Go Back   EcoModder Forum > EcoModding > Hypermiling / EcoDriver's Ed
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-28-2008, 09:48 PM   #1 (permalink)
lyd
It smells funny in here.
 
Join Date: Sep 2008
Location: Southern Wisconsin
Posts: 63

GeeOh - '97 Geo Metro Base
90 day: 33.41 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
Geo drivers, please help me get a few things straight.

I've been reading these forums pretty voraciously for about three weeks now, and while I have learned tons, my head is spinning a bit with some of the technique info. So much seems to be contradictory at first glance, and a lot of it has continued to seem that way after many repeat glances. ;-)

Please, just tell me if this statement is correct, as a summation of all the many things I have read:

I want to be accelerating as quickly as possible, shifting at peak torque (3300 rpm), until I hit cruising speed, at which point I want to keep the vac guage above 10.

If that's correct so far, as far is it goes, then I have a couple of initial questions:

- What am I trying maintain on the vac during that "quick as possible" acceleration? It drops to 0 pretty fast.

- Keeping the vac gauge above 10 seems to result in my frequently going well below the speed limit. Even a moderate incline scrubs me down to 50 or 45 mph pretty quickly, and slightly steeper ones have me dropping below 45 and down shifting to 4th gear. Is this pretty normal?


Clearly, I need to get that boarduino and other bits ordered to get more feed back than the vac-n-tach setup is giving me, but I'd a appreciate a little help in the meantime. I cranked out a couple hundred miles of 48mpg just vaguely trying to go slower, use high gears, and shut the car off to coast once in a while. Now that I am all equipped with new knowledge and instrumentation I feel like I'm doing much worse and have been all over the place in the way I'm driving. I need to get centered on an approach again.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-28-2008, 10:29 PM   #2 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,234

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,796
Thanked 6,649 Times in 3,446 Posts
I can't tell you exactly how much throttle to use when accelerating, except to say my own technique has me shifting below that 3300 RPM mark the BSFC chart suggests is optimal for the non-XFi engine.

I'm more likely to shift around 2800-3000 RPM simply because I don't like winding the engine out, even if it is a bit more efficient.

That said...

If there's any chance you're going to have to brake or otherwise slow down shortly after accelerating in this manner, don't do it. Just accelerate gently and upshift as early as you can. Braking after brisk accel is about the worst thing you can do. (The best thing, speaking only of efficiency, is to shut the engine off and coast after accelerating - Pulse & Glide).

Re: the vac gauge, I've never used one in my car, but you're effectively describing "DWL" (Driving with Load), which I do regularly when highway driving (I've moved away from extended P&G cycles on the open highway). And the answer to your question is "yes" it's pretty normal for your speed to fall off on even modest inclines if you've picked a relatively low load target (e.g. inches of hg or instant MPG on the MPGuino or ScanGauge).
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 09-28-2008, 10:47 PM   #3 (permalink)
Addicted
 
bbjsw10's Avatar
 
Join Date: Jul 2008
Location: Findlay,OH
Posts: 555

bbjsw10 - '91 Geo Metro Xfi
90 day: 51.06 mpg (US)
Thanks: 0
Thanked 11 Times in 7 Posts
Quote:
Originally Posted by MetroMPG View Post
I'm more likely to shift around 2800-3000 RPM simply because I don't like winding the engine out, even if it is a bit more efficient.
When you do this do you shift to 5th as soon as possible, like skip a couple if you are going 30-35mph?
__________________
  Reply With Quote
Old 09-28-2008, 10:48 PM   #4 (permalink)
lyd
It smells funny in here.
 
Join Date: Sep 2008
Location: Southern Wisconsin
Posts: 63

GeeOh - '97 Geo Metro Base
90 day: 33.41 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
'Kay, that helps a lot, thanks. I just needed someone to reassure me that I hadn't gone completely off the rails. ;-)
  Reply With Quote
Old 09-28-2008, 11:08 PM   #5 (permalink)
lyd
It smells funny in here.
 
Join Date: Sep 2008
Location: Southern Wisconsin
Posts: 63

GeeOh - '97 Geo Metro Base
90 day: 33.41 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by MetroMPG View Post
I'm more likely to shift around 2800-3000 RPM simply because I don't like winding the engine out, even if it is a bit more efficient.
I've been driving this car for years, and have generally shifted at 4k as a minimum when trying to accelerate at a decent rate. Freeway on-ramps and such I'd wind it out almost to 5k.

