11 replies to this topic

[designadviser]

Just wondering if there was any performance difference between the conical and pancake type K& N air filters for twin SU 1 1/4 carburretors ?
Would one perform better than the other ? I assume they both fit without clearance problems.

http://www.minimania...5/InvDetail.cfm
http://www.minimania...X/InvDetail.cfm

Also are the velocity substacks worthwhile on a fast road car ?

http://www.minimania...0/InvDetail.cfm

Edited by designadviser, 15 February 2011 - 03:07 AM.

[cooperrodeo]

I certainly would not regard $55 for one stub stack as 'worthwhile'. I have a pair of pancake K&Ns and homemade stub stacks but I do not have any data on their performance relative to any other setup.

[Pooky]

I'd get the conical filters. They have more surface area so will allow more air (obviously the mixture/needle will need tweeking) and will give better clearance from the bulkhead.

[Dan]

In a Mini, possibly due to the proximity of the bulkhead and the turbulence it causes, pancakes seem to allow better flow than cones. They fit fine as long as you get offset mounting types. Stub stacks are worthwhile, can't comment on the price though.

[bmcecosse]

If you get flat pancake filters - make SURE the thickness of the filter is at least 1.5 X the diameter of the inlet on the carb. So - for 1.25" carbs they need to be almost 2" thick. Any less restricts flow. Either fit stacks - or radius the inlets on the carbs.

[monster_mini]

hi:) i was just wondering, i've just finished building up my twin inch1/4's and used the k'n conical filters.

however i havent fitted any stub stacks or radius'ed the inlets.

out of interest, how much would i benifit from doing this?(would it be a noticable?) and finally do you have any pictures of how much rounding would be needed and any tips ect?

thanks

nick

[MiniLandy]

...or radius the inlets on the carbs.

Beat me to it

As for how much to radius the entrance of the carb, Vizard says that any more than a 1/4 inch radius has no real benefit.

So, a 1/4 inch radius

[smileytony]

You might find this article interesting: Click Here

[monster_mini]

ok thanks:) whats the best method of doing this? and with what tools?

Also i was quite surprised at that article!!! but then again, when its only a small bore, and a small single carb, the standard air filter wasnt ever going to be much of a restriction, but on bigger engines and bigger carbs, i'd definitely put a bet on that because the conical filter will allow the abilty to suck more air in, this would outway the negative effects of induction shock waves?

anyone else got any theorys:)?

[bmcecosse]

You can pretty much forget 'shock waves' with the hopeless BMC twin carb manifold with the big balance pipe.

[finch661]

whts the alternative to the BMC manifold then?

[monster_mini]

and care to go into more detail:)?