forgive me as this is not a specific ford truck post but i am wondering what you guys would think of this idea. Just like your speedometer has a odometer under it, make a odometer under the rpm gauge. This will measure the engine lifetime rotations. I think it would be a good way to measure the way a car is driven over time. it would be electronic, since the rpm count would be very high over time. You could divide the lifetime by the miles driven and determin if the pedal was to the metal all the time or if grandma was driving..... It would also be a cool gauge to look at... What you guys this?

 

It would have to number in the billions to be useful. Think about it, if you drive for an hour at 2500 rpm you'll get a total of 150000. It would probably not be very useful.

Our tractors have something similar, but it tracks hours of use.

 

it would be usefull for example you could say a car thats 10 years driven 2500 rpms a hour a day 5 days a week 52 weeks a year @ 60 mph year should have 390,000,000 engine rpms at 156K miles. now if were looking to buy a 10 year old car and it had 4,000,000,000 rpms @ 156k miles then you know something was up. Since its in the computer it would say 390M or 4.5B to make it more readable. woulednt it be a better gauge for doing engine service? i have seen hour meters that are rated at a certian rpm ex: 2500.. running less rpms will add time slower, running higher rpms will add time faster.

 

makes sense. i could see its usefulness. once you add something like that, an hourmeter would be the next logical step too.

 

I dunno...I think I like the hour meter suggestion. I see how the "RPM odometer" concept works, and it's not a bad idea, but it'd be complicated unless you have a decent electrical engineering background. An hour meter would do basically the same thing in telling you HOW a vehicle was driven. If you saw a car with 1000 miles and only 10 hours, you could tell that someone was flying under the radar with it. But if it had 1000 miles and 100 hours, you'd see that some grampa couldn't find the skinny pedal.

FWIW, I've only seen hour meters that vary with engine RPM on tractors with cable-driven tachs...and even at rated PTO RPM, I've never seen one that's all that accurate. Electric hour meters run at a steady pace, regardless of RPM. Heck, I've even toyed with the idea of putting one in my pickup as a more consistent gauge for oil changes.

My 2¢...
Pat

 

an hour meter CANT tell you how an engine is driving., only the amout of TIME the vehicles engine was running. Heres another example. You are looking to buy a boat. you find one thats 1 year old and has 100 hours on it. Sound normal. but wait, How do you know if this guy was flying his boat across the lake at WOT all day or was he just out slowly looking for fish? You cant know. Lets say i wanted to drive to work every day in 2nd gear... How would you know?

 

The one thing a hour meter can tell you is how long the engine was running, a vehicle may have 100,000 miles on it, but its possible to have 200,000 miles worth of engine wear if the owner left the car idling all the time. If the owner always left the car running while pumping gas, or left it running while they ran into the store, then that engine will have more wear then a vehicle with simulair miles that was shut off when not in use. Another benefit is you can use the hour gauge for services intervals, you can change your oil after a set amount of hours. You may have only driven 3000 miles between oil changes, but your engine may have ran 100 extra hours on this oil then the previous oil.

I have a digital hour gauge in my 82, I added it when i rebuilt the engine. The gauge was hooked up before the first start up, it counted .5 hours through the cam break in period, and it being counting ever since.

I also like the idea of a rpm odometer, simply for the fact that it'll tell if a engine has been run hard for most of its life.


Most people may not see the need for added gauges, but I love them, the more my truck can tell me while driving the better.

 

Most engine wear occurs when you start it, because no oil pressure is available when the engine isn't turning and full oil pressure is not available before during cranking.

Only when the engine catches and reaches idle RPM does the pressure climb to acceptable levels.

And just because a device with an engine (car, boat, riding mower, chipper, etc) seems okay when you look at it doesn't tell you if the owner drove it around for 50,000 with the oil light on, replacing the oil pump 10 minutes before you arrived to consider bying the device/vehicle.

Hour meters and odometers merely give you a clue. While they are good clues, that's all they are.

 

There are two different ways of measuring engine hours. One simply measures how long in clock hours the engine has been turned on. The other measures hours by counting revolutions and converting that to hours at a certain RPM.

Piston type aircraft have both type. The Hobbs meter measures clock hours based on how long the engine has been running. If the meter gets power from the ignition being on and oil pressure from the engine running, it records time. This meter is used to log time for rental and logbook purposes.

The other meter is part of the tachometer and counts revolutions in easily managed numbers. IIRC, an hour of tach time would be one hour at 2500 RPM or 150,000 revolutions. This time is what is used for maintenance purposes.

I've always thought that tach time is a much better indicator of how much a vehicle has been driven. Around here you could find a low-mile truck that was used to plow snow that had the engine run at high RPM in low gear - an tach-hour meter would show that.

 

Well, I'll concede that the plow truck example is a good argument for why an hour meter wouldn't work. But if I was in the market for a plow truck, I'd be all 'caveat emptor'...it's general automotive knowledge that no matter how well a plow truck is maintained, they're "rode hard and put away wet." Even the "drive to work every day in 2nd gear" would undermine an hour meter/odometer comparison. But DO YOU drive to work every day in 2nd gear? Do you know ANYONE who does? 99% of us are reasonable in our gear selection, and that's why comparing an hour meter to the odometer would work. Of course, this is going on the assumption that we know at what mileage the hour meter was installed.

