i want to get 35MPG out of my pick up truck
 

i have a 2002 2wd reg cab toyota tacoma 2.4 4 cylinder 5 speed pick up and i would like to get 35mpg. the stock epa was i believe 26 mpg highway. i have the tires inflated to 44 psi and i have the grill blocked off 90% . i also have a drop in k&n air filter on the truck and driving at 65mph with the tailgate down i am just cracking above 30 mpg (on a gps not the speedo) of straight highway driving. i would like to know what people think i should do to get my mpg up. i am not looking to spend lots of money to get 5 more miles per gallon. also the truck has 200,000 miles on it and it isnt the nicest truck and i would have no problem with modifying it.

i am thinking about an areo cap on the back from the back of the cab to the bottom of the bed with the tail gate removed so it makes the back more of a point. any thoughts on how many mpg i would see out of that? i dont really want to put a whole bunch of funny looking areo stuff on the truck if it is only going to give me 1 more mpg.

i am also thinking about a hot air intake.

how about taking off my ac belt for the winter? anyone have any experience with that?

i tried taking off my fan on the motor but the motor started creeping up in temp so i put it back on. an electric fan? anyone have any experience with that?

THere's a lot you can do depending on how detailed you want to get, but generally its a myth that trucks get better mileage with the tailgate down. Try some runs with the tailgate up, that should take you one step closer to your goal. For more ideas look at "The Beast" in my garage.

-Jay

Jay's right about the tailgate.

Your ideas are good.

Aero cap: Read up on it, I think you want an 11? slope.

HAI: Go for it.

A/C belt: Your truck probably has a single serpentine belt. You could replace the whole thing with a shorter one that skips the A/C, but I'd just rig it to not run the A/C when running the defroster.

Electric fan: Common mod on GM full size trucks, but usually the people doing it aren't tracking MPG and are looking for horsepower. For the GM full size I think people are doing it with junkyard Ford Taurus electric fans.

More thoughts: Usually, the best MPG mod you can make, and one of the only cost-effective ones, is to adjust your driving. What have you done to your driving style?

on my truck the ac belt just goes around the harmonic balancer and the ac compressor.

i would feel better putting a ford taurus electric fan on my truck instead of a cheap auto part store fan that is made in china.

i was just driving real light on the gas and trying not to use the brakes. the time i got over 30 mpg i was on a long trip and filled up. got on the highway and ran the tank out

so you think i should build the areo cap with the taligate off or on? any ideas on the areo cap mpg? 1 mpg or 4 mpg? i have no idea just wondering if anyone has info.

Definately do it tailgate up. You are looking for no more than an 11 degree slope going down from the roof. Once the air is already flowing that way it will continue in that direction beyond the tailgate, kind of like a kamback. The whole notion that tailgate down is better was put in our minds by companies trying to sell us tailgate nets.

if i make the aeor cap with the tailgate up isnt there the same flat spot as behind the cab just a little smaller behind the tailgate? wouldnt it be better given the angle from the roof to the end of the bed is less than 11 degrees with the tailgate removed?

No, because of the 11 degree angled slope. The air will continue to slope and taper beyond the tailgate, as if the vehicle had the slope continue beyond the tailgate.

The flat spot behind the tailgate is there whether or not there's the flat spot behind the cab, so at least improving the one behind the cab is better than nothing at all. If you really wanted to, you could extend the cap past the rear of the vehicle.

You could also install a belly pan.

For driving style, you can do a whole lot of different things. Your manual transmission enables you to use even more techniques than an automatic would allow -- namely, you get real control of what gear you're in without gear choice being related to throttle usage, and you get to try engine-off coasting (advanced technique that I wouldn't recommend trying immediately, or ever depending on various factors).

I would recommend experimenting with shifting at different RPM and with using the throttle differently. In my manual transmission car, I am never light on the gas, and I'm 74.8% above the EPA rating. However, that doesn't mean that I go particularly fast. I shift very low, entering my next gear at almost idle, and I floor the gas pedal every time. Most vehicles can't use those extremes; you might need to enter your next gear at 1500rpm and use 75% of the gas pedal. Granted, that won't help you on the highway.

You might also experiment with coasting (engine-on) and Pulse & Glide.

For the tailgate thing, check out the myth buster's episode..

where can i find the myth buster's episode?

Right here:

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As usual, their science is awful, they fail to measure anything accurately or control their variables...but they've provided more data than anyone else on the issue.

[gv]-2400605931519184533[/gv]
Edit: Deleted second one since Jay posted it while I was writing up my post.

one thing about being on the gas really deep is to remember that at some point you go into open loop and your a/f ratio changes because it puts in more gas to give you more power. some vehicles (like theholycow's VW) has a wide band 02 sensor so it doesn't do that.

another thing about the slope of your truck bed thing. I have heard 11 degrees and 10 degrees but any mor than that and it might as well be straight down because the air is separating and causing drag. if you want a good example of the ideal slope, look at the back of a toyota prius or for a home made version here is basjoos' car

https://www.gassavers.org/garage_imag...12g66c7b6f.jpg

his car is "keeps on rollin" and is in the top 10 for gas vehicles (but not in the overall top 10 because of the motorcycles) he just replaced the motor and is now getting 78ish MPG. now that is impressive.

interesting stuff. i guess unless i get a scan gauge i am just guessing at getting better mpg.

so what would be a good scan gauge to get?

The current model is the Scangauge II w/X Gauge. Any Scangauge II can be upgraded to X Gauge if it doesn't have it though. I think its $25 for the company to upgrade the firmware in the device.

