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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 03-14-2009, 05:41 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: Mar 2009
Location: Suffolk, UK
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Bumpstarting - Worth it for half a mile or so?

I'm trying to improve my MPG, and on the road I live on it's a quiet dead straight road for about half a mile - So far i've been practising coming round the bend at 50 MPH and then just turning the engine off, coasting the distance to my house and then starting it in 3rd at about 20 using the clutch.

I drive a 2002 Proton Wira 1.5 using the Mitsubishi 4G15 engine.

Is this bad for the car? Do the benefits outweigh the savings for a "normal" car?

Thanks.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 03-14-2009, 07:20 AM   #2 (permalink)
Master EcoModder
 
Join Date: Feb 2008
Location: belgium
Posts: 663

vectra a - '95 Opel Vectra GLS
90 day: 37.51 mpg (US)
Thanks: 14
Thanked 61 Times in 44 Posts
i've never seen any negative effects of occasional bump starting... i'm not sure how much it will save, that'll depend on a lot of factors... i find bumpstarting works best in 5th and 4th gear, i've even bumpstarted while i was coasting to a stop and the light turned green just before a was about to come to a standstill.

i think the forces experienced by the clutch is comparable or even lowever than when you shift gears or when you take of from standstill so i think think and abnormal wear wan resuly from a smooth bumpstart
  Reply With Quote
Old 03-14-2009, 08:56 AM   #3 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,237

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 6,655 Times in 3,447 Posts
Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - Threads Tagged with bump starting

Of course you cause a small amount of wear to the clutch & drivetrain every time you bump start (there should be no "bump" if you're doing it well). Nobody can 100% guarantee the financial savings will outweigh the potential maintenance costs, or if you will even incur any maintenance costs.

We have several users who have been using the technique for hundreds of thousands of miles on the same vehicle, with no ill effects. (Yet.)

I do it.

FYI: Coasting experiment: engine off VS. engine idling - MetroMPG.com
__________________
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 03-14-2009, 09:59 AM   #4 (permalink)
Coasting Down the Peak
 
skyl4rk's Avatar
 
Join Date: Jun 2008
Location: M I C H I G A N
Posts: 514

Toyauto Pickup - '94 Toyota Pickup 2WD
90 day: 36.32 mpg (US)

Versa Base - '09 Versa Sedan 1.6 Base
Team Nissan
90 day: 41.69 mpg (US)
Thanks: 27
Thanked 41 Times in 34 Posts
There are huge fuel efficiency benefits to engine off coasting. Bump start in a gear one or two higher than you would be driving at the speed you are bump starting.
__________________
Nissan Versa Aeromods
  Reply With Quote
Old 03-14-2009, 12:04 PM   #5 (permalink)
PaleMelanesian's Disciple
 
hummingbird's Avatar
 
Join Date: Dec 2008
Location: Noida, UP, India
Posts: 197

City - '04 Honda City iDSI EXi
90 day: 47.47 mpg (US)
Thanks: 3
Thanked 3 Times in 2 Posts
I do it whenever I can avoid 100m of idling, without getting into trouble with traffic. My City is very forgiving about bump starts, and can take up from almost crawling in 3rd. If there is a bit of residual speed, I prefer 4th or 5th for bumping and then reengage using the technique so clearly explained by MetroMPG here.
__________________
  Reply With Quote
Old 03-14-2009, 02:47 PM   #6 (permalink)
EcoModding Lurker
 
Join Date: Mar 2009
Location: Suffolk, UK
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Cheers guys
  Reply With Quote
Old 03-19-2009, 06:39 PM   #7 (permalink)
Boxhead
 
whokilledthejams's Avatar
 
Join Date: May 2008
Location: Fredonia, NY
Posts: 322

Boxy Brown - '04 Scion xB
90 day: 35.48 mpg (US)
Thanks: 0
Thanked 1 Time in 1 Post
Send a message via AIM to whokilledthejams
I usually bump start after short coasts. I've yet to see ill effects.

As has already been pointed out, bump starting in a higher gear than you'd be driving in at that speed is ideal. It smooths it out a lot.

In my car, for example, if I'm coasting at 25-30mph, I can bump start in 5th pretty well. As soon as the engine fires up, disengage the clutch, and shift into the gear that you'd normally use at the speed you're traveling at.
__________________
  Reply With Quote
Old 03-21-2009, 11:12 PM   #8 (permalink)
Master EcoModder
 
Join Date: Oct 2008
Location: Mid-Atlantic
Posts: 491

OurInsight - '06 Honda Insight
Thanks: 170
Thanked 69 Times in 44 Posts
It is going to cause a bit of extra wear to the clutch mechanism, but many have good luck with bump starting. Skill helps lower the mechanical impact.

Perhaps the worst impact is on the synchronizers. When the engine is dead (cluster gear & individual gear stationary) and the third motion shaft (output shaft) is turning at several thousand RPMs, there is very high relative speed between the synchronizer/dog clutch parts, therefore there is a lot of synchronizer stress. Apparently modern synchronizers at up to the stress in many cases.

I have an AT, but I'd do some bump starting if I had a MT. I just wouldn't be doing it unless there was a clear and convincing fuel savings. That would include long coasts, and long downhills. It may make more sense to restart with the starter, since that is an "external" component and less expensive to replace. In addition, using the starter would allow for double clutching which would lower synchronizer wear considerably. I don't know of any actual data, but clearly a lot of extra shifts/clutch cycles is clearly outside the designers intent. JMHO
  Reply With Quote
Old 03-21-2009, 11:24 PM   #9 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
Just a note - if you're doing the work yourself, ease aside, the clutch is actually usually cheaper to replace than the starter, given new vs. new components.. rebuilt starters are often much cheaper, and can't be held as a comparison to new clutches.

The only problem is that many times, you have to perform all the steps to replace the starter even if you're changing the clutch, so better to have to replace the starter for the sake of ease. Then again, I drove one of my cars for 5 months with no starter installed... I used to push it and dump the clutch as soon as I got it rolling in 2nd gear to start it, no matter where I was. When I pulled the engine out of that car to put it in my next Civic, the clutch face still had the OEM wear indicator grooves in it, and the clutch was installed in 1991 (the car was a 1988 Honda Civic LX, the original owner "learned" how to drive stick in it.)
__________________
"ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
Old 03-22-2009, 11:05 AM   #10 (permalink)
Master EcoModder
 
Join Date: Oct 2008
Location: Mid-Atlantic
Posts: 491

OurInsight - '06 Honda Insight
Thanks: 170
Thanked 69 Times in 44 Posts
I didn't mean to come down very hard on any of this. Clearly some folks have success with bump starting for the duration that they own the car. I think technique and practice may be the main factor.

Just a note - I don't think many folks do their own heavy work, such as clutch replacement, but that is just a guess. Yours is as good as mine ;-)

  Reply With Quote
Reply  Post New Thread


Tags
bump starting, clutch starting

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
The 500 mile club trikkonceptz Success Stories 48 01-06-2009 03:39 PM
--- 600 Mile Club!!! --- basslover911 Success Stories 8 11-20-2008 09:18 AM
Woohoo, this place is worth more than CleanMPG dcb The Lounge 4 10-16-2008 10:24 AM



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