MMA_Alex

Cold air is denser, so more gas can be added to the cyl. for more power

Dirt Driver

Yeah, I've heard that quite a few times also. Something about a pocket of turbulent air behind the cab that actually causes more air to go over the truck than through the bed w/the gate down. I had a pair of wet shoes by the gate that I was drying out and after an hour on the freeway with no stops, they were behind the cab.

To expand on what MMA_Alex said, cold air has more "air" molecules(actually a number of different gasses) per given volume. It simply has the effect of making an engine more volumetrically efficient. If the air:fuel ratio doesn't change, then mileage tends not to either. Ideally the brake specific fuel consumption(BSFC) is as low as possible, meaning that it takes the least amount of fuel for an engine to make one horsepower for one hour. That usually means lean AFRs.

86 TurboSR5

I have a turbo . Everythings stock. 35lbs in tires. Cruise control at 62 mph about 2400 rpms. 5 speed R 150 in truck. 2wd. I.ll bet I can do a lot better mpg since truck has since had a tune up and injectors cleaned and I took my weight out. This truck runs forever in neutral doesnt seem to have any resistance at all. Like a good casablanca fan. LOLMotor has 50K on it orig. x cab with camper.

GrimReaper

Chirst dude thats HORRIBLE! my 454 6700lb Suburban with TH400 (no overdrive) can pull 11.5 on the hwy. It would get 10.5 pulling your Runner on a trailer!

You either have a serious problem or your odometer is way off. You running stock size tires?



As to the original question:

MPG is a combination of Aerodynamics, Gearing, weight, driver. You change any of those and the MPG will change as well. Weight, once it is rolling, while important is not going to have as much of an effect as Aerodynamics or gearing.

The amount of weight you could take out of a truck and still have it usable and comfy is not going to have much of an effect....Yeah having an extra 500lb in the bed will hurt but if you stripped that truck to the gills you might realize a 1/2mpg gain at the very best. That would be no sound insulation, carpet, passenger seat, A/C, heat, spare tire, radio.

There is a threshold where the the Gearing puts the engine into its sweet spot where it will get the best economy. If you go to a larger tire size you not only throw off the odometer you move that sweet spot. A narrow light tire wheel combinations has less wind resistance and the lower weight cuts down rotational mass.

The stock steel chromes are unbelievably heavy! I just swapped out wheels and tires on my truck. The factory 86 Chromes with 235x75x15 Unijunks were 61.5 lb. The 33x12.5x15 BFG KO's on a set of 15x7 AR OutlawII's I put on were just a hair under 68lb. Now most of that extra weight is on the radius so I'm still suffering but a Set of 33x10.5's would be about the same weigh as the stock set up...maybe lighter. The BFG;s look to be about 4.5lb per inch of tread width between a 10.5 and 12.5.

Toyota did a pretty good job setting the gear ratio to maximize MPG at about 60-65 mph with the tire size the truck came with from the factory. Ideally any tires size changed you want to try to keep that effective gearing.

Now as speed increases so does wind resistance. So the faster you drive the harder the engine has to work to overcome the extra wind resistance. The taller the truck (4wd vr 2wd) the worse it will get. So anything you can do to keep the truck lower to the ground and cleaner aerodynamically will help.

Tail gate closed has repeatedly been proved to be much more aerodynamic then gate open. It helps make the air coming off the back of the cab cleaner.

A/C or no A/C: On the hwy you will probably get better mpg with windows up A/C on then no A/C on windows down. The wind drag from the open windows will be more then the engine drag from the compressor. My Dodge 1500 work Van gets almost 1.5 mpg better at a steady 65-70mph cruise with windows up A/C on.

Now when it all comes down to it. The MPG your getting is respectable for the vehicle. The best reasonable thing you could do to improve it is slow down on the hwy.

GrimReaper

33 is quite impressive. Have you verified odometer accuracy?

Everything is done right on your truck. The shell is doing more to improve aerodynamics then the weight of it does to make it worse. Stock gearing, stock size tires. The low compression motor helps at steady cruise when its not boosting even.

