Mods I will try

[pmistel]

Hi

New to the site.

I have an 83 Mitsubishi Mighty Max with a 4 cyl diesel and 5 spd. I also use waste vegetable oil, so I am not too concerned with gas mileage, I look upon this as something interesting to try. A challenge!

What I was thinking is I will try "Airtabs" on the roof, I am getting a Tonneau cover for the bed, I ordered some racing disk hubcaps, I will try some grill blocking and if I get really ambitous, a belly pan and wheel skirts.

What is a reliable, low tech way to measure MPG? I don't drive the truck much so it will have to involve some short measured distance? I normally drive 90% of the time on vege oil but I don't mind using petro diesel to do testing.

Thanks

Peter

[MetroMPG]

Hey Peter, welcome to the site. Good list of planned mods you have.

I'm at a loss for what to recommend for instrumentation for measuring fuel economy though. Normally the stock answer for pre OBD2 vehicles is the SuperMID, but I can't tell you if it'll work on a diesel. (Also it doesn't really qualify as low tech.)

Maybe someone with more info will pipe up...

[pmistel]

For measuring MPG, I was thinking just fill it up as much as I can, drive a measured distance, 10KM?, drive back to gas station and fill it back up. Calculate.

Peter

[omgwtfbyobbq]

I'm not totally sure about this, but it's something to try. Route the fuel return line into a bottle and measure how much fuel gets in at idle, and at some higher rpm over the same time period. I'm pretty sure an increase in the amount of fuel injected results in an increase in the fuel headed back to the tank, but I could be wrong. If more power -> more fuel flow, you can test your return flow before and after your mods under the same conditions to see if there was a measurable difference by comparing the difference in fuel in the bottle.

There are also electronic devices that can measure flow (fuel in less fuel out is fuel consumed) but I've heard they aren't very accurate and you'd need to rig a way of recording the info. You could put piezos on injectors, but that requires testing the breaking pressure of them, figuring the flow rate, and rigging a way to record the results as well.

[Yoshi]

Originally Posted by theclencher

SuperMID measures injector pulses doesn't it? So it wouldn't work on carbed or diesel engines.

Yes, the SuperMID measures the injector pulse period.
The period is between 2 and 6 msec on Toyota Prius.
If the diesel injection is controlled by electric pulse, it may work.
But...
The fuel pressure on diesel engine is very high and the pulse period may be too short for the SuperMID.
On the modern ultra high pressure common rail diesel, it does multiple injection on a single combustion cycle and the pulse period is between 0.1 and 0.5 msec, then there is no chance for my SuperMID here.

Yoshi

[Ted Hart]

Originally Posted by pmistel

Hi

New to the site.



What I was thinking is I will try "Airtabs" on the roof,

What is a reliable, low tech way to measure MPG?
Thanks

Peter

Hi, Peter!
Welcome to the scrappiest bunch of consumers on the Web! LOL!
I was surfing by...and saw your question about low tech (make it yourself?) and low cost (scrap wood) way to measure MPG.
I, too, was disappointed by all this high tech / high dollar stuff ... to measure MPG! It's just so not necessary!
Do this : -be sure to park the vehicle in the same spot each time you check! This ensures the slope / tilt is the same (mark the tire contact patches with paint? ...something permanent).

-Prepare a "dipstick" (a straight,clean wooden stout stick?) to insert into your gas / diesel / veggie oil tank. Insert it to the same depth each time (bottom? As far as it will easily go? Mark top of 'stick. since the vehicle is stopped on the same spot, this stick angle will not change.
-Divide the total 'stick length...from the full mark to the bottom mark... into 10 evenly spaced segments. These become 10% divisions. F l----l----l----l----l----l----l----l----l----l----l E
-Now, the most difficult part of the entire process...you must determine how many gallons your tank holds. There are two ways, one is to look up the tank capacity in the owner's guide (or a motor's manual on your specific vehicle)...the other way is to fill your DRY tank to the top rim , reading the gallons / liters from the pump. Because your dipstick is divided into tenths ( and quarters of these)... you can convert to gallons or liters directly.
- If you wrote everything down as you noted it...the MPG / LPKm is easily taken from your notes. And, it only takes a minute, and you don't have to mess with refueling periods! Do this at home, on your chosen spot, at any time! Easy? Cheap? Simple? Just take good notes...in a secure notebook!

- Now, at evenly spaced mileage segments (100 miles?more?), stop the vehicle on your chosen spot, let it sit a minute, remove the fuel filler cap, insert the "dipstick" to the full mark, remove the 'stick, and measure the wet depth on the 'stick. It will read some % of full. Write this % no. down.Write the mileage showing on the odometer down, too.
- Repeat this "dip measure" at the next chosen mileage segment. Write the new %, mileage no. down. You now know how much fuel has been consumed in how many miles. It will be in %, but you can convert.
Note: This only works until you refuel. then, you start over. The changes in segments when new fuel is added changes the point from which you start.

[JanGeo]

If only the filler spout was a straight path to the gas tank this would work but alass they are not and may even contain snares and one way flappers to grap onto objects that are inserted so they can not be removed.