Mike Murphy

ProCoach

The author, in a 488C at Misano.
Video and on screen data using RaceNavigator.

sbelles

I watched it. He does a good job.

One thing I was surprised by was that he didn't mention the downside to maxing out castor which is that it increases the wheel base.

dan212

This is really exceptionally interesting and informative. Thank you for sharing

Blue Chip

I've actually watched it once now and listened to it like a podcast another time. It's really cool in a very techno-geeky way. I love it.

mark kibort

that was a very good presentation.

StoogeMoe

I finally had time to watch this. That was done very well and an excellent speaker! I loved all the math incorporated into the lecture for each point.

Even if you're not into the math, I think you can understand why we do the things we do to our cars to make them go around the track faster. It should also become apparent how complex car handling is and how changes may not always do the thing you expect. Sometimes you just have to experiment.

Thanks for sharing

dbbarron

That was great.
Thanks for posting

Blue Chip

rbahr

Blue Chip :I would suggest that you read https://www.caranddriver.com/feature...11-gt3-feature

This story is based on putting both cars on a 7 post rig...

Ray

aryork

I love how these quotes stick in your mind. I laughed out loud!

Blue Chip

Very cool read. Thank you - though I would expect that a GT3 outperform an R - the science is interesting in practical application.

aryork

Interesting, but having 100 HP more, better/bigger tires, and more refined suspension set-up pretty much makes this not a great comparison of how physical properties (moment of inertia) affect handling. It's a totally valid comparison of individual car performance, however.

If you could take the same GT3, flip the motor over the rear axle, move it up about a foot, and hang the tranny over the rear axle (like the new 911 RSR), then repeat these tests it would better.

rbahr

I had a conversation with the guys who ran the tests (the 7 post rig) and it was interesting. I asked exactly the same questions WRT Polar Moment and the hypothetical equal HP, tires, etc . There generalized comment was the the 911 (GT3) chassis was better at the limits than the Caymen. They also indicated tat they did not post all the data (in the story) than was generated.

aryork: WRT rearranging the motor / transmission absolutely true, no argument there, but the generalized comment was that the Caymen would never be as good was hat struck me.

Ray

lowside67

That was about as flawed of a test as they come... seems insane to try to pass that off as "science." The Cayman R is not the same prep level as a GT3... suspension bushings, power to weight, wheel/tire size, and of course the actual compound of tire. A new Cayman GT4 vs a GT3 would address some of these items a bit better.

G-Circle: GT3 wins based on total tire size versus total weight, nothing to do with weight distribution. Also bonus points for ("911s are known to be hard to handle at the limit, but this long, steady state corner is totally where we will disprove that!")
Slalom: Both of those were so poorly driven that there is absolutely nothing to be gained from that test other than driver dispersion.
"6 turns": you see and hear them get to full throttle between the turns so obviously the implication that they are tight enough to eliminate that is wrong. More importantly though, the tire compound and overall higher level of grip from more tire.
Spin Threshold: might be the actual dumbest test of the bunch. At full throttle the 911 has far less weight on the nose so is going to experience understeer by rapidly adding 90 degrees of steering... which will essentially allow it to "pass" this test since the only criteria is when does it swap ends.

I think it is well proven that the GT3 has a higher limit than the Cayman R - as it reasonably should given its position in the hierarchy and the specs of the two cars. But this test "scientifically" attributes that to the weight distribution which is just silly.

-Mark