air filters

[dellerie]

i am looking for a decent air filter for a single 1.25 SU. i have one of those silly pancake things with the foam in. i doubt it does what it should. i haven't got any other filter system at present.

i have been looking at these K & N filters. i have found a conical shaped one. comes in at around £40 delivered. is it worth the effort? those paper ones that go in the metal housing don't seem to do much.

[bmcecosse]

On a single 1.25" SU it's not going to make much difference - the carb itself is the limiting power factor on a 1098 engine. If you want more power - you should upgrade to a 1.5" SU - either the HS4 of the HIF 38 - and then get a decent filter for that. The flat face of of the filter must be at least 1.5 X the diameter of the intake hole away from the carb. So - for a 1.5" carb = 2 1/2" away. The mouth of the carb should also be nicely radiused to ease the air in - and the carb can be 'Vizardised' too of course.

[dellerie]

On a single 1.25" SU it's not going to make much difference - the carb itself is the limiting power factor on a 1098 engine. If you want more power - you should upgrade to a 1.5" SU - either the HS4 of the HIF 38 - and then get a decent filter for that. The flat face of of the filter must be at least 1.5 X the diameter of the intake hole away from the carb. So - for a 1.5" carb = 2 1/2" away. The mouth of the carb should also be nicely radiused to ease the air in - and the carb can be 'Vizardised' too of course.

are both those carbs able to fit onto the standard manifold then?

[bmcecosse]

You need the later manifold from a Mini - very common and readily available for v little money. However an alloy inlet manifold (ie MG Metro) NOT connected to the exhaust manifold is worth ~ 3 bhp in itself! An H4 SU fits the original manifold - of course you need to open up the centre hole to 1.5" diameter,

[chrisryder]

i would avoid a conical one if possible. they're designed to fit in the limited space in a mini, and it sacrifices some performance because of it. the one on mine is conical and has an offset hole (rather than a central pickup) offset for the mini fitment aswell. serves me right for getting it from a mini specialist!

if you do order a K&N you'd benefit from ordering a filter service kit with it, or you'll find yourself having to make another order (and another lot of postage) when you get around to servicing it. my service kit has lasted me two services so far, and isn't showing signs of letting up yet!