Air filter box removal/ replace w/ cone filter
 

Hey folks, in the next week or so i have to replace the alternator in my 83 944, all of the forums I've found on how to do this says to remove the air filter box. for the past year I've been thinking about replacing the box with a cone filter, much like a K&N filter, one to free up some space under the hood and two, I've broken 3 of the screws that hold the lid on the first time I replaced the air filter.

I know the good and bad of putting a filter like that close to the hot engine but i was curious if anyone has already done this and had any other problems with sensors or the car not starting right? would this effect the Mass Air Flow sensor? since these cars are so bipolar to begin with I'd like to know of any possible problems before i commit.

Also, are there any kits available for this? any tips?

P.S.
any tips or advice for changing the alternator would be much appreciated :)
Thanks in advance!

1) these cars don't come with a Mass Airflow sensor
2) K&N filters are garbage
3) there is no performance benefit from running anything other than the factory airbox/stock-type paper filter on an NA...dyno tested by both me and the guy who developed the available aftermarket MAF conversion.

you can get replacement screws for the airbox at any hardware store, I found some at Lowes one time, they are M5 (5mm thread) screws.

alternator...the lower bolt that holds the alternator to the bracket is kind of a pain to reach...I have found that if you remove the two bolts that the AC compressor hangs from (both 17mm heads, one front and one back, can be reached from the driver side wheel well next to the sway bar drop link) and drop the compressor a little bit (support it on a brick or something to keep strain off hoses) then you can reach the alternator bolt easily.

I love my k&n filter set up on my 951, a lot of room has been freed up under my hood. I knew my air box was toast from the original owner, you know with and without the k&n set up I don't really notice any difference. Keep it cleaned and properly oiled and you should be ok......

a cone filter CAN produce more power, but it has to have more surface area than stock, be isolated from engine heat, and have a short, direct and non-turbulent path of colder intake air. failure to do any of those will result in power loss.

K&N filters are the BEST filters on the market. you just have to use them and maintain them correctly. most people don't. ignore the argument about "dirt getting past the filter". this is an urban myth, when they are properly maintained

you can prove all of this easily with a manometer. you will not necessarily see the gains on a dyno, unless you test it as it would be on the road, with an 80mph 4' diameter fan, and most importantly, the hood closed. most dyno shops don't have any of that, and most of them want the hood open. the one i use does things correctly. also, you can't use a standard dynojet for stuff like this. you have to use an eddy current dyno.

i have yet to see a car not gain by a PROPERLY DESIGNED cold air intake. i have tested dozens of different model cars, and without exception, gains were there.

to date, i have not seen anybody do this right, hence the mixed reviews. i never mass produced one, only because there was no market for one, and as soon as it was out there, every broke-assed 944 kid in the world would be knocking it off, rather than buying mine. i know for sure that it can be done though. i did it once, and then the owner destroyed the car in a race, and never went back to the 944. the design died with the car.

you can also look into the 944 NA Tune MAF and put a K&N on it. Pricey but from my friends experience on his 87 944, he said it is loads better then the factory choke box.

I bought the car with one on it from PO and they just swap the stock one out and put this one in I bought mines none running so don't know how it performs but I bought a stock air box to replace it anyway

http://forums.pelicanparts.com/uploa...1483545976.jpg

I recently did this to my 924S autocross project. I love not having the OE air box as there's much more room now to work in the engine compartment. I initially went to Lindsey Racing but all they offered was the intake adapter for 951. Dave steered me to MSDS Inc.

MSDS Inc. -Â* HIGH QUALITY HIGH PERFORMANCE ACCESSORIES

who does have the cone filter adapter for NA 944/924S. You'll also need a bracket to support the MAF which is supported by the OE air box. That bracket and the cone filter comes with the adapter. I actually found a used MSDS adapter at a buddy's and rigged my own bracket directly to the AC delete bracket. Then I purchase a large 3" x 6" cone filter through a speed shop.

