Ok, so now that Spring is here I have a few projects I want to do. I've got the Automotion Chip, Shubert Primary Bypass, and an airbox I want to drill. After reading the diffferent boards I know that many are drilling one to two inch holes in the airbox. If you look at the 993 Motorsound airbox, it has rows of what look to be 1/4" holes drilled six across from top to bottom at the front side of the cover or else completely open in another case. So without opening a big can of worms, any thoughts to which is better? I'm leaning towards the lots of little holes are dremeling out the better portion of the airbox lid. TIA.

 

There are 2 basic options, both which accomplish the same goal of getting air directly to the filter: Cut out all of the cover in front of the filter, leaving enough on the edges to hold the filter, or cut holes in the case, be they big or little. I've done both (total cutout and holes), and when coupled with a primary muffler bypass, both add some nice tones to the exhaust with pedal to the floor and rising revs. Depending on what your definition is of 'better', I think you'll find that either of the options works fine.

If you didn't have anything better to do, you could do some baseline dyno runs, then cut small holes and do some more dyno runs, then cut big holes, do some more dyno runs, then cut out most of the center, do some more dyno runs, and for grins, remove the filter and do some more dyno runs. My guess is, asides from the pocket being lighter, you'd be disappointed with the results.

 

Craig,
Legend has it that drilling your airbox will give you an extra 25 hp.
See my website - Technical section.

J

 

Wow... that looks just like mine... must be because I copied the idea from you

Now... about those additional 25hp... I do not know... all I know is that it sounds so sweeeeeeeeettt!!! That alone is worth the mod in my book.

Oh, and by the way... I went back to the factory paper air filter... did not see a difference with the K&N (still have it) and I no longer have to clean it or worry about putting too much oil and risk messing up the airflow sensor...

 

The Cup airbox has just enough of the lid left to hold the filter in place and I guess Porsche must have known somthing when they did it.

 

Yes if you have a M64/03 engine set up for a Carrera Cup with a racing program DME and all the other trick racing parts.
Ciao,
Adrian.

 

That reminds me of the PerformanceProducts advertisements that say I'll get 15-20 more horsepower with their $200 airbox lid. What a deal!!! Then in small print, in the corner of the page, it says you get that horsepower gain if you use the airbox lid, MAF upgrade, chip upgrade, 100 octane gas, balanced engine, headers, 3.8 P/C's...

(slight exaggeration but you get the point!)

 

I've drilled holes in my airbox just for the extra noise above 4500 rpm...
I think anyone who is hoping for extra bhp are fooling themselves...
Anyway, I think it's worth it just for the sound!

 

how about just putting a cone filter, like K&N. why would you even go through all that, and you keep you stok airbox as is.
iam pretty sure that a k&N cone filter will flow more air. right??

 

K&N uses a special layers of cotton impregnated with an oil. There is some concern by many people that the oil will enter the air intake and foul it or affect the MAF.

I went with a cup airbox, purely for sound, but I stayed away from the K&N for that exact reason/concern.

Marc

 

K&N is very specific about not over-oiling the air filter. It comes pre-oiled and has the correct amount already applied. When cleaning it, just apply the cleaner, clean it and let it dry thoroughly. When appling the oil you only want to add enough to stain the fabric red. I add a little at a time and let the capillary action take effect. I might have to add several more drops over the next few hours to ensure the oil is evenly distributed and it's not over-oiled.

I've been using K&N air filters for years with no ill effects... Only slight (seemingly) power gains, a slight increase in mileage... And that sound when you hit the throttle!

 

thanks for the info, iam still going with the cone. how often do you have add oil to it. and if you dont what happens to it

 

I go by the manufacturers recommendations... except on the Porsche. On some of my cars I have let it go for almost the 50k miles they recommend. I'll check them about every 5k... The Porsche is obvious because you can see it every time you open the hood. If it looks dry... or dusty (overly dirty) I'll clean it. K&N says that (To some degree) the dirtier it gets... The better it cleans. I'm assuming that means that the spacing in the membrane that the air flow goes through gets smaller... Trapping smaller and smaller pieces of dirt, dust and debris. The dirt and dust will absorb some of the oil incorporating it into the filter. (Theoretically)

When I first started I did over oil it once. It's easy enough to check... Drive the car for a few miles, take it off and look inside. If it's too oily, clean it, let it dry and start over. The key is obviously not to glop the oil on it. When applying the oil, don't try to color it all red to start off. Let the capillary action do the work and give it time to do it. A few hours should work. Then check it again... If you see white add a drop of oil.

If you don't oil it... or let it go too long you'll probably pay the price. But... as I said, with the cone filter, you'll see it every time you open the hood. You'll know...

 

The cup car air box mod ( completely cut out the air box cover) is worth 4-5 rwh on a rebuilt m64/01 964 engine with a euro premuffler and primary and secondary by passes. Both on a stock chip/90 DME fuel switch @ position 2, and Carrera cup DME. I did the Dyno runs last year.
Bob

 

I have read in Adrian's book that drilling the air box results in a net loss of -0.6 to -2.5 RWHP