Took a ride in an 06 Uplander yesterday

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It's simply inexcusable to be so abusive of someone else's property. A better mindset would be a better disciplined mind. It wouldn't possess an inclination toward destructive or such abusive behavior.
 
There is a HUGE difference in hittingt the Rev limiter unloaded and loaded. I have posted on this before as others have.
I was raised to treat other peoples property I am "borrowing" better than I would treat my own(respect for the privelege to use it) and return it in as good if not better condition than I got it(in this case top off the oil and keep it clean)
 
Maybe it's just my way of thinking since I tend to drive with a heavy foot. Once again, I don't think revving an engine to 6000 rpm for 3 seconds is going to hurt any. You could get a group of people to say revving an engine up won't hurt it and actually might do some good, and you could just as easily get a group of people to say the exact opposite. I guess you can tell which group I am in.
 
Since you think it's not bad for the vehicle why don't you do it to yours? A rapid change in RPMs is BAD (such as reving under no load). Use a little common sense.
 
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By the way, it's a rental vehicle, and as such probably had been driven hard ever since it was delivered to the rental dealershp, so tell me how going to 6000 rpm for maybe 3 seconds is going to ruin an engine?

Ok, since it's a rental outfit and it's been driven hard, it's ok.

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Thanks for proving my point.

Just because it's a rental that SOMEONE is going to spend their MONEY to own and spend their MONEY to fix sooner than later because some people don't respect other peoples property. It's ok since it's a "Rental".

Sorry, But due to a mindset like yours, I had a 1999 Taurus that that had a 3.0 Vulcan motor (which is one of Fords good engines) eat $2400 worth of Headgaskets, heads and labor in 110k miles.

Ford paid for the first one, I paid for the second set.

The outfit was a rental car.

But it's ok to rev them to the rev limiter since it's a "rental" car.

Enough said.


Bill

PS: 55, No need to respond since you think it's ok and I don't. We will agree to disagree.
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[ December 15, 2005, 01:02 PM: Message edited by: Bill in Utah ]
 
OK, here's your explanation:

When you spin a "loaded" engine to 6K rpm, the combustion processes aid in slowing the piston down before it reaches TDC (Top Dead Center). The air/gas mix is compressed and then fires just before TDC (typically 6-12 degrees). On the exhaust stroke, the piston forces the spent gasses out the exhaust valve(s).

When you spin an unloaded engine (to 6K rpm), you take away much of the combustion processes and the piston approaches TDC with less resistance. This puts increased strain on the connecting rod bearings. The connecting rods bolts are on the back side of the rod and can stretch causing the film of oil that the rod bearings "float" on to be broken and then it's metal to metal contact (most often ending in a spun rod bearing).

When you see those engines on TV during the wide open throttle competitions, those things are specifically built using lightweight pistons, HD lightweight rods, and they've been balanced & blueprinted. So you see, that holding your unloaded engine at redline (or rev limit) CAN be destructive or at least do damage in only three seconds. Heck, I've spun connecting rod bearings under load at New England Dragway during a pass.

Regardless of whether you belive me or not, it's still disrespectful to hold someone elses vehicle at the rev limit. Even if it is only a rental van. If you get anything out of this thread at all, I hope it's an understanding of where most of us are coming from.
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I thoroughly agree that mistreating a rental car is disrespectful. I rent cars frequently and treat them with respect. However, ripping on this guy for reving a car to 6000rpm for 3 seconds is rediculous. First of all, he did not think it would hurt the car. Therefore, he was not being disrespectfull. Secondly, you can argue 'till the cows come home about how bad it is to rev an engine that is not under load. His 3 second experiment would not produce any significant wear or damage, even if you used SWRI's radioactive oil wear measurement techniques. Get off the soap box.
 
>Take a baseball and throw it as hard as you can, then, go through the motion of throwing just as hard as before but without the baseball, then ask your shoulder the difference without load on it. Same principle

I think Blair and Zaedock are both right, but explaining it in different ways. I've never really thought about it from a purely mechanical sense, but in a theoretical sense, revving an unloaded engine is analogous to an electrical short circuit.