Performance gains are debatable and because it's an autocross car, engine compartment heat isn't that big a deal (a quick lap and the cool down). I did it more for convenience and access.

http://i1336.photobucket.com/albums/...psty5jqutd.jpg

I run a K&N in the stock air boxes on both of my 944s. The stock box is a true cold air induction and the stock filter has way more surface area than the cone shaped ones the kids love these days. Any air flow that might be smoothed out by the cone filters is going to get AFU'ed again once it passes through the AFM anyway.

it isn't always easy to get the right size filter in there AND isolate it from heat AND have a smooth path for the air AND have it be serviceable. it's no simple feat in the 944 either, but it can be done, if you are willing to make the changes necessary, and spend some money. you definitely won't see gains by just sticking a filter on there.

the other issue is that as a rule you will only see a 5% gain. that isn't a lot of power when you talk about a 150hp motor. it can also bring with it cold start issues, because it is exposed to colder air. the older the car (with its inherently older controls) the more this is the case. on a race car, this is not an issue, and every little bit counts, but on a daily driver, it may be more headache than it's worth

the K&N can help, even if in the stock airbox. as an example, on the 968, by merely opening up the airbox to direct cold air, and installing an OEM K&N replacement, we saw almost 12hp on the dyno. it took some pretty serious manometer testing to figure out just what to do, but in the end it worked extremely well

Not 100% on the early cars, but on the later cars you can change the brushes on the alternator without removing it from the car. Usually it is just the brushes that wear out, and they are much cheaper to replace than the whole unit.

I'm not concerned about adding power with K&N this and K&N that, i just want to free up space under the hood and make changing the air filter easier.

I've noticed a few people here say the surface area on the filter must be at least the same as the surface area on the stock filter, if not more.... can someone explain to me why exactly? I don't know what diameter the intake is but for easy math lets call it 4'', now that's just over 12.5'' of surface area, so if a filter with 24'' of surface area is feeding a hole with 12'' of surface area, isnt that a little over kill? can someone help explain in more detail?

it's all about fluid dynamics. all other things being equal, it takes a certain amount of surface area of filter to pass a particular volume of air at a specific rate. the engine is drawing in the air. it is not being fed into the filter and pushed into the motor. it needs a certain amount of area at normal density to provide that volume of air. the filter itself will present restriction, dictating more area than what it is feeding. part of why a K&N works better is that the restriction per square inch is less than with a paper filter. so, to see gains, you have to have at least the same surface area as the paper filter. additionally, OEM filters are generally less than optimal from a flow standpoint, so as to provide for enriched starts. hence, having a filter with more surface area AND freer flowing, naturally allows more air into the engine. as long as you don't increase the intake temps, you can see gains. for example, you could gain about 5hp on a 944 with a free flowing filter the same size as stock, but then lose it if the intake temps go up 50 degrees. that's why we use manometers and temp sensors in our intake designs.

Buy mine:
http://forums.pelicanparts.com/porsche-924-944-968-used-parts-sale-wanted/933747-k-n-cone-air-filter-w-custom-bracket.html

Here's a question that puzzles me, for the pod-filter fans.

If they are performance-enhancing, safe, have no negative effect on engine behaviour or wear, and use less space, why is it that not one single car manufacturer in the world uses them from the factory?

that one is simple. they are over 5 times more expensive, AND they require a lot more frequent service, and more importantly the kind of service that most car buyers are not willing to do. you can't let a K&N sit in there for a year of driving and not service it. if you had to pay somebody to service it, you would be looking at over $100. most car buyers won't pay that, or even want to deal with it.

It's all about induction noise abatement. Most of you guys are too young to know the sounds of a large cubic inch muscle car engines sucking in huge amounts of air. It was thru exposed paper air filters under lovely chrome tops with stickers boasting the displacement and horsepower. The induction moan was much louder than the exhaust note and music to a High School gearhead. My 396 would moan like a lonely ghost. Yamaha 250 and 305 two stroke twins of the mid 60's had un-silenced intakes and would make quite the intake moan when riding in groups as the sound carried. My own hopped up RZ350 makes a nice moan thru it's Swiss cheesed air box. In it's case the plenum of the air box plays a important part in performance.

it is true that germany has the strictest noise regulations of any country, and any car made there has to comply with them. that does factor into the airbox design. it really doesn't affect the filter material itself though it can certainly affect the design shape. more flow means more noise. pretty basic physics there.

of course most of us like a little more growl, so this is a good thing

flash968. Do you have specific recommendations and or pictures of how to properly mount a K&N in a NA engine bay? I'm also interested in finding a source for the correct sized (diameter and length) tubes from the cone to the housing. Thanks for any help.

you can use the formulas on the K&N website for sizing the filter.

unfortunately i do not have pictures or anything on the airbox design. this was way back before digital cameras. i stopped playing with 944s over 20 years ago. i'm sure i could do it again, but then we would be right back to how much it would cost, since there would be almost no chance of selling it. the time and materials involved for me to do it would be ridiculous, given that the gains might be 5hp. you would be much better off installing my 968 centrifugal supercharger kit, retuning for the 944, and then going away with an extra 75-100hp and a whole lot more torque.

Cone it bro! Just cone it!http://forums.pelicanparts.com/uploa...1483980864.jpg;)