I have never got why porsche puts a box in that measures and counts how many times someone has taken the the car to redline or hit redline. I mean weren't these care built to be driven like a sports car? Also does it hurt a boxster to get to redline anyway?

 

The bean counters could potentially use it to deny warranty claims from abusive drivers.

That said, many would argue that driving the snot out of it is good for the motor. I know I use every opportunity to wind it out that I can get. I am not paying for a Porsche to drive it like an old granny Toyota!

 

Several reasons. One is to gather data from a population of vehicles. I suspect every time a car brought in to dealership and the diagnostics computer hooked up this info along with other info of interest -- known only to Porsche -- downloaded and shipped back to Porsche for a database and analysis.

Second reason is to protect Porsche from a customer's warranty claim where the driver missed a shift -- went from 4th to 3rd instead of from 4th to 5th say and blew up engine.

Yes, it does "hurt" Boxster engine to take it to red line. Making max. demand of engine's output puts more stress -- heat and mechanical -- to engine and its internals. This shortens the life of the engine. However, there is enough margin in the engine to withstand numerous excursions to red line as long as engine fully warmed up and oil of good quality and not too old or loaded with high levels of water or uinburned fuel.

Driving car and engine sedately, too sedately, can be almost as bad as taking engine redline. An engine can fail from various causes and a failed rod bolt from repeated trips to red line over time is one way. But another way is to be driven in such a way that the engine oil gets diluted and remains in engine too long and chemical wear and oil break down lead to catastrophic failure of one of the engine's critical components.

Sincerely,

Macster.

 

What really bugs me is if the car is not suppose to rev that high, why not adjust the rev limiter to a lower rev range. They do this simply to deny warranty! Spend 70k+ on a car and how nice of them! LOL

 

Generally the upper rev limit is determined by the valve hardware. Red line is set to avoid valve float and the rev limit has to have some margin.

Also, stresses on other engine components has to be considered. For instance how much stress is placed on the rods and rod bolts keeping the pistons in check at high revs.

Then piston speed needs to be considered. I can't recall the piston speed guidelines anymore and my info may be (probably is) out of date even if I could remember it.

AFAIK no warranty is denied even if the rev limiter hit. There could be an exception if one took a brand new car/engine out and started banging the engine off the rev limiter right away.

Other over engine speed events occur when a driver misses a shift and gets a lower gear vs. a higher one. Depending upon the speed of the vehicle in the higher gear selecting a lower gear accidently can see the engine speed maybe several thousand rpms over its rev limit.

Early on in the Carrera GT intro in Europe a car mag writer was test driving a demo Carrera GT and missed a shift and the engine blew up. Reports were engine speed was around 14K rpms when the engine let go. This is around 6K over the engine's red line. Still the engine managed to hold on until 14K rpms.

Do our Porsche engines have that much margin? Hard to say, but they have to have some. Otherwise given the use some owners give their cars -- lots of track time -- these things would be blowing up right and left and that is not the case.

Sincerely,

Macster.

 

They also help in conviction of traffic offenses. True story, two teenagers were racing on a highway (corvette vs mercedes) they hit and killed a woman in a jeep cherokee. There were no witnesses but they were convicted due to the fact that both the mercedes and the corvette had speed recording "black boxes" and were allowed as evidence.

 

So in reference to the question of the rev limiter. This is a great preventive measure for people with a heavy foot, however will not protect the engine from an over rev on a blown down shift.

For instance if you blow your down shift from 5th gear to 4th and mistakenly select 2nd gear and slide off the clutch, the gearbox will spool that engine far in excess of the redline. BANG, blown engine. A rev limiter would have no use in a scenario like this. So how is the factory to know what really happened here, well enter the black box.