Vancouver83LTD

earplugs?

avillena

How about a pricey one, Bose noise cancelling headsets; while you're at it, might as well buy one for you passenger; this way you can really have a very nice conversation while driving.
"Just drive the darn thing"

ignomini

The power change is going the wrong way. It looks to me as though air velocity in the intake tract has been dissrupted by poking the holes. There have also been scenarios demonstrated where a surface across from the air intake interacts with airflow in a positive way. Poking the holes may have eliminated this effect.

While a highly restrictive muffler could make it impossible to realize a gain, I'm not aware of a scenario where an adequate flowing muffler can "interact" with intake changes.

Porsche probably did a good job of optimizing the intake. They are unlikely to have left free horsepower lying on the table. Any additional flow - assuming there was ever a restriction - is likely offset by lower velocity and hotter air. I flatly do not believe a car has been made noticeably slower by going back to a stock intake. Show me the time slips.

Whew, that was thirsty work.

Bull

I see. So, why did they put the open boxes on the Cup Cars, etc., with more free flowing exhausts and engines tuned to move more volume through? The engine is only a big pump really. I agree that on a stock engine, not modified to handle more volume, all you get is sound from an open airbox, but not because an open airbox isn't better than a restricted box at moving more air in. ALL of the efforts of the Porsche engineers were focused on the best set of compromises that would meet the requirements/desires of the many controlling interests....customers, governments, accountants, shareholders, etc.

ignomini

I agree with you there. Better flowing cylinder heads, more aggressive cams, and higher rpm equals higher air volume needs. Changing the intake and exhaust makes sense in that scenario.

What we've often seen in the supercharger business is stock intake and exhaust systems flow well enough that changing them has no real effect. However, supply pressurized air, or make other changes to increase air flow capacity of the engine, and then there are additional increases to be had by changing intake/exhaust pieces.

There are exceptions. For whatever reason, Honda (Acura) strangled the RSX Type S. We saw 15-18 more front wheel horsepower simply by changing the intake and adding a header. That was an eye opener.

Blue Ocean

Robin Sun (Robin 993DX) did a dyno comparison a while back. I can't find the threat, but result was that using a drilled airbox cover (with large holes) produced less HP due to higher air intake temps from the engine compartment. A drilled airbox cover with smaller holes did not loose HP because it did not suck up as much hot air.

hidden impact

correct me if i'm wrong, but that was a test using a fixed rear wing.

with the standard wing raised at speed, the air the compartment is cooled considerably.

Edward

Yes, but remember that a dyno is a static car on a rolling road. Temps can very likely be higher due to static air around the engine bay. Not to mention the very real possibility of normal variations between runs ...heck, there could have been the very same variation on a 2nd run with NO changes made. 3rd run could have been different again. Remember we're talking about a few ponies here: that's 1%-2% deviation between runs ...statistically insignificant and definitely inconclusive if you ask me. No slam on Robin, to be sure ...just pointing out that drawing conclusions based on such limited findings can lead one down the wrong path.

Edward

Steve Weiner-Rennsport Systems

Jeff:

Running the risk of repeating myself, I'd caution anyone against drawing any conclusions about airboxes based on chassis dyno test results since one cannot replicate airflow when the car is strapped to the dyno,.....

"Ventilated" airboxes do work when the car is moving or when the engine is run on an engine dyno where suffficient airflow is present. Porsche figured this out as well with the 964 Cup cars.

slider

I tried to unsnap that snorkle an I had a hell of a time...in the end, I just left it on, but if you can pass along any tips for removal, I'd be grateful...it seems very straight-forward, but then again, I'm in the 1/3 prickly crowd...

dsandfort

Seems to me the best mod here (at least for C4's) is a series of holes in the airbox with a rotating wheel that will alternate bursts of air to the airbox and rear spoiler. That way the airbox will receive "supercharged" bursts of air and the spoiler will flap up and down allowing the cars to keep up with C2's. In the spirit of this thread.

I drilled the box on my 964, hated the noise, felt no difference and went back to stock.

Bull

Agreed. It depends on the car. Just like 964 stock exhaust and 993 stock exhaust. Completely different results can be obtained with aftermarket products.

Red rooster

ignomini ,
Cute little A series with a Shorocks blower . Now theres a motor .120bhp ?

Geoff

Thaddeus

On mine, there were 4 little locking tabs that are beveled, so they are like triangles in cross section. I pried up the rim of the airbox lid right where the locking tabs are, very carefully, and worked two of the tabs out, then flipped it over and did it gain with the other 2 tabs. Once all 4 tabs were free I slid the tube out by pushing it outwards from inside the lid. YMMV.

Mike Murphy

You just can't take the other 1/3 too seriously. Hey, it's been said that P-car owners are ********, right? Well...