I had an old airbox from my prior 993 so I finally got around to cutting the top off, a la the cup airbox.

There is definitely more growl that comes on sooner. What I notice is that the motor sound drilled airbox had a nice sound that turned into a high pitched howl at about 5k+ rpms.
Now there is a nice low growl that starts at about 4k rpms and then turns into a louder growl - kindda mean sounding - before transitioning to the cool howling sound. Lastly, at wide open throttle I can hear air sucking into the engine which I never heard before. All in all, the sound is a definite improvement.

The only concern I have is the snorkel - which I believe is used to deliver some type of clutch exhaust that pushes out into the airbox. However, now that the top is wide open and the inlet area is removed I don't know what is happening with all those particles, I imagine that they are getting sucked into the air filter but who knows...

All in all, very nice sound improvement. And who knows, maybe there is a few extra ponies being generated with all that air sucking noise...

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

 

How do you do this to your airbox?? Do you cut out the side where the filter is, please explain in more detail. Thanks

 

A potential downside to cutting the whole top off is it will now be easier to get the filter wet (while washing the car, for instance).

Just something to keep an eye on...

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

-Chris

 

Ever tried cone filter as PowerFlow or others?

Smaller filter (on the picture) is for the snorkel.

 

Rob,
I have also cut the top off of the air box lid. What I did with the clutch vent tube was wrap a very thin breathable piece of fabric around the end and zip tie it on. Now that I think about it the toe end of a thin dress sock would have also worked.

ddixon, The way I cut mine was to use a dremel tool with a cut-off wheel. It cut thru the plastic like a hot knife thru butter. I was surprised at how well it went.

Jack, Thanks for the pic of the small filter. Although my homemade fabric filter works I like the look of the professional made filter.
I may get one of those although, I do wonder if there is enough suction to draw the clutch particles thru the tube up to the filter. <img src="confused.gif" border="0">

 

I also cut the airbox lid open using a dremel round cutting tool. The whole thing took about 10 minutes.

I did have a powerflow on my prior 993 (which is why I had this extra airbox).

some problems with the powerflow.
1) it is expensive
2) it has been known to trip the check engine light.
3) it has been proven to lose power on the 996 and some say it loses power on the 993. Simply because it is positioned in a way that draws hot air into the engine.

 

[quote]Originally posted by Chris W. - '96 Targa:
<strong>A potential downside to cutting the whole top off is it will now be easier to get the filter wet (while washing the car, for instance).

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

-Chris</strong><hr></blockquote>

True, but it still isn't that easy to soak it since the airbox is on it's side and the top side is still protecting the filter. I can always be mindful and put the original airbox cover back during washes as it only takes 5 min.

 

[quote]Originally posted by 993Widebody:
<strong>3) it has been proven to lose power on the 996 and some say it loses power on the 993. Simply because it is positioned in a way that draws hot air into the engine.</strong><hr></blockquote>

I've been kind of wondering about this point. Seems like any of the modified airboxes would suffer from this problem, no?

 

I also cut an extra airbox lid. I cut mine open but left the transmission snorkel hook up so it had some where to connect rather than the snorkel bouncing around.

I love the sound and have not noticed any lose in horsepower but then I have not really done any real quantitative analysis though.

I am going to be adding the RSCS rear wing in the next week (when it comes back from paint) so if there is some engine performance lose due to hot air I am hoping that the wing, with the air in takes, will force cool air into the engine compartment mitigating the possible removed airbox lid issue. Anyone think that is reasonable or am I just wishful thinking?

 

Kary, that seems reasonable to me.

But then I am also hoping so since I have a wing with the side air intakes -- an aero kit turbo s wing.

 

[quote]Originally posted by kary993:
<strong>I love the sound and have not noticed any lose in horsepower but then I have not really done any real quantitative analysis though.

I am going to be adding the RSCS rear wing in the next week (when it comes back from paint) so if there is some engine performance lose due to hot air I am hoping that the wing, with the air in takes, will force cool air into the engine compartment mitigating the possible removed airbox lid issue. Anyone think that is reasonable or am I just wishful thinking?</strong><hr></blockquote>

Kary,

I had done some test before with the intake air temperature to notice a small difference in instake temperature when you have a fix tail on the car. The detail of the test I did can be found in my web site under this link <a href="http://p-car.com/diy/intake/" target="_blank">air intake temperature test</a>

On the RSCS tail you are adding you could add some air ducts from both side of the scoop directly to the air box area to bring in more fresh air, I am sure it will help lower the intake temperature.

 

Here’s an alternative to cutting your airbox. Remove it and hold the filter in place with clips. No need to own two covers or modify your single cover or purchase an expensive carbon fiber replica. Note the filter over the clutch vent. The inside of this filter gets dirty, implying that the clutch is positively vented. This can get pretty loud at full throttle.

Tom
'95 993

 

Tom,

Thanks for the tip. You had mentioned this in the past and I did purchase the socket clips and tried it - works just fine.

However, for my purposes since I do have the extra lid I liked the fact that the lid still provides some protection from water (even with the lid cut open) as well as providing a place to seat the snorkel hose.

 

[quote] On the RSCS tail you are adding you could add some air ducts from both side of the scoop directly to the air box area to bring in more fresh air, I am sure it will help lower the intake temperature.<hr></blockquote>

Robin,

I may not be understanding you correctly in the above post, but the RSCS wing already has side air intakes that feed to the engine compartment. Is that what you meant or did I misunderstand?

 

I was under the impression the clutch vent actually pulled air and clutch dust from the clutch and that the position of it attached to the intake was to from some sort of vacuum for sucking air and such out of the clutch. I remember there was a big discussion on the loss of a vacuum could be harmful to the clutch and that the cup car air box had the top removed but maintained the clutch vent very close to the intake for this purpose. Anyone remember this conversation?