I'm tired of this "designed to be driven hard" nonsense
02-18-2011, 01:22 PM
#166
Race Director
Thread Starter
Okay, I'll bite: please define what you mean by "driving hard"? Does this mean track driving where one is always hitting redline in gears 2, 3 and 4 for 20 to 90 minute durations or does it mean street driving with frequent forays to redline once every five miles with wide open throttle application or does it mean driving at high speeds (over 110 mph) for durations of 30 minutes or more or does it mean something else? I think if you desire empirical proof, the question needs to be defined with a much higher degree of reference.
" You could have a failure if the previous owner ran low on oil, used the wrong plugs, or consistently shifted below 3,000 rpm.
The improved reliability of 964, 993, and 996 has enticed many individuals to buy their first Porsche. But getting first-time owners to run the engine past 4,500 rpm is difficult. The truth is, it's more harmful if you don't run these engines."
I personally define driving hard as longer periods or many instances of high revs (above 4500) and high load (75% throttle opening or more)
I drive the **** out of my car because it is a more enjoyable experience for me and so far the engine is holding up just fine.
When it wears out i will have just as much fun rebuilding it as I did wearing it out.
I have proof that tires last longer with zero camber and taking turns at the minimum speed possible.
I also have proof that brake pads last longer when not used.
I am not going to drive in straight lines at slow speeds and never use my brakes just to preserve the components.
Even if you have proof that redline is best are you going to change your driving habits because someone on the internet said so? Did you buy a Turbo because of it's documented incredible reliability under 3000k rpm?
Sometimes "proof" of what is best just does not matter, tonight I'll have a cigar and a scotch because even though there is proof that they are bad for me I still enjoy them.
Drive it how you want, it's your car.
When it wears out i will have just as much fun rebuilding it as I did wearing it out.
I have proof that tires last longer with zero camber and taking turns at the minimum speed possible.
I also have proof that brake pads last longer when not used.
I am not going to drive in straight lines at slow speeds and never use my brakes just to preserve the components.
Even if you have proof that redline is best are you going to change your driving habits because someone on the internet said so? Did you buy a Turbo because of it's documented incredible reliability under 3000k rpm?
Sometimes "proof" of what is best just does not matter, tonight I'll have a cigar and a scotch because even though there is proof that they are bad for me I still enjoy them.
Drive it how you want, it's your car.
You say revving the engine to between 3000rpm and 3500rm causes [more] wear than revving higher. What parts are being worn in this instance, and why is that rpm band so dangerous?
How do higher revs benefit the engine?
Had a 99 cobra for 9 years. The car made more horsepower at the wheels than a GT2 RS makes at the crank, yet the engine was very solid.
I know you guys poo-poo mustangs, but my cobra had a factory cylinder block capable of repeatedly withstanding over 1300bhp, and a forged and fully counterweighted crank.
02-18-2011, 01:24 PM
#167
Instructor
can i ask a question in a different way/
suppose
you had two identical porsche engines and
you drove one at 3000 rpm and
the other one at 5000 rpm
would it be logical to conclude that the
engine driven at a slower engine speed
would have less wear on its movable parts
and as a result last longer
(all other things being equal)
suppose
you had two identical porsche engines and
you drove one at 3000 rpm and
the other one at 5000 rpm
would it be logical to conclude that the
engine driven at a slower engine speed
would have less wear on its movable parts
and as a result last longer
(all other things being equal)
02-18-2011, 01:27 PM
#168
Race Director
Thread Starter
Based on racing engines, shifting short of the redline increases engine life. Cup engines redline higher than GT3 engines and PMNA suggests 40 hour refresh intervals vs 4 years 80,000 KM on the street car. Ferrari Corsa Cliente F1 cars reduce the red line by 3,000 RPM and are considered to have indefinite life compared to 19,000 RPM redlines. At peak piston speeds, bolts stretch, bearings take a beating etc.
OTOH that is not to say that the occasional trip to the red line with shorten engine life. Street engines have a rev limit which is in keeping with the expected life of the engine. I seriously doubt if shifting at 5,000 RPM has any effect on engine life as opposed to say 3,500. But, I have no proof of this
There is a difference between using and engine "hard" and abusing it.
OTOH that is not to say that the occasional trip to the red line with shorten engine life. Street engines have a rev limit which is in keeping with the expected life of the engine. I seriously doubt if shifting at 5,000 RPM has any effect on engine life as opposed to say 3,500. But, I have no proof of this
There is a difference between using and engine "hard" and abusing it.But I also don't think its beneficial or extending the life of the engine.
