F1CrazyDriver

FWIW,
98.000k miles on 996t. Tracked, driven "hard", always under 3k rpm before engine up to temperature, once at temperature i do my best to stay above 2,700+ rpm all the time-- 0 engine issues, 0 power loss.

then i have friends who lug their motors around, to baby motor, and periodically have CEL issues.

Berra

Ive driven all different brands with DC transmissions and they all shift very early when in D, 2-2,5k rpm and they shift. If just driving very gentle around town they don't even make it past 2k rpm before shifting.

Found a perfect example while writing this post:

Demonstration starts at 1:30 min

"02996ttx50

pdk cars have different "switchable" maps that access/activate the different modes eg sport/sport + etc.

so i dont think the analogy is apt since "sport" is going to shift at different times than "auto" will.

Berra

The mapping is done as you would drive yourself. If you drive gentle and slow, you don't rev much and shift early. If you wanna go fast, you rev higher and shift later.

These cars have been around for 17 years now, and I'm sure most are driven as normal cars and I'm also sure that most owners won't even think or wonder as to which rpm one should keep when driving. Just enjoy this master piece and drive it like you want/prefer...there is no right or wrong.

I only do one thing and that's keeping the revs higher when going uphill, but I do this with every car.

What's interesting here is that my X5 40d which has 306 hp and 445 ft lbf at a mere 1500 rpm will go up steep hills in 8th gear and rarely downshift. Sure, this is a totally different car and engine but that would be considered lugging but the car doesn't mind.

Dock

Depending on the situation, I have no issue with driving my 996 Turbo around at 2000-2500 RPM.

Kevinmacd

Have to disagree, water temp on a TT always comes up first. Test it, as soon as the water temp comes up, do an oil level check, it will say oil not at temp for a reading! Btw the water temp and oil temp are two different sensors!

Mike Murphy

Correct, but it's not that far behind. Someone did a test on RL here and charted a graph with water temp vs oil temp. They were only a few mins behind each other. They then crossed over where oil was hotter than the water. The water then became an oil cooler.

T10Chris

Yep exactly.. It is within 5-10 mins. Water temp stays 15-20 degrees higher than oil temp until around 180 when the water temp levels off and the oil temp catches up and passes it/hovers in the same ballpark temperature.

Dock

I think the conservative approach is to use whatever the warmed-up idle oil pressure is as the target prior to using "high RPM" or aggressive acceleration/throttle application. Once you know what the idle RPM lowest oil pressure is (the pressure reached when the oil is as warm as it is going to get during normal driving), then you've done due diligence in protecting the engine and transmission..

Dans996tt

My X50 Tip shifted between 1500-2500 unless you were really on it.

Dan

dprantl

Sure, but the engine designers made it that way on purpose. At lower RPMs the engine's frictional losses are decreased, as is the heat generated due to a lower combustion event rate and less power generated, so there is no need for high oil pressures. There's no reason to design an engine where you could get into a situation where the oil pressure would be too low for a given RPM/throttle combination when it is relatively easy to configure the RPM-oil pressure relationship and you have complete control over when and how much fuel is injected into each cylinder and when each cylinder's spark fires at any given moment (and even how far to open the throttle, regardless of actual throttle pedal position).

Dan

Macster

Uh, no.

At low speed with relatively large throttle opening such as is encountered when one is driving in a higher gear the engine experiences high load conditions. The cylinder filing is very good and the ECU will really dial in the advance. There is a lot of pressure put in the rod and main bearings.

The engine is very efficient under these circumstances. In spite of the good cylinder filling and of course with this more fuel being added with my 2006 GTO with its instant mpg readout/display I'd see 35mpg often under these conditions. I'd also see a lot of ignition advance. This gets the mixture burning early so the peak pressure of combustion occurs at the time the positon of the cylinder's crank pin is most optimally positioned to derive the most mechanical energy from the burning mixture and the pressure it generates.

With these older engines there is no configuration or adjustment available of the oil pressure/volume. The capacity of the oil pump is fixed. The pressure relief is fixed. The amount of oil delivered and pressure of oil is what it is.

As I said above at lower engine speeds the volume and pressure of oil is less and this is why I avoid low speed driving in higher gears. Outside of 1st gear I try to keep the RPMs above 2K in 2nd and higher in the higher gears. At around 2.5K RPMs oil pressure is at 4 bar. It doesn't require much effort or focus or concentration. It is a habit that I developed years ago when I understood the situation and wanted to avoid subjecting the engine to high loads with low oil pressure.

Granted what oil pressure there is is certainly adequate for I dare say many owners drive if not the opposite of how I drive they certainly subject the engine to relatively low RPMs high load conditions and the engines aren't blowing up or manifesting any problems from this treatment. I just feel better knowing I'm not subjecting my engines to high loads as low RPMs and lower oil pressure.

Macster

You can't go by the shift points of the Tip or PDK. These shift points are selected to "game" the fuel economy and CO2 emissions tests.

(Might add with a Tip even though the gear box is in the next gear the torque converter still offers some "slip" and the effective gear ratio is a bit lower than the actual gear ratios imply. The PDK obviously doesn't have this "feature".)

The engine is very efficient under part throttle low RPM high load conditions and the shift points are aimed at keeping the engine operating under those conditions to maximize fuel efficiency and lower CO2 emissions.

(This desire to "game" the fuel economy and CO2 emissions tests is why "no warm up" is specified.)

Might mention all automakers engage in this behavior.

The bottom line is I would not make it a habit of driving my cars in such a way that mimics the type of "driving" the car experiences during a fuel economy and CO2 emissions test.

Kevinmacd

Oil pressure is controlled by rpm, there is nothing fixed. The higher the rpm the higher the volume and pressure! I know of no internal combustion engine that has fixed volume or pressure. The only thing fixed is when the relief valve opens at certain designed pressure to keep excess pressure from occurring!

dprantl

I think Macster meant the oil pump output/pressure is fixed for any given RPM. What I was saying was that when building the engine, it was easy to select that relationship, so there would be no reason to come up with one that would have damaging effects on the engine at low RPM/high load conditions. They must have determined that 3 bar of oil pressure at 1,500RPM (just an example) should be sufficient under most operating conditions, otherwise they could have designed the pressure/RPM relationship differently.

Dan