Welcome to the North American Subaru Impreza Owners Club Wednesday August 20, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Factory 2.0L Turbo Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 10-17-2001, 11:19 PM   #1
driver8
Scooby Specialist
 
Member#: 6997
Join Date: May 2001
Chapter/Region: South East
Location: lahrnceville, GA
Question Turbo fuel efficiency question

Curious about fuel efficiency of the turbo. Specifically, is there a significant difference in fuel consumption in a lower gear at ~3500rpm or in a higher gear at ~2500rpm (assuming your traveling at a constant speed)?

So if maintaining a constant speed at 3500rpm, is it better to upshift (for fuel efficiency) or just stay in the lower gear (and enjoy acceleration when needed)? Thanks.
* Registered users of the site do not see these ads.

Last edited by driver8; 10-18-2001 at 09:57 PM.
driver8 is offline   Reply With Quote
Old 10-18-2001, 09:59 PM   #2
driver8
Scooby Specialist
 
Member#: 6997
Join Date: May 2001
Chapter/Region: South East
Location: lahrnceville, GA
Default

Bueller? Bueller? anyone?
driver8 is offline   Reply With Quote
Old 10-18-2001, 10:33 PM   #3
rkkwan
Scooby Specialist
 
Member#: 5596
Join Date: Apr 2001
Chapter/Region: TXIC
Location: Houston, TX
Vehicle:
2010 Honda Fit Sport
Black

Default

Don't ask me to explain it, but I'm certain that you'll use less fuel running at a lower rpm and higher gear.

-Ray
rkkwan is offline   Reply With Quote
Old 10-18-2001, 10:39 PM   #4
Jon [in CT]
*** Banned ***
 
Member#: 2992
Join Date: Nov 2000
Chapter/Region: NESIC
Location: Connecticut, USA
Vehicle:
02 WRX Sedan
Silver

Default

Quote:
So if maintaining a constant speed at 3500rpm, is it better to upshift (for fuel efficiency) or just stay in the lower gear (and enjoy acceleration when needed)?
You're asking us to make a lifestyle judgement for you. We'll be happy to do that, but first you'll need to tell us more about yourself.
Jon [in CT] is offline   Reply With Quote
Old 10-18-2001, 10:59 PM   #5
driver8
Scooby Specialist
 
Member#: 6997
Join Date: May 2001
Chapter/Region: South East
Location: lahrnceville, GA
Default

no, but thanks for the offer Jon. At least I know where to turn if it ever comes to that.

Normally, I like to stay in the lower gear to minimize affect of turbo lag and have the acceleration readily available. - it's a lifestyle choice. I drive a lot of miles and was curious if there were inherent efficiencies of a turbo system (read: rationalizing my lifestyle choice).

Anyway, it's probably as simple as this:
higher rpm's = higher turbo rpm = more air = more fuel

Thanks again.
driver8 is offline   Reply With Quote
Old 10-18-2001, 11:22 PM   #6
Silver_Bell_WRX
Scooby Specialist
 
Member#: 7677
Join Date: Jun 2001
Location: Burlington, VT
Vehicle:
2005 WRX
Blue

Default

You have answer your own question. With the turbo spooled up the car will use more gas.
Silver_Bell_WRX is offline   Reply With Quote
Old 10-19-2001, 08:17 AM   #7
AlexM_UK
Scooby Newbie
 
Member#: 6825
Join Date: May 2001
Location: London
Vehicle:
1999 Impreza Turbo
Silver

Default

I would like to know the answer to this too...

I think that by using more rpm you are getting closer to peak volumetric efficiency (torque peak) so economy is potentially better, but this is offset by increased friction and pumping losses (nearly closed throttle at cruise).

Anyone know?

Cheers,

A.
AlexM_UK is offline   Reply With Quote
Old 10-19-2001, 08:31 AM   #8
bsquare
Scooby Specialist
 
Member#: 1911
Join Date: Jul 2000
Location: Seattle, WA, USA
Vehicle:
2000 Impreza 2.5RS
Silverthorn Metallic

Default

Higher gear, lower rpm is best for gas mileage. That's why 6-speed transmissions typically make 6th essentially unusably high except for highway cruising at low rpm.

Also, with a turbo, staying off boost will improve mileage in direct proportion to the decrease in fun.


Ben
bsquare is offline   Reply With Quote
Old 10-19-2001, 08:38 AM   #9
driver8
Scooby Specialist
 
Member#: 6997
Join Date: May 2001
Chapter/Region: South East
Location: lahrnceville, GA
Default

bsquare,
Quote:
Also, with a turbo, staying off boost will improve mileage in direct proportion to the decrease in fun
i disagree. it's not direct - it's exponential!
driver8 is offline   Reply With Quote
Reply

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
increasing turbo fuel efficiency moonzie Baja Forum 5 06-12-2007 12:36 PM
Question on NA vs Turbo fuel efficiency G.Subramaniam Normally Aspirated Powertrain 4 08-07-2006 06:00 PM
fuel efficiency question nhmtns Newbies & FAQs 3 09-18-2005 05:04 PM
300ZX Twin Turbo Fuel pump Question. BADWRX Factory 2.0L Turbo Powertrain 22 10-31-2001 04:13 PM
turbo fuel pressure questions bttune2.5rs Normally Aspirated Powertrain 5 03-01-2001 12:47 AM


All times are GMT -4. The time now is 08:50 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.