iloveporsches

Man, why does Cali have to have such stupid laws and rediculous living costs? I really like San Diego when I was there.

Bill

So true! But if you go over to the turbo board you will see many "Failed Smog" posts from many different states.

macleod911

Yesterday,Feb. 18th, I was at Tom Charlesworth's repair shop in Tulsa. I asked him about the K & N cone filters. He said that when he worked for the Porsche factory, they had a 944 on the dyno. While the car was running, he pulled out the stock filter element. He said that the horsepower figure did not move! K&N say that increased air flow equals increased horsepower, but... they measure the air flow on a flow bench, without the air box. Tom said if no filter had no effect on H/P, how could the K&N increase power. He also said that he has seen oil spectral analysis of vehicles with K&N air filters and without. When K&N filters were being used on these vehicles, the oil had a lot more dirt in it. This caused this company to return to factory paper filters.

Geo

Interestingly enough, a MAF conversion should allow much better emissions control. Assuming of course you have a well programed ECU (DME). A hot wire MAF will give you the most accurate engine management.

Skip

[discussion not limited to K&N per se] - With great respect to Tom, that is not a very fair or scientific analysis of any air filter's effect on flow characteristics or efficiency. In many ways this supports the discussion here that not everything you do to apparently increase air volume actually helps the engine produce more power. Similar to the "Tornado" intake systems; sometimes it works, sometimes it doesn't. While the air filter itself may not make the huge gains the companies claim, there are certain and continuing benefits pursuant to their proper use. The dirt-in-oil story is true - but, there's more to it. K&N and others have continuously defended themselves (even in court) against this type of claim. In most cases, the excess particulate-in-oil has been a result of improper use or a combination known to decrease the filters capacity (higher than expected air volume, over/under-sized filter for application.) I don't try to defend them as a reseller, but as an informed consumer. There is so much misinformation on the airwaves that it sometimes requires a bit more investigation than a casual conversation or glancing Google search.

Do the claims of performance air filters err on the side of optimism? Absolutely

Danno

Another thing no one has brought up is the resonance-effect of an NA motor. It's like a pipe-organ with pressure waves going back & forth from the beginning of the intake to the exhaust-outlet and back & forth. This causes ranges of RPMs with inefficient breathing and other with more. Factors like intake-length/diameter, intake-manifold volume & lenght, intake-runner diameter & voume, valve-sizes, cam-lift & timing, exhaust-headers and length, exhaust pipe diameter & lenght all have effects on the resonances, their frequency and velocities. Your torque-peak is area of highest efficiency but the pressure-waves also coincide in negative ways where they cancel each other out. This typically occurs at 1/3rd to 1/2 the RPMs as the torque-peak, and higher harmonics. So while it's possible to re-tune the system by changing any and all of the parts listed before, it's impossible to make a single change that affects the entire powerband evenly.

Typically mods that increase peak-HP will usually rob low-end torque. Variable intake systems have been developed that can optimized the intake resonances and expand that range of RPMs where the engine is at maximum efficiency. Things like variable intake-lenghts, variable valve-timing, lift & duration, variable exhausts, etc. Honda even has an exhaust header that switches between a 4-2-1 tri-Y configuration for low-end torque, into a 4-1 set-up for higher high-end HP. etc. etc. etc...

With all these variables, one has to look at actual numbers to really make any kind of statement. Like those K&N numbers that claim a +15hp increase, HAH! Hogwash!!!

"Man, why does Cali have to have such stupid laws and rediculous living costs? I really like San Diego when I was there."

iloveporsches, you answered your own question...

Geo

Actually, I've been talking about that since my first post to this thread.

bcridez

Thanks for all the posts. Much appreciated

bcridez

Thanks for all the posts. Much appreciated

Roral

Has any one taken the time to do temperature readings of all the places we have mentioned in the post. Or even pressure readings? I mean you could use one of those cheap remote readings one for the outside of your house then mount the LCD in your car then take readings all the time, Dyno's are great for controlled environments but really they don't show you actual driving condictions like changes in barometric preasure, air temp, humidity, air speed and so on. If you had a something you could constantly monitor, you could take ambient temp, humidity and the temp of the air in the wheel well, or the temp in the nose area.

I mean if we are talking about cold air, we can talk about which place should be cooler all day. Infact i have the next three days off. I'll do some tests in the next couple of days. (whether people would care for the data or not. I'll just do it for my own knowledge. But I will not get pressure readings unfortunately)

Steve

Geo

I've not heard of anyone doing pressure readings, but don't even dream of true ram air.

I do know of people who have installed thermocouples on a Nissan 200SX SE-R, a Nissan Primera (world market G20) in Australia, and I thought a 944.

All read near ambient.

Porsche-O-Phile

Here in CA that's the truth - it doesn't matter whether it makes sense or not: if it doesn't have a CARB (CA Air Resources Board) Number, you flunk. End of story. Doesn't even matter if the mod makes the car run CLEANER - if it ain't stock and it doesn't have a CARB, you fail.

Personally I just think its a way of ensuring that the aftermarket manufacturers keep feeding the state kickback money, but that's another conspiracy theory for another time. . .

Mongo

Yea, sooner or later they'll take the bear off our flag and throw a hammer and sickle in the center

It's sad how the 944 has fallen to a statistic among tuners, but yet these cars still hold strong with enthusiasts. As owners, it's up to us to retain the value of these cars and maintain an exceptional appearance of these sleek and sexy watercoolers...

Andy

dyson

I experimented with cold air/ram air about 10 years ago on my 83 NA. Originally I was concerned that the air in the front guard would get hot enough to hurt performance especially on the track. If you are braking down from 100mph for a hairpin, when you accelerate out of the corner I figured you must be picking up hot air.

I removed the headlights replacing them with small QI units at the top of the headlight hole. The bottom of the left hand hole was a funnel cut to fit with a 3" PVC pipe to the air filter box.

Tried a stock and K&N filter in the box. The mod seemed to give the car a bit more top end but any difference in my lap times was swamped by different ambient temps (1 sec between 5C and 30C) and tyres (5 secs between Yokos AOO8RS and Dunlop street tires).

Put the stock lights back in when I strated to do more night highway driving. The little QIs were terrible.

Tony D
83 NA almost sold
86 951

mick944

The cone vs.box debate is a interesting one.I changed from the stock air box to the cone filter mainly because I like(d) the look(before anyone thinks I am some young fast and furious punk I must admit I am in in my mid 40s and on my 4th 944.I think the cone filter looks more at home in an engine bay(I think the 944 engive bay is as impressive as any I've seen when properly maintained) of a Porsche than any of the so-called ricers out on the market.My opinion.My filter(and the smaller timing breather filter) are both gray and look very nice in that compartment.But ,as usual, I have found that the Porsche engineers designed things with purpose.The airbox config was obviously well thought out,designed to draw fresh(cool) air in from outside the engine compartment.I believe the fact the cone filter sits above the alternater(and apparently robs cool air from it) led to a premature failure of that unit.If I had to do it all over again(from what I have learned-a lot of which has been debated in this post) I would have left the box in.