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Old 04-09-2009, 11:45 AM   #10 (permalink)
Shawn D.
Harebrained Idea Skeptic
 
Join Date: Jun 2008
Location: Alpharetta, GA
Posts: 211

The White Car - '84 Mercedes-Benz 300td
90 day: 28.84 mpg (US)

The Blue Car - '86 BMW 535i
Last 3: 23.86 mpg (US)
Thanks: 19
Thanked 13 Times in 9 Posts
Quote:
Originally Posted by PaleMelanesian View Post
When you say "lug", what rpm are you talking about?

I routinely accelerate from about 1200 rpm (30 mph in 5th gear). I have a 107 hp 4-cylinder, from Honda no less - famous for having little torque down low.

You could probably adjust your driving and easily use 5th even lower than what you are now.
40 MPH in 5th is now just under 1100 RPM and is just above the idle position on the throttle position sensor. Trying to accelerate even at 1/3 throttle from that state brings loud, low-frequency rumbling and vibration -- it's definitely lugging.

Doing the math (1200*40/30), you're doing 1600 RPM at 40 MPH, which means my 535i has about 30% taller final gearing (drivetrain & tire radius combined) than your Honda.

I can't really adjust driving to go any lower in 5th than that.
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