K&N

[alanh]

how much of a horsepower increase can i expect to get with a K&N air filter on my stock 1987 325i

[alanh]

also how much from ignition wires?
and spark plugs?

[m42technic]

Are you talking about going to a cone filter or a replacement drop on K&N? Either would produce negligible HP gains.

As for spark plugs and plug wires, unless they really do need to be replaced because of wear and tear you will get no gains from them whatsoever...

[alanh]

just a drop in i hear the cones need some mods

[stovski]

If you think about it, not that much. If you can intake more air than you can release your've accomplished nothing(assuming you have no exhaust or catback). Need the works to get get some noticeable hp gains.

[alanh]

whats a catback? catayltic converter?

[MrM3]

Originally posted by alanh@Oct 16 2003, 11:40 PM
whats a catback? catayltic converter?

a catback exhaust is a one piece exhaust system that includes the tail pipes all the way to the cat. putting in a less restrictive filter wont be affected by your exhaust, but wont gain much or any hp in the first place. you can actually lose hp in humid conditions with a cone filter

[daniel318is]

i heard something that u can get away with not having cats in australia...but why bother

[m42technic]

Originally posted by stovski@Oct 16 2003, 09:05 PM
If you think about it, not that much. If you can intake more air than you can release your've accomplished nothing(assuming you have no exhaust or catback). Need the works to get get some noticeable hp gains.

Bolt-ons in general are pretty dumb for BMW's, considering how much engineering already went into getting the most HP possible out of the stock setup.

The real bottleneck on M20's is the head. 2 valves per cylinder = crap.

If you want more power from your stock motor, get a chip and feel some real gains. B)