that osama part is halarious!!!

you wrote "I don't need any road tests to know why fuel mileage goes down with speed"

that is my point its not the road speed its the lack of 6, 7, 8, gear or RPM.
Its primaraly the rpm of the engine that causes the fuel mileage to go down. thats why overdrive saves gas regaurdless of road speed its the lower rpm.
Thats why my test will prove correct.

You drive at 55mph in 4th gear. 11mpg
you drive at 55mph in 5th gear. 16mpg
you drive at 55mph and had 6 gear 18mpg
you drive at 55mph and had 7 gear 20mpg
you drive at 55mph and had 8 gear 22mpg double the gas milage of 4th gear!

 

I didn't ever know about gear vendor when i started this post, I beleve these below posts proves my point about rpm and fuel mileage.

http://www.gearvendors.com/testimonials.html

FROM: THE R.V. DRIVING SCHOOL

I am writing this letter to thank you and your company for the GEAR VENDORS Under/Overdrive you installed in my pick up on, Sept 9, 1995. I have already saved on fuel economy, about 24%. That is worth the unit alone. As far as towing with the unit, it is great.

We ask ourselves, how did we get by without the Gear Vendors Under/Overdrive? I have demonstrated the unit to at least two people already. One a past student, and also my new instructor. Both will be installing units in their vehicles soon.

Please feel free to use me as a personal reference as to how great your Gear Vendors Under/Overdrive works in towing and driving. I am looking forward to seeing you at the RV Manufacturers' Show in Pomona.

Sincerely yours,
Signature
Richard (****) Reed
1512 E. 5th St. #149
Ontario, CA 91764
(909) 984-7746



Subj: Gear Vendors
Date: 5/9/00 5:07:15 PM Pacific Daylight Time
From: Johnsontwdd@aol.com
To: info@gearvendors.com

I just returned form my first trip with my new gear vendors under/overdrive. The unit was installed by Chance transmission, one of your dealers here in Kansas. I am extremely pleased with the service and treatment I received from this shop. The unit was installed in my 27 foot, 1989 Jayco, class C motorhome. I have a 460 V/8 with a 3 speed C-6 transmission. I only have 30 K miles on it and have averaged between 7 and 7 1/2 mpg since it was new.

On this 600 mile trip I average 9.5 mpg. I could barely hear my engine on the highway at 65 mph. We drove in some of the Missouri Ozark hills and I am amazed at the performance of this motorhome. Second gear over is an absolute thrill to use in the mountains. I read and studied all the literature I could get on the Gear Vendors under/overdrive before purchasing the unit. However, nothing prepared me for the mpg increase, or the performance change it made in my motorhome. Thank You, Thank You, for building a product that does everything you say it will and then some. I've just retired and I feel like a kid with a new toy. Feel free to use my name as an endorsement on this fine product.

A HAPPY CAMPER!

Tom W. Johnson
2448 Cardinal Dr.
Wichita, Kansas
(316)832-9105

 

I didn't say $#!+ about your character. Talk about twisting something! But since you brought it up: I don't think you have much. HAPPY?A) Driving while watching a tachometer (that most vehicles don't even HAVE) isn't "simple"; it's 'simply dangerous', and more importantly POINTLESS because B) as I said: it's no test for anything. It's a dumb idea, and a waste of time & gas. Right. If you suggested we all cut off one leg & dye our hair purple to see what happens, I might encourage people NOT to do that, too.You already can't read (or write) English!Terrified. Shaking in my boots. Tell it to the engineers & chemists who study it their whole careers....and you obviously have neither. For the last time: it's not. Chemistry is quite complex, especially at a few thousand degrees, at a few hundred psi, with as many components as air & gasoline contain.Ooooohhh... You really got me with your fry-cook physics. You obviously have a MUCH better understanding of the way things work than people who get paid hundreds ouf thousands of dollars a year. I guess I'll just go back to playing with my slide rule & finish up writing Pi's last digit. How would you know how much my degree cost, assuming I have one?Are you out of 3rd grade yet?Probably not. Stop whining. Every thing is still IN CONTEXT (he says, assuming you know what that means). It's not our fault that your context is dumb.


