As I am about to plop either a reman eng or a 2001 60k used into my F150, which I've had but 4 yrs, I ponder, mpg and things to upgrade when the swap occurs.
I got a 5.4. I like the 330, but a 4.6/280 would have done the trick. Now, I realize, it takes X HP to push 4500 lbs of this Cdc(drag coeff) x Frontal area down the road. 5.4 ot 4.6 OUGHT not matter 1%, theoretically. Practically, that is largely true. But with less HP, one also has less F to = ma^2, so that saves gas.

I'm pondering the effects of a smaller injector than stock. I'd think that the 'puter would just tell the injector to stay open for a longer duty cycle. Thus, no real change in economy. 🤔

It may starve for fuel IF ever at high rpms. (Which a good tuner could block.) My rear is already a 3.35, and I went to 17's from 16's... making it a 3.005 equivalent... or, a 5.4/330 like a 4.84/296 w a 3.35. (UpBuilt 4R70W, California.)

 

I would just get the same engine, but if youre sold on changing it , try to find a low mile wrecked F150 with the 4.6L and I suppose you will need its computer too, try to match the trans if you can otherwise its gonna need reprogramming, get it running right first then play with the injectors. Just a thought.......

 

I'm in California. We are not allowed to think for ourselves, and swap engines. I'll have to stick w a 5.4. Now that I've done the math, and see it's like 296 CI, versus the present 330/5.4, or the 280/4.. I'm reasonably happy. I'm just looking to do what I can, and not spend money twice... E.G: IF I need to buy injectors, is there any reason to, or not to, go 1 step smaller...? It makes no sense to me. Well, if the injector is forced to pulse open, longer, maybe finer atomization could result. But my gut says, it's not significant enough to be discernable. It's not like going 1 jet size down in a carb. A tuner has to do this, I think. Belts & hoses are new. Maybe coils...

 

5.4 is 310 hp on the 3 valve model, 235 on the 2 valve, the 3 valve does make 320 on alcohol. 4500 lbs??? My 2010 was 6400 pounds. Just saying that you might want to re-check your baseline numbers.

Generally speaking it is NEVER a good idea to go with an injector with a lower rate...most tuners will agree.

Ultimately this is a confusing thread...do you want hp or fuel mileage? The two are mutually exclusive.

 

[QUOTE=bajaman;
> Generally speaking it is NEVER a good idea to go with an injector with a lower rate...most tuners will agree.

> Ultimately this is a confusing thread...do you want hp or fuel mileage? The two are mutually exclusive.[/QUOTE]

Gotcha on the smaller injector being ill-advised. My own logic said, this is aplace injector size snd carb jets cannot be easily compared. Saying it out loud, helped.

Economy is the goal. My 140HP Dodge 360 was enough. Now I have 235 or 265... just don't need that, very often, if ever. I grew up in NV when the last sign leaving town, after, 75mph, was, End Limit, Resume Speed. After a brief time in Spokane wrenching on bikes,(where the boss garnered the CA-MX speed record, and I mat hed him half way,) I found myself on the Autoban.

This 5.4, 3.35 geared 150 is TOO easy to be found wanting 90 mph, on trips, over 80, after an hour passes, and others have continually passed you after you gave up doing only 70. I rarely tow. I've had hot cars and interceptors. This is a truck. Lotta frontal area. And gas is $5.559 at CostCo in CA. I will LIKE doing 65, if I can tame its thirst just a tad more, so that I am just a lil more rewarded for doing 65. It's just so nice at 80++. Dunno what my limiter might be. Been 95-98 ish.

 

Base curb weights on these 10th Gens are on the 4500# range. My SuperCab 4.2 shows 4200# curb, probably around #4500 with me and a few tool bags in the back seat. You must have about a half ton of stuff added to yours because that’s F250 curb weight range.

That aside, OP going smaller wheels probably didn’t do a thing to his effective gearing unless he has a much skinnier tire as well. Smaller overall diameter of tire and wheel = higher RPMs.

If you really want a full size econotruck, find a 4.2. Even that is iffy, since the revised EPA ratings were 14c/17h and that’s with a new engine. One of these newer truck with DOHCs, VCT and six or ten-speed transmissions would help. These trucks just did with the brute force of cubic inches.

 

[QUOTE=Johnny Paycheck;
... That aside, OP going smaller wheels probably didn’t do a thing to his effective gearing unless he has a much skinnier tire as well. Smaller overall diameter of tire and wheel = higher RPMs.[/QUOTE]

Skinnier drops wind resistance, but I suspect you may have meant rim-to road. I DO know tire math. Not hard, but took me a cpl years to force myself to bother to come to understand it.

I'm the OP. Orig rubber per the door was 235 or 255/70-16. It was an XL with some XLT upgrades. I got the 5.4 '01, 4 yrs ago, found it w 265/70-16... (and 3.35 rear dif.) Went to 265/70-17's. Did the math. My 3.35 rear is now 3 or less. (It depends if you work from a 235, 255, or 265..Some got 265 stock on 16's, but not mine. I cannot *KNOW* if a 3.25 was sold w 265s, so in conservatism, I work from 265/16s. My Dodge MaxiVan (custom purchase in '76 as I left the service,) I ord'd w 2.71. Who doesn't love acceleration?!?

But this IS a truck, and no Harley-Raptor, (with no-tow hints,) and I need economy, so I can downshift IF I need more power. And IF I have to pick between city-useable acceleration and top-end for looong speedy cruises, I grew up in NV and the autobahn, so I'll pick economy that can also allow top-end, "when required."

IF I had deep pockets, I'd order up an uber-built small but TOUGH V8 with a mild turbo, say, 8psi. No over-normal engine stresses of high HP engines, (strong valve springs, high CR, high wear,) until you actually turn on the tap, for serious part-work. I can deal with a lil boost lag.

Gotta start looking at my next set of tires, with mild 4x4 use, not excessive hwy noise. But I cannot quite decide on load range. The other half doesn't like the rough ride of the stiffer sidewalls. Everything is a compromise, and I'm good at that only due to sheer persistence.

But tire info which auto tires might offer, like road noise and economy, is not available except by seat of pants from guys such as on these forums. Depth of tread, A/B qualities, mileage SOMEtimes, is it. Rotations per mile, I can do, & relative economy shifts. Lack of data makes decisions very difficult for me. W Sears gone, Costco was my car-tire go-to, but they are poor in 4x4 tires. WheelWorks has only a few selections but offer me financing. But, engine first. Tires soon after.