Easy Gas Mileage Bump - Defender Source
Defender Source  

Go Back   Defender Source > Defender & Series Technical Discussions > Defender Technical Discussions


Reply
 
Thread Tools
  #1  
Old May 25th, 2007, 06:55 PM
jimngo's Avatar
jimngo
Status: Offline
Jim Ngo
1994 D90 #80
Member
 
Join Date: Aug 2006
Location: Salt Lake City, UT
Posts: 118
Easy Gas Mileage Bump

About a month ago I advanced my timing from the factory spec 5 BTDC to 7 BTDC. The downside is that I have to run mid-grade fuel now, but the upside is that my gas mileage went from around 13 to 15.5-16 MPG. It's well worth the extra 10 cents per gallon.

I waited a while to post this in order to run through a few tanks of gas to make sure it wasn't just a fluke. But the last 3 tank fulls have all come in between 15.5 and 16 MPG. There hasn't been performance degradation as far as I can tell.
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old May 25th, 2007, 09:11 PM
JimC's Avatar
JimC
Status: Offline
Jim Cheney
NAS 110 #145
Site Team
 
Join Date: Sep 2003
Location: Stuttgart, Germany
Posts: 7,154
Registry
So you used to run the 3.9 on regular? Is that what most people do? I'm a V8 newbie!
Reply With Quote
  #3  
Old May 25th, 2007, 10:01 PM
themaxx's Avatar
themaxx
Status: Offline
Ade
94 ST
Member
 
Join Date: Aug 2006
Location: MD
Posts: 1,835
Registry
Quote:
Originally Posted by JimC
So you used to run the 3.9 on regular? Is that what most people do? I'm a V8 newbie!
I believe we're suppose to use premium.
__________________
"It insists upon itself" Family Guy
"Your Defender insists upon itself" Dave Parker
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old May 25th, 2007, 10:11 PM
oldscratchggf's Avatar
oldscratchggf
Status: Offline
nate
95 d90
Member
 
Join Date: Apr 2005
Location: california
Posts: 660
I`ve always used premium, for what it`s worth. For those of us that arn`t the most mechanically inclined (which will prove interesting next year when I start building up a 110), what all is involved with adjusting the timing?
Reply With Quote
  #5  
Old May 25th, 2007, 10:27 PM
themaxx's Avatar
themaxx
Status: Offline
Ade
94 ST
Member
 
Join Date: Aug 2006
Location: MD
Posts: 1,835
Registry
Quote:
Originally Posted by oldscratchggf
For those of us that arn`t the most mechanically inclined (which will prove interesting next year when I start building up a 110), what all is involved with adjusting the timing?
I resemble that question!
__________________
"It insists upon itself" Family Guy
"Your Defender insists upon itself" Dave Parker
Reply With Quote
  #6  
Old May 26th, 2007, 11:54 AM
jimngo's Avatar
jimngo
Status: Offline
Jim Ngo
1994 D90 #80
Member
 
Join Date: Aug 2006
Location: Salt Lake City, UT
Posts: 118
I ran regular fuel because it didn't cause any knock. I figured, why waste money otherwise? Octane is not a measure of fuel quality or potential energy. It's just a measure of preignition (knock) resistance.

To adjust the timing all you need is a 14mm box wrench and a timing light. Make sure the engine is warmed up to normal temp. Attach the timing light to the battery & #1 spark plug lead. Loosen the nut on the distributor retaining clamp. Start up your D90. Shine the timing light on the main engine pulley and you will see a metal marker on the crank case lined up with marks on the pulley. On my D90 each mark is 2 degrees. Rotate the distributor a teeny bit until the marker is lined up where you want, in this case between the 6 & 8 degree marks. Shut off the engine, clamp the distributor back down, and restart & recheck the timing to make sure you didn't bump it off your setting. That's it.
Reply With Quote
  #7  
Old May 26th, 2007, 06:32 PM
Billakris's Avatar
Billakris
Status: Offline
Kris
Alpine White 95 Soft Top
Member
 
Join Date: Sep 2003
Location: Kansas City/ Manhattan, KS
Posts: 271
The octane rating is the percentage of pure octane (the organic compound) in the fuel. The higher the percentage of octane, the more reactions per molecule takes place. So it actually is a measure of potential energy.

I just spent a semester in organic chem and that was one of the few things i retained.
__________________
Kris
Reply With Quote
  #8  
Old May 28th, 2007, 01:35 PM
jimngo's Avatar
jimngo
Status: Offline
Jim Ngo
1994 D90 #80
Member
 
Join Date: Aug 2006
Location: Salt Lake City, UT
Posts: 118
Kris,

You are right. Octane does have a slightly higher heat of combustion and higher octane gas does have slightly higher energy though a two percentage point difference in octane/heptane rating (e.g. 89 vs. 87) results in a pretty small difference. But I do stand corrected on that.
Reply With Quote
  #9  
Old May 28th, 2007, 07:02 PM
Billakris's Avatar
Billakris
Status: Offline
Kris
Alpine White 95 Soft Top
Member
 
Join Date: Sep 2003
Location: Kansas City/ Manhattan, KS
Posts: 271
no problem, im just happy that i actually learned something that I can apply to my daily life....
__________________
Kris
Reply With Quote
Reply

Lower Navigation
Go Back   Defender Source > Defender & Series Technical Discussions > Defender Technical Discussions

Tags
gas

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Best way across the US Mike Hippert Defender Technical Discussions 173 April 29th, 2010 04:56 PM
Gas Mileage - quite impressed proulx70 Misc. Chit-Chat 41 October 2nd, 2008 10:48 PM
Gas Mileage DaineseUSA Misc. Chit-Chat 23 November 1st, 2007 01:34 PM
Summer Gas Mileage mdmccallum Defender Technical Discussions 5 June 9th, 2005 12:10 AM
Gas Mileage mdmccallum Defender Technical Discussions 2 October 6th, 2004 12:14 AM


All times are GMT -5. The time now is 05:27 AM.


Copyright