1998 Grand Caravan

Reply to
Bill Putney
Loading thread data ...

I suspect at least some of that 33% is not true loss, but, as I said in another post, some have speculated that a seemingly excessive loss figure is due to DC's possible exaggerated engine output claims being eplugged into the efficiency formula as the input.

Well you just shot your argument in the foot because LH cars do in fact have *two* coolers: The radiator tank (of course acting more as a temp. stabilizer or buffer), plus an air coil hung out in front of the radiator.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

You've just proven your ignorance of the English language. Wow - I was only halfway kidding that you would be equating 'accepted' and 'acceptable' - I didn't think anyone could be that ignorant, but I guess I was wrong (see - I can admit mistakes on my part). But I guess to you, someone stating facts is "talking down" to you. I'm starting to understand your inferiority complex.

I could explain the difference between 'accepted' and 'acceptable' but something tells me that you still wouldn't get it and/or would want to continue arguing against the obvious. I bet my teenage daughter understands the difference. I try to avoid such imbecilic discussion - though with you it is difficult. I have said before that sometimes it is difficult to separate out dishonesty and stupidity, and you're illustrating why (you have to make up explanations to justify an erroneous position that you don't even understand but don't even realize).

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

Budd - I'll say this in the least offensive way I know how (Matt said it and I said it before): Torque and energy are different units - losing torque thru levering or gearing is not in itself energy loss. Energy is work x speed x time. In your lever and gear examples, what you lose in torque you gain in speed - the product of the two is proportional to energy and will be the same - except - yes - for some energy loss due to friction, but that friction is not inherent in the lever or gear multiplication or division factor. Think about this example: Situation

1 - The fulcrum point is on a sliding friction bushing. Situation 2 - The fulcrum point is on a roller bearing of some sort. If you truly think it thru, you will realize that there are friction losses in both cases, but it is not directly related to the ratios. You will also have sliding friction between the gear teeth - but its amount is not a given relation to the torque multiplication factor - it can be varied all over the place depending on wheter it is lubed or not, and if lubed, what lube is used.

I will give you that, simplisitically speaking, if you have two meshed gears for one multiplication factor, you will have half the friction losses than if you have a series of two pairs of meshed gears to achieve the same final ratio (the difference between the OD and direct drive scenarios). But *that's* where the added losses are coming from that you're talking about - not in the ratios themselves.

In a nutshell, as I and Matt have already pointed out, your fallacy in your explanation is in trying to equate torque multiplication with energy multiplication. You trade off torque and speed, and energy being the product of the two (with time factored in), well - you do the math. The same kind of arguments occur about torque and horsepower because of the same failure on people's part to understand what they are mathematically (and in reality).

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

Less torque, yes, but not less power. Efficiency is related to energy/work/power, not force/torque.

I see the problem now. You are talking about engine efficiency, not gear ratio "efficiency" whatever that is. Keeping the engine in an efficient RPM range is a different discussion altogether, but, again, it doesn't matter how you keep it there (whether OD tranny and numerically higher rear end ratio or 1:1 transmission and a lower numerically rear end ratio. I thought that was your original argument, but you've now changed horses mid-stream. I'm still waiting to see how moving the point of reduction from the rear axle to the transmission makes a fundamental change in efficiency of power transmission.

Matt

Reply to
Matt Whiting

No, I'm not. Look up any definition of efficiency. I will not involve forces or torques (just force in a rotational form). It will involve energy (or work or power). Gear ratios don't have efficiencies, that is the point.

You are confused. You need to refresh your memory on some basic physics definitions.

And, again, I say you need to look up the definition of work and apply it to both sides of your transmission. Assume for the moment that there are no frictional losses since the discussion here is the gear ratio itself. Now try different gear ratios and compute the work at the output vs. the input and divide to get the efficiency. Show us how different ratios change the efficiency. The only requirement is that you must use the correct definition of efficiency, which you haven't thus far. Look it up, it is in any high school physics book or easily available via Google.

Matt

Reply to
Matt Whiting

They are if they have an engineering degree from an ABET accredited university. If they don't, then they aren't unless they hold the PE license.

Matt

Reply to
Matt Whiting

But that has nothing to do with the gear RATIO. It has to do with how you achieve the overall reduction ratio, but it isn't related to the ratio itself, that is the point. Sure, if you use 10 sets of gears to achieve a 2:1 reduction that will have more parastic loss than using one gear set. However, it doesn't matter what the reduction ratio is. It could be 10:1 or 100:1. What matters for frictional loss is how many mechanisms you traverse, not what the ratio is.

Matt

Reply to
Matt Whiting

Wouldn't be the first time. :-)

Is the cooling capacity of these two equal to the engine radiator? If it is, then maybe the 33% loss is closer to reality, but I still HIGHLY doubt it. Is the fuel economy of this car much worse than similar weight and horsepower cars?

Matt

Reply to
Matt Whiting

Yes, it does. OD ratios are inefficient, like it or not.