About the only thing you can do to help any more is synthetic fluids and lower it with an air damn to clean up the airodynamics some more.

old 86

I got my truck 25,000 miles ago. Getting 17-19 miles to the gallon, its a 22re, and I've since started putting good oil, good wires (7mm), plugs (bosch platnium2's), everything else is pretty much stock (except the horn from a 57 caddy), and I am up to 21.5 around town, just put a cap on the bed last tank and adjusted the spacing on the valves/lifter(?) back to stock so will see if it improves, haven't done a hiway tank in a long time. The things has 229,000 miles on it now and seems to keep running better and better, oh its got 235/75/15's on it 5lbs over on pressure, can anybody think of an other little things I can do to raise the mpg other than tire size, those will probably get bigger sooner or later? Does synthetic oil really make a difference, I run high milage castrol gtx with a quart of lucas everychange right not, would a K&N filter make a difference? Are there any fuel additives to stay away from, as in are total crap or can actually damae the engine?

misterzee

my 87 4-runner gets 21 mpg on a 22re with 197000 miles. It'll be interesting to see how it improves when I replace the engine.

curtiswyant

Weather can make a big difference, too. I've noticed a 3-4 mpg drop (27 to 23) in my carbed truck in summer vs. fall.

trythis

That says everything

good wires (7mm), plugs (bosch platnium2's), everything else
You might wanna switch to NGK plugs. THey work better in tehse engines. Bosch plugs go in german cars, NGK go in Toyota's

nat88toy

if you want to get really picky give it a wax job to get better arodynamic flow and rip off the pasanger side mirror there is a reason why alot of 90's erra hondas only had a drivers side mirror

Dirt Driver

Got that, but what about a regular camper shell? Everyone has said to leave a shell off the truck to save weight, but what about reducing drag?

BTW, 31.5mpg today.

amrshalaby

what about Seafoam try it

Dirt Driver

Wow, eight years later...

Most of the U.S. uses ethanol to oxygenate gasoline these days and there's nothing in Sea Foam that will do what that ethanol isn't already doing.

Elwiney

Lol now you have 1k+ Post's around here

ev13wt

But remove the tailgate. Must be 1mpg of resistance

(sorry guys, new to the board :p )

Co_94_PU

iTrader: (-1)

Busted...

ev13wt

I have a 3K mile old "brand new" OEM 22-RE in the truck. Adjusted air, tps, cleaned and "balanced lol" injectors, new fuel filter. New cap, rotor + wires (well, I have another in the garage, but enough with the bragging)


1:4.11
31x10.5 MT BFG
New bearings everywhere.
Manual.

14l / 100 KM
19/20 MPG
Measured at 15°C / 59°F

Speedo corrected with GPS, it's 5.7% off
Filled up from "start of fuel light when on slight incline down" and ran it until same light.
250 miles (+5.7%) . I pushed the last mile.

I need to pull a plug later. But I think ... 19 MPG is what these trucks did when new.

ev13wt

When the tailgate on your pickup truck is closed or “up”, it actually increases fuel efficiency. This is because there is a type of air pocket created that is called a “separated bubble effect” within the bed of the truck. Wind that is flowing over your moving pickup truck bed is deflected by the bubble of slow moving air. This bubble of air pushes and guides the air over your tailgate making it more aerodynamically efficient. The effect of the vortex creates less drag which increases fuel efficiency.

https://removeandreplace.com/2015/07...te-up-or-down/

Neemox

I have almost the exact same story to add to this ancient thread, but just as an additional point of data, I now have about 9K on a new OEM 22RE, 5 spd, almost identical set-up I also get between 18 and 20 mpg (driving in the colorado front range, city and highway). I do have an oil burning issue that the shop won't fix, but another mechanic says that's probably not affecting my mileage or power too much. Can't imagine getting 30mpg, that sounds,... nice.

ev13wt

Thanks for the data point. I do think some of the milage claims are erroneously calculated. I can see 24 highway with skinny small tires on a lowered truck if you keep it under 50mph / 80KM. Under 50, aerodynamics play close to "no" role. Above that and it get's interesting.
30% of CW is tires, 20% is undercarriage. A Surfboard on the roof will screw it up with -40% CW (10% Fuel), empty tray up top -10% cw , open window -5% cw.

I got really fking lucky with my two OEM brand new 22-REs - a grand a pop on the German ebay. These trucks where never sold here, but some dude that went out of business had 2/3 still for sale months later after the shop closed down. They where intended for a VW Taro Pickup Truck.

How did you come to a "new" 22-RE?