8 replies to this topic

[samt88]

I'm looking at just getting a bit more power out of my 998, but getting a 1275 soon. I was thinking of getting a K&N air filter, would it do anything for my 998 now and my 1275 when I get that? Also, I read somewhere about drilling three holes in the air box...is that right? Does it not mean some of the air going to the engine is dirty or am I wrong...?

[HarrysMini]

K&N filter in a standard drilled box works very well. you can put as many holes as you can physically fit on it, obviously on the outside!

[samt88]

Ooh I see...and if I combine that with an RC40 exhaust what sort of difference (if any!) am I likely to notice?

[AVV IT]

Realistically a high flow air filter is going to make a virtually no difference to performance on it's own. However it could well make a difference to your insurance premium, as an insurer will deem it as a performance modification, even though you won't get any discernable increase in performance. You really need a full stage 1 kit to make any noticeable difference to performance. (i.e. high flow filter, updated carb needle, gas flowed inlet, exhaust manifold and system etc).

I believe that in a particular comparison flow bench test performed a few years back, the K&N element filter mounted in a standard housing with a series of half inch holes drilled in the housing wall, marginally outperformed a K&N cone filter. The reality is that you're not really likely to notice any discernible difference between running the two types of filters on most classic minis though, (other than how loud they are). The series of holes in the side wall increases air flow passing through the filter, all the air still passes through the filter though, so dirty/unfiltered air shouldn't be going into the nine.

[samt88]

So with a K&N air filter and an uprated exhaust system I'll notice a bit of a difference? I'm gonna have both of those before I fit my 1275 so just trying to work out whether its worth fitting them early!

[AVV IT]

I doubt you'd notice any real difference with a filter and an uprated exhaust either. To be honest whilst fitting a full stage 1 kit will make a noticeable difference, it isn't a massive one. You really need an uprated cam and modified head as well, in order to release any significant power in an A-series.

The other issue with fitting an aftermarket exhaust like an RC40, is that it won't connect directly onto the standard exhaust manifold, so you'll also need an aftermarket exhaust manifold (LCB, Cooper Freeflow etc) to connect it to. Unfortunately you'll find that the standard inlet is cast/joined to the standard inlet, so if you're fitting an aftermarket exhaust manifold, then you'll also need to fit an aftermarket inlet as well, at which point you've basicly got yourself a stage 1 kit minus the correct carb needle.

If you really want to fit an aftermarket exhaust system to the standard manifold on a 998, I beleive that it is possible to do so by fitting a "magic pipe", http://www.minispare...|Back to search but I dont think it will work if you then upgrade to a 1275.

[samt88]

Aha....seems like a little too much work for the very little potential gain....cheers for your advice!

[alex-95]

Drilling some holes in the filter box wont help if it's not done/set up correctly or too many holes are drilled, it can make it worse, I had a cone filter on mine and you could here the air being sucked in, causing a flat spot fitted a standard filter and it runs hell of a lot better.

[racingbob]

my mates mpi made more power with standard filter set up

over the KN quite amazing and not having the horrible noise

done at slark rolling road recently

think twice about a KN

I have a MED substack and ITG and I realy could feel the difference

pariculary mid range and above ( mg metro engine)