7.3 IDI vs 460 EFI

69oiler

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today i had the oppurtunity to compare similar trucks, both '87-'91 style Super Duty (F450) dump trucks with 5 speed trannys. the 7.3 has 5.13 gears in back and i assume the 460 does as well, being a SD. i was driving the 7.3, running EMPTY, and my buddy was driving the 460 powered truck, with a load (at least 3 TONS) of dirt/clay. he was leading, i was following. we came to a hill, posted 9% for a half mile or so. i purposely fall back a little, expecting the loaded truck in front of me to slow down climbing the hill. he rockets up the hill, in 4th gear at 3000 rpm i later confirmed. i was in 5th with my foot to the floor and i was eating his dust. i couldnt catch up intil we passed the top of the hill. dont think downshifting would have done a lot for me as i was already running 2000 rpm at 45 mph. gotta love 5.13s.

the 7.3 i was driving has a brand new injection pump on it, installed and timed by me. having driven this truck many times, as well as my own 6.9, and ridden in numerous other IDI trucks, i can say that the truck i was driving is a strong running NA 7.3. i guess my point is that i was very impressed by the 460's power. it was blowing smoke, burns quite a bit of oil, and gets 6 mpg, but it sure run circles around the IDI. even the turbo IDIs i've ridden in would be hard pressed to run with the 460.

for now i'll still keep my 6.9 though. even at 60+ cents spread gas/diesel 6 mpg is tough to swallow.
 

NapaBavarian

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:D I have 2 similar, but not identical, trucks, 6.9 and a 460, both standard transmissions, that 460 sure is fun :) but it gets 9mpg with an overdrive and the 6.9 pulls about 14, I tend to drive on the Governer cruise controll on that one...
 

Jarlaxle

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We had 2 F-350 wreckers at work...the 1992 460/E4OD truck got 4.5MPG. The 1986 6.9/T-19 truck gets ~11MPG and has almost 600,000 miles.

The 92 got sold.
 

Nickbf2504x4

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69oiler said:
today i had the oppurtunity to compare similar trucks, both '87-'91 style Super Duty (F450) dump trucks with 5 speed trannys. the 7.3 has 5.13 gears in back and i assume the 460 does as well, being a SD. i was driving the 7.3, running EMPTY, and my buddy was driving the 460 powered truck, with a load (at least 3 TONS) of dirt/clay. he was leading, i was following. we came to a hill, posted 9% for a half mile or so. i purposely fall back a little, expecting the loaded truck in front of me to slow down climbing the hill. he rockets up the hill, in 4th gear at 3000 rpm i later confirmed. i was in 5th with my foot to the floor and i was eating his dust. i couldnt catch up intil we passed the top of the hill. dont think downshifting would have done a lot for me as i was already running 2000 rpm at 45 mph. gotta love 5.13s.

the 7.3 i was driving has a brand new injection pump on it, installed and timed by me. having driven this truck many times, as well as my own 6.9, and ridden in numerous other IDI trucks, i can say that the truck i was driving is a strong running NA 7.3. i guess my point is that i was very impressed by the 460's power. it was blowing smoke, burns quite a bit of oil, and gets 6 mpg, but it sure run circles around the IDI. even the turbo IDIs i've ridden in would be hard pressed to run with the 460.

for now i'll still keep my 6.9 though. even at 60+ cents spread gas/diesel 6 mpg is tough to swallow.

you would have been better off downshifting the diesel, peak hill climbing power is right around 3,000 rpm's, redo the test like this... :Sly
 

rthomas

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i also have a 67 f250 w/460-c6-3.55's, right now it has a foolinjected block w/ carb heads, its pretty much a slug my 86 will run circles around it. but my old 460 (about a '70) was a rocket, at 35 mph you could floor it and clean off the dash. i dont ever remember loosing a stoplight race with that motor, i even spanked a modded cummins once, it was close but with a 6k redline i was able to get ahead and stay there
 

Mikes91

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69oiler said:
today i had the oppurtunity to compare similar trucks, both '87-'91 style Super Duty (F450) dump trucks with 5 speed trannys. the 7.3 has 5.13 gears in back and i assume the 460 does as well, being a SD. i was driving the 7.3, running EMPTY, and my buddy was driving the 460 powered truck, with a load (at least 3 TONS) of dirt/clay. he was leading, i was following. we came to a hill, posted 9% for a half mile or so. i purposely fall back a little, expecting the loaded truck in front of me to slow down climbing the hill. he rockets up the hill, in 4th gear at 3000 rpm i later confirmed. i was in 5th with my foot to the floor and i was eating his dust. i couldnt catch up intil we passed the top of the hill. dont think downshifting would have done a lot for me as i was already running 2000 rpm at 45 mph. gotta love 5.13s.

