injector swap

[broncobuckinaround]

91 f350 460 automatic.

i was wondering if it would be a good idea to swap the stock 24lb injectors with 19lb injectors from a 93 mustang HO.

curious because im looking for ways to save few bucks at the pump. i realize this is a big block. but theres no harm in trying. thanks for the feed back

 

[adsm08]

No. At best you end up using the same amount of fuel with a longer duty cycle, which means more wear on the electrical component of the injector. At worst you end up running it lean, and a lean engine runs hot.

The injector rating is how much it can flow when left wide open for an hour. Not how much it flows per shot.

The computer is measuring the amount of air coming in and trying to add an amount of fuel that is balanced to the amount of oxygen that should be in that air. Putting lower flowing injectors in won't save fuel, it will just make the computer hold them open longer.

 

[RonD]

+1 ^^^

Fuel injection systems are not like carbs, i.e. changing "jets" to set fuel flow, and even that doesn't work, lol.

Gasoline engine needs 14.7:1 air:fuel ratio, and that is a WEIGHT ratio not volume(why "pre-vaporizers" are hooey)

14.7 POUNDS of AIR to 1 POUND of gasoline
14.7 grams of air to 1 gram of gasoline
WEIGHT ratio

Fuel injection gets better MPG because it can do real time adjustments to that ratio, but it needs good information to do that.
Clean MAF sensor
Good O2 sensors
Good ECT sensor
Working thermostat that keeps engine coolant at 190-200degF, under 190degF lowers MPG

Also never shift to Neutral when going down hill, while this was helpful with Carbs it actually costs you fuel with fuel injection
Computer can turn off the fuel injectors, 0 fuel being used, when going down hill in gear
If Speedometer is above 5MPH and RPMs are above 1,500 and throttle is closed(foot off the gas pedal) then computer shuts of injectors, so going down hill in gear is 0 fuel use.

Computer is set up for stock injectors and stock fuel pressure, so it knows how many grams of gasoline will flow from each injector when it opens it, for say 100ms(milliseconds)
If you put in larger or smaller injectors all that will happen is that the computer will have to open them less or more that 100ms to get the same grams of fuel
Best case is that you won't notice any change at all
Worst case is that CEL(check engine light) will come on with Rich or Lean codes because computers calculated Open Time for the injectors is no longer correct.
Rich and Lean codes come from fuel injector open time calculations being off
Which can be caused by air leaks, low fuel pressure, failing sensor or wrong size injectors

Watch spark plug tips, if they are getting a darker color then engine is running Richer, if O2 sensors are over 80k miles then replace them

 

[broncobuckinaround]

you guys are awesome. love it when both of you reply because ron you have the most detailed info and adsm08 you have very simple straight to the point answers.

ive done a really good tune up in it. plugs cap rotor. fpr fuel filter. tested pressure at pump. iirc 74 psi at the pump and 33 psi at fpr while running. its a 91 so no mas just a map. it has a bolt on direct fan no clutch. so i know that will rob my mpg. i plan on doing dual electric fans with a capacitor. that way it doesnt make the alternator run harder.

and later on if i can just put in the 7.3 powerstroke. and get a tuner. lol i have a friend who says hes getting in the 20s for mpg. i dont know if i should believe it. i can see high teens.

but hey thanks again both of you

 

[adsm08]

Diesels are very different animals. A diesel has no stoichiometric ratio that it needs to hold to run properly, unlike a gas engine. So on a diesel with a good tuner you can turn the fuel way back when you don't need a buttload of power and get good fuel economy, even on a turbo engine, and then dial it back up when you hook up to your 10K lbs 5th wheel.

 

[broncobuckinaround]

how hard would it be to swap in a diesel.

 

[adsm08]

Probably similar to almost every other engine swap done around here. You will need engine, trans,wiring, computer, probably some fuel lines.

 

[RonD]

And a small enough engine to fit between heater box and steering shaft

5.0l(302) is 60deg V and 19" wide and kinda fits
90deg V wouldn't
And if you add OHC V then pretty much won't fit

Google: ford ranger 4bt swap

The 4BT swap fits, mostly, lol, and gives good power and economy

 

[lvwill]

7.3 would be an awesome swap. I've been looking for an F250 with 7.3 like forever. They just keep getting more expensive.

 

[adsm08]

And a small enough engine to fit between heater box and steering shaft

5.0l(302) is 60deg V and 19" wide and kinda fits
90deg V wouldn't
And if you add OHC V then pretty much won't fit

Google: ford ranger 4bt swap

The 4BT swap fits, mostly, lol, and gives good power and economy

I think we are still talking about the 350 Ron.

 

[alwaysFlOoReD]

I lost track too...lol.

 

[broncobuckinaround]

ive located a few 7.3 turbo diesels with trans. i know ill need the computer and wiring. should i get the dash. and will my transfercase bolt up.

 

[Curious Hound]

sorry. I posted something, not realizing we are in the full-size truck forum here. Content deleted to make my stupidity less obvious.