[Jase007]

So ... more questions on the normal accepted premise for 911s [assume high speed operation 110mph + so that aero is a factor]:

chin spoiler no wing = OK
rear wing no chin spoiler = not OK

1. With wing and no spoiler, is wing decreasing lift over rear of vehicle still?

2.Does only a spoiler and no wing reduce lift at front of car?

3. Does OEM spoiler without wing create more lift at rear of car?

4. Does wing and no spoiler make the front end loose b/c of R weight bias, aero lift under nose of car, reduced lift from wing, other ?

5. Does it matter if the car is lowered and stiffened [track only car]?

6. How much does rake of car affect lift?

Just some food for thought.

Jase

[Marc A]

That's not food . . . . . that's a freakin BUFFET

[William Miller]

7. While on the subject, what speeds do SC acheive at SP for instance in the various sections of the course?

7.5 Are rocker extensions just for looks?

[APKhaos]

Some where in my files I have the original factory lift measurements....

Found 'em. These measured numbers make things crystal clear.
What they show is that the effects follow the square of speed, which means that negligable lift is generated below 80MPH, and considerable lift is generated above 120MPH.

What they do not show is the interaction between the front and rear spoilers. I have that chart somewhere, but you will have to take my word for it right now.
- The chin spoiler by itself reduces lift front and rear, but not dramatically.
- The rear spoiler by itself REALLY unbalances the car. Lift effects are considerably higher at the front axle.

That said, I ran my 911 with a chin spoiler and no rear spoiler. I ran a very stiff torsion bar setup.
The car was stable in high speed turns and on straights.
It was not AS stable as a similar car with similar sulpension setup AND a rear wing. It was faster in terms of terminal speed that that car because of the drag penaly associated with the rear wing.

FWIW, the only reason I didn't run the rear spoiler was becasu I preferred the lines of the 911 without it [unless we are talking wide bodies or serious race cars]. That one of the reasons I went to an all-business race car.

[Jase007]

7. While on the subject, what speeds do SC acheive at SP for instance in the various sections of the course?

Is Pari driving ...? [I'd guess a green student would get up to 110-120]

7.5 Are rocker extensions just for looks?

Do you mean rocker covers? If so, you'll be fine ... leave them off. Better cooling for oil lines to front.

Jase

[Jase007]

Tony: from Frere's book?

Do you think it is incorporating the various chin spoilers and / or no spoilers when contemplating those particular three rear wings?

Jase

[APKhaos]

Jase,
Yes, these are Paul Frere's charts.

This set is rear wing only, and Frere used it to illustrate the impact that the rear wing had on both front and rear axle lift numbers.

I have the other chart, but can't locate the scanned file right now. THat chart [and the text] talks to the interaction between front and rear spoilers, and highlights the non-intuitive finding that the rear spoiler only has a detrimental effect on front axle lift numbers - they go up considerably vs the no spoiler case.

[Jazzbass]

Originally Posted by Jase007

Is Pari driving ...? [I'd guess a green student would get up to 110-120]

That's about right - at the end of the front straight you'll be redlining in 4th, which is about 115. For your HPDC, Bill, you'll be on the Jefferson Circuit and probably won't see speeds above 100.

[michael lang]

So if I'm reading this correctly, what you're basically saying is, if a car (normal street ride/occasional DE sled) were to have a spoiler the spoiler to have would/should be a chin spoiler. And that this spoiler alone will help in keeping the car closer to the ground than that big thing in the back. How if any will that help in speeds below 100 mph?

Mike

[Trak Ratt]

Like TK I have some information on aero aides but can’t find it! From memory the “Duck” reduces lift. Whale, tea table, turbo, GT wings and others add down force. Now I wonder if the 993’s does down force or reduces?