50 years different

[Les Paul]

I think there is a vid out of Randy Probst beating 918’s time at Laguna Seca with the GT-2. Over 700hp but not AWD. That’s like 962 power. I’d like to see Jack Olsen drive one at Willow.

[Jack Olsen]

Originally Posted by pwd72s

Jack:

"Through a long 100-mph sweeper, the weight advantage my car enjoys means I can go through that corner faster than a GT3 or even the 918 -- even with all of their technological innovations (four-wheel steering, suspension sophistication, torque vectoring, whatever). Lateral acceleration is where 'plain old weight' is a huge factor. 'Power-to-weight' really only applies when you're talking about straight-line acceleration (or deceleration). Power and cornering speed are not directly related at all."

Bingo! Colin Chapman had it right all along.

But Jack, you have to admit, your skill on Willow is higher than most...higher than many who run a variety of tracks. A well deserved skill earned through many hours of practice.

In a way, you're like the guy in a local pool hall named as the area "shortstop"...the guy called when a road hustler comes through town, lightening wallets. Call in the shortstop, and likely as not, the road hustler finds his wallet lightened, especially if he agrees to play on the shortstop's favorite table. On that table, the shortstop knows where a rail may bank funny, where a slow speed object ball will take a funny roll, etc.

I doubt there's a driver out there who knows Willow and it's nuances as well as you.

To get back to the original topic. Hell, let's face it...fat tires look much cooler than skinny ones.

Originally Posted by GH85Carrera

The real difference is 90% of the racers at the track could drive the 918 with good lap times and not crash. Only a few could do it with Jack's 911. The computers do amazing things for average drivers. Jack's car is 100% driver controlled.

No ABS, traction control, power steering or rear wheel steering and the other nannies.

I would love to have a ride in either car around Willow Springs.

I appreciate the kind words. But here's what I think: if I switched cars with Randy Pobst, both the 918 and my 911, I think I'd be slower than him in the 918, and he would be quicker than me in my own 911. I don't think I believed this, deep down, until a few years ago. I do know this one track very well, and I do know the quirks of my particular car very well. But after spending time with Patrick Long and another factory test driver for the 911R thing in Germany, I think a pro-level driver has such a depth of knowledge and skill that -- good as I think I am -- it's just in a different category altogether. Those guys are able to learn a car and a track so effectively, it just blows away my long-honed specialization.

You can see how meaningful the weight difference is in this short clip, I think. It's a case of steady-state cornering without either driver doing anything exceptionally difficult. But glance between the two speeds displayed. Assuming both are calibrated correctly, the heavier 918 is just plain slower in the same situation as the lighter 911.



https://youtu.be/1_tlN4S5a4w

[Eric Coffey]

Originally Posted by unclebilly

Well I know that on every race car (and kart) I have owned / driven, keeping all else equal, a 10cm wider tire has allowed us more speed through a corner and faster lap times. As mentioned, a bigger tire allows you to push harder before it steps out or ‘goes off’.

Originally Posted by GH85Carrera

Find me a race team anywhere driving on dry pavement that wants to go to a skinnier tire to increase speed. Good luck.

I think what some are missing is the "why" that wider tire performs better. It's not just the sole function of increasing the width dimension.

As Island mentioned above, a wider tire spreads the weight/force/pressure load more so the contact patch is wider, but also shorter, so no real increase in surface area. And besides, any increase in area is equally offset by a reduction in pressure (err something like that). So, the only real determining factor of "grip" is the friction coefficient of the materials involved.

So, all else being equal, a wider tire doesn't generate as much heat (and/or generates more cooling). Therefore a wider tire allows a softer compound to be used for a given "optimal" temp range.
Softer compound = higher coefficient of friction (i.e. more "grip").

At least that's how I understand it...

