Cruising regularly at 4000 rpm

[Jordanwolf]

Originally Posted by Tcoat

The diference between your engine lasting 1,000,000 miles and 999,999.00000000000000000000000000009

[ermax]

But come on Tcoat. How about that 1st gear bicycle race?

[Tcoat]

Originally Posted by ermax

Yeah for sure not double due to improved oil flow. But yes more, extra, additional. Hahaha

Miniscule, non measurable, insignificant, microscopic.

[Tcoat]

Originally Posted by ermax

But come on Tcoat. How about that 1st gear bicycle race?

When I have somebody pedaling my car it will be relevant.

[ermax]

Originally Posted by Tcoat

When I have somebody pedaling my car it will be relevant.

Nah. Nothing is relevant in your eyes. Hahaha

[Tcoat]

Originally Posted by ermax

Nah. Nothing is relevant in your eyes. Hahaha

Well it isn't.

[ermax]

Originally Posted by Tcoat

Well it isn't.

That’s debatable...

.....

....

I kid I kid.

[Capt Spaulding]

Originally Posted by ermax

I agree with you about the distance variable in his test. Here would be my test.

Two engines on an engine dyno with proper cooling to simulate travel at 60mph. Both will operate 24/7 for one month. One engine will be turning 4000rpm the entire time and the other will be turning 2000rpm the entire time. No transmission, no distance is covered. I think it's obvious which one would wear the most.

And then a real world comparison. When cruising on the highway at a consistent speed, the same speed for an hour. Which one will have more wear, one that is driven the whole time in say 4th (yes one guy said he actually cruises on the highway in 4th) or one driven in 6th? Again, completely obvious. How much additional wear may be negligible I agree. But that doesn't change the facts.

As for which part of the engine would wear. Well any part that is moving. But primarily the ring to sleeve contact. If two parts are incontact with one another there will be wear. If the number of passes is higher in one scenarios vs another it will definitely wear more. Why are we even debating this (not directed at you, you obviously understand the topic)? It's so incredibly obvious.

My issue with your experiment is the use of time as a constant. The engine run at 4000 for a month would have turned twice as many revolutions as the one running at 2000. It is not the time that wears the engine nor is it the speed at which the engine operates. It is the number of revolutions the engine turns that is causing the wear. If you want to impose a constant, use number of revolutions. Run the 4k engine half as long as the 2k engine.

At 2k the engine will turn 2880000 revolutions in 24 hours. At 4k it will turn 5760000 revolutions. Which do you think would show more wear? Would it be due the higher engine speed or the greater number of turns. My bet is on turns. To make your example work you'd need to run the 4k engine 12 hours and it too would turn 2880000 times. Then measure the wear differences. Those differences will (or may) be due to the speed of the engine. I'd wager you couldn't measure them.

Or if you wanted to get statistically fancy you could do whatever you want but measure everything precisely and run the collected data through a linear regression routine and identify the relative impact on wear of each of the potential wear factors, holding ALL the others constant. But you REALLY need to compare apples and apples. Your model doesn't.

Your real world example falls victim to the same fallacy. You hold time constant when neither that nor road speed is the important variable. If I run my car in a lower gear, I'm spinning the engine more times. The engine is traveling "farther." More revolutions = more wear. Engine speed may or may not affect wear but you can't determine that until you control for turns. My bet is engine speed is far and away the smaller of the two influences - probably to the point of being inconsequential.

[Brink]

Originally Posted by Tcoat

When I have somebody pedaling my car it will be relevant.

Will this be the next "engine" swap we see?

[ermax]

Originally Posted by Capt Spaulding

My issue with your experiment is the use of time as a constant. The engine run at 4000 for a month would have turned twice as many revolutions as the one running at 2000. It is not the time that wears the engine nor is it the speed at which the engine operates. It is the number of revolutions the engine turns that is causing the wear. If you want to impose a constant, use number of revolutions. Run the 4k engine half as long as the 2k engine.

At 2k the engine will turn 2880000 revolutions in 24 hours. At 4k it will turn 5760000 revolutions. Which do you think would show more wear? Would it be due the higher engine speed or the greater number of turns. My bet is on turns. To make your example work you'd need to run the 4k engine 12 hours and it too would turn 2880000 times. Then measure the wear differences. Those differences will (or may) be due to the speed of the engine. I'd wager you couldn't measure them.

