Thanks for the information guys. I would like a little more stability when I'm driving and a little help with the cross winds would be nice also. My car came w/o the front lip but the holes are there for one to be installed.... I will probably end up with the front lip and the duck tail. I was trying to decide between the duck and the carrera tails. If I don't like the duck I can always get the carrera later on.
BTW has anyone received their new Performance Products catalogue??? Wayne's prices are getting better by the day! I think evey time I get a new one the more popular parts are going up.

One of the main problems with reducing lift at one end is that it acts like a "teeter-totter" and usually increases lift at the other end.

For instance (hypothetical numbers)

no spoilers
Frt lift 150lb rr lift 250lb

frt spoiler only
frt lift 20lb rr lift 300lb

rear spoiler only
frt lift 200lb rr lift 50lb

both spoilers
frt lift 15lb rr lift 30 lb

I think it's best to have both spoilers regardless of what type of rear you're adding. The Frere book does list something like what I've listed above for an early car with "duck" tail and "S" style front air dam.

All of that being said. My car, '88 targa, came to me with a front lip spoiler and no rear spoiler. I want a rear, but have had other things to spend money on. I've had it tached out in 5th. It's pretty stable up to around 135 then feels light. Of course the time I did the jump to hyperspace I went in a mostly straight line and had cover on either side of the freeway to block most of the wind.

Paul,
I'm going to Pocono in April with NNJR PCA. I have heard many stories about 'the bowl.' Will you be there? (April 13-14)

Back to spoilers: My car does have a rear spoiler, and the front adn underbody are aerodynamically designed. But I have a lowly 944, so my speeds probably won't reach high enough to really need them! :eek:

turn 13 at MID-OHIO tells the tale pretty well. It's a lefthand sweeper with no camber and leads up to the carrousel. The guys with no trim need to brake significantly or have brass balls. Those with the spoilers just tap the brakes to settle the car and motor through.
So far I've been using the brass balls method but i'm really looking forward to this year with a 930s front airdam and teatray. :p

Thanks John;
You finally answered the question that needed to be answered. The handling requirements of driving straight at 100+ MPH are very different to the handling requirements of driving a turn at 100+ MPH.

I'm curious what track experiences people have had driving a 911 with only a front spoiler versus a front spoiler with either a duck tail or a whale tail. Is the car uncontrollably loose :eek: or mearly "lively":D ? I know that in the Up-Fixen article they supply some numbers that suggest a spoilered car is much easier to control in a lane-change situation then a non-spoilered vehicle. If I chose to not use a rear spoiler for style or rules reasons, what is the affect of using no front spoiler,a small (S or RS style with no lip) spoiler or a deep front spoiler (RSR Style)? What are people's track experience?

The real benefit of spoilers (any and all) is in crosswinds. This can be felt at modest freeway speeds, even when passing a semi.

I believe they are mandatory for safety at any higher speed track that is subject to high winds. Without spoilers, the car will really move around under a strong gust and change its set and weight distribution. This is unacceptable. When cornering near the limit, you are commited to stay precisely on your line and not change the balance of the car (hence the term "don't lift"). A 911's movement under crosswinds without spoilers makes this very risky. If you are at 98%, as any red-blooded trackmeister should be, it will put you off. You simply can not drive to the limit at places like turn 8/9 at Willow Springs without spoilers on gusty afternoons with that wind off the desert.

Porsche introduced the front spoiler in, I think, 1972, before they had even invented the ducktail. It was standard on 911E and 911S models. It has a definite decrease in front-end lift. I bet the front spoiler is what helps in crosswinds.

Porsche would not sell any rear wing without the front spoiler. Any rear wing effectively increases front axle lift. Porsche measured a decrease in rear lift with the Carrera wing as slow as 35 MPH. Porsche also found that the ducktail did reduce drag and helped keep the rear lights clean (per Ludvigsen).

No spoiler is fine for even semi-legal driving. Front spoiler is great for almost any situation. If you compete (formally or informally) or need additional high-speed stability, front and rear is good. Rear and no front is BAAAAD and immediately marks your car as "not right" and poser (sacrificing performance for looks).

My personal preference? Like Ferry Porsche, I like my 911s with no rear spoiler.

Spoken like a true sailor.

(no offence to sailors intended)

Spoilers actually reduce drag by reducing the lift, provided the do not increase the frontal area of the car. The energy used to lift the car is paid for in drag. So there are two benefits, reduced drag and less lift (putting more weight on the tires, increasing traction.

Wings on the other hand are a different animal, but that is another story.

Yeah, with lift comes "induced drag", so killing off some lift would reduce drag, induced drag specifically. Parasitic drag (the other kind of drag) comes from things sticking out in the breeze, like rear view mirrors, hence those streamlined mirrors on the 935, for example.

And, Dug 89, you're right, I should have asked "How fast before you need a spoiler ", not a wing. Two different things, indeed!

I know there is a design difference, beside age, between my 78 SC and my 66 912. The SC feels more stable above 70 mph, but the cross winds, especially in Oklahoma, are BAD! Sometimes I feel like I'm getting thrown around, and sometimes I do get tossed half way into another lane. The 912 over 60 mph is very light, it just feels like it is ready to fly off the ground. Strangely it is not as affected by cross winds as the SC???

Z-Man

I have registered but not received confirmation for April Pocono I. Assuming the stars all line up just so, I will be there. I have a noisy white Carrera number 827 with a duck:D Hope to see you there. My brother (Eugene) will be there with his nasty black 944 Turbo number 92 instructing neophytes like me.

Back to spoilers- I would suggest that people balance their cars properly with both front and rear aerodynamic aids especially for high speed motoring. My 0.02.

Paul

My 2.7 powered (1968) 912 feels more stable at 120mph than some brand new cars, even some German ones, with spoilers and wings everywhere. It has high profile tyres, no anti-roll bars, the original round chin and no ducktail. With all these handicaps, I still outrun most modern Jap-cars through any turn, at any speed, on any surface. And some German ones.

I can only imagine how much better the later models must stick to the road.