Proper technique when 911/930 oversteers?

[Dave at Pelican Parts]

Any time you change the throttle, you change the weight distribution of the car. So even if you're only maintaining speed, if you lift off the throttle you are shifting some weight from the back to the front wheels of the car. Usually the amount of throttle you use for maintaining speed isn't a lot, so the weight change isn't a whole lot, but it's there. If you're close enough to the limits of traction, that reduction in weight on the rear tires will cause them to lose grip, and the tail will start to come around.

If you're accelerating hard, lifting off the throttle will be a larger change in acceleration, so more weight will transfer. Your chances of the back coming loose are much greater in that circumstance.

--DD

[Trackrash]

Originally Posted by bpu699

Thanks guys, follow up question about taking high speed sweeping turns in a 930...

Let's say you are going 80mph through a consistent radius turn...

If you are traveling a steady 80, and then let off the throttle suddenly, does the car continue its arc, or does it spin out?

I would think that since the suspension is evenly loaded, it wouldn't spin? Correct?

Whereas if you were accelerating, and the rear is squatted down, and you lift off...it spins?

If you are at the limit and you are using neutral throttle THEN suddenly lift,you will most likely spin (assuming no further action).

At steady state cornering, neutral throttle, the car is balanced. When you lift off the throttle the weight shifts to the front and off the rear. Less rear traction will be the result and it could initiate a spin.

Search: throttle steering

[bpu699]

Thank, I will keep practicing.... I have been slowly working my speed up, have done 2 track days so far... Getting better. Hope to go to roadamerica next year. I just want a track with some curves that aren't surrounded by concrete... At this last hpde 2 guys damaged their cars. One was a vette going 120 in a sweeper that collided into the concrete surrounding the sweeper. He is lucky to have walked away. The boom of the collision was awefully loud. Another guy spun into a tire wall with a Honda.

Milwaukee mile track is pretty neat, but there is tons of concrete. It's an oval with an inner run. The oval is surrounded by concrete walls, no runoff whatsoever. If the vette drivers had runoff, I wonder if it might if helped. On the other hand, he might have spun off and hit something head on at 120mph on another track...

The possibility of the back end swinging out has made me paranoid...I think.

I see Ford Focus's, miatas, and Boxsters taking corners at pretty darn high speeds... I am baby crawling my way towards higher speeds. Honestly, I could probably take the corners faster in my suv .

So, for those who have tracked 911's and 930's and actually know how to drive them... Would these cars be faster on a track than a Miata? A boxster? A wrx?

Not looking to beat any of these cars, just trying to figure out where to set my expectations. Should a 930, assuming comparable drivers, be able to keep up with these cars?

With the turbo lag out of sharp corners, and the concern over taking other corners at high speed... I am not keeping up even at the novice level. On the straights, I am pretty much level with the others. Figuring a 930 probably has 300hp on a good day, that's about where it should be. Most of these other cars are 250-300 hp plus...

I enjoy tracking the 930, as I finally feel I am getting some use out of it. Driving it on city streets isn't that much fun...

Bo

[Trackrash]

I would suggest you do a couple of things.

Ask for your instructor to drive your car. If he is familiar with Porsches (as in a PCA instructor) you may learn a few things.

Take a few laps in other Porsches driven by instructors.

Find a local PCA chapter that offers a Performance driving school and enroll.

Participate in auotcrosses. Fast enough to be challenging, but probably much safer than a big track. If you spin out at an autocross, no big deal, we have all done it. It's a fairly safe way to learn the handling and limits of your car.

It is a huge step going from driving on the street to a race track. It will take time to learn the limits of your car. There is no reason to push it hard on dangerous sections of the track.

Originally Posted by bpu699

So, for those who have tracked 911's and 930's and actually know how to drive them... Would these cars be faster on a track than a Miata? A boxster? A wrx?

Not looking to beat any of these cars, just trying to figure out where to set my expectations. Should a 930, assuming comparable drivers, be able to keep up with these cars?
Bo

I have a 190Hp 911. Typically the Miatas and Boxters will beat me in the twistys if they are driven by good drivers and have decent tires, but I can leave them behind on the straights. Those newer suspensions just work better.

[wayner]

Originally Posted by bpu699

It's an oval with an inner run. The oval is surrounded by concrete walls, no runoff whatsoever.

Lots of professional drivers have chosen not to race on ovals. There is no need to be a hero in your 930 on an oval.

Originally Posted by bpu699

I see Ford Focus's, miatas, and Boxsters taking corners at pretty darn high speeds... I am baby crawling my way towards higher speeds. Honestly, I could probably take the corners faster in my suv .

Maybe don't try to take their lines

A front wheel drive car tends to apex earlier. In a loose situation they typically get understeer. You get the opposite.

A mid engine car excels at turn in and mid corner speeds. A 911 excels in the braking zone and at the corner exit (though our corner exit starts a whole lot earlier in the corner).

A 930 driver might want to square off the line entering an oval to get a straight drive onto the banking. Also straighten out the braking zone so that you don;t have to lift while turning. Find some videos of 935 racing with in car footage and notice their lines just as an example of how they drive differently than competitors.

Also look for same race videos of hopped up 914s picking their way through a field of 911s just to get an idea of different lines that the 911s take.

[wayner]

Here is a cool 935 video taken from Brian Redman's mid engine Lola

Note how much the 935 straightens out the esses, pulling the trigger when straight , while Redman in his mid engine naturally aspirated car can flow through them
The best parts starts at 3:19



...And... on an oval here is a great example of squaring of the turn so that you can drop the hammer.
This seems to be the safest technique rather than have the turbo spool up mid corner.

Start watching this next one at 11:34, listen to what he says about the car, then watch his line onto the banking at the end of the interview.
Also watch his line after he is onto the banking. He doesn't treat is as a curve, but drops down to straighten it out even more.

Also, check it out at 25:00
in the same video, and then 47:15



I used to race a big two stroke motorcycle, and what I learned is that very bad things happen when the huge power band hits mid corner.

In this picture (I'm in yellow) with the cement wall to the left, you can see the tire marks on the wet pavement to my left where momentum bikes used cornering speed to be fast. (This is an endurance race and the guy ahead of me who I had passed earlier, saw me coming two corners ago and moved over on the straight to let me by, so ignore his line).

For me, in these conditions, rather than maintain corner speed,I'd give up a bit in the corner and then I'd apex early, exit much straighter and run a diagonal line from the apex to that cone at the end of the straight, then braking in a straight line, tossing it in, straightening out the next right and pulling the trigger again on the next straight. There is no one best line. It differs depending on vehicle dynamics and conditions, but it is really nice to be pointed in a straight line when you hit an abrupt powerband as in a two stroke or an early turbo.

Cement walls aren't worth it.

[bpu699]

Thanks all. Plan to practice more...

Have to say I think I am now addicted to track days... Heck of a lot more fun than just driving around the neighborhood...