Or if you wanted to get statistically fancy you could do whatever you want but measure everything precisely and run the collected data through a linear regression routine and identify the relative impact on wear of each of the potential wear factors, holding ALL the others constant. But you REALLY need to compare apples and apples. Your model doesn't.

Your real world example falls victim to the same fallacy. You hold time constant when neither that nor road speed is the important variable. If I run my car in a lower gear, I'm spinning the engine more times. The engine is traveling "farther." More revolutions = more wear. Engine speed may or may not affect wear but you can't determine that until you control for turns. My bet is engine speed is far and away the smaller of the two influences - probably to the point of being inconsequential.

I don't understand, RPM is just that, revolutions within a specific duration (1 minute).

The topic was cruising at high RPMs. My experiment was related to that. And you just said it yourself:
"If I run my car in a lower gear, I'm spinning the engine more times. The engine is traveling "farther." More revolutions = more wear."

Case closed. When cruising you put less wear on the engine if you do it at a lower RPM/higher gear.

It really doesn't need to be so complicating.

Edit: Also, I agree that an engine running 2K for would have similar wear as an engine running 4K but for half the distance. Actually the one running 4K for half the distance would probably wear less due to extra oiling. But this is hard to apply to the topic at hand, "cruising". Your drive is going to be X number of miles. The goal would be to get there with as few revolutions as possible. Again, it's all negligible. My suggestion to cruise low (not low gear but low RPM) is just a general rule of thumb. No one is going to blow their engine if they don't follow it to death.

[VoltsFRS2013]

Originally Posted by Tcoat

The question wasn't "why" the question was "will it hurt the car"? The answer remains no.

May not hurt the car, but will hurt your pocket

[Capt Spaulding]

Originally Posted by ermax

I don't understand, RPM is just that, revolutions within a specific duration (1 minute).

The topic was cruising at high RPMs. My experiment was related to that. And you just said it yourself:
"If I run my car in a lower gear, I'm spinning the engine more times. The engine is traveling "farther." More revolutions = more wear."

Case closed. When cruising you put less wear on the engine if you do it at a lower RPM/higher gear.

It really doesn't need to be so complicating.

It's possible we're saying the same thing different ways, but I don't think so. I'm not sure how to explain it any more clearly so I'll finish my part by reiterating that it is not the number of revolutions per minute an engine turns that wears it out as it is the absolute number of revolutions the engine turns.

Edit: we may be on the same page after all. Let me ask this. Say I am taking a trip of 300 miles. On the way up I drive at 80 mph (say 3500 rpm) and on the way back I drive at 90 mph (4000 rpm). Does the return leg put more wear on the engine than the outbound leg?

[ermax]

Originally Posted by Capt Spaulding

It's possible we're saying the same thing different ways, but I don't think so. I'm not sure how to explain it any more clearly so I'll finish my part by reiterating that it is not the number of revolutions per minute an engine turns that wears it out as it is the absolute number of revolutions the engine turns.

Yes, we are saying the exact same thing.

[ermax]

Originally Posted by Capt Spaulding

Edit: we may be on the same page after all. Let me ask this. Say I am taking a trip of 300 miles. On the way up I drive at 80 mph (say 3500 rpm) and on the way back I drive at 90 mph (4000 rpm). Does the return leg put more wear on the engine than the outbound leg?

Just ran the math... even though your 90mph trip would take less time, the total number of revolutions is slightly higher on your 90mph trip.

300/90*60*4000=800000 revolutions
300/80*60*3500=787500 revolutions

Seriously splitting hairs. But as you can see we are on the same page.

But just to clarify, my advice was never really intended to be applied to top gear cruising. It applied to times where people cruise in 4th gear when they could be cruising in 6th.

Here is the main post I was referring too. He said at 60 he is typically cruising in 3rd and at 80 he is typically in 4th. That is 5200RPM in the first example and 5400 in the second example. 60 in 6th is 2600rpm and 80 in 6th is 3450. That is where I feel wear isn't as negligible.
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