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Re: <E30> K & N Air Filter

> Has anyone installed a cone K & N air filter in his/her E30 325i?  Have you 
> noticed any improvement over the enclosed stock unit?  A friend of mine said 
> that the opened area is so close to the heat from engine that it could 
> actually affect the performance.

I have installed the K&N cone air filter in my '90 325i, the one which
replaces your original air box. There is a small increase in power throughout
the rpm range, which is good as the 2000-3000 range is outright bad in a
standard 325i.

You have three problems you'll have to cope with.

1) As you pointed out, the air is heated by the engine and a heat shield is
the first thing you should install. I made an aluminum one (about 2 mm) which
is easy to shape and will soon coat the engine side with some sort of heat
shield (like the one under the hood).

2) The plastic adapter which is to be mounted on the AFM had (in my case) to
be removed as there were a short interval around 2500 rpm where the engine was
running very rich. Jim Conforti came up with the solution which was a resonance
phenomenon in the AFM which could be cured by making your own adapter. I made
an 4" adapter which cured the problem.

3) Take the time and effort to assure that you get enough *cold* air from the
outside. 

FWIW

///Micke, Sweden
BMW Club Schweden #2384

'90 325i, SuperSprint exhaust, K&N cone, Bilstein Sprints, Bilstein Sprint
Springs, Hartge front strut brace. No Jim C. chip.