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I want to add some insight to the airbox mod. I have the airbox cut to look like the cup car one. 4000+ rpm is god. but you do have this "hissing" sound below 4k rpm. it's constant and very noticeable. I am still trying to get used to it.
I would never drill an airbox to improve the sound. Of any car.
Drilling the airbox is a factory method of improving the sound in 993's. This in 993's is known as the Motor Sound option. Below is a photo showing the OEM drilled (Motor Sound) box (left) versus stock (right). Lots of 993 owners buy a stock box and drill the holes themselves. (There's even a template that copies the OEM drill pattern floating around somewhere in the Rennlist community). It's a known and proven mod, just FYI.
^^^^^^^^
Great post kreeshp. I didn't know that about the 993 box. Awesome pic, thanks!
Originally Posted by tfitch03
do you have to chip with just a primary bypass?
No chip is necessary with any of these bypasses.
I spoke with Steve on the phone before I purchased mine. I just had a primary bypass and was committed to running higher octane (93). So I was going to get a 93 oct and exhaust bypass chip. But, based on our conversation, it was OK to order a chip that was already programed for a cat bypass, even though I didn't add plan to add a cat bypass until much later. So I ordered a 93, cat and exhaust bypass chip.
Originally Posted by Cadrega
I would never drill an airbox to improve the sound. Of any car.
? It's no problem and doesn't hurt these cars....
I can understand if you want to keep your airbox stock, for aesthetic or sound reasons. But this goes out the window if you are interested in chips and modifying your exhaust...
Originally Posted by FlyinTomato
I want to add some insight to the airbox mod. I have the airbox cut to look like the cup car one. 4000+ rpm is god. but you do have this "hissing" sound below 4k rpm. it's constant and very noticeable. I am still trying to get used to it.
Good call. I think you're right!!! I assumed that humming noise was from a combination radio/electrical hum or something from the ventilation/servo system. I'm looking forward to hoping the car in a couple hours and listening to it with a new understanding and fresh ears.
And I also think that if I can save 50lbs of hanging mass I'd do it in a heart beat!
That being said, I'll shoot you over a PM to discuss some options with you
Originally Posted by Cadrega
I think an airbox keeps the air in pressure inside. Making holes defeats the purpose.
This is in very basic lehman's terms without getting into backpressures, but think of the engine as a giant air pump sucking in air and pushing out exhaust. The easier you can pull in more air and the quicker you can expel more exhaust the more power you're going to make. In the interest of pursuing more power for their factory 964 Cup Cars, Porsche Motorsport actually completely cut out the factory airbox and ran the filter open completely. This has been a proven method for more horsepower and increased engine sound not just from us, but from Porsche Motorsport
I would never drill an airbox to improve the sound. Of any car.
That's a pretty definitive statement, especially if you haven't hear what it does... (and it's basically a free modification)
It's a very common modification. (increased roar at 4,000+ and WOT)
Originally Posted by Cadrega
And I also think that if I can save 50lbs of hanging mass I'd do it in a heart beat!
How about 35lbs? One exhaust bypass + cat bypass...
Originally Posted by Cadrega
I think an airbox keeps the air in pressure inside. Making holes defeats the purpose.
It just changes the flow of the air before going into the intake system. No harm to the motor or pressure/fueling issues.
That's a pretty definitive statement, especially if you haven't hear what it does... (and it's basically a free modification)
It's a very common modification. (increased roar at 4,000+ and WOT)
How about 35lbs? One exhaust bypass + cat bypass...
It just changes the flow of the air before going into the intake system. No harm to the motor or pressure/fueling issues.
Yep gonna do the bypass + cat bypass! (Although, honestly and ready to be insulted, good sounding Porsche cars are very few).
You may gain HP thanks to the more free flow but the losses at low RPMs are significant. Experience from previous cars that I had (Naturally Aspirated)
*** DISCLAIMER! Have not tried the car and it may very well be that, just like in the fantastic handling, PCars defeat laws of physics when it comes to intake pressures!
This has been a proven method for ... increased engine sound not just from us, but from Porsche Motorsport
The Porsche motorsports modified airbox has rib stiffeners that prevent the cover and air filter from crippling. The lack of these on your solution causes the filter to not seal against the intake completely and allows unfiltered air directly into the engine. I imagine this situation only gets worse as the thermoformed cover heat cycles.
The Porsche motorsports modified airbox has rib stiffeners that prevent the cover and air filter from crippling. The lack of these on your solution causes the filter to not seal against the intake completely and allows unfiltered air directly into the engine. I imagine this situation only gets worse as the thermoformed cover heat cycles.
Originally Posted by 911Jetta
+1
I heard about that also from a couple Rennlisters over the years.
Drilling the stock box cover seems much safer.
Interesting, this is the first time I've seen a fitment issue like on our cup airbox. I don't suppose you have any more pictures of this from different angles with the mounting points, and what filter was being used? If you could email any info on this to john.gaydos@fabspeed.com it would be much appreciated!
Originally Posted by aceking4u
I have a fabspeed primary (only) + Steven Wong chip. Shoot me your email or cell phone number if you want a sound clip.
Interesting, this is the first time I've seen a fitment issue like on our cup airbox. I don't suppose you have any more pictures of this from different angles with the mounting points, and what filter was being used? If you could email any info on this to john.gaydos@fabspeed.com it would be much appreciated!
This was brought to Fabspeed's attention back in 2006 by multiple people. You have to drop the motor to really see the fitment issue, although you might be able to finger it if you know what you're looking for. The filter in the photo was OE but does not matter. The two large clamps on the backside cause the thermoformed cover to buckle which pinches the filter.
This was brought to Fabspeed's attention back in 2006 by multiple people. You have to drop the motor to really see the fitment issue, although you might be able to finger it if you know what you're looking for. The filter in the photo was OE but does not matter. The two large clamps on the backside cause the thermoformed cover to buckle which pinches the filter.
Appreciate the insight, that was before my time here and will look into it to see if anything was resolved/changed
04-28-2017, 11:30 AM
