Bill I have an 86 Carrera, good to know some numbers. I like the duck tail look but there is the added efficiency with the larger tail.

The total amount of lift reduction (in pounds) is dependent on speed. A better way to look at it is that a front spoiler/ducktail combination will kill about 80% of the lift at a given speed and the front spoiler/early turbo style tail does even better, at about 90%. The 3.3 turbo tail is even more effective, if you don't mind the looks of it on a narrow-bodied car. The other benefit, and the one that is most noticed in real world driving, is the much reduced sensitivity to crosswinds. That and the lower oil temps...

JR

I have the front spoiler without the rear spoiler. I did some DE events and noticed some oversteer so I must assume that the rear is getting too light compared to the front. I like the plain look but probably should balance the car.

Yeah, that's the problem with that combination.

I got the same combo on my 1976 911. I don't exactly remember when and where, but Porsche warned against putting front spoilers on early 911s without a rear spoiler as well. As you said: The rear is getting awfully light. The German Autobahn at 130+ mph in crosswinds can be a pretty demanding experience.

No need to do anything. As I said: You've won bigly.

At one point I got a front splitter and a rear gt2 wing at hardest setting. Then I switched to duct tail and left the splitter just to see the effect. It felt like the rear end was lifted on highway. I just had to lower the speed to feel safe. 315 rear tires.

When the Duck directs more air that cools the, does it also make more power???
 

The duck, (with front chin spoiler), seems like a win, win, win: lower oil temps, (and likely lower cylinder head temps), less drag and near 0 lift generation.
Does the increased air, that lowers oil temps also provide more air to the intake system, thus generating more power????

Curious,
chris

You'd find a bigger change by adjusting your tire pressures. So, technically yes; no you'd never feel the difference.

JR

According to the COA and how I I got it from PO who imported it, my 76 Carrera 3.0 Targa shipped with a front spoiler and a standard decklid, without a tail. At highway speed, it felt unstable. I did a DE without and with an early turbo tail. The stability is incredibly noticeable with the tail. There was an article describing the same as you say Slush, that a front or rear spoiler should not be used without the complimenting end installed; to use both or none.

If you are implying that Porsche built the car in that configuration, I think you may want to go back and do some additional research on it. Not only was there no option for that configuration in 1976, it's worse than the opposite arrangement (nothing on the front, with a spoiler on the rear) and it's not something Porsche took lightly.

JR

I hate this argument and yet I'm irresistibly pulled in. With a wing, the air moves faster under the wing and slower over it. Creating downforce on the WING and therefore downward pressure on the car. With a spoiler, or a ducktail, you slow the air moving over the car itself and the air under the car is moving relatively more quickly, so the car itself in effect becomes the wing. Both applications create downforce.

Whether its possible or not and if an option existed for front spoiler without some form of tail, this is all I know from records that came with the car, COA, and pictures from the previous owner. The COA says rear decklid without insignia, without option number. Could a customer get what he/she wanted contrary to what Porsche recommends, that I don't know. Whether the tail was stripped and pawned off or the front spoiler was added at a later date, I don't know for sure either. Point well taken, I will go back to PCNA and ask them to dig deeper.

In this thread, I was simply trying to add a data point of what I observed with and without the tail vs front spoiler only.

You'll find that PCNA didn't exist when your targa was produced. In that era, Porsche was represented in the USA by Volkswagen of America. From my point of view, VWOA was less than helpful with respect to Porsche so I imagine the transition to PCNA was ugly. Certainly, it had a lot of controversies. In any event, they had no useful info on ROW vehicles, since they had nothing to do with them. Fast forward to now, the folks at PCNA try their best to interpret what info they have and they often get it wrong. Porsche makes it tough, by having reused many option numbers in different eras for different things. Then, some of the records at Porsche AG were accidentally destroyed at some point, so they don't even have all the records at this point.

In any event, I did a lot of research into spoilers back in those days. I probably still have some of the documentation from that era, not that I could probably find it now. There was no option in those days for just one spoiler or the other. That's not to say that one couldn't have been added by a dealer when the car was delivered. A front spoiler can be added relatively quickly, at not a huge cost. Porsche even offered a kit at one point, containing the spoiler and all of the hardware needed to attach it. Obviously, it takes a little more work to add the rear one, but a bunch of those were added by owners, after the fact.

No question they help the stability of a 911. I won't own a 911 without them.

You might want to look into the "deletion of model designation" option. It's a legitimate option, but I don't recall it being available in 1976 on a 911. I recall that it came along later.

JR