Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-02-2009, 07:09 AM   #21 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
Good find, Pete. Nice to see some numbers on the subject.

They make it clear why Suzuki went with a 2-ring piston on the higher-efficiency Metro XFi rather than the 3-ring pistons in the garden variety engine.

I've never seen any mention of valve spring differences between the two though.

__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
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
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-02-2009, 11:42 AM   #22 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
Yes, good find. Still wondering about the savings or potential savings from spring changes. Also should find out more about those two engines- one with 5% valvetrain losses, one with 19%. What's the diff?
  Reply With Quote
Old 02-02-2009, 01:05 PM   #23 (permalink)
Master EcoModder
 
tasdrouille's Avatar
 
Join Date: Jan 2008
Location: Mirabel, QC
Posts: 1,672

The Guzzler - '08 Hyundai Elantra GL
90 day: 33.12 mpg (US)

Got Soul? - '11 Kia Soul 2U
Thanks: 35
Thanked 86 Times in 57 Posts
Diesel vs gas engine Frank. Makes sense the gasser would have an higher percentage of losses from the valve train since they rev higher and have lower compression.

19% of 1.5 kw is roughly .38 hp. Suppose you halve the valve train losses, and your car uses 15 hp going down the road at 55 mph, that's 2.5% better FE.
__________________



www.HyperKilometreur.com - Quand chaque goutte compte...
  Reply With Quote
Old 02-02-2009, 01:38 PM   #24 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Silly-Con Valley
Posts: 1,479
Thanks: 201
Thanked 262 Times in 199 Posts
Making the valve train lighter can also help reduce the forces needed to keep adequate control of the valves. If you know that you're never going to run the motor over 3000 RPM, for instance, you can likely get away with an awful lot of lightening of the rocker arms, retainers, and so on. Going to a lighter material (e.g., titanium) for the valves themselves will pay potentially large benefits for weight reduction.

That can let you reduce the spring pressures even further...

I don't know enough about the subject to begin to guess at how light you can go with the parts, or with the springs. But note that often times the super lightweight materials are super expensive... Titanium valves in particular!

-soD
  Reply With Quote
Old 02-02-2009, 09:28 PM   #25 (permalink)
EV OR DIESEL
 
Join Date: Dec 2007
Location: South Louisiana
Posts: 1,758

FarFarfrumpumpen - '03 Volkswagen Jetta Wagon GLS Premium

Quorra - '12 Tesla Model S P85
Thanks: 57
Thanked 113 Times in 86 Posts
Send a message via AIM to dremd
I just had a thought.

The spring resist rotation when opening, but aids rotation when closing.

Not sure what that means just yet.
__________________
2016 Tesla Model X
2022 Sprinter
Gone 2012 Tesla Model S P85
Gone 2013 Nissan LEAF SV
2012 Nissan LEAF SV
6 speed ALH TDI Swapped in to a 2003 Jetta Wagon
  Reply With Quote
Old 02-02-2009, 09:37 PM   #26 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
I think it's a zero sum situation, because there'd always be another lobe resisting rotation while one lobe is aiding. The net effect is just a lot of friction on the cam. Moreso without rollers (as is the case in the Suzuki motor).
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
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 02-02-2009, 09:57 PM   #27 (permalink)
EV OR DIESEL
 
Join Date: Dec 2007
Location: South Louisiana
Posts: 1,758

FarFarfrumpumpen - '03 Volkswagen Jetta Wagon GLS Premium

Quorra - '12 Tesla Model S P85
Thanks: 57
Thanked 113 Times in 86 Posts
Send a message via AIM to dremd
Quote:
Originally Posted by MetroMPG View Post
I think it's a zero sum situation, because there'd always be another lobe resisting rotation while one lobe is aiding. The net effect is just a lot of friction on the cam. Moreso without rollers (as is the case in the Suzuki motor).
I think that depends somewhat on the number of Cylinders (and arraignment

For example I was adjusting valves on a 7m (I6) last week and it "feels" easier to turn the cams than a 5sfe (I4). Very very not scientific, I'd guess it is a case of smoother, not less energy, just thinking . . . .
__________________
2016 Tesla Model X
2022 Sprinter
Gone 2012 Tesla Model S P85
Gone 2013 Nissan LEAF SV
2012 Nissan LEAF SV
6 speed ALH TDI Swapped in to a 2003 Jetta Wagon
  Reply With Quote
Old 02-02-2009, 10:13 PM   #28 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 1,803

Appliance White - '93 Geo Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Chevy Sprint Base
Thanks: 91
Thanked 459 Times in 327 Posts
Let's remember that valve train losses are pretty much linear with RPM, while other internal friction varies with load. There seem to be many benefits to lower speed engines. Too bad racing formulas were based on displacement, rather than weight or fuel.
  Reply With Quote
Old 02-03-2009, 08:21 PM   #29 (permalink)
Master EcoModder
 
Join Date: Jan 2008
Location: Victoria , Australia.
Posts: 499
Thanks: 20
Thanked 46 Times in 33 Posts
Quote:
Originally Posted by Frank Lee View Post
one with 5% valvetrain losses, one with 19%. What's the diff?
Frank ,
Apart from the obvious RPM differences for the two engines mentioned (1300 for the Perkins and 2500 for the Mercedes) I a guessing the detail design differences (finger roller valve operation versus bucket tappet operation etc) may account for the rest.

The comments about the actual values of the valve springs themselves being basically a zero sum item is essentially correct as Metro MPG stated above.
The force needed to compress the valve spring is returned as the compressed spring releases the energy stored in it.
There is a small amount of internal friction within the steel and this is released as heat.

The differences in spring pressure add to the friction component of the engine by the added pressures they apply to the items they contact like camshaft bearings , rocker bearings and pushrod contact points.

Cheers , Pete.
  Reply With Quote
Old 02-03-2009, 09:07 PM   #30 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
AHA! I wasn't crazy. I had already started a thread on this topic a while ago. Different forum though:

valve springs - GasSavers.org - Helping You Save at the Pump


__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
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
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Honda IACV explained TomO Off-Topic Tech 16 12-21-2015 01:49 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com