The spoiler wall on my 92 C2 was split when I purchased it. I'm referring to the black piece of plastic which helps to force air down into the engine. I used black duct tape to repair it rather than replace it because I heard that it would probably split again anyways; plus, the repair was very hard to notice.

Lately, I've noticed that my engine temperatures were a little higher than normal, and it's also been taking a little longer to cool down once I get up to freeway speed. Then today I noticed that the spoiler wall was split again. I know it's very unscientific, but it leads me to believe that having a split spoiler wall has a measureable effect on engine cooling.

The ambient temperature where I live has been about the same or even cooler lately, so I don't attribute it to a change in seasons. I'm going to tape it back together shortly and see if I notice a difference.

Anyone else noticed this?

 

When I purchased my C2, half of the spoiler wall was missing...I didn't care. I really don't think it plays that BIG of a role in engine temperatures, although it does make sense that it encourages fresh airflow to the engine.

I don't know that I ever experienced any adverse affects to the engine by not replacing the wall.

Any possible issues with the aforementioned item has been cured now...with the addition of an RSA tail!

 

There's a person on the DIY 993 web site who found when they installed a turbo tail, that their performance dropped. They measured the temps at the air intake, and found they had, interestingly, increased with the new tail. They also found a turbo option which added a scoop to bring air in directly from the tail opening to the intake, as opposed to farther back in the engine compartment in the stock location. When they added this scoop to their non-turbo 993, the lost performance returned. As I consider adding an RSA-style tail to my C2, I wonder if there's a 964 lesson to be learned from our 993 friends....

 

I have a related inquiry -- is there any difference in engine cooling between a fixed (RS America-style) wing and the factory active wing on a 964?

I fitted an MA Shaw RS America-style wing to my '91 C2 and my perception is that my car now gets hotter, quicker if idling at a stop or in stop-and-go traffic (i.e., the temperature gauge reaches the 9:00pm position quicker and stays there). However, once I get moving, it cools off quicker and stays cooler (i.e., the temperature gauge drops to 7:30-8:00pm) than it did with the active wing.

There is a string on the 993 board about fitting a "turbo" fixed wing to a normally-aspirated 993. Apparently, Robin Sun put a factory turbo-style intake horn, which is designed to work with the fixed tail to pull in outside air (rather than heated engine compartment air), resulting in lower engine operating temperatures.

This is consistent with my experience with my car: i.e., the fixed wing causes the intake horn to pull in heated engine compartment air, rather than cooler air, causing my car to run hotter when standing or in stop-and-go traffic. Once moving, the greater intake area of the fixed wing results in more outside air cooling the engine compartment, causing the engine to run cooler.

I would be curious to hear any thoughts concerning the above and anyone's experiences with fixed wings and engine temperature. I would also be curious about whether or not the turbo-style intake horn that Robin described would fit and be beneficial for a 964.

Thanks in advance for all replies.

 

John, I got your personal email...and felt obliged to return to this subject, as requested.

I can't possibly understand how your engine would run hotter, light to light?? Think about it, with the electric "pop-up" spoiler, it CLOSES when stopped. The RSA style tail is wide open, all the time...this would let heat rise as it normally does, especially at a stop. Compared to the closed condition that the "pop-up" tail is in, the vents in the RSA tail provide more surface area for heat escape/disapation, even though it's still vented through the same size hole in the deck lid.

Now, there is certainly a difference at speed...the engine runs MUCH cooler, especially on a cool night...sometimes too cool. I rarely check my oil level via the dipstick, as my gauge works very well...so if the car never gets up to temperature, the gauge won't read accurately and I could overfill the oil system. So, secretly, that gets annoying.

Sometimes when I return home from work in the morning, I let the car run in the garage, while I eat breakfast...then I go out and see the level on the gauge. Mind you, I only do this maybe once a week, as my car doesn't consume much oil.

As far as the 993 guy losing performance, sounds like he's been fairly scientific with taking air intake temps...but I still find it hard to believe, nothing against him, I'm just a skeptic in this case, that's all. Although "swirling" effects of air may encourage warmer air from the engine compartment to be ingested vice the cooler air from the wing.

At speed, the fresh air brought into the wing would certainly be gulped up by the engine cooling fan...so it's possible that any heat disapation from other areas of the engine may be ingested by the airbox??

This is certainly a good point for discussion. I must say I notice a performance increase in my car on cooler nights, but the last few days have been warm. I may be paranoid, but it feels like I have lost a few ponies as well...we'll feel the difference tonight, enroute to work I'm sure...as it's cooling down quite a bit as I type this.

Guys, I wouldn't be too concerned about the possibility of any significant loss in performance. The 964s OBD I system may be short on providing consistent performance, but it seems to cut the mustard. If you want REAL inconsistent performance, buy a CIS injected 911!!

