bcridez

Ok so I searched through past topics but i couldn't find exactly what i am looking for. I wanted to know if anyone has any information on the advantages/disadvantages of going to a K&N cone filter intake vs. the stock 944s intake. any information would be appreciated.

iloveporsches

Advantages: More engine noise, weight reduction due to lighter wallet

I don't think just sticking a cone filter in the stock filter location will make any difference, as you're just sucking in hot engine-bay air. If you re-routed it to be like an S2, though (in the nose panel), you might see a *slight* gain. But don't expect anything even noticible either way.

Throwing a K&N flat-panel filter in the stock airbox will help it breath a little better.

Geo

One of the major problems I see with the cone filters out there is the adapter. They disturb the air flow into the AFM when they should be smoothing it. 9X Auto and Broadfoot racing have both come out with improved adapters, but IMHO they are still not as good as they should be.

Ideally what you want is a cold air intake. What passes in the Porsche community for a CAI is not worth talking about. What generates power with a CAI is not so much the cold air, but the length of the pipe. In fact, AEM designs their CAIs through dyno testing. They create an adapter for whatever airflow meter, attach a length of pipe with a filter on the end and dyno it. Then they remove 1/2" and redyno and repeat. They determine which length makes the most power than that's the length they put into production.

What I would do (short of getting a custom-made adapter) is to get the 9X kit and create a CAI by attaching a custom-made pipe that places the filter in the stock air pick-up location. What would be even better is to create a new pipe to replace the piece between the AFM and the TB. I am not able to do this per the SCCA IT rules, but I will be making a CAI and having my machinist make a better adapter that really smooths the airflow.

iloveporsches

You know, they make programs that can calculate all of this. I know we used one to do the intake and exhaust for our car this year.

But you are right, the flow of the air is much more important than the actual "cold air." I'll bet most aftermarket systems out there don't have any CFD done on them. Who cares if the air is 20* cooler, if you aren't optimizing the flow all the way up to the engine?

Danno

On the NA cars, the air-temp really is a factor. Putting a K&N in the engine-compartment will typically pick up air that's 30-40 degrees warmer than outside ambient temperatures. Every 10-degree difference is worth 1% in power, so you've just lost 3-4%. Then the actual increase in flow would be minimal because the major restriction is the AFM, not the air-cleaner. It's like trying to drink faster through a straw by using a bigger cup, not gonna make a whole lot of difference.

The NA cars are much, much tougher to extract extra power from. The most you can hope for is a VE=1, perhaps a little percentage more in some RPM-ranges. On a turbo car, you can make up for that increased air-temperature by just turning up the boost. So VE=1 is a piece of cake and you can get VE=2-3 for a 200-300% increase in power over an NA easily. That little 3-4% loss from higher air-temps won't even dent the increased flow of a turbo, but on an NA, you'll end up taking a loss on that K&N filter.

Geo

Far less that folks might think. With a typical well designed CAI, perhaps 20-25% of the improvement (at best) comes from the cold air. The rest comes from resonance tuning of the pipe.

That's about in line with what I just wrote above. On a 150 bhp car, that would calculate out to be 2.25 bhp.

Not quite. The resonance tuning makes it more like putting more pressure on the fluid you're trying to such through the straw, making it easier to drink. Less sucking losses.

Moot point. Almost all NA cars have "sucking losses." A good CAI with a well tuned pipe will increase VE.

BTW, you can get greater than 100% VE. Just not with a road car. F1 and Moto GP engines have VEs greater than 100%. Not much greater, but they are greater. Amazing what you can do with millions of dollars.

Perhaps. Most K&N kits make a couple of hp. Don't know about the 944, but then pretty much nobody is doing meaningful dyno testing with these cars. I think the problem with the cone filter kits for the 944 is the adapters suck. They screw up the air flow instead of smooth it out. That ends up hurting air flow instead of helping it. Jim Wolf Technology makes big honking venturis to bolt to the Nissan MAFs to smooth out the air flow and the K&Ns attach to the venturi (about 5-6" in diameter).

Blue S2

So why did Porsche not put the air filter in the nose panel like on the S2 on all the N/A cars?

Geo

Indeed. But there is theoretical and there is real-world. The theoretical gets you mighty close. But the real-world is the real-world. Given how quick and easy it is to cut a pipe and then redyno it, makes sense to use the real-world in this case.

ERAU-944

they also travel at extremely high speeds, and have a forced-induction style intake for those engines. i doubt they have greater than 100% VE while sitting still, but i'll agree they have more than that while shooting around the track.

mmm F1

-Michael-

Geo

Who knows? But it put the filter in the fender which is as good a place or better.

iloveporsches

Yeah, forgot about that. The factory already gave us a CAI, since it sucks in air from an area isolated from the engine's heat. I'd say just go with the flat K&N filter if anything. They do make good filters, there's just too much BS out there about CAI's giving people 10hp and stuff like that.

Peckster

Here are several recent posts on the topic, this has been covered many times. Some people say K&Ns flow "more" air, tell me how much.

If you really want to buy one, that's fine, but don't try to convince me there's a power improvement unless you have the facts to back it up.

It's like all the bike guys who buy loud performance exhausts and don't realize they're getting less power, not more

https://rennlist.com/forums/showthre...er+better+cone

https://rennlist.com/forums/showthre...er+better+cone

https://rennlist.com/forums/showthre...er+better+cone

tifosiman

And, for an even "more-spirited" discussion on the same topic:

http://forums.pelicanparts.com/showt...hreadid=148586

Blue S2

If you guys want to laugh for days, check out the VW boards and just type in CAI. Its the never ending argument. Its really rediculous. For Mk4 Jetta/Golf the debate about a CAI vs. Short ram vs. stock box is outta control. It got me wondering the other night as i read through some of it.
I have seen sooo many 944s with a cone air filter next to the engine. Basically a "short-ram" as it is considered. I assume at least the 944 Turbos run hotter than my VW. (even my S2 feels hotter after normal driving) I figured how much worse could it be on my VW and i have added a short ram cone to mine.

A lot of people talk about "heat soak" on the VW engines from a cone next to the engine. Is this an issue on our 944s ??? Ive never even heard about this.

I have yet to dyno either of my cars, but i plan on it this spring.

Geo

That is absolutely not BS. Well controlled dyno testing proves their worth. Some cars do may 10 hp. Most make a little less. The Nissan Sentra SE-R is well documented to make 7-8 hp. In fact, I watched a friend make a bit more by changing pipe diameter (added a couple) and then added a bit more by playing with the MAF location.

The BS is in what people attribute the gains to and then do a crappy job in making one themselves. A cone filter blocked off under hood will make almost no hp. BTW, at speed, the air temp at the filter is damned near ambient. I know of three people who have done instrumented testing that has confirmed this.

CAIs work if they are designed right and use a tuned length of pipe.