First real mpg test
Some of you know about my 12v Cummins powered Ford F-450, did the original conversion 7 years ago and swapped in the completely rebuilt 215 with upgrades 5 years ago.
I use this truck locally hauling hay and equipment between farms, it has only accumulated 30k miles in 8 years but hauls over 1000 rolls of hay per years plus moving skid loader and tractors, it's running average hauling, empty truck and trailer and occasionally just empty truck has been 10-12 mpg, not bad for traveling mostly rural secondary roads here in Ky.
Yesterday I had to go 280 miles into northeastern In to pick up a 2000 lb piece of equipment that would fit on the trucks bed, this was the first time the truck had been driven any distance empty on interstate highways so figured it would be a good time to do some testing on how the truck performed at speed and what mpg it could get.
First off let me say I was pleasantly surprised at how well the truck rode and drove, not as smooth has our 1/2 ton pickups we normally take on trips but the wife wasn't complaining about the ride so that's a + score anytime.
Most of the trip was at speeds ranging from 70-75 mph but I did run it up to 80 to get some gauge readings as well as a couple slower speed readings.
Truck is a 04 F-450 flatbed dually 4x4, 12v Cummins with 215 pump and inj, Colt Stage 3 cam and Borg S300 Super B 57mm turbo, ZF6 manual trans, 3.73 gears and 32" tires, terrain was mostly flat, truck weighs 9500 lbs, return trip weight was 11500 lbs.
60 mph at 1725 rpm, 3-4 psi boost, 500-600 egt
65 mph at 1850 rpm, 4-5 psi boost, 600-650 egt
70 mph at 2000 rpm, 5-6 psi boost, 650-700 egt
75 mph at 2150 rpm, 6-8 psi boost, 700-750 egt, the truck likes to cruise at 74 mph.
78 mph at 2225 rpm, 8-10 psi boost, 750-800 egt, I've always been told fuel mileage takes a noticeable drop above 10 psi boost.
80 mph at 2275 rpm, 10-12 psi boost, 850-900 egt, although the truck was cruising along fine the increased boost and egt's for only 2 mph increase told me we had passed the point were fuel milage was going to take a hit.
On the way back we stopped for fuel with 496 miles on the trip meter, 34 gallons later the tank was full which hand calculated to 14.6 mpg, I was hoping for 15 mpg and would have been tickled to see 16 mpg, had I stayed closer to 65-70 mph it may have gotten 15 or better, but that's not the way I drive and I wanted real numbers for my style driving.
I will be making some changes in the future but not sure when, while going over the truck greasing and checking fluids before the trip I noticed a good size oily mess at the left front side of the engine, after looking and wiping we found a crack in the bottom of the timing gear case between the block and power steering pump mount, the engine leaked a qrt of oil out in that 560 mile trip.
We'll be pulling the engine at a later date to repair of replace the gear case, at that time I'm going to swap in a stock cam in place of the Colt Stage 3 and probably replace the S300 with a K27, hoping these changes will help with a turbo lag issue I'm having below 1800 rpm.
Mine-04 F-450 SCFB 4X4 drw,5.9 12v 215 Ppump,ZF 6,KYclutch,KDP fixed,gauges,5x12's,15deg,3k GSK,60#,AFC Live, Super B single,Pusher intake,D celebrator brake,07 coil spring front conversion.
Her's-18 F-150 STX SC, 4x4, 5.0
Toy- 64 Fairlane, future 406FE, 3 Holley 2bbls, 4 spd
Last edited by Destroked 450; 01-23-2020 at 02:34 AM.