Regear for lower cruising RPM
Lower engine RPM at a set speed means reduced friction losses and increased engine load to maintain a given power output. Higher engine load increases engine efficiency.
Note: This modification is much easier on manual transmissions compared to automatics. There are no reports of automatics being regeared at ecomodder.
A very easy way to improve efficiency with a change in ratio of engine RPM to speed is to install tires with a larger radius.
Instructions for mod
Information required: How do people perform this modification, pictures, problems, what to look out for
Information required: A listing for different ways to do this if its different on different types of cars
Please enter your user name and any relevant data in the table
|User Name||Car Make, Model, Year||Cost of Mod||Time to Perform Mod||MPG Before Mod||MPG After Mod||MPG improvement guess||Instruction Link|
|MetroMPG||Ponteac Firefly 1997|| 65kph-72.9|
|Metro taller transmission swap thread: +5% efficiency gain (taller final drive)|
|Big Dave||00 F-350 XLT||Mod= regear||20 MPG||23 MPG||15% (3MPG) data is tank to tank before/after mod||[]|
|Big Dave||00 F-350 XLT||$4000 installed||Mod= add 7th gear (overdrive)||26.7 MPG||28.2 MPG||7% (1.5MPG) ABA testing||[Seventh Gear!]|
|cfg83||99 SW2 Wagon||$240 ($140 parts, $100 labor)|| 41 MPG |
| 49 MPG |
|20% (at steady speed highway) 21% theoretical gain (steady state highway) from gear ratio change.||[Saturn S-Series 5th Gear Swap]|
Problems / Consequences of mod
- Higher RPM required at speed before shifting into new higher gear and therefore lower efficiency at some speeds.