PT Cruiser Forum  
Advertisements
       

Go Back   PT Cruiser Forum > General Forums > General PT Cruiser Discussions

PT Cruiser Forum

Advertisements
MPG as it relates to RPM

 
Like Tree2Likes

Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 10 Apr 2013, 08:09 pm
Gru's Avatar
Gru Gru is offline
Young Cruiser
 
Join Date: Oct 2012
Location: Lousy Oklahoma (Tecumseh)
Posts: 68
Default MPG as it relates to RPM

Just some general assumptions...

Most fuel efficient in top gear.
Lower rpms = higher mpg.

Setting the cruise control at 45mph/1500rpm would be more fuel efficient than 55mph/2000rpm.

Considering 1500 rpm is as low as I think the cruise should be set, 45mph would yield highest mpg possible. Correct?
__________________
In case I don't see you...
Good afternoon, Good evening, and Good night.
Reply With Quote
  #2 (permalink)  
Old 10 Apr 2013, 09:13 pm
needmoretoys's Avatar
Fanatic Cruiser
 
Join Date: Jul 2012
Location: Rising Sun MD
Posts: 643
Default Re: MPG as it relates to RPM

45 MPH? I do that in my driveway. But I guess if you don't mind people going around you like your standing still then Low rpm's would make for better mpg. Along with cutting out jack rabbit start(which I will not do). Tire pressure too. good luck with better mpg from these cars. It's really bad when you have to use premium. Oh well. I'll just pay more money and drive happy.
__________________
Lenny

FEBRUARY CRUISER OF THE MONTH
Reply With Quote
  #3 (permalink)  
Old 10 Apr 2013, 09:15 pm
UptownSport's Avatar
Veteran Cruiser
 
Join Date: Jan 2011
Location: 55403
Posts: 3,912
Default Re: MPG as it relates to RPM

Wind resistance is lots less- So it'll get much better economy.
Cars get best fuel economy somewhere in 35-45 range before wind comes into it.So you'd be measuring something different.

Engines are most efficient at a certain RPM, Nitro could tell you more about powerbands and overlap.
Reply With Quote
  #4 (permalink)  
Old 10 Apr 2013, 09:19 pm
Chriscokid's Avatar
Regular Cruiser
 
Join Date: Dec 2012
Location: Mobile al
Posts: 197
Default Re: MPG as it relates to RPM

It's funny we see posts by people wanting to get better mpg (like 30) and I would also. I wanted to reply to them to keep their rpm below 2000 and they might be able to get that. If you can stand goin that slow!

With your speed (1500 rpm) you might get even better than that, but you'd be slower than grandma, lol.

Btw, on my last tank, I purposefully did not exceed 70 and mileage went from 22 to 24

Good cruisin to ya!
__________________
[SIGPIC][/SIGPIC]2005 PT GT Vert
2004 Honda Aquatrax turbo Jetski
2006 Honda Aquatrax
1998 Dolphin 36' motor home
1949 Piper Clipper taildragger
Reply With Quote
  #5 (permalink)  
Old 10 Apr 2013, 10:58 pm
Cool Cruiser
 
Join Date: Sep 2010
Location: SoCal
Posts: 405
Send a message via AIM to mole
Default Re: MPG as it relates to RPM

i would get a gauge to monitor your MPG. look at a Scan gauge or Ultra Gauge. i just ordered one for my car Thanks to NitroGT
__________________
Mole'@DCR

2004 SRT-4 built
2005 SRT-4 mole' 16g bws setup. 380hp 444tq 11.7@122 100% stock motor/head/axles. Dsp tuned.
2003.5 MazdaSPEED Protege stock
2004 PtGT Atx BWS SETUP and a few bolt ons. stay tuned for dyno #s
Contact me for all your BWS/DCR needs..........
Reply With Quote
  #6 (permalink)  
Old 10 Apr 2013, 11:03 pm
Banned
 
Join Date: May 2011
Location: Dallas Texas
Posts: 3,722
Exclamation Re: MPG as it relates to RPM

I have found that 60 mph is alot more efficient than 70-85 mph.

