How do I improve my MPG.

I have heard that some of the things you can do to improve HP will also help in the around town MPG area.

Such as: Hi compression heads, smooth flow manafolds/glass packs, smooth flow exhaust, port and polish heads.

Also, I have a NP 4spd and 4.10 and going to a 5 speed and 3.55?(Don't know if I really want to do this part but I'm over 3K RPM at 55MPH)

Any help th I get around 12MPG now)
:-X12

 

You know, I don't think you will get much of an improvement over what you are getting now, no matter what you do to it, and maybe just a mile or two increase for all of the work. 12 mpg is pretty darn good for a 4x4 with a 429 in it.

 

No doubt, my 2 wheel drive only gets 8.5 on a good day. You have to consider, it takes alot of fuel and air to fill 460 cubic inches. So it will never be great. It's the price you pay for awesome power!!

 

Tell us more about the truck. What year what model, what engine, 4X4, etc?

In general unless you want to do drastic things to your truck, you will only get a little improvement. Trucks are by nature heavy, flow through the air like a brick, and have terrible friction losses through the power train. 4x4 and heavy bodies do the worst damage.

My 94 F250 4x4 460 E4OD 4.10 supercab long bed, yadda yadda gets maybe 11 to 12 mpg in mostly freeway with some city driving with no load. Almost doesn't matter how I drive it. Whem I tow, I get maybe 8-9mpg with at least 8,000lbs load. Only on nasty hills do I get down around 5-6mpg. This is good and bad. The 460 is not affected a lot by load unless extreme. Also bad since there is not a lot that will help unless you get radical. Hope I am wrong for your sake. But most of us settle for low teens.

Things that are cheap to try and might help a little are.. Tuneups, clean filters, correct air pressure in tires. Maybe synthetic lubes, a good wax job(really, but only a tiny boost). Drive gently and slowly. Try not to get into stop and go.

Going up in cost... Skinny tires with highway tread(those big mudders will suck gas), A shell on the bed, headers and free flowing exhaust(I am told this is the big fix on our trucks), a better ignition system(I hear Jacobs? gives a few mpg), intake and cam with power range in the RPM where you drive, high compression.

Expensive... turbocharger(tuned for mileage) different tranny, total engine rebuild(Blueprint and balance) with economy in mind. Windage trays, lightened reciprocating mass, port and polish will help a tiny bit, lower # gears(4x4 means both axles, yeow$$).

Ridiculous extremes... lighten the body a lot, ditto wheels and drivetrain.

Sorry to say you are driving a big heavy brick, gas mileage will vary but it will surely suck.

Good Luck,

Jim Henderson

 

Jim,

Thx for the input. My 74 crew cab weighs in a t 6500. My winter runners are 235/85R16s all seasons trk rads on white spokes. Summers are 275s and I am looking to put them on some new wheels.

The truck came originally with a 360 but now has a 79 460 case with 429 crank etc. It runs smooth. If I am gently on the pedal I get 12MPG.(Thats hard to do.) I have a NP 4spd devorced transfer case.(So only have rear turning mass when not in 4x4 and fronts unlocked)


I am now looking for a 5sp ZF S542 tran. I want to keep my 4.10s
I plan on raising the compression some by going to earlier heads or custom heads(still want reg gas, so not too hi compression for pinging(predetenation)problems), at the same time do a port/polish job, headers,and free flow exhaust, already have electronic igi.. Cam timing chanages.
I am going to be rebuilding my standard motor craft carb and adjusting the idle speed down to around 600(950 now), maybe changing out some jets and running lean as possible. Also, going to electric radiator fan, and possible other pumps(?)


Tell me more about:
Windage trays, lightened reciprocating mass, turbocharger(tuned for mileage)-- does a shell really help?

Will not lighten the body or wheel/dirve tran. keep the body bone stock.


I would like to hit 15 to 18 MPG-- I know GOOD LUCK trying.

I enjoy driving the 'big brick' esp. putting my foot to the floor when the light turns green(At least once or twice during the week!)and oh that growl/roar of that engine!- nice music.

Greg

 

Mid teens is possible. Some of the guys do get that.

With a carb motor, you may have some more options. You could go for a manifold with good low end response(RV type) or one with dual planes(small short primary runners, big long secondaries). If you have the money, a nice 4 barrel carb with small primaries will help, especially if there is a dual plane manifold available. The Motorcraft carb may still be usable and may also work with a dual plane or lowend power manifold

Windage trays are sheet metal trays that fit inside your crankcase. Essentially they prevent the oil in the pan from being whipped up by the spinning crankshaft. Some trays also have "crank scrapers" to "scrape" some of the flying oil off of the crank weights as it swings by. The crank creates a mini tornado in the oil pan, the flying oil causes drag which saps maybe 5-10 horses or so, this hurts mileage a little. Many performance engines come from the factory with a tray. My LT1 has one. Windage trays are cheap but require pulling the pan. You may already have one so read up on your engine.

