Hi guys,

I have a '97 HD F250 with a 5.8L.
We bought it in '98 and lets just say we don't drive it much. It has less than 70K on it.

We only use it when we need to use a truck and for the most part is going on holidays towing a 4000lb trailer. (1958 Silver Streak. Soon to be a 1948 Airstream).

Anyway, with the price of fuel being what it is and going up, I'd like to improve what the truck has to offer.
Also, when we hit the hills, it would be great to have an increase in torque. Even though the trailer isn't heavy, there are a LOT of hills in the Pacific North West.

History:
I've got a free flow muffler with 3" pipe back. (First thing I did)
Air intake has been done.
Did headers a year ago.

Future:
I am going to covert to mass air. I was going to use the kit from Fiveology.

I already have a roller cam which I understand is already good for torque.
I would like to swap heads and intake. I was planning Edelbrock heads and Typhoon intake.

Here is where the questions start.

If I swap to mass air AND swap heads and intake, should I increase the injectors to 24lb? What happens to fuel consumption once you increase injector size? Would that be the correct injector size? Can I stick with 19lb?

Head and intake combo, is that a good idea for building some power, not breaking the bank and work with mass air?

Do I need to do all that for more power? Mass air is a given.
I would perfer to increase fuel economy if possible but I don't think it's likely. I just don't want to make it worse.

Your input and thoughts are appreciated.

Thanks guys,

Rob

 

MPG and vehicle weight vs what you intend to do with it often leads to fuzzy math.

Big vehicles and big blocks don't get less mpgs then the same vehicle with small blocks when weighted down. Empty maybe a different story.

You likely won't get worse mpgs in your truck with the upgrades if, and I do mean if you drive the same as you did before. You may even get ever so slightly better mpgs becouse you'd put down more torque at a lower rpm thus needing to give it less gas.

Also you'd probily get a bit better towing becouse your engine will once again put more torque down low where you need it to tow. Making you less likely to drop a gear, and rev a bit to keep up.

My reference were some friends who I've known.

1 of them had a GMC 3500 CCLB 4x4 with the 8100 big block. He did all the bolt-ons and a custom tune, and would regularly get 15-16mpg going down the hwy.

Another had a GMC 2500 CCSB 4x4 with the 6.0 with all the bolt-ons. 13-16 mpgs hwy, and always felt down on power. According to my friend.

We could insert Ford, Dodge, Toyota or any company with 2 different motors in the same truck. And the results should be similar.

So I say go for it.

Have you considered turbo charging? Big hp gains, and likely increase in mpgs greater then heads+MAF.

 

Welcome to the forums!

it will be fine with the bigger injectors because the computer will inject X amount of fuel regardless. they just need to be matched to the MAF.

if you don't go for a turbo or something, make sure youre compression ratio is at least 9.0:1 (I prefer higher, but live a mile above sea level and am willing to take the time to get the timing just right) and you might do a little bit better with a 4x4 cam for the torque.

speaking of which, if you were interested in learning how to tune fuel injection and get even more benefits, you could try out megasquirt or tweecer.

what drivetrain (gears and tires) are you running?

you might want to look into some aero mods too. even running a light topper when your pulling that airstream will help the air transition well from the truck to the camper.

the best thing for fuel mileage is a vacuum gauge- fixes the nut behind the wheel!

 

No.. not quite right. The computer holds the calibration data for the injectors and MAF meter so it is the part that need to be matched(tuned) to the injector/MAF combo meter being used. The "calibrated" MAF meter trick sorta/kinda works OK for performance applications, what it doesn't do very well is produce good fuel milage.

 

You could stick with 19s, they are good for 300hp and it's unlikely you'll exceed that with the stock cam. If you build the motor to a point it needs larger injectors it will consume more fuel when you're utilizing that extra fuel capacity(at rpms) but it shouldn't when the motor isn't spinning so hard. This assumes the computer has been recalibrated for these larger injectors however, all bets or off if that isn't done.

Yes it's a good idea since the stock 302 heads Ford installed on these motors are rather restrictive with this displacement, and same goes for the intake.

Mods that increase the volumetric efficiency of a motor and build more TQ will also increase fuel economy, and given that Ford badly smothered these trucks there is a lot of room for improvement. Sounds like you already have a decent exhaust system(assuming the stock cats/Y pipe are gone..if not that should be next), and have plans to address most of the choke points with the motor, but while the stock cam is a good RV grind it doesn't quite produce enough lift so some 1.7 rockers would be a good addition to help in that area. The other thing worth considering is axle gearing, many of these trucks have 3.55's which are OK with stock sized tires but leave a bit to be desired when towing or with larger tires. 4.10s would be great for towing but they will impact fuel milage so 3.73s is more of a happy medium, but it may not be worth the cost for such a small ratio change and considering your engine upgrades should produce substantial power increases. If your truck is an automatic it will have an E4OD, all auto transmissions have problems with heat but this one seems to have more than it's share so it's a real good idea to install an extra trans oil cooler.

 

That last F-150 I tuned had Edlebrock Perf. heads, roller cam and GT-40 intakes, and the factory MAF went above the range of the ECU before it ran out of injector. 24's and an aftermarket air meter would be ideal for your combo and it shouldn't hurt your fuel milage once it has been tuned properly. Even if you keep the 19's on it, it'll still need some type of aftermarket tuning.

 

This is all good stuff! Thanks for the support guys!

Ya, the old girl has stock tires, 235/85/16, 4.10's in the pumpkins and I have a toppper already. 5 speed all the way for me. I don't like autos, I've got 2 feet.

Aftermarket tuning eh, I had no idea. I thought it was just as simple as bolt on the parts, hook up the new computer and bada bing!
I guess I'll have to do some more reading.

I could do 1.7 rockers. That's a piece o cake.

It looks like my CR is 8.8. Kind of low I know. Can I fix this with a thinner head gasket?


For the most part I'm on the right track for fuel economy along with the torque gains for towing. The trailer won't be that heavy but anything would help.
Heads, intake, rockers, fuel management and I should be good to go.

Time to get the credit card out! LOL.......

If anyone else has tips, tricks or suggestions, I'm all ears.

R

 

At only 8.8 CR, I think a boost in air pressure would bring better improvements than the reduced flow intake. And better fuel economy if is tunned right.
I was planning something like that for my 302 too...

 

Well that thing is built or towing then.. but it's going to chug-a-lug the fuel unless you keep it at or below 60mph all the time. If you want to travel faster and/or get better milage you'll need to drop the axle gearing down to 3.55.

 

i would only do that if most of the towing is done on flat interstates at 80 mph. and if thats the case, the speed is killing your mpg more than anything else. remember the golden rule of aerodynamics: it takes 4 times the power to go twice as fast.

i usually run my 88 in 4th considering my local terrain, and granted its a tad underpowered (stock 302) thats also while running empty in an f150.

 

Actually, drag force goes up with the square of the speed, so drag power goes up with the cube of the speed. So it take 8 times the power to go twice as fast, given everything else being constant (which they never are).

If you're pushing a brick through the air on a flat road, the only way to improve gas mileage is to go slower. If you're going up a hill, it's possible that a higher speed will allow you to run in a higher gear, which will give you better gas mileage than revving the engine in a lower gear at a lower vehicle speed; it depends on the hill and your load.