As long as I am in the right lane, let Em pass me
Reply With Quote
  #7 (permalink)  
Old 11 Apr 2013, 12:04 am
Gru's Avatar
Gru Gru is offline
Young Cruiser
 
Join Date: Oct 2012
Location: Lousy Oklahoma (Tecumseh)
Posts: 68
Default Re: MPG as it relates to RPM

Yes, it feels very slow. Painfully slow. Embarrassingly slow.
But driving slow is better than walking. I have been scrounging all I can to make it to the next paycheck.

I am usually on rural two lane roads. If someone comes up behind me and can't pass, I ride the shoulder.
If I am on the interstate with 65 or 70 speed limit I set the cruise at 55 and turn on my hazzards.
I havent done 45 yet. I just wanted to know if my logic was right.

I coast whenever possible, try not to have to use the brake; the whole hypermiling thing.


As I mentioned in another post, this is probably why I am not enjoying my GT. I don't think I have disturbed the turbo in over two weeks! I am going to kick my heels up a bit this weekend, though! Friday is payday! Yay!
__________________
In case I don't see you...
Good afternoon, Good evening, and Good night.
Reply With Quote
  #8 (permalink)  
Old 11 Apr 2013, 12:35 am
Senior Cruiser
 
Join Date: Jan 2013
Posts: 1,266
Default Re: MPG as it relates to RPM

This is a question with complex answers. If an auto trans the lock-up converter might unlock at 45 mph. The timing might retard some. The computer might increase fuel richness with a small hill, etc.

Efficiency [but not power] is done by smaller intake ports, larger exhaust ports, milder cams, more timing advance, leaner mixtures etc. Auto manufacturers design their engines to show the highest mpg on the epa highway test. This is probably done between 55 and 65 mph. And; to show high hp figures for advertising purposes. Quite a feat!

2006 n/a auto: 70=25 mpg; 65=27; 55=28. -- AC off - no defrost - cruise on - 40 psi in front tires. -- Have not noticed a gain in mileage by going slower that 55 mph.
Reply With Quote
  #9 (permalink)  
Old 11 Apr 2013, 12:54 am
needmoretoys's Avatar
Fanatic Cruiser
 
Join Date: Jul 2012
Location: Rising Sun MD
Posts: 643
Default Re: MPG as it relates to RPM

Quote:
Originally Posted by Gru View Post
Yes, it feels very slow. Painfully slow. Embarrassingly slow.
But driving slow is better than walking. I have been scrounging all I can to make it to the next paycheck.

I am usually on rural two lane roads. If someone comes up behind me and can't pass, I ride the shoulder.
If I am on the interstate with 65 or 70 speed limit I set the cruise at 55 and turn on my hazzards.
I havent done 45 yet. I just wanted to know if my logic was right.

I coast whenever possible, try not to have to use the brake; the whole hypermiling thing.


As I mentioned in another post, this is probably why I am not enjoying my GT. I don't think I have disturbed the turbo in over two weeks! I am going to kick my heels up a bit this weekend, though! Friday is payday! Yay!
What grade of gas are you putting in there. I wonder if lower octane gas would hurt the mpg. It needs premium but maybe you could get away with the mid grade. Just don't get on it. it will knock.
__________________
Lenny

FEBRUARY CRUISER OF THE MONTH
Reply With Quote
  #10 (permalink)  
Old 11 Apr 2013, 07:37 am
Ray_Dockrey's Avatar
Senior Cruiser
 
Join Date: May 2012
Location: Mustang, OK
Posts: 1,213
Default Re: MPG as it relates to RPM

I have a 09 NA and for me it gets its best mileage at slightly below 60. I stay in the right hand lane and could care less if people are passing me or not. I also accelerate slow which helps too.
Busa_Powered likes this.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 05:25 am.




Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
LinkBacks Enabled by vBSEO 3.6.0 PL2 © 2011, Crawlability, Inc.
vB.Sponsors