02-18-2011, 01:30 PM
#169
Race Director
Thread Starter
can i ask a question in a different way/
suppose
you had two identical porsche engines and
you drove one at 3000 rpm and
the other one at 5000 rpm
would it be logical to conclude that the
engine driven at a slower engine speed
would have less wear on its movable parts
and as a result last longer
(all other things being equal)
suppose
you had two identical porsche engines and
you drove one at 3000 rpm and
the other one at 5000 rpm
would it be logical to conclude that the
engine driven at a slower engine speed
would have less wear on its movable parts
and as a result last longer
(all other things being equal)
I'll even go down to 2000rpm.
02-18-2011, 01:38 PM
#170
Rennlist Member
Please define "longer period" in terms of either a specific time period or a range of time, and please define "many instances of high revs" in terms of an actual number occurrences per minute or hour or days or weeks or...
02-18-2011, 01:45 PM
#171
There's nothing wrong with someone challenging the way you think, and asking follow up questions. That's how our knowledge gets better.
02-18-2011, 01:59 PM
#172
Race Director
Thread Starter
Many instances would be 1 rev above said rpms every few minutes (few meaning between 2 and say 5)
02-18-2011, 02:17 PM
#175
It is heat from friction that wears out engines.
So as long as you are within the specified operational window it probably doesn't much matter if you are running at 1000 rpms or 6000 rpms as long as it doesn't operate in excess of X degrees, which is somewhere in the neighborhood of 260 degrees at which point oil starts to break down.
Automotive engineers typically use a 30% safety margin, which is quite a lot.
The rest of this is just a philosophical debate to kill time and burn up 12 pages on nonesense.
If I have a cast iron ring and run it along an alu cylinder wall that is infinately long and the manuafacter says the service life is 459,000 miles. Does mater much if I go along at 1mph or 2? It's still going to wear out in 459,000 miles.
So as long as you are within the specified operational window it probably doesn't much matter if you are running at 1000 rpms or 6000 rpms as long as it doesn't operate in excess of X degrees, which is somewhere in the neighborhood of 260 degrees at which point oil starts to break down.
Automotive engineers typically use a 30% safety margin, which is quite a lot.
The rest of this is just a philosophical debate to kill time and burn up 12 pages on nonesense.
If I have a cast iron ring and run it along an alu cylinder wall that is infinately long and the manuafacter says the service life is 459,000 miles. Does mater much if I go along at 1mph or 2? It's still going to wear out in 459,000 miles.
02-18-2011, 02:24 PM
#177
Race Director
Thread Starter
It is heat from friction that wears out engines.
So as long as you are within the specified operational window it probably doesn't much matter if you are running at 1000 rpms or 6000 rpms as long as it doesn't operate in excess of X degrees, which is somewhere in the neighborhood of 260 degrees at which point oil starts to break down.
Automotive engineers typically use a 30% safety margin, which is quite a lot.
The rest of this is just a philosophical debate to kill time and burn up 12 pages on nonesense.
So as long as you are within the specified operational window it probably doesn't much matter if you are running at 1000 rpms or 6000 rpms as long as it doesn't operate in excess of X degrees, which is somewhere in the neighborhood of 260 degrees at which point oil starts to break down.
Automotive engineers typically use a 30% safety margin, which is quite a lot.
The rest of this is just a philosophical debate to kill time and burn up 12 pages on nonesense.
Is driving the car hard (high load and high rpm) beneficial to the engine?
02-18-2011, 02:38 PM
#179
It is probably on a dyno the average of torque and hp meet because theoretically that is where it’s running at it most efficient.
It is frictional heat that kills them, therefore at it's most efficient it would creating the least amount of fictional heat for the longest distance - in very simple basic terms.
Which I suspect is in the higher rpm ranges.
02-18-2011, 02:53 PM
#180
Quote:
Originally Posted by J.B.H.
Did anyone mention these engines are bullett proof?
at least 993 times
Yes but I can't believe that no one asked are they bullet proof even with the engine tray removed.
After all that is some really strong plastic.
Mike
Originally Posted by J.B.H.
Did anyone mention these engines are bullett proof?
at least 993 times
Yes but I can't believe that no one asked are they bullet proof even with the engine tray removed.
After all that is some really strong plastic.
Mike