the 7.3 i was driving has a brand new injection pump on it, installed and timed by me. having driven this truck many times, as well as my own 6.9, and ridden in numerous other IDI trucks, i can say that the truck i was driving is a strong running NA 7.3. i guess my point is that i was very impressed by the 460's power. it was blowing smoke, burns quite a bit of oil, and gets 6 mpg, but it sure run circles around the IDI. even the turbo IDIs i've ridden in would be hard pressed to run with the 460.

for now i'll still keep my 6.9 though. even at 60+ cents spread gas/diesel 6 mpg is tough to swallow.

2000 RPM ain't nuthin. No wonder you couldn't keep up. Not sure if you'd have been able to keep up if you'd had a similar load, but... these old diesels weren't made for power back in the day. They were made for fuel economy and durability, which is where the 460 will lose out all day long.

In today's economy, I think you're safer taking your time with an old diesel.
 

towcat

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rthomas said:
i also have a 67 f250 w/460-c6-3.55's, right now it has a foolinjected block w/ carb heads, its pretty much a slug my 86 will run circles around it. but my old 460 (about a '70) was a rocket, at 35 mph you could floor it and clean off the dash. i dont ever remember loosing a stoplight race with that motor, i even spanked a modded cummins once, it was close but with a 6k redline i was able to get ahead and stay there
How did you compensate for the longer crank snout on the FI 460 block? When you put in the FI block did you use the FI timing chain set or the pre'72 set? If you don't have a degree wheel the pre'72 set advanced the cam 12 deg and will give you back all the balls the 460 should have. Problem is it wouldn't pass smog without a 12 deg retard at the cam. :eek:
I used to have a F450 repo truck with a internally modded 460 and dead cat. Driver was caught streetracing with it. Even with the Eagle EB2 on the working end, it moved like a scalded cat. ;Sweet
 
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rthomas

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i didnt have any troubles putting the pullys on, but i found out the hard way about the external balenced flexplate that i didnt have when i droped it in. i did have to change it to a front sump setup wich means changing timing covers. at the time i didnt know about the 8 & 12 deg timing so im sure thats where the power is lost, it feels good in the primarys but falls on its face as soon as you open the secondarys. IMO its the best V8 ford made, my old 460 had over 250k when i pulled it and the only reason i did was the valve guides were getting pretty loose. one day ill rebuild my old one and put it back in :D
 

69oiler

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Mikes91 said:
2000 RPM ain't nuthin. No wonder you couldn't keep up. Not sure if you'd have been able to keep up if you'd had a similar load, but... these old diesels weren't made for power back in the day. They were made for fuel economy and durability, which is where the 460 will lose out all day long.

In today's economy, I think you're safer taking your time with an old diesel.


in hindsight i would have been better off in 4th gear around 2500 rpm and rising...but there's still no way i'd have caught that 460.

normally i'd agree with the statement about the economics of the diesel vs gas. however i just spent $44 to fill my TDI with 14.5 gallons of fuel. not to mention the fuel the 6.9 drinks. the spread between gas and diesel prices is getting a little unnerving. seems as though every time the prices fluctuate, the gap grows. what to do... at least i have the option of WVO with my diesels. (thanks Carl. :thumbsup: )
 

Agnem

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Rob, I used to drive my father in-laws Lincoln, which had a 460 in it. 20 more cubes plus higher RPM's and gasoline is going to produce more horsepower then our diesels. I'd say it was not a fair comparison if based on speed alone. I'd bet if that hill were longer, the 460 would have eventually overheated, started knocking, burned a valve or ate a spark plug, where as the 7.3 would go up that hill all day long. Remember, our diesels are rated for their horsepower on a continuous basis. I've yet to meet a gas engine that can make the same claim.
 

Pacific

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I had a 88 F-450 with 11' dump with 460 power it loved gas but it would run circles around my 89 IDI. I had 9000lbs of gravel on my 88 it carried it like nothing the engine never powered out. Most F-450s with 460s had the 4:63 gearing the IDIs came with 5:13 gearing.

My old IDI wouldn't even come close to the power empty or loaded as my 88 had. I put 8000lbs on my IDI it would suck wind the only benefit is the truck got 10-12 mpg the 460 only got 6-8.

If the 460 wasn't such a pig on fuel I would be driving one if the price of diesel stays the way it is a 460 gas might look like a better deal.

Oh ya I used to beable to roast ricers with the 460 the IDI no way and my current PSD maybe.
 

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