The lower the efficiency of the ratio plus the extra parasitic losses from extra gearsets equals a stupid design. (KISS principle).

Reply to
Budd Cochran

Hold it!!! Hold the presses!! You just contradicted yourself. First you say there is no energy loss then there is . . you don't know squat.

What the fixation with friction losses?? Is it some thrill for you? How many times must I agree that there is parasitic losses before you set them aside and discuss ratios?

Reading comprhension isn't your strong point is it? Again, how many times will I hacve to tell you that I agree with this BEFORE IT GETS THRU YOUR THICK SKULL ( no, I am not a politically correct person, thank you)

I did the math and the net effect is a major measurable loss of efficiency.

No, the same arguments happen because overeducated idiots like yourself have the misconception you know everything.

The only reason you think I'm in error is because you added parasitic losses into a discussion ABOUT RATIOS.

So, you failed to discuss the topic.

Reply to
Budd Cochran

Then how come cars running north of me at the Bonneville salt flats run faster with low numerical axles and direct trans ratios than cars with higher numericals and OD ( case in point: Summers Brother's Goldenrod. A still standing land speed record with a car that could not pull in 4th gear, that is OD).

No, I'm talking ratio efficiency, but you keep avoiding / clouding the topic.

You'll never find it. Your head is buried in the sands of overeducation.

Reply to
Budd Cochran

ROTFLMBO!!!! Spoken like a well trained engineer.

Matt, I've worked on gear trains that make automotive, even semi truck transmissions, look like toys and gear ratios do have efficiency quotients.

No, that would be you.

Make up your mind . . .parasitic losses or no parasitic losses . . .never mind. The fact you keep changing the "rules" means you've lost the discussion.

Why? You're not using the laws of physics, why should I?

Reply to
Budd Cochran

Aha, so you do want to be selective, but will not allow me the same privilege.

Reply to
Budd Cochran

Can I get some of that "overeducation"?

Roy

Reply to
Roy

AH, Bill, you-da-man! Good job. I hate lawyers after the crap that happend in my divorce.

Nice to hear that you managed (no pun intended) to avoid some nasty legal crap.

But do tell, message from God? A dream perhaps?

(e-mail privately if you wish).

Reply to
NewMan

The only "inferiority complex" around here is those who feel they need to wave diplomas and position at others in order to "win" an otherwise factual discussion.

I could explain thats its merely a matter of tense...

Main Entry: ac·cept·able Pronunciation: ik-'sep-t&-b&l, ak- also ek- Function: adjective

1 : capable or worthy of being accepted

Main Entry: ac·cept·ed Function: adjective : generally approved or used

- ac·cept·ed·ly adverb

But I'd bet you would argue with Merriam Webster about it, so I'll just let it be at that.

Yeah, I bet she does... she likely does things to be ACCEPTED that you don't find ACCEPTABLE.

Except that you engage in it almost every time you post.....

Not really, drop the pretentious attitude and you'll find that most people will like you better.

Ya see, I knew ya couldn't do it. I asked you to be succinct, and you failed. You instead resorted to personal attack as a means of reply. And that after I tried to explain to you why you get perceived a certain way.

So go ahead, continue your acrimonious behavior, and stop asking why people think of engineers as pretentious and egotistical.

Reply to
Max Dodge

Another fine example of how engineers have little time for those without better credentials than their own.

Those mentioned by Budd are in fact engineers, just not the same type as your exalted number crunching know-it-alls. Most of those named by Budd probably know more about their respective equipment than the engineers that created the equipment on paper.

Reply to
Max Dodge

It doesn't matter if I life it or if you like it. It is simply a dumb statement. A gear ratio is neither inherently efficient or inefficent. A given engine runs efficiently within a certain RPM range. A given gear ratio may or may not keep the engine in that range, but it doesn't matter if the ratio is an OD ratio or not. Some diesel engines are most efficient between 1500 and 2000 RPM and often an OD ratio is just the ticket to keep them in that range.

There is no efficiency to a ratio so it can't be lower (or higher) as it simply doesn't exist. For one who keeps referencing math and physics, you have a very meager comprehension of either.

Matt

Reply to
Matt Whiting

Because the OVERALL gear ratio wasn't correct for the power curve of the engine. Ideally, you want the overall ratio to be such that the engine hits its peak horsepower RPM at exactly the same time that the car hits its maximum aerodynamic drag speed. If the car is geared too tall, which this one obviously is, then the aero drag on the car is increasing faster than the power curve of the engine and once they cross, the car will no longer gain speed.

This could easily be fixed by using a numerically higher rear axle ratio. It has nothing to do with the transmission having a ratio less than 1:1, it has everything to do with the OVERALL reduction ratio of the driveline being incorrectly matched to the engine for this particular situation (top speed on the level).

That is because the topic simply doesn't exist. Find us even one reference that talks about a gear ratio efficiency. Just one...

I won't find it because it doesn't exist. And that is the same reason that you can't find it and post a reference to it.

Matt

Reply to
Matt Whiting

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.