And BTW, the boat analogy is flawed. True that an hour meter wouldn't tell you how the boat engine was driven, but by the same token, boats don't typically have odometers (I haven't seen it all yet, so they might for all I know).

The moral of my story is that dividing mileage by the number of hours will get you the average speed the vehicle was driven. And barring any abuse, you could infer how hard or easy a life an engine has had.

Just an aside...I've often thought that the average speed of a vehicle over its lifetime has got to be pretty slow...maybe 25 MPH or so. When you factor in all the idling, stoplights, slow traffic, etc., that's got to bring the average down.

Pat

 

Not at all - these are examples of exactly why they would work. A tach-hour meter shows total number of revolutions so if you compared a vehicle with 100,000 highway miles at say 2000 rpm (1333 tach-hours) you would see that it has roughly the same number of engine revolutions as a truck driven 30,000 miles at 3000 RPM (1200 tach-hours). The disparity between miles driven and engine revs would be obvious.

Here's another example of where it would be handy..my old boss had a 95 (?) Taurus that had the shifter on the column. He would always shift into D instead of OD and at highway speeds the engine would be racing at 5-600 RPM more than if he had it in overdrive. When he traded the car it had decent miles but much more engine use than it should have.

 

Oops...sorry Nitramjr. I was referring to a straight, plain ol' hour meter in my previous post. The tach-hour meter sounds nifty, but aren't aircraft gauges typically pretty spendy? I've never priced one anywhere else, but hell, Tractor Supply wants $25 for a regular hour meter! OTOH, a fella could probably build the RPM counter with $10 worth of parts from Radio Shack, if he knew what he was doing.

And this is completely off-topic, but you're the first person I've ever run across that that was born the same day AND year that I was! How 'bout that!

Pat

 

everyone keeps talking about adding one to your truck only. i think the original idea was that it'd be a new standard on ALL cars. sort of a new benchmark as opposed to just mileage

 

I have a question, though. Wouldn't the Revometer read a lot differently for automatics vs manuals? I mean if I use the tranny/engine to slow my truck before braking, that's gonna rack up a lotta counts when the throttle is actually closed. Number of revolutions is a relative thing. Some don't like the torquey feeling of driving the M5 in 3rd below 40 and above 20, but it's gotten me outta trouble many times being in the power band for the 5.0 when I needed the torque to plant my Michelin sneakers and get outta the way. 5.0's are gutless wonders below about 1500 RPM. Mine has been from day ONE at 16 miles, and still is at 152K, especially with a 3.08 pumpkin (which btw will also affect the revometer). Now, tighten the rubber band a little, and she'll jump to attention. Just because I keep the revs up on the engine does NOT mean I'm abusing it. It's a habit I got in with the VW which has a pretty radical cam in it. It won't pull your hat off below 1500 RPM. But, at 1600, you better hang on. Now, the I6 on the other hand, is a VERY strong engine at low RPM. Even the '64 my step-dad's father had, it was a strong old truck. If I remember right, that thing had like a 232 CI displacement or some such number. Still, you could load the wagon and forget the mules. Ever seen a 2000 lb black angus bull in the back of a '64 F-100 with NO suspension mods and bone stock I6 with single barrel carb and breaker points ignition? Very fond memories of that old truck, though. Called it the Diller Killer. Solid axle about 4.5 inches off the ground in front. That was Saturday night amusement; Diller Hunting on the backroads (as if there's any front roads) in Washington County, AL.

A lot of revolutions does not necessarily indicate abuse. It simply indicates a lot of engine cycles. A more comprehensive data logging system would be in order if you wanted to know how a vehicle's been driven. Like, how many of those revs were at WOT in a quarter mile in 1st and 2nd gear, versus how many were at 2000 RPM cruising down the interstate at 70mph in OD. I just simply don't see how one could relate the number of revs to anything but expected engine life.

Starting with EEC-V and VI, as well as the new GM ECM's, there's tattle-tale diagnostics that only the dealers can access (or so my reading leads me to believe) to clue them in when a vehicle's being abused under warranty. Don't blame 'em, really. I wouldn't want to be replacing an engine for free when someone's been drag-racing it every friday night. Some of the GM stuff will even tell you how many mis-fires on WHICH cylinder. Pretty slick, but if the idiots trying to interpret the info don't know how to use it, well so much for that theory.

It's just my opinion of the Revometer. Not a bad idea, but it needs something a little more quantitative and qualitative. (How do you like them big words from a country boy?) Perhaps a pass-band filter system that will log separate counters for various RPM ranges and throttle positions? High RPM does NOT mean WOT. Something that logs when oil changes were done? Air filters? Spark plug changes? Engine temps? Oh crap, why not just get a bunch of analog transducers and log EVERYTHING an engine does in it's life. Would need a tractor trailer to chase it for the mass storage system.

 

Exactly....it is just a counter. But total revs divided by number of miles would give a good idea what type of driving the vehicle saw.