The crankshaft has large weights on it, the weights cause 2 things that are "bad". Swinging the weights eats some power. The weights also act like a club against the flying oil, see windage tray above. Two things can be done about this, BUT there are tradeoffs. You can lighten the weights by knife edging them so they cut thru the flying oil and air easier. You could also remove some of the weights. The lighter weight also helps by not eating power to swing them around. The draw back is that you loose the energy storage ability of the crank. Swinging weights create momentum which helps to smooth out the engine and supplies a momentary force when you drop the clutch. So a lighter crank may bog the engine when you drop the clutch but the engine will rev up faster. This is NOT a job for the home mechanic. You need a good machine shop to work with you on this and keep in mind this is more a racers trick and you may not like the tradeoffs. I think a good blueprint and balance will give you more bang for the buck. Lightening and knife edging are more expensive and will give more results but you will loose some flexibility.

You could also use lighter rods and pistons. I also have read that shorter piston skirts and thinner rings will help power and mileage, but the tradeoff may be less durability. Aluminum rods are light but they don't take the pounding like steel does. There are good light steel rods available.

A turbocharger if properly sized and tuned for your truck will allow your engine to loaf along much of the time, while it beats the heck out of the fuel droplets(good for gas mileage). When you need the power, the turbo will kick in and allow your engine to do its work more efficiently. Most big rigs use turbos for these reasons. A turbo can also be a gas hog, so you need to know what you want to do with the truck and choose the turbo to fit the application. Turbos require differnt cam specs so choose both to work together. Ditto Turbos and pistons.

I have read that running with a shell does smooth the flow over the truck. Essentially it causes the turbulence in the slip stream to be further behind the truck which supposedly reduces the drag. Most big rig trucks have those funny deflectors or a "penthouse" on the roof to push the slip stream up and over the top of the trailer behind them. Must make a big difference, becuase maybe 20 years ago none of the big trucks had them, then gradually they all strated to have a deflector and now most have the deflector or penthouse.

Keep in mind I am no expert but do read a lot, I also did experiment with engine tricks way back and I do think the shell helps smooth the ride. I notice less buffetting when I drive with a shell. Don't go wild and get a high camper unless you really need one, this actually cuts mileage according to my friend's experience.

Good Luck,

Jim Henderson

 

Something else you can do is install a roller lifter cam, and full roller rocker arms, whenever you decrease internal engine friction, that is always a positive for better mileage. Keep your tire air pressure up tp max PSI, and even go a couple of pounds over, this decreases rolling resistance. Something to think about to tune your carb into tip-top shape is to get an aftermarket air/fuel ratio monitor, this will allow you to fine tune your carb for better mileage. Toss the absolute best coil, wires, and distrutor cap and rotor you can afford, it all helps.

 

 

Thanks very much for the input.
I have copied and pasted repleys for future review as I work toward beter mpg.

 

From what I hear and read, theres not much you can do. With 429/460 engines, guys say they get 10-13 mpg no matter how they drive or what they pull. The fact is, its too much of an engine for the application. As for all the mods you mentioned, you would be better off spending 300 bucks on a rice burner, if efficiency is your goal. Now, if performance is what you want, you got the right engine. And polished/ported high comp heads with headers would be money well spent.
As for the tranny, if strength is an issue, I would definitely stay with the np435. Very tough tranny. Your gonna spend alot to get a 5sd to take the power from a 429. Dont even think about it if the 5sp has an aluminum case and is from the yard. The ring gear will help tho.

 

everybody should read this http://www.corvair.org/chapters/chapter017/resources/tips/vv/engine_efficiency.html

 

[updated:LAST EDITED ON 27-Nov-02 AT 00:06 AM (EST)]I have a 90 f350 4door 460 injected dually that i use as my business truck. i pull a 8000 pound trailer with me everyjob im on.everyday pretty much.this truck is by far the best gas guzler ive owned. Ive had ford diesels turbo and not ...big block cheavy duallys and a dodge diesel.this truck would be the best if mpg wasnt a issue but i work mobile and that hurts my wallet. Im gonna get another diesel.I think a
non turbo 7.3 f350 dually and park this one until mpg isnt a worry
Just my thoughts....Jesse..