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Any improvements for the 7.3L non-Turbo Diesel engines for MPG or Performance

71K views 17 replies 10 participants last post by  gushaman 
#1 ·
I have two IDL 7.3L diesel vehicles:

1. 1989 Ford E350 Ambulance
2. 1994 Ford F250 Truck

Are there any safe improvements that can be done for the 7.3L non-Turbo Diesel engines for better miles per gallon or performance.

I see many improvements, chips & re-programmers for the turbo engines, but have a tough time searching for the above info for the non-turbo engines.

Thanks.
 
#2 ·
There are no electronics on the 7.3l IDIs so you won't find a chip or programmer for them.

Adding a turbo is going to be the single biggest performance mod you can make. Plus you may find your fuel mileage increases, or at least doesn't get any worse, when you add a turbo, because your engine is now getting enough air to burn more of the fuel that's injected. At higher accelerator settings, typically about 15-20% of injected fuel is blown out the exhaust as the black smoke of partially-burned fuel. That can be reduced to about 10-15% with a turbo, because once the turbo lag is taken up you have enough air for a more complete fuel burn. The drawback is they can be expensive and make certain maintenance tasks more difficult.

Nitrous oxide is another performance mod, though it's not really suitable for continuous use. Air is about 20% oxygen, nitrous is 36%. A shot of nitrous has almost twice the oxygen by volume that air does, so it allows more fuel to be burned. Turn on the juice before you hit a hill and keep it on til the top and you'll see a difference. The drawback to nitrous is that you either have to buy a kit (expensive) or build your own (less expensive but not really a job for someone without experience working with flammable gas systems.)

Propane will also add power by causing more of the diesel to be burned, but since it displaces oxygen-carrying air in an NA engine it's best used with a turbocharged engine that can deliver more air than the engine can use. It has the same drawbacks as nitrous, for the same reasons.

The easiest and least expensive tip for getting better fuel mileage is to avoid any extended idling, and to drive like a granny. If you see black smoke in your side mirrors, back off the fuel a bit til it's gone.
 
#3 ·
you forgot water injection, cools the cylinders from within so you can burn more fuel. allegedly works best (and is most useful) with a turbocharger.

Obviously a turbo is the winner...
 
#4 ·
There's also alcohol injection, which has the benefit of adding to the fire as it cools.
 
#5 · (Edited)
It's painfully evident these old IDI's are a joke when it comes to performance not to mention doing anything to increase it. I just got a issue of the NRA American Rifleman mag yesterday and they have a feature on the new Chevy 3/4 ton diesel. 397HP, and an amazing 765 ft.lbs. torque at a low 1600RPM and that's straight from the factory. That's almost twice the torque of a 7.3 after installing a aftermarket turbo system. The 18.9 highway mileage would'nt be hard to live with either.
 
#6 ·
A joke when compared to modern engines, but at the time of their introduction the only way you could get comparable power was with a big block gasser at half the fuel mileage.

For longevity and durability I'll take the joke any day.
 
#7 ·
I agree with Phil, my engine has over 215,000 miles on it and runs like a champ. It's a 93 and has taken me back and forth across the south several times without one problem.
 
#8 · (Edited)
A joke when compared to modern engines, but at the time of their introduction the only way you could get comparable power was with a big block gasser at half the fuel mileage.
Got to agree there, that's why I bought mine (towing) back in '91. The guy I drove truck for had a like-new showroom condition '90 F250 460 with a Paxton blower on it. When I asked him why he didn't buy a diesel he said he listens to the @%#$ diesel engines all day long in his Pete's but it ain't going to happen with his personal pickup. When I asked him about mileage (9), then told him what I get he said he didn't want to talk about it.:lol: Heard later he bought a new loaded Dodge diesel.
 
#9 ·
Every time I visit the 'stroke forums and see them talking about 2397230 things that go wrong on their truck that we don't even have, I feel vindicated. I feel the same way about my Mercedes. Sure, it may be a dog, but it also gets 30 on the freeway, and they just don't build cars like that any more.
 
#10 ·
You are lucky to live where you do. Here in western PA, most vehicles die from rust due to road salt long before they have the chance to rack up the kind of mileage I see from folks in the sunbelt ans west coast. The only reason my dump is still around and in decent shape is the PO kept it garaged. I wish I could do that, but it's a foot too long (my garage was built for the model T) so I'm doing the next best thing, parking it for the winter. It will see the snow and rain, but at least no salt. Next year I'm hoping to put up a carport.
 
#11 ·
I've been doing a little timing testing and I'm finding that lined up with the factory timing mark or slightly retarded can make a big difference in fuel economy. I tried advancing my timing in the search for more power and instead had my fuel economy drop substantially. I've almost got it back up to where it was previously. I'm getting around 18-19 mixed city/highway now in my '86 4spd turbo 3.55 CCLB as long as I drive it easy and stay at 65 or less when on the freeway.
 
#12 ·
I'm considering tweaking the timing a fuzz come spring when I put her back on the road. I think the manual transmission makes a big difference, folks with them seem to post higher mileage numbers than folks with automatics. The E4OD also seems to do better than the C6 because of the lockup converter, but they also seem to have have more troubles.
 
#13 ·
X2 for late timing achieving better mileage. For the week that my rig was advanced, the mileage was considerably worse!!
 
#14 ·
With the 6.9 and this pump I got 19mpg towing 3200# 300 miles and the empty trailer at 1800# on the way back I got 21mpg. With that same setup I saw numbers as high as 24 in the city. Then I put the turbo on, mileage was about the same, increased the fuel and mileage the same as long as I drove it sanely. Advanced the timing and mileage went to hell in a handbasket, down as low as 14. Tweaked it back up to about 18-19 then the head gasket blew. Installed the 7.3 with this same IP and the timing just slightly advanced, mileage was about 15. Now it's pretty much on the mark and I'm getting the 18-19 again. I'm hoping I can retard it a little more and get back into the 20's around town. If that doesn't work I'm gonna install the injectors from the 6.9 in the spring. I may be beating a dead horse though, 19 is about 10% off what I used to see with the old engine and now it's dead of winter, longer warmups, more idling etc. My mileage is always down in the winter. Still I want to see what a touch more retarded does for the mileage. When I get my best numbers, best egt's, and best feeling of power I plan to get the timing checked for reference.

And yes a manual trans should post better numbers, much less drive line loss. Look at the numbers for new cars, the stick is always 2-3mpg better. A stick can do better but it depends on the driver a lot. I can make my truck get 12mpg just by accelerating hard all the time. If I shift as soon as it won't bog the next gear and keep my speed down I get high numbers. I find on the highway if I'm patient and just cruise the slow lane at 60-65 mph nice and steady I get nice mileage but with no OD and poor wind resistance if I push it much faster the mileage drops to less than what I get in town.
 
#16 ·
Yep, I know I'm "lucky" to live where the roads aren't salted. Very few rust-throughs out here except in the corners of the cabs of chevy trucks :D
 
#17 ·
Yeah, I know. This is :ford: country, where if you listen closely on a quiet night, you can hear Chevys rusting. :lol:
 
#18 · (Edited)
daaaaaaaaaayyyyyyyyuuuuuuuuummmmmmmm.....I filled up my first tank (rear, 15 gallons) the other day and hit the trip meter. Im at less than 100 miles and less than half a tank. That puts me under 10mpg if i can do math right. I do have lots of blue/white smoke almost all the time, 3.55 gears, BFG AllTerrain TA ko 33"s, n/a, and keep the o/d off till i get it to stop shakin in o/d....anyone have any ideas?
 
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