[pwd72s]

Jack, this reminds me of an old column I read years ago. I think by Jean Shepherd, but don't hold me to that. The article covered how in all human efforts, it's really difficult to reach the highest level, and how some learn this. One episode I read was in military Boxing...Army's best vs. Navy's best...the poor Army boxer discovering that the Navy fighter was named Robinson, went on to be Sugar Ray Robinson, world heavyweight champ. The Army guy recounting how he first tried to outjab his opponent...nope, he got outjabbed. Then he figured he'd move in, deliver crunching body blows. Nope, he received crunching body blows. Next he tried head hunting...and quickly was knocked out.

What happened to you has happened to many...those who learn we just weren't destined to be the best. Doesn't mean we can't enjoy our amateur activity while striving to be as good as we can be. It just means that top pros are top pros for a reason...they are beyond good at what they do, and it's all they do because it's their living.

Pool is my fun activity now, so I'll go there again. Here in the Pacific Northwest, the top two amateurs are a guy named Steve, with a Fargo rating of 699. This system is used to rank players based on matches played, balls missed, difficulty of match, other factors. It lists every tournament player on the planet. Nobody reaches the theoretical 1,000. My honorary nephew Matt has a Fargo of 696. This means that when Steve & Matt match up...flip a coin to pick a winner.

Steve has the means and the time to enter open tournaments. The tournaments the elite pros enter. I recently watched a video of Steve playing the first match of the Derby City classic. His drawn opponent? None other than Shane Van Boening, the South Dakota kid. The highest ranked player in the USA. Shane's Fargo? Around 825. Race to 9 games won in 9 ball.

Steve fought valiantly, used every skill in his arsenal, including safety play of placing the cue ball where I'd swear Shane didn't have a shot. Shane always had a shot, would answer with an even better safety, or in one case, a two rail kick shot knocking the ball in. Final score? Shane 9, Steve 5.

So, yes....the pros are better. Natural talent honed with tons of practice. It's their living. This applies to pretty much any sport or game.

[DanielDudley]

Originally Posted by masraum

Contact patch doesn't increase as tire width increases. The contact patch just changes shape.

What also changes is the contact patch's relationship to the sidewall. With a skinny tire, you get enough roll in a corner that you may need to over inflate the tire to maintain a more even contact patch. With a wider tire, you can retain your contact patch and run lower pressures for an optimal footprint.

Part of the reason we run negative camber on track alignments is to optimize contact patch on a distorted tire. You look at that early Michelin, and you will see a pronounced heavy tread on the outside of the tire. In heavy cornering, the inside of the tire is going to have very little loading. Your contact patch is going to go from a long oval to a sausage shape. With a wide tire, teh contact patch is going to go from a sideways oval to a rounded triangle. The contact patch is still going to increase on the outside, but overall, you are going to maintain more contact patch, and use more of the tire. The contact patch will actually grow on teh outside of the tire, and not decrease drastically at the limit.

[DanielDudley]

Originally Posted by masraum

Contact patch doesn't increase as tire width increases. The contact patch just changes shape.

Originally Posted by GH85Carrera

.

What also changes is the contact patch's relationship to the sidewall. With a skinny tire, you get enough roll in a corner that you may need to over inflate the tire to maintain a more even contact patch. With a wider tire, you can retain your contact patch and run lower pressures for an optimal footprint.

Part of the reason we run negative camber on track alignments is to optimize contact patch on a distorted tire. You look at that early Michelin, and you will see a pronounced heavy tread on the outside of the tire. In heavy cornering, the inside of the tire is going to have very little loading. Your contact patch is going to go from a long oval to a sausage shape. With a wide tire, the contact patch is going to go from a sideways oval to a rounded triangle. The contact patch is still going to increase on the outside, but overall, you are going to maintain more contact patch, and use more of the tire. The contact patch will actually grow on the outside of the tire, and not decrease drastically at the limit. With either tire, the contact patch is going to increase under heavy braking.

[island911]

Imagine how much harder these guys could corner if they had a bigger contact patch.

[Eric Coffey]

^^^ But, uh, that's different...those guys defy the laws of physics all the time.

[island911]

Point!