Wanting my CIS to sing!

[jguthr]

My 73.5 T has CIS...and I love it. It's a daily driver in all weather conditions and runs like a dream...with the exception of backfire at start up every so often. Thank God for pop-off valves! However, I will admit it's a bit tame. At the risk of being labelled a poser I'm not talking tame in the sense of performance, rather sound. I'm fine using all 140 horses as much as possible instead of using 140 of 200. I'm not looking to swap out the stock exhaust because I'm not just looking for more noise. I'm looking for more "growl" and only at WOT. The other day I was changing out the air filter and decided to take a short drive with everything off the air box. Wow! Now that was more like it. Of course this is not an option. I then just threw on the stock air filter and took it out again. To my surprise the sound was almost identical to that without a filter. Lastly, I tried a K&N filter with the air box cover and didn't notice much difference from the stock set up. So now I'm getting optimistic. How can I secure the stock filter to the air box without the stock air box cover while at the same time keeping water out of the system? With all the CIS systems out there I'm surprised nobody's come up with anything to replace the music-muting stock set up. Any ideas?

[Adam]

You'll need a good rain deflector/shield! I doubt it could be done, but if you were handy fabricating a shield, then it might work.

[1980SC]

When I first read this post, I thought of the "swiss air box" thread. Just drill a bunch of huge holes in the cover, but Adam brings up a good point about rain. Performance Products lists a cone air filter for CIS 911's. I'm not sure how it connects, but I would imagine it would provide more intake noise. Has anyone seen a cone filter on a CIS 911?

-Rob
1980SC

[RarlyL8]

Check out the picture I posted on Wayne's "request for supercharger pictures" post. He uses a cone filter.

[jguthr]

Thanks guys. I'm thinking some fabrication is in order. The "supercharger solution" looks rather complex, not exactly water proof, and I'd hate to go to all that trouble and expense only to find out it doesn't sound any better than stock. I'm thinking the first (and biggest) challenge is how to secure the filter without the airbox cover. After I've done that I'm thinking there's enough room in there to slide a 1/2 pipe of sheet metal over the airbox and secure it to the fan housing. I'll let you know how I get on.

[dougcl]

Just a thought... why not buy a spare snout from a junkyard and cut off both ends leaving a halfpipe shape? Attach it like you normally would. That would hold the filter, keep the rain off (mostly) and allow the sound out.

[Wayne 962]

Put a beefier muffler on it - it will soon muffle the sound from the air box...

-Wayne

[jguthr]

Wayne, I'm not sure I follow you on this one. I don't want to muffle the sound of the airbox...I want to set it free!

[Adam]

What about a piece of polypropylene sheeting (or acylic sheet)?
Using a heat gun, heat it up while bending it over a large diameter soup can to form a half-pipe shape.

Allow it to cool, then using a dremel or holesaw, cut holes on the forward section (shielded by the top of the engine lid and front of the engine bay). When you're done, spray it matte black and fit using the original rubber airbox straps. Then you've got side entry on both sides, while retaining protection from falling rain. The holes in the front side of the unit allow the sound etc to permeate through.

I doubt there'd be any performance increase, but it would sound pretty cool. Tell me what you all think. I may even give it a try, although I'd recommend it only for summer usage.

[Wayne 962]

I meant you wouldn't be able to hear the air box after that...



-Wayne

[Eric Coffey]

How about taking all of that "tangled mess" (CIS) out and throwing on a set of PMO's? That would definitely make that T sing! If that still isn't enough, start saving up for headers and megaphones! A 2.4 with carbs, headers, and megaphones, now THAT would be music to my ears!!

[jguthr]

Hey Adam...Now we're talking! Great idea. That's exactly what I had in mind...I just couldn't figure out how to do it without using another airbox cover. I'll give it a go in the next couple of weeks and let you know how it works.

Freefly, I appreciate your enthusiasm...headers, megaphones, PMO's...Great, so my bank account would be the only thing lower than my mileage! Did I mention this was my daily driver in Portland, Oregon?...Where people don't tan, they rust!