I donned the wing and front spoiler to increase downforce at the track, and for asthetic value...to date, I believe I have achieved both.

 

I've seen the same article @ the 993. In a nutshell, he found that his intake temp was slightly higher after mounting a 993 Turbo style fixed wing vs. the popup spoiler. He was using OBDII software to actually monitor the IAT (intake air temp.) He ended up adding a "snorkel" to reach up and get some fresher air. For the full scoop you can check it out here:<a href="http://p-car.com/diy/intake/" target="_blank">P-Car.com</a>.

I just wish there was similiar OBDI software for our cars <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Enjoy!

 

Hi guys,

I was directed to this post from a post on the 993 board.

I am Robin, p-car.com is my web site.

Here are some answers I hope will answer some questions.

(1). I never tested the intake temperature with the motorized tail compared to the turbo tail. Only with the turbo tail.

(2). I am not sure if having a fix tail will help cool the engine better than the standard motorized tail, personally I never noticed any difference with my oil temperature with either tail.

(3). Adding the snorkel difinitely will decreased the intake temperature according to the OBD2 read out, if anything the results was bias against the snorkel since I did the snorkel test 2nd.

(4). The test does not conclude that the factory motorized tail do not cool the engine better than the fix tail. If anything I think they both will sufficiently cool the engine.

(5). The test only conclude that if you add a fix tail to your car you should consider adding the snorkel device to get maximum performance.

Personally I believe the flexible spoiler wall does a great job in deflecting cool air into the engine bay, in the same time directing cool air into the air intake opening. (Assuming the car is moving) However, having the snorkel on a fix tail car will allow more cool air to enter the intake at any speed.

FWIW, Every 10 degree = 1% horse power. I think.....

 

I too had a split wall on my spoiler when I purchased my car. On inspection it appeared that this would not allow a lot of cooling air to enter the engine compartment, so for this reason I replaced the wall with a new one. (Quite a simple job). I didn't notice any difference in temps at all with the new wall fitted, but my psychology factor feels much better. The guys from Stuttgart are the experts after all.

 

Hi Drew,

Back when I had a spoiler wall (pre-VRAM engine), I don't remember the car running warmer when the spoiler wall was split--which happened to me twice.

My experience has been that the engine typically runs hottest when immobile--e.g., stuck in traffic. I believe my experience is typical here.
Since the spoiler wall isn't deployed at these times (it's folded, of course), doesn't seem like it would be of much worth, would it??

My car doesn't have a spoiler wall, and it runs quite cool at 50 mph (+), when Porsche (as I understand it) implies the extended spoiler wall aids in cooling. I believe my experience here is typical. Perhaps at Autoban speeds the spoiler wall's benefits might become apparent? Anyway, what I've always thought a bit odd is the spoiler wall's maximum effect occurring when I don't really need it ....

FWIW, I have an old factory brochure that says (with respect to the extendable rear spoiler):

"Improves engine cooling (it actually doubles intake air flow volume when extended!)"

When you say your car is running a little warmer, how warm would that be?

 

Robin,
Is it counterproductive to have the snorkel combined with a drilled airbox? (Would have thought the drilled airbox increases warm air intake from engine...)

 

Phil, (993RS)
I responded to your question in a private e-mail.

 

Thanks very much for your replies!

Jeff, I think that my low-speed fan may be out-of-service, aggravating the temperature issue. I'll have it checked the next time that I bring the car in for service.

Robin, one more question: do you think that the 993-fixed wing horn will fit a 964 with an RS-America wing? (I'm concerned that the decklid opening in my 964 may be a little narrower than the decklid opening in the 993, causing the 993 horn to not fit into the decklid opening). Also, does anyone know whether or not the 964 and 993 airboxes are the same?

 

Hi Randall,

You asked about how much warmer the car has been running. Previously, the engine temperature needle would always stay below the 8 o'clock line (the 194 degree F line), typically a little more than halfway between that line and the line below it (i.e., closer to the 194 F line). For about a week now, the operating temp has been right at or slightly above the 194 F line, even when I arrive home from work in the evenings, which is very unusual.

I'm not really worried about it since the car isn't even close to overheating. If anything, the engine is running at a better operating temperature, but I just wanted to see if anyone else had any insight on the spoiler wall.

My wall is split about half way down, and the top half has folded into itself so only the bottom half is forcing air into the engine compartment. I'm going to fix the wall this weekend and see if I notice a difference.

 

J-McDonald,

The air box assembly between the 964 and the 993 are completely different.

I don't think it will be a plug a play solution using the 993 trumpet, but who said you can't make you own?