OK Assuming this thread doesn't get locked in the next few minutes, I'm "CHICKENING OUT" (for all the 3rd-graders). I won't participate in it any more.

 

steve calm down.
your above post has nothing to do with the subject and is a rant please edit it before the whole thread gets deleted unless that is what you are trying to acomplish to hide your embarrasment.

 

Danco,
I'm not taking sides here, but Steve is more correct. There are way too many variables to take into account then to be able to make a simplified statement such as, " Lower RPM = Better fuel economy." My wifes Jeep Grand Cherokee does have the built in economy gauge, and I can tell you at 70 mph, in o/d, on the highway, it gets about 18.5 mpg. However, at 74 mph, it gets better, at around 19.1 mpg. I don't have the vehicle here, she's in another state, but I would try it with and without o/d if she was here. Since it has the 5.2L, I've never had to take it out of o/d no matter what I've pulled.

Now, as a generalization, yes lower RPM's do mean better economy. However, that theory is more correctly applied to start/stop driving. If I put my foot down halfway to the floor at every stoplight, revving up to 3,800 before shifts, then I will use much more fuel than if I gently got into it and shifted at 2,000.

For highway driving, the greatest volumetric efficiency is the 'sweet spot' in the RPM band. What defines this 'sweet spot'? The camshaft! It controls the airflow in and out of the engine. Other factors are port matching, carbon buildup, valve spring wear and rocker wear. The manufacturer controls the 'sweet spot' with the choice of cam, but since all engines are different, they'll all have different numbers. I challenge you to build 10 identical engines, down to the last bolt identical, and have them flow tested and dynoed. Bet you my paycheck they're all different.

BTW, it's real hard to convince someone that you're a knowledgable individual and are having an intellectual discussion with them when you're grammer and spelling are crap.

 

98 your post say's i am 100% correct in this para graph below. yet you write that steve is more correct???

"Now, as a generalization, yes lower RPM's do mean better economy. However, that theory is more correctly applied to start/stop driving. If I put my foot down halfway to the floor at every stoplight, revving up to 3,800 before shifts, then I will use much more fuel than if I gently got into it and shifted at 2,000.

if you read all the post' up to now you will have a clear picture of what the argument is starting from my first post. (overdrive saves gas due to lower rpms)

please ask your wife to test @ 55mph overdrive on and overdrive off on a level road and what the mpg is on both. if there is a rpm meter that also with the results. thank you.

Also if you read the gearvendor testamonalys from pick ups and Rv's it says in so many words that higher gears=lower rpms=better mpg.
"nothing prepared me for the mpg increase"
"I am writing this letter to thank you and your company for the GEAR VENDORS Under/Overdrive you installed in my pick up on, Sept 9, 1995. I have already saved on fuel economy, about 24%. That is worth the unit alone. As far as towing with the unit, it is great.

 

I said GENERALLY. It's sort of convantional wisdom, a partial wives tale that does have some merit. It applies mostly to older carburated cars, where the flow of fuel was actually dictated by throttle position. Today, it's derived from about 10-15 variables, and calculated by fuel maps in the PCM.

I have read them all. I have a great intrest in anything that puts money back into my pocket. In Utopia your theories do hold water. However, 'all things being equal' is not the way of our world.

... My wife is lucky enough to stay on the road. I wouldn't ask her to do that and then have to explain what the O/D button is and what a tachometer does...


Yeah, umm, for what thats worth... Ever heard of the Tornado?



“In my 40 years living the automotive service life, I can’t remember any automotive aftermarket product that was as inexpensive and maintenance free as Tornado and that delivered such positive results.”



-- Bobby Likis, Car Clinic Network Inc. syndicated radio host
__________________________________________________ _______

"My listeners are pleased with the results they have gotten by installing the Tornado on their cars and light trucks. RV and Motor Home users also report some great results."
-- Sam Memmolo, co-host of the original Shadetree Mechanic TV show and syndicated radio host.

 

THIS is the hasty generalization that we're talking about and trying to explain to you that it's not a cause and effect relationship. EVERY engine/drivetrain/vehicle is different. In *some* cases, taller gearing leads to better mileage under certain operating conditions. We're not disputing that. However, the blanket statement that lower RPMs will always result in better fuel economy is a load of crap. If it was that simple, why don't the OEMs make the overdrive insanely high to drop the RPMs to just off idle? By your theory, the taller the final drive ratio, the better the economy. Maybe in a perfect utopia.

