no cat converter...the only time you know that i am there is when i really punch the gas, the car will adjust to the new unrestricted breathing on it's own.

Pat
80 635 euro
85 M6 euro
89 dinan 535i
92 525td euro
****** all Performers*******
my

Follow Ups:

[ Follow Ups ] [ 6-series (E24) Message Board ] [ Msg. Board FAQ ]

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