I know this subject is old but just wanted to know if anyone has any real proof that the bbm is a better choice than log manifold? Like some dyno figures or 1/4 mile times

ford wouldn't have used it if it didn't work

thats a good point, but ford also changed the diff ratio and non tickford vehicles to 3.08:1 to to increases fuel economy so was the bbm just another fuel saver and a low end torque increase for the way tall diff ratio?

At a guess the bbm is about 10kg heavier, so it has to compensate for that too.

While ford reverted back with some things, such as rocker cover design, and ignition lead placement, it has stayed with the bbm.

A challenge to assessing their worth is that the inlet system changed at the same time. Perhaps most notably getting much longer.

for the cost of a bbm these days it's well worth a play with. i know i bought one years ago n am still impressed by the differences between the manifolds, then the difference between the butterflies open n closed with the eecIV

The idea of the bbm is very good.. the log manifold is a compromise to give the best performance for low and high RPM.

The BBM allows them to have the manifold change to better suit low/high rpm rather than compromise somewhere in the middle.

VCT does for Cams, what BBM does for intake manifolds.. It changes it to better suit the current environment rather than having to choose one setup that doesn't hurt either high or low rpm too much but compromises both abit to do it.

Obviously if you are blown with turbo or SC then it's a moot point because the air is forced in, in either case, but for NA, the torque and power curves seem to be wider on the EF- than the EA-ED's and that would most likely be mostly because of the BBM.

As someone said, this would be considerably more expensive for ford to manufacture over the log... they would almost have to be a lot better for ford to consider the extra expense worth it.

Also JMM loves the BBM and has said the motors with them are the best ones to push to the edge. (Up to you whether you choose to value his opinion).

Rgds

Frank

For those interested, do a seach on www.autospeed.com

There's a detailed article on the operation of intake manifolds, which deals specifically with dual runner intakes and the ford bbm.

They describe it basically as a cheat which works quite well, giving long runners for low down torque, and short for high rpm, in a compact package.