View source for Regear for lower cruising RPM

[[Car_MPG_Efficiency_Modifications_Main#Drivetrain_Mods_-_Transmission.2FDifferential|Back to main mod page]]

[[Image:Regear.jpg|right|thumb|400px|Frame|]]
'''Introduction'''<br>
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<br>
''Information required:'' A listing for different ways to do this if its different on different types of cars<br>

== User experiences  ==
Please enter your user name and any relevant data in the table<br>
{| cellspacing="0" Border=1
|+ User data
! 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<br>75kph-64.95<br>85kph-57.9 || 65kph-79.9<br>75kph-70.3<br>85kph-62.85 || 65kph-9.6%<br>75kph-8.2%<br>85kph-8.5%<br>Ave-8.8%|| [http://ecomodder.com/forum/showthread.php/metro-taller-transmission-swap-thread-5-efficiency-gain-107-2.html 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 || [[http://ecomodder.com/forum/showthread.php/taller-top-gear-makes-real-difference-10-a-2748-2.html#post83857]]
|-
|Big Dave || 00 F-350 XLT  || $4000 installed || Mod= add 7th gear (overdrive) || 26.7 MPG || 28.2 MPG || 7% (1.5MPG) ABA testing ||  [[http://ecomodder.com/forum/showthread.php/seventh-gear-13539.html Seventh Gear!]]

|-
|cfg83 ||99 SW2 Wagon  ||$240 ($140 parts, $100 labor) ||  || 41 MPG <br> steady state|| 49 MPG <br> steady state || 20% (at steady speed highway) 21% theoretical gain (steady state highway) from gear ratio change. || [[http://ecomodder.com/forum/showthread.php/saturn-s-series-5th-gear-swap-2779.html 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.

== References ==
=== Forum thread links ===
[http://ecomodder.com/forum/showthread.php/taller-top-gear-makes-real-difference-10-a-2748.html Taller top gear makes a real difference (10%)]

[http://ecomodder.com/forum/showthread.php/metro-taller-transmission-swap-thread-5-efficiency-gain-107-2.html Metro taller tranny swap thread: +5% efficiency gain]

[http://ecomodder.com/forum/showthread.php/saturn-s-series-5th-gear-swap-2779.html Saturn S-Series 5th Gear Swap]

=== External links ===
[http://www.pansypatrol.com/the-gas-mileage-mod/ Regear how to]