-Jay

Gauges can give you instant feedback, but nothing is as accurate as a gaslog. You certainly wouldn't be able to tell the difference with the tailgate using a ScanGauge.

what were the mythbuster guys using that was showing the differences?

They said they were using some kind of high-accuracy flow meter (in the 2nd video; in the first they just ran a specific amount of gas until the vehicle stalled from running out of gas), and I am not confident that it was really showing them the difference anyway. I'm pretty sure that the amount of the difference is totally lost in the noise of the uncontrolled variables.

The ScanGauge can't even directly measure fuel flow rate; it calculates a guess based on other variables, which is why it's necessary to adjust it manually.

Anyone tried a partial bed cover? One that covers the tailgate and rear 1/3 to 1/2 of the bed? I seem to recall reading that such a setup reduces drag against the tailgate without breaking up the circulating bubble behind the cab. I imagine the ideal length to leave uncovered would be slightly more than the height of the cab, measured from the floor of the bed.
Aerotabs?

i dunno but i do know a regular ol toneau cover has helped me (covers entire bed)

Somehow I just think that may end up operating like an open parachute.

Is the circulating bubble a good thing? I thought maybe the only reason it helps anything is that it could help air get over the tailgate. If you block off the tailgate area then you may not need the circulating bubble anymore.

My understanding of the bubble is that it forces the air over the tailgate, instead of hitting it.

some quick calculations. i figure at a 11 degree angle on a 6 ft pick up truck bed the back would only be 9" lower than the cab of my truck.

so rather than building something 9" lower in the back. does anyone have any experiece with a cap on a pick up truck and what kind of impact it makes on MPG?

Yep, that'd put a damper on things. The best you could do would be to make it from clear material and shape it like a Prius/Insight with the flat rear end and Prius/Insight/CRX-style vertical rear window at the back under the sloped one.

but to go through all the work of building somethimg like that would it have that much of an advantage over a standard cap?

There was a guy a while back that had designed an aero camper shell, I don't know if it ever went beyond the prototype stage though...


https://www.fuelly.com/attachments/fo...b5522a5722.jpg

https://www.fuelly.com/attachments/fo...8be6197cdf.jpg

https://www.fuelly.com/attachments/fo...e5c4c9ac0e.jpg

https://www.fuelly.com/attachments/fo...774e112373.jpg

Did he ever at least post some results for his prototype?

As I recall, we were discussing his cap, and he registered and chimed in on the discussion, then he kinda disappeared. We never really heard from him since. I can't find his post, or his username right now.

something like this??

https://www.evworld.com/images/pknox_toyota.jpg

sounds to me like it didnt make much of a difference on the mpg's or he would have been posting up the results

many people have good intentions to do elaborate modifications but when the chips are down, they just don't have the time or the drive.

this isn't to say that they are failures (the modifications that is) but rather any modification is a failure that is left undone.

I think we all have things that we want to do that end badly or end up on the backburner. I recently tried to make my bumper look better and due to time constraints and lack of fiber glass experience, it ended bad....very bad.

I am now revisiting this as my bumper looks worse than it ever has.

just because he didn't post results doesn't mean that the mod was a failure. many people don't post when they mess stuff up or when life threw them a monkey wrench and everything gets put on hold.

I can't say whether it is a good mod or not but someone elses silence won't sway me one sway or the other.

As I recall, he had cited the fact that he had no outside funding, so he still had to pay the bills and go to his regular job, this was a project that got whatever time and money was leftover.

scangauge II is on its way any advise from those of you who used them extensively. what setting to display? what kind of driving style changes are best? any info to maximize the use of it?

As far as what to watch... Depends on what you're trying to do. I usually watch instant MPG, Tank MPG, O2 sensor reading (so I can detect DFCO) and the 4th I will switch out. Right now its intake air temp. I've been thinking about programming the xgauge for distance to empty, but I just haven't done it.

-Jay

You'll decide on your own what data to display. I like current trip average MPG (I had to make that one as an XGauge, the instructions tell you how); open/closed loop for detecting DFCO; instant MPG; fIA (intake air temperature); fWT (coolant temp) if I'm afraid my grille block might be too much; and sometimes others. In my truck, which has an automatic transmission, I like to monitor torque converter slippage to see when it's locked and how much I'm wasting when it's not...that was a tough XGauge to make.

Edit: I often display distance to empty too.

As for what driving style changes, all the usual ones we discuss here; you can observe them in the current trip average to see if they're helping.

You got that one to finally work? Do you think it will work on my 98 K1500? i'd be interested to know when the T/C is locked.

-Jay

Yeah, it definitely works. The only issues are that it doesn't display negative numbers; instead it rolls around from 6553.5, so -500 would display as 6053, and that it seems to actually work off calculations rather than a sensor, so when neutral coasting it displays its equivalent of a negative number rather than 0.

i got a base reading on my truck before i installed my scangauge

i drove 65 mph with my tailgate up on my truck for 200+ miles. half the ride was with the lights on and the other with the lights off the air temp was below freezing due to the frost on the car in the morning when i left but got warmer as i drove. i put the truck in neutral on big hills and coasted ( i would say about 20 times). i recorded 30.11 mpg. this was straight highway driving.

also i took a 100 mile reading on my odometer and it was 101.9 miles on my gps. so my truck's odometer is 1.9% low. i noticed on the scan gauge to calibrate the speedometer it is in + or - a mph. how do i calibrate my scangauge being that the calibration is not linear?

can i download my gas log from my scangauge?