Question for Mechanics: 2200-2500rpm or 2700-3000rpm, what is best???

[Steve Tinker]

Didn't I read somewhere about a natually occuring harmonic vibration in the flat 6 engine design that happens at around 3,000 rpm?

I've always had it in the back of my head to drive either just below or just above the 3,000 rpm threshold - there again at my advanced years, I could be talking out of the back of my head too......
But the everyday sweet spot must be in the 3,500 to 4,500 rpm pulling through the gears - very addictive!

[stephen wilson]

IIRC Jake mentioned avoiding cruising @ 3000 RPM a few years ago, but haven't heard anything since. I'm at 3K all the time, since it equals my 75 MPH highway cruise speed.

[Coffinhunter]

Originally Posted by stephen wilson

IIRC Jake mentioned avoiding cruising @ 3000 RPM a few years ago, but haven't heard anything since. I'm at 3K all the time, since it equals my 75 MPH highway cruise speed.

I am usually just a hair over 3,000 since I cruise between 75-80 to work everyday. With the speed limits on US freeways being what they are, there would be no need for 6th gear if we couldn't drive at 3,000 RPM.

I do shift down to 5th if I am going to pass though.

The only thing that I have ever heard as being bad is driving at less than 2,000.

[Perfectlap]

Originally Posted by stephen wilson

IIRC Jake mentioned avoiding cruising @ 3000 RPM a few years ago, but haven't heard anything since.

Other way around. He instructs 3K RPM driving for his engine customers.

[stephen wilson]

He may now (and I think it's Above 3k, not At ), but at some point in the past it was recommended to not stay at that RPM. I'm not 100% sure it was Jake.

Here's one mention of it:
http://www.renntech.org/forums/topic/38120-3000-rpm-ims/

Another:
http://www.pedrosgarage.com/Site_5/The_Bad,_the_Ugly_and_the_Good,_part_2.html

[Perfectlap]

Originally Posted by stephen wilson

He may now (and I think it's Above 3k, not At ), but at some point in the past it was recommended to not stay at that RPM. I'm not 100% sure it was Jake.

Flat6 say 3K. At least once, in response to a forum member asking about Pedro raising the issue of harmonic vibration in the m96.

[Ian c]

I thought it was all about the variocam kicking in around 4k ....

In all honesty , with learning on the fly ecu maps the best thing to do is unplug the battery for 30 minutes then drive it like you stole it .

Don't believe the snake oil , don't believe the Internet , don't worry , just drive

[stephen wilson]

I agree. Don't drive by fear of what may happen, it's about having fun!

[BYprodriver]

Originally Posted by Steve Tinker

Didn't I read somewhere about a natually occuring harmonic vibration in the flat 6 engine design that happens at around 3,000 rpm?

I've always had it in the back of my head to drive either just below or just above the 3,000 rpm threshold - there again at my advanced years, I could be talking out of the back of my head too......
But the everyday sweet spot must be in the 3,500 to 4,500 rpm pulling through the gears - very addictive!

75% of my driving is on LA freeways with the cruise control set @ 73mph & 2900rpm.
After rebuilding my engine & balancing all recipricating parts & flywheel & pressure plate, I was amazed at how much smoother the engine feels & sounds. So much so that it seems tamer & a little boring. That was the 1st time I was motivated to buy a louder muffler.