Anyone got a dyno?

[SVOboy]

Well then! Willing to come it with a testing procedure with the group that'll be accurate and then go test it out actually?

[MetroMPG]

smog dyno may be perfect. you can measure fuel consumption directly from carbon emissions (if you can measure that directly). they're proportional to fuel burned:

the total amount of fuel used is determined through the "carbon balance" method (the mass of carbon emitted from the exhaust must equal the mass of carbon in the fuel consumed) and hence the overall fuel economy is calculated. -

[Matt Timion]

Originally Posted by MetroMPG

smog dyno may be perfect. you can measure fuel consumption directly from carbon emissions (if you can measure that directly). they're proportional to fuel burned:

Be careful with this one. This is how the EPA used to measure fuel economy, which they are now changing due to it being too inaccurate.

[MetroMPG]

that may be, but they tried to *extrapolate* MPG figures from the carbon emissions - that's the problem.

if i had a smog dyno, i wouldn't care about extrapolated mpg numbers. fuel used is still directly proportional to carbon emissions, and it's the *difference* in those directly measurable figures (or not) between mods that i'd be most interested in, not some calculated mpg figure.

(not surprisingly, this was how the EPA defended its lame mpg extrapolations: by saying the tests are still a valid way to *compare* different vehicles' relative efficiencies, regardless of the accuracy of the mpg extrapolations. which is true.)

for testing purposes, isn't that the data you're really after?

[SVOboy]

I totally agree with you metro. All you need to compare is the number and a percentage,

[GasSavers_Diemaster]

it's a 5 gas analizer, CO2, O2, HC, CO, and NOx. for those that dont know those :P :

carbon dioxide, higher the better % shows eficenty of cat. bad cat or hollowed = ~11% good new cat ~16%

oxygen, lower is better. 0% is best but will is ok w/ 0.02%

hydrocarbon, unburned fuel. should be like 20-30 ppm gota a missfire this goes up to like 2-300 running super rich like black smoke this is ~3000

carbon monoxide, this is the one that kills u. should be below 100ppm

nitrates of oxygen, this is reason u got the dyno. needs to be mesured on loaded motor. more load more nox. most difficult to control. EGR directly accotiated with nox.

[JanGeo]

Hey all you get from the dyno is a properly running and tuned engine - your mileage result is a function of the engine and the rest of the variables that make the car move through the air and over the ground. Friction, air drag, inclines, all affect mileage and can't be easily measured or simulated on a dyno so why bother - tune the engine the best you can on the dyno and run mpg testing on the road in the real world.

[SVOboy]

Originally Posted by JanGeo

Hey all you get from the dyno is a properly running and tuned engine - your mileage result is a function of the engine and the rest of the variables that make the car move through the air and over the ground. Friction, air drag, inclines, all affect mileage and can't be easily measured or simulated on a dyno so why bother - tune the engine the best you can on the dyno and run mpg testing on the road in the real world.

Think you missed the point...all of those things like wind and air drag and friction differences are whatmake testing in the real world an issue.

[JanGeo]

Yeah But that IS my point - you can't simulate those variables so why even try - drive the roads as you usually do and see what you get. Doesn't matter if I can get better gas mileage on my roads than you can on your roads, only that you get the best that YOU can get. My main drag here is concrete but really bumpy - my neck is killing me from going up and down it today. Thinking about doing my 12 mile lap tonight to see if I get better mileage in the rain. Typically I get 48-53mpg on the trip ScanGauge 25-30mph some hills and a traffic light twice and four stop signs.

Got a friend that is about to take a long trip in his F150 and I got him to try the acetone and maybe the GP-7 in his 25 gallon gas tank. He drives like a madman so it will be a good test.

[SVOboy]

Yeah But that IS my point - you can't simulate those variables so why even try - drive the roads as you usually do and see what you get. Doesn't matter if I can get better gas mileage on my roads than you can on your roads, only that you get the best that YOU can get.

THe point is not to simulate variables, it's to eliminate them. If you can prove that a mod does something without the effects of bull**** like wind then you know it acutally does something, whereas you and I could drive on our seperate roads and get opposite results. Less variables is better for testing, that's just that.

Just look at Metro's latest long drive. 10 mpg difference between tailwind and headwind, that kind of variability that makes all MPG claims suspect isn't present on the dyno.