A Porsche engine is depending on air both for the cooling and, like other cars, for the combustion itself. My Porsche is a 911 Carrera 3.2 from -86 with an A/C. This means that the air intake on the hood is completely blocked by the A/C radiator which makes it almost like a closed box.

I don't have the rear wail tail but the original hood on the car and as I see it the venturi more sucks out air from the intake than push it in.

Some people say that I need to drill holes in the air box or install the Fabspeed solution but as I see it it wont do me any good. The engine bay is full of warm air with pour density and I don't want that kind of air. I want cool fresh air witch IMHO would give me a better response from the engine .

Any solutions?

 

You are correct about these engines needing outside air for best performance.

Porsche really did a very good job in engineering these cars,... When they are moving, there is plenty of outside air being forced into the engine compartment by the airflow over the car at speed, and by the cooling fan.

You may prove this for yourself (like I did) by installing a high-quality thermocouple into the engine compartment that will permit you to monitor temperatures while moving.

Porsche A.G, having excellent wind tunnel facilities, did a very good job in this area and ensured more than enough airflow for adequate cooling of the engine as well as enough airflow to develop more than the rated power.

That said, there is room for improvement at the air cleaner cover, due to the draconian Swiss noise regulations. Simply drill several 30mm holes in the air cleaner cover and you'll be set.

 

I've thought long and hard about this one and decided like Steve that Porsche know best , so I'm surprised but intrigued that you say Steve drilling 30mm holes in the airbox makes a difference . If it does I would try it , my car is a stock '78 SC and in this weather 95º my SC feels a liitle flat.
On a cool crisp early morning or late at night it feels like it has 20-30bhp more! . It seems more prone to atmospheric consitions than a two-stroke at times .
Do you have experience of driving an A-B test with stock and drilled airboxes Steve? I'm not doubting you but before I head for the garage with my hole saw in hand and ruin a perfectly good air box are we talking more bhp , more torque or just cooler running?

 

Thank you again Steve and thank you bones,

I have all respect for Porsche AG and if you say that the airflow is sufficient it's OK. I will fit a K&N, or possibly a JR, filter in the airbox and drill some holes after I have tried the new filter.

Nearby where I live there is a company that specializes in some kind of bypass chip called "Unichip". They install it on the cables outside the ECU and program it while the car is on the dyno. This chip can be reprogrammed after you have done some modifications on the engine. Could it be that you have any experiences on this type of chip?

http://www.dastek.co.za/

Best regards
Anders

 

Bones:

LOL,....I've tried many things in my 29 years career with racing these cars and this subject is near & dear to my heart. I've gone to a GREAT deal of effort in fabricating all kinds of cold air boxes that did not make one bit of difference, once the car was moving.

IMHO, the CIS engines do not benefit from additional holes in the air cleaner cover, the only thing you get is more noise,..

Anders: I am aware of the Unichip but I do not know if they make an interface for the 3.2 Carrera's. The final results are only as successful as the competance & experiences of the operator.

 

Dear Steve,

They do make an interface to the 3.2 and it is what you say "The final results are only as successful as the competence & experiences of the operator" that makes me afraid of doing it. Though they do have some good track record on Porsche cars. But I can say this, I visited them when they was working on a BMW M3 and he lifted the airfilter when the car was on the dyno ...and nothing happened. Except from the sound that is.

Thank you Steve for a very straight answer, I appreciate it.

Best regards
Anders

 

Damn!....no more free horses

 

What?!? You mean I won't get a bizzilion HP gain even with a K&N filter charger?

Snicker

 

Dwight,......

YOU will,....ROFLAMO.

 

I wondered about this also when I first started tinkering with my fathers 88 911. I then drove the car for about 2 hours on a very cool evening. I opened up the engine compartment when I got home and put my hands on the intake manifolds and they were ICE COLD. I was very suprised, but realized that even with the AC it must flow well enough to keep the large aluminum manifolds from warming up from the engine.

 

The blower pulls a HUGE volume of air through the engine compartment. At idle, it's not much at all. But if you were able to feel it when you're at 5000 rpm, it's a different story.

 

With a turbo tail on a 3.2 carrera, would it be wise to cut out some more of the metal (under the tail) to allow more cool air to enter?

 

No, you don't need it.

 

Soomewhere, I saw info that a ducktail will enhance external air flow to the engine compartment. It may have been factory data.

Thermocouples and readers are cheap these days -- many mutimeters can do this.

re power and air flow -- you need to distinguish the poer demand from the vehicle's seed -- you might want power and hence cool air at low vehicle speeds. A temp. sensor will tell you what you are getting -- I'd use two -- one at intake and one outside -- and read in differential mode, unless you se a datalogger.

re K&N - There are quite a few reports of fouled hot air sensors from the oil on such filters. I doubt they add any airflow over the stock paper filter. I do use them on my carbed engines, partly 'cuz they came that way and I don't see a bunch of oval paper filters being offered.

 

I have just been down this road on my 84 3.2 Carrera. I spent 10 minutes with a table saw and my airbox lid and viola, the Carrera Cup air box.

Didn't Porsche just use the face of the airbox lid on the 3.2 Club Sport cars? I think there was a pic in the latest issue of Excellence.

Anyway, the results seemed to be more throttle response and a little more repsonsiveness overall according to the butt dyno. I have a Steve Wong chip, Fabby cat-by pass and a RUF one in and dual out muffler. This combo is pretty impressive in my book. First gear is almost useless, I can't shift(nor do I want to) fast enough when I am full on in first. I have 255's in the rear on Fikse FM-10's and they light up pretty good. I need to get it on a dyno and get some real numbers, but overall the mods REALLY wake up the 3.2. Chip wise - I think the 84 3.2 has the most to gain

I think I may get Steve to flow my intakes this winter and smooth those out a bit for a little more oomph...maybe Steve would be up for a group discount or maybe not

Anyway...Steve gives great info...the airbox mod is the way to go. If you want your 3.2 to sound like a 2.4 MFI at full wail then the faceless box is the way to go...want a little tamer and just drill some holes.

-Jeff
nolift911@hotmail.com