air filter

[Pellycars]

Want to install new air filter. Stock, oem, is ok but wondering if an upgrade here is easy and increases performance.
Know about sales pitch on K & N filters and how much better these are, but also read the oil in the filter is not good for this engine
1987 928 S/4
Can anyone help

[Bills928]

Stick with the OEM...... Most folks on here will say the same.

[curtisr]

Could just be me but, I found that I had to twist the straps to get the top of the air box to fit on the K & N filter.

[Danglerb]

K&N not a good match for a hotwire MAF car, ok in earlier cars, but you get nothing for spending the money.

[Landseer]

The MAF hot wire is key/core to the operation of electronic ignition.

So important that on shutdown the MAF wire gets a 4 second burst of electricity to heat it and burn residue.

KN filter is oiled, so its a source of oil residue.

Its unneccesary, potentially harmful and provides zero performance, all BS marketing stuff.
Probably has a different sound that folks equate with power.
I've run a MAF car, 84 Euro 928, with no air cleaner a couple of times and it sounds like I've added 100hp.
Like flipping the lid on the air cleaner of a 327.
No power, just sound.

Similarly, most insist the KN has no value to the 84 and earlier cars either.

For incremental performance, ensure knock sensors are not crumbled (if they are, they fail in the engine protection mode, adjusting timing a bit), then consider sharktuning and some opening of exhaust. There may soon be a set of chips available from Porken that would likely be a huge improvement, basically a substitute for sharktuning for a stock (non supercharged) 928 S4. It is said that the autoauthority chips aren't near optimal, just cheap quick moneymakers that won't have the mapping of the (hopefully) soon to be available chips.

That's the rough synopsis as I see it regarding S4 performance mods in reading rennlist and here over the last 5 years.

Stock air filter, fram, avail pretty widely.

[harborman]

Stick with stock filters. They fit and less trouble. Anyway, the stock filter looks pretty big to me.

[Maleficio]

I wish'd that Amsoil made an air filter for the 928. I love my Amsoil filter in my Volvo. Non-oil type.

Years ago you could custom order an air filter from Amsoil. Probably not now.

[5l32v4c]

I've not really looked into it much but, to my mind, if free-flow filters like the K&N are letting more air through, aren't they letting more dust and crap through as well? Some OEM filters a rediculously small and restrictive but the stock 928 filter is pretty large. I would think much of the restriction is with the plastic intake ports.

[Danglerb]

K&N use oil and gauze that somehow grabs dirt, like static or something.

Prime lesson on filters, do not believe any test devised by a manufacturer of filters.

Second lesson, use the factory filter unless you have a good reason otherwise.

[lfausty]

to note. arrows/disregard as known to show both directions. installs convex side up/towards the airbox cover.

[curtisr]

The Porsche folks at Hershey had a couple of ONS 928 filters for $10.

[924CarreraGTP]

My take on K&N filters is that they don't give any difference in performance when they are new and oiled. Most cars that I've put a K&N filter in don't start to make any difference in power until the oil subsides from them. I recently put one in my 944 and it's just now feeling like it's running better. That's been about 3 months. I can say the same thing about my other cars. It always takes a while for the oil to leave them. At that point you might feel a very marginal increase of power. You could just buy a new one, clean it, let it dry, and it wouldn't harm your hot wire Mass Air Flow with oil. Still I wouldn't expect but maybe 1 or 2 horsepower if that. You probably don't get as good of a filtrations if the unit is not oiled.
K&N makes a full recharger kit with oil and cleaner, but you can buy a bottle of just the cleaner that will strip the oil out of it.