Redline is 8400 RPM isnt it? several

[mkoesel]

Originally Posted by sayemthree

that would be false advertising then - just got this off BMW website:

I agree it would be a bit deceptive, but no moreso than the more efficient S65 that gets worse mileage than the S54 for example.

The question is, does "maximum engine speed" require that fuel shutoff actually happens no sooner?

Also, when not in gear, my car won't rev to 8k. It only revs to 7700 or so (if the tach is right) before fuel cutoff. I realize that this is a special case (free rev) but the point is things aren't always as clear cut as they might seem.

[GregW / Oregon]

Originally Posted by mkoesel

Also, when not in gear, my car won't rev to 8k. It only revs to 7700 or so (if the tach is right) before fuel cutoff. I realize that this is a special case (free rev) but the point is things aren't always as clear cut as they might seem.

Tht is a safety feature because the engine winds so quickly with no load. It's supposed to be a 7k cutoff, I believe.

[footie]

Originally Posted by sayemthree

hmmm - so official redline could be 8400 but fuel cut off could be 8450? or 8500?

I'm pretty sure it is 8500rpm, I think I remember Chris from Autocar saying as much on the ring video they did.

[mkoesel]

So can someone with a broken-in car test all this and see?

http://www.m3post.com/forums/showthread.php?t=111105
http://www.e90post.com/forums/showthread.php?t=4320

Second thread says RPM is function 07.03, whatever that means.

[rai]

Originally Posted by mkoesel

I agree it would be a bit deceptive, but no moreso than the more efficient S65 that gets worse mileage than the S54 for example..

the engine is more efficent if it gets 100 more HP and is quicker yet in a heavier car for similar gas mileage. IMO

[mkoesel]

Originally Posted by rai

the engine is more efficent if it gets 100 more HP and is quicker yet in a heavier car for similar gas mileage. IMO

You could interpret it that way sure.

And I could say an engine has a max speed of 8400RPM, and then make fuel cut-off at 8300RPM. Then I could say the engine will still hit 8400RPM due to angular momentum (assuming it actually did), or maybe that it will could hit 8400RPM on downshift without concern, or whatever else. You get my point.

[rai]

I guess there is no way for us to know (nor do we need to know) how many revs the engine is turning, I think a ballpark estimate should do.

[GregW / Oregon]

Originally Posted by rai

I guess there is no way for us to know (nor do we need to know) how many revs the engine is turning, I think a ballpark estimate should do.

You're right with that point--a few hundred one way or another is esoteric, as long as you are reaching maximum power.

[sayemthree]

well - we know the offical max RPM is 8400. thats really my question - some mags improperly listed it at 8300.

[ersin]

Originally Posted by GregW / Oregon

You're right with that point--a few hundred one way or another is esoteric, as long as you are reaching maximum power.

I liked the tach lights on the SMG E46 M3. They would move up the dial and then flash at the optimum shift point. It was said, but not confirmed AFAIK, that it took into account the speed at which the rpms were building (faster in lower gears for example), tach needle rise time, and driver reaction time. Gotta love technology.

[mkoesel]

Originally Posted by GregW / Oregon

You're right with that point--a few hundred one way or another is esoteric, as long as you are reaching maximum power.

Agreed.

[Longboarder]

Holy 2008