tgilgan

Gang,

This has been bothering me since my track day on Monday. It was a normal Porsche event at our local track - very bumpy and pretty short track. I used to shift into 4th on the back straight, before the bumps but my instructor and I decided to leave it in 3rd. at the end of the straight I am at 7200-7300 rpm and about 175km/hr.. It is an uphill climb and it is in that range for a while. the rev limiter isn't kicking but it is very very close. I gained 15-20km/hr leaving it in 3rd.

This is a stupid question I think, but I am worried about longevity of the engine red-lining every lap.. since we aren't racing, is it smarter for me to get it into 4th and keep the revs down a bit? I am assuming the smart germans have rev limited it before any damage can be done but I want to keep the car forever and would rather be conservative and not quite as fast. Any other spot on the track or street, I am shifting as it hits 7000 rpm, and it isn't actually staying there very long. the back straight isn't that way. Car is a 997.2 C4S and it is my first Porsche.

Am I being paranoid?

T

JW911

Yes. It can handle that.

JTT

Hey Tom! Joe here from the event. Glad you made it out and hope you had a good time!

wouldn't worry about the revs, although can appreciate why you would be. They have been engineered to handle those revs. There are some distinct advantages to holding a gear as it avoids not only the upshift on the back straight, but the subsequent downshift into turn 9. Each shift is another opportunity for a missed shift, which can be far more disastrous than the rev limiter. All that said, peak torque on these engines is well below redline, so it's still pulling hard at 6000rpm. I'd go with what "feels" best, as far as the car being settled for the transition up the hill and through T8 into T9.

tgilgan

Hey Joe,

It was a great day, and John is a great instructor and I went way faster then I have before.

Perfect. After the guy next to me lost all his coolant on the ground (new-ish boxster).. I started getting worried about how tough the cars really are. Agree 100% on the shifting strategy of staying in 3rd if the engines are robust to keep doing that for 10-15 years... and the speed it added was awesome (the sound even better). That being said I will probably eventually try to find a place after the kink to shift up and see if I can push past ~170km/hr.

thanks!

T

Quadcammer

My opinion...unless you are at the highest level of de, ahift into 4th. there is no trophy here.

The reality is that the m96/m97 is a piece of junk when it comes to track use. if its not oil starvation, then its a crappy rod bolt, or bore scoring or chain tensioner pads or oil pump drive hex or 47 other failure modes.

Lowering the revs will have a distinct oil temp advantage and when not running whiz bang xp9 race oil, you probably dont want to see too much time at over 250 degree oil temps.

kisik

Always upshift. Perfect your shifting to the point tat Instructor wouldn't notice it. Do not rush shifting. Slow and smooth. Fall in love with your car by making her work easier at lower temperatures. She will reward you back. Zero reasons to hold at 7k RPM. Even your power steering fluids would be way cooler. Trust me. This is another weak point.

Hella-Buggin'

I short shift all the time. I'm not racing anyone and the meager time gained in some areas isn't worth my anxiety over oil temps, AOS, oil starvation and any number of things mentioned above.
I look at it like this... the engine was designed to accelerate up to redline and shift. Not to drive at redline for extended periods of time. Maybe I'm just a nervous nelly, but whatever.... I have fun.

JTT

Yeah, that sucked for Michel. I'm hoping it's nothing too serious, likely a hose or fitting. A weak spot that would have eventually failed regardless of the track likely. Personally, I do short shift just past the compression in T6 and before the left kink. For those others replying, this is not a Daytona banking style turn, your at full throttle for a second or so, then feathering for an immediate transition right to left and then hard braking zone.

Charles Navarro

I would not be concerned with the stock rev limit and running the engine up to that point. If you have a tune that raises the rev limit though, you do not want to push the engine past the stock rev limit. We have seen too many rod bolt failures coupled with tunes that raise the redline.

jamesinger

This is slightly unrelated but relevant:

I haven't bounced off my rev limiter on my 997 yet but I also have not been to the track with my new car (as of 2/2018). However, what I have noticed that as I approach 7k, I feel as if power tops out and in a non-adrenaline flooded environment, my instincts from driving a stick for 25 years is to shift at, or just before, 7k.

At the track, sometimes people will bounce off their redline because their adrenaline is redlining too. I do not think this is what you are asking. One thing I learned getting my race license through NASA in their HPDE series is that at first, I was shifting too much in an attempt to keep revs up. My instructors taught me how to stay in my power band without shifting too much, and without sitting on the very top of my rev range in all situations (BRP, WSIR, Streets...).

The other main reason people seem to go over redline is from mis-shifting but this is also not your question.

In any case, I would rethink what the benefit is of where you are sitting at if you are sustained above 7k. In most cases, it seems like it is not worth it for my previous experiences . I was not as worried about blowing a motor as what benefit does sitting that high in the rev range serve? For example, Here in CA, at Streets of Willow CCW, when you climb that last hill before turning to go downhill on the straight towards the skidpad (turn 13?), I realized coming out of that little turn before you climb the hill (turn 12?), if I am in second and I floor it up the hill, in my EVO on non-R comp tires, I would be (at best) over heating the tires to where my grip was very clearly diminished. When I had an off there a couple times, it is because I was actually spinning tires all the way from turn 12 to 13 and the tires overheated. As a result, I started up shifting earlier and it didn't affect my lap times seriously for a non-competition hot lap, and it saved my tires for sure + my overall temps were lower as well. If I was a better driver, I would modulate my throttle more. Regardless, I noticed that sometimes it isn't worth it to be in the upper rev ranges for power, control, fluid temps, or for tires..., so I will shift a little earlier, even if it means shifting a bit extra in those situations.

Here is a link to the map if you're interested just to get an idea:
http://www.speedventures.com/events/...il.aspx?id=677
streets seems similar to what you're describing whereas WSIR is a big track with lots of speed.

rap