Performance vs MPG
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Joined: Mar 2000
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Performance vs MPG
I've finally started to narrow my engine rebuild options down, but I have a couple of questions regarding performance accessories.
* I understand how I can get a close estimate of * potential hp and torque but what about mpg?
I now alot of factors go into this besides the engine (ex. tranny, gear ratio, tire size, etc.)
but I'm getting 7 mpg now and I can't afford to fill it up. The last thing I want to do is spend $2K on my 400 and only get 5 mpg!
* I understand how I can get a close estimate of * potential hp and torque but what about mpg?
I now alot of factors go into this besides the engine (ex. tranny, gear ratio, tire size, etc.)
but I'm getting 7 mpg now and I can't afford to fill it up. The last thing I want to do is spend $2K on my 400 and only get 5 mpg!
Senior User
Joined: Jun 1999
Posts: 140
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From: Bander, TX (Hill Country)
Performance vs MPG
IMHO, all things being equal, unless you have an overdrive tranny or are running FI, most Performance engines are not going to get very good gas milage.. I have a '70 351W that I spent close to $3000 to build to develop around 325-350hp... running a '76 C4 to 3.25 gears in my '64 F100 Shortbox, I get about 9.5 to 11 mpg.. I recently put an Accel 300+ ignition in, but can't drive it enough with the gas prices to see if the milage improved significantly.. I am considering going to a AOD tranny for the overdrive as I am turning 2500 at 60 now...
Good luck,
Bill in Mobile
'64 F100 Shortbox ('70 351W/'76 C4)
Good luck,
Bill in Mobile
'64 F100 Shortbox ('70 351W/'76 C4)
Senior User
Joined: Jan 2000
Posts: 161
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Performance vs MPG
All that I can do is give you a list of my trucks' modifications and specs., it sounds like you're getting pretty bad mileage. I have a '66 bronco with a mild 351w (rv cam, 600 cfm Edelbrock, edelbrock performer intake) 35" tires, 4.10 gears and a c4. That gets 12mpg all day long cruising at 65ish, better if I go slower. I also have a '76 f250 4x4 with a pretty radical 390 (aluminum heads, decent sized cam, Holley 750dp, performer rpm intake). It has 4.10 gears, 38" tires, and a 4speed. It gets 9-10 mpg cruising at 65mph. You didn't list your setup but if you're looking for a good compromise, run 3.50 gears with 33" tires, 3.73's with 35's, and 4.10's with 38's. You can figure it out from there if you have other tire size. I've owned a number of 4x4's and those tire/gears are best for all around.
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ernesteugene
1999 - 2003 7.3L Power Stroke Diesel
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Jun 9, 2008 07:42 PM
