I had a strange thought the other night. I wondered if anyone trying to get better gas mileage from a F-150 had ever swapped in a 240 with all the fuel injection stuff.

It kind of makes sense that better mileage would result since the engine has roughly 4/5 the displacement of a 300. I imagine the easiest way would be to simply bolt a 300 top end onto a 240 block, but I could very easily be wrong on this.

The only real downside I see for a pickup that is used mainly as a people hauler is the fact that Ford didn't build the 240 for very long, thus making it kind of hard to find.

The fuel pump mounting location would also have to be blocked off, but that is a pretty minor operation.

Any thoughts?

Robert

 

The smaller motor has to be more efficient(more power per cubic inch) to see any gains. The 3.5 EcoBoost is proof of this as it can deliver much greater power and efficiency, but unfortuately the most common truck platform these days is a crew cab with much higher cargo capacity that the older trucks(the same or greater than an F250 from our generation) so the end result is a vehicle that is on average 1000lbs heavier and still only manages about 15mpg city or the same as a 300I6 powered '90's truck.

The idea has merit but given the abysmally low efficiency of the stock motors in these truck there is a lot of room for gains without having to do a custom build. Exhaust and ignition upgrades help improve pumping efficiencies and will deliver better milage though most gains will be attained at constant cruising speeds. In stop and go traffic it's all about weight, the heavier the vehicle the more fuel it's gonna burn and there's nothing you can do about it except drive a smaller vehicle.

 

Interesting idea. I've thought about this before as a possibly fuel efficient setup. After a bit of thinking and researching, I came out with the general thought that it might be better to modify a truck with a 300. As Paul says, you can get a lot better efficiency out of a stock engine without having to do a custom build. I've known of as high as 25 MPG highway (65 MPH) with a 300, manual with OD, and 2.75 gears.


Nailed it right there. Without stripping weight, driving in the city and/or in traffic is greatly affected by weight. The 240 may do a little better here because it won't guzzle as much fuel sitting still, but the weight is still a killer.

 

The 240 and 300 are the same engine just with different rotating assemblies. The 240 head has a smaller combustion chamber and slightly higher compression. A typical mod was to drop a 300 internals into a 240 engine for a cheap stroker motor.