What it boils down to is that in *some* cases, overdrive results in a lower operating RPM, and *sometimes* results in better fuel economy. However there is no direct correlation between fuel consumption and engine RPM. There are too many variables that influence fuel consumption.

-Joe

 

I don't know about how much gas I'd save, but I would love to have a GearVendor over/under thing a ma gig (did I spell that right) on my 5.4 3V. Eight gears would put such a grin on that the gas pump wouldn't be as much of a concern. Maybe that's just as good as better gas milage.

 

Be careful about the gear vendor's thing. Most of their info is in regards to DIESEL engines. Where the physics of the higher gear ratio would predict better fuel mileage, I doubt that your computer's programming would reap full benefit. Not to mention the camshaft etc. selection. You see, it all goes back to my previous post. Ford built this thing as a truck. Now, you can do some things to help a little, but you're probably not going to see a huge increase even with the gear vendor's unit. Mainly because the strategy of the pcm will start taking drastic measures (such as enriching the mixture) when you're running near WOT in O/D at 1,100 rpm's trying to maintain 55 in 8th gear!!! You can't go monkeying with these trucks and expect "gearvendor's testimonial" results.

We keep crossing the line of basic gasoline engine physics, and FORD TRUCK gasoline engine physics.

 

Paradigm Stuckness

which is the tendency in all people to cling to the framework they are confortable in, even in the face of overwhelming logic.

i feel that many of you have Paradigm Stuckness. Maybe when someone post a real world test of rpm and fuel and set speed... just maybe then you might do the test yourself and get your minds un-stuck in what you are comfortable in beleveing. i feel like i have been argueing with a brick wall's one excuse after another why it doesn't work yet none has done an actual test with your own vehicle....pathetic...sad...
http://www.urbanecology.org.au/ecoci...ginfuture.html

 

I think that the GearVendor Over/Under drive addition still depends on the logic of the OEM transmission. So if you were at WOT it would shift to the next gear to compensate. It basically works like your original tranny just putting an extra gear here and there. And it may not be able to pull 8th gear with a tired old engine and it might not save you any gas, but when the Toyota guys tell you about their new 6 speed tranny, you can tell them you got 8. Now isn't that worth a messily $2500 bucks?

 

Yeah I know, I meant that when you're in 8th gear, even a new engine is gonna be at 60-70% throttle at least. That's fine in a "test tube" environment, but your truck's engine starts doing a lot of inneficient things around 70% throttle. Such as enriching the mixture, going open loop etc. So, in theory it would work. But on a FORD GASOLINE, it probably wouldn't do right. The demands wouldn't jive with the programming. Now on a diesel, it would probably do fine.

 

This is an excerpt from the Gear Vendors above. I think it justifies the comments that there's a lot more variables than just RPM - after all, he's using SECOND gear with an overdrive to gain MPG - if it were all about RPMs, then second would be costing him mileage.

The right gear to acheive minimum throttle position is most likely to acheive maximum MPG... although not always, it's a good generalization.

 

To those of you who have an Edge, or similar gauge system, here's what you do: Put engine load % in one window, RPM in another, then IMPG, and AMPG. Watch the relationship between IMPG, and engine load %. They are directly proportional, regardless of RPM. In fact, when you accelerate with a load (this is especially noticeable when you are pulling a hill, and cruise control fights to keep up... this takes the human factor out with the pedal), you will see engine load increase, then it downshifts, RPM goes up, and engine load decreases. Additionally, IMPG Increases when the load percentage goes down, despite the fact that the RPM has gone up. Lower RPM's does not always equate to better fuel economy. Also, it makes no sense to keep it in overdrive if it is slipping out of lockup, since you are spinning fluid, creating heat, and therefore losing driveline efficiency, lowering MPG.



Aerodynamics has far more effect on fuel economy, all else being equal. Try pulling an enclosed toy hauler, empty, and see your mpg. Then, haul a flat bed with 5000 lbs of low profile weight, and see the difference. In highway conditions, you will get worse mileage with the empty enclosed trailer, than with the heavy, aerodynamic trailer.