Dyno Summaries? PBRV???

[bimmerlovere39]

Oops, I misread "valves" as "values" 

v and u do look kinda similar 

anyway...

The thought of them actually modeling the valvetrain float is very appealing.  If I recall correctly, they said that they modeled the engines in the physics engine - very impressive that they'd get this detailed.

I am, however, perplexed by how this would improve the power numbers past redline.  I don't know crap about the Miata's engine, but from what I know of the M3's engine, the redline is dictated by the bottom end, and not the top.  (Rod bearings, and the oiling thereof, specifically)  Its solid lifter, too... I don't think valve float would become an issue until slightly higher revs, right? 

Would valve float account for the extra little bit of power?

[Drift2XL]

There's two types of valve float Bimmer.

The actual float due to spring harmonics. And ramping, where the lifter jumps off the high point on the cam.

When a spring has a force applied to it (especially rapidly) it reacts in a wave pattern. It affects the first coil then moves down. Until it hits bottom and comes back up. Now at certain times you can have the spring compress itself when the waves are at both ends. 99% of the time the second wave would cancel out the first.

[Hoplee]

I find it difficult to define the end of the "first coil" and the beginning of the "second".

I also find myself in awe of the physical equations necessary to accurately define the behavior during both compression and decompression of torsion bars, leaf springs, and coil springs. Add dampers to this theoretical equation and it becomes a veritable miasma of complex variables.

[Drift2XL]

I find it difficult to define the end of the "first coil" and the beginning of the "second".

Its an oversimplification. But it helps to look at it that way from the side. If the rocker goes to hit the spring and its already dealing with the first wave going down. There is reduced pressure if a second wave would be sent down before the first one has hit bottom and started recoiling back up.

You know that little dip midway up a dyno sheet. Its usually caused by the spring harmonics and loss of valve control for that extremely brief moment. This is with a single wound coil spring. This is the reason for double, triple, and recently the bee hive springs. To quell that little harmonic dip.

[BarbecuePete]

Hey Hop...

I found this site the other day, I think this might be just what you are looking for to compare different engines... It's called Brake Mean Effective Pressure. 

http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm

[Hoplee]

Pete, nice link.

It's a perfect "BS Test" for claimed engine output!