How many RPM's at 70 mph is normal

Reply Subscribe

Thread Tools

Search this Thread

04-10-14, 04:54 PM

#16

cobalt91

Lead Lap

Join Date: May 2012

Location: MI

Posts: 586

Likes: 0

Received 0 Likes on 0 Posts

Nice chart Yamae!

Reply Like

04-11-14, 04:06 AM

#17

Yamae

Moderator

Join Date: Aug 2011

Location: Japan

Posts: 3,876

Likes: 188

Received 902 Likes on 682 Posts

Quote:

Originally Posted by PureDrifter

tire size?

Why do you ask that?

Reply Like

04-11-14, 04:13 AM

#18

BluesImage

Driver School Candidate

Thread Starter

Join Date: Apr 2014

Location: GA

Posts: 37

Likes: 0

Received 0 Likes on 0 Posts

Thanks for the chart!

Reply Like

04-11-14, 09:45 AM

#19

Legender

Racer

Join Date: May 2010

Location: TX

Posts: 1,856

Likes: 16

Received 85 Likes on 76 Posts

Now I'm really confused... yesterday I left work and pegged the cruise on 70 going home and it hit 2150 RPMs...
Today I went to Ft. Worth at 6 AM and traveled down to the toll road and hit 75 and pegged the cruise control... RPMs were at 1950... huh? How did that happen? Then about 30 minutes into the trip RPMs hit 2300 and stayed there the rest of the time and all the way back. I never touched the cruise or changed the speed and the RPMs changed on me. I don't know how/why that happened....anyone?

Reply Like

04-11-14, 09:46 AM

#20

PureDrifter

BahHumBug

iTrader: (10)

Join Date: Aug 2004

Location: California

Posts: 23,919

Likes: 9

Received 97 Likes on 89 Posts

Quote:

Originally Posted by Yamae

Why do you ask that?

Because tire size, gearing, and trans gear/overdrive are what determine RPM at speed.

If he's running very undersized tires his cruising RPM will be considerably higher. Same issue when running shorter (numerically higher) rear end gearing.