About GM creating nothing but ugly things, it seems the perfect time to use the old saying "A camel is a horse designed by a committee."
 
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I thoroughly agree that mistreating a rental car is disrespectful. I rent cars frequently and treat them with respect. However, ripping on this guy for reving a car to 6000rpm for 3 seconds is rediculous. First of all, he did not think it would hurt the car. Therefore, he was not being disrespectfull. Secondly, you can argue 'till the cows come home about how bad it is to rev an engine that is not under load. His 3 second experiment would not produce any significant wear or damage, even if you used SWRI's radioactive oil wear measurement techniques. Get off the soap box.

Thank you.
 
Sorry Winston, don't see it that way. I think 55 just wanted to see what would happen. He had no way of knowing or belief what would happen, as you claim in his behalf. Whether or not damage ocurred to the motor was of no concern to him - just some trivia to share one way or the other.

I can see this post from an entirely different angle had things went awry, goes something like this:

"After it hit rev lmiter there was this G0d-awful vibration and it started knockin' like you would not believe! Man, don't try this at home kids, hehehe... "
 
If you every find yourself reving the engine to red line in neutral, you must immediately pull the shift lever into drive to stop this situation. Then, to protect the engine don't let off the gas all at once. Count to ten, then gradually let up.

The damage caused to an engine reving in neutral, to very high rpm, is vibration. The transmission and running gear help to dampen vibration and protect the engine. The engine package is not designed to handle this kind of situation. The vibration can transmit forces that can damage bearings, fasteners, upset boundry layer lubrication and cause structural failures. Many modern engines will not allow this to happen. You can test this at a Mercedes dealership. Pick any model with a V8 engine. Start the engine and by all means, don't let it warm up. Press the gas pedal to the floor and hold it there. The engine will protect itself. The only thing that will happen is that they will ask you to go buy a Jeep, instead.
 
It has a lot to do with acceleration and momentum. When a part is designed it is tested to what the engineers antipate as normal service and then a little extra margin. When you rev an engine with no load the piston's and rod's can reach dynamic loads that grossly exceede the design spesifications. Remember that each piston has to start and stop and the top and bottom of the bore. The speed witch witch an on loaded engine can rev can also exceed the lubrications systems ability to supply oil at the needed volume when it is needed most. When you let off the acelerator the oil pressure will fall off quicker then RPM's. The rapid acceleration/deceleration of a free reving engine can also strip the oil off of the rings.

You also have issues like increased risk of ring breakage especialy if the engine is still cold and softening the rings in localized hot spots due to the rapid acceleration deceleration.

Their is a reason why so many ( all OEM's that I am aware)recomend against reving the vechile with no load on it in the owners manual.

I am not an powertrain engineer but know from practical experince as a Technician that free reving an engine is bad and has never been recomended by any car company that I am aware of!
 
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If you every find yourself reving the engine to red line in neutral, you must immediately pull the shift lever into drive to stop this situation. Then, to protect the engine don't let off the gas all at once. Count to ten, then gradually let up.

Whether it was intentional or not, I find that insulting to my intelligence. Rather than resort to verbal bashing and name-calling, maybe I'll just ask a moderator to delete the thread in its entirety. This is just getting out of hand.
 
SS, I think my statment was clear, don't do it, and it was followed with a explination. It was then followed up by JB saying exactly the same think, in his way. Engines running in neutral, at any speed, are burning up too much fuel, shaking too much and should be immediately driven or shut off. Avoid neutral as much as possible. There is one exception that I can think of, extremely cold weather, where you need some heat before the engine can even move the car, at all. And, please, as someone else stated, don't abuse vehicles, even rental cars.

And back to the Uplander. Maybe a name change from the Venture will help the image and sell more vehicles.
 
I just want to say it one more time.

There is no way that you will be able to measure any damage, to any engine that has been reved to redline for 5 seconds under no load. Ever, ever, ever.
 
It might be difficult to measure, but it's not good, either and if there is some problem, that could be the one thing to upset things when otherwise the engine might run trouble free for years. How would you know? I think we can stick a fork in this thread.
 
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