It took an act of will to start shifting in the low 2k's these past weeks. ;-)

Last edited by lyd; 09-28-2008 at 11:14 PM..
  Reply With Quote
Old 09-29-2008, 10:18 AM   #6 (permalink)
Master EcoModder
 
Join Date: May 2008
Location: Briggsdale, Colorado
Posts: 296

Wildfire - '96 Ford Bronco XL
90 day: 14.88 mpg (US)

Blackford - '96 Ford Bronco XLT
90 day: 20.26 mpg (US)

Y2k - '00 Honda Insight
Gen-1 Insights
Team Honda
90 day: 73.98 mpg (US)

Redford V10 - '01 Ford F250 Lariat
90 day: 15.64 mpg (US)

FireFly - '00 Honda Insight DX
90 day: 69.43 mpg (US)

LittleRed - '00 Honda Insight
Thanks: 3
Thanked 31 Times in 14 Posts
I am using moderate acceleration, shifting at around 2000 - 2500 or so. I sometimes shift earlier if I am going downhill, so this RPM varies on terrain. The idea is to use the least amount of horsepower I can. I do my best to stay in 5th gear going up hills, and generally either slowly decelerate, coast, or at least try to maintain 35 mph up the long ones if I am out in the back roads by myself. I have also limited my top speed to 55 mph. But that is me - still a work in progress.

I am trying to work on a theory of P&G while shifting through the gears. In other words, every time you shift up and put in the clutch to shift to the next gear, allow the car to drop 5 mph before engaging the clutch again to accelerate. It's kind of a patience issue on my part to do this - and it depends on what traffic is behind me. Again, a work in progress.
__________________
  Reply With Quote
Old 09-29-2008, 11:15 AM   #7 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,234

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,796
Thanked 6,649 Times in 3,446 Posts
Quote:
Originally Posted by bbjsw10 View Post
When you do this do you shift to 5th as soon as possible, like skip a couple if you are going 30-35mph?
Yep, if I'm going to drive with load after accelerating.
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 09-29-2008, 02:13 PM   #8 (permalink)
lyd
It smells funny in here.
 
Join Date: Sep 2008
Location: Southern Wisconsin
Posts: 63

GeeOh - '97 Geo Metro Base
90 day: 33.41 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by MetroMPG View Post
Yep, if I'm going to drive with load after accelerating.
I've been trying this today, accelerating briskly up to 55 then DWL from there. Thing is, I'm dropping back to 45mph early and often anyway. Then, following a DWL strategy, I'm slooowly regaining 55 on the next flat or downhill, keeping the vac guage at 10.

Seems like I should either give it more gas to maintain speed on the uphills, which would be closer to the whole 3300 under load thing, or drop even further in speed on the uphills and then accelerate briskly again.

Any thoughts ok which might be better?
  Reply With Quote
Old 09-29-2008, 03:19 PM   #9 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,234

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,796
Thanked 6,649 Times in 3,446 Posts
You're basically describing a "pulse and bleed" strategy, and I don't think it works. (At least I've never been able to come out ahead the few times I've tried it.)

I think a strong "pulse" (accelerating briskly, near peak BSFC, up to speed) will only pay off if you maintain a high mpg for a long time afterwards, or if you plan to immediately follow it by a glide, and rinse/repeat.
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 09-29-2008, 03:38 PM   #10 (permalink)
lyd
It smells funny in here.
 
Join Date: Sep 2008
Location: Southern Wisconsin
Posts: 63

GeeOh - '97 Geo Metro Base
90 day: 33.41 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
That makes sense. I guess I'll go back to my slow acceleration, except where I know I am going to have an EOC coming up. I haven't been doing that systematically (EOC I mean) but have been taking advantage when really good opportunities present themselves, like long downhills or steadily decreasing speed limits coming into towns.

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
How I lightened up my Geo Metro by 70 lbs ATaylorRacing General Efficiency Discussion 16 06-07-2011 09:29 AM
Geo Metro Fuel Pump Circuit bennelson EcoModding Central 12 10-05-2009 04:43 PM
Good take on things (long) Daox General Efficiency Discussion 8 08-30-2008 04:11 PM
1990 Geo Metro Idle test cinaroh EcoModding Central 2 07-08-2008 10:15 PM
Geo Metro on Best of Craigs List bennelson The Lounge 2 03-13-2008 11:09 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com