Air Filters - K series

[Toby S]

Hi All

I have a 1992 1400 K series Supersport - Currently has a K&N cylinder air filter around 7 inches long 10 inch diameter which sits at the front of the engine bay in the nose cone and its looking pretty shabby (may well have been the original - cars done 36,000 miles) so I'm thinking changing.

Looked on K&N website and there's more universal filters than you can poke a stick at - However I've  seemed to have found one which looks a direct replacement.

However now the questions:-

• Cylinder filter or cone - seems to be a very similar one which is cone shaped (same length, diameter and  flange diameter) - has anybody any experience of both and can advise whether there is any difference in performance
• During my googling, I found an article testing the induction resistance of performance filters and the foam Pipercross and IFG filters seemed to come out very well (less resistance than the K&N one tested albeit the K&N tested was a smaller filter) - has anyone tried the Piper cross of IFG or any foam filters  - any comments on performance
• Does anyone have any  other recommendations
• Given the position of the filter (just behind the radiator, sitting on the offside of the car close to the side of the nose cone) - has anyone tried putting a vent/air intake hole in the o/s side of nose cone in an attempt to improve air intake of colder air - I've always wondered whether it would make any discernable difference in performance.
• Am I just thinking too much (whatever you do won't make any significant difference) and I should just get the direct comparable one (and probably a life !!)

Main use of the car is fast road blats

Cheers

Toby 

 

[elie boone]

By a refurbishment set from K&N these filters are perfectly serviceable.  

[rj]

Am I just thinking too much (whatever you do won't make any significant difference) and I should just get the direct comparable one (and probably a life !!)

Yes :-p

 

[Jonathan Kay]

• Given the position of the filter (just behind the radiator, sitting on the offside of the car close to the side of the nose cone) - has anyone tried putting a vent/air intake hole in the o/s side of nose cone in an attempt to improve air intake of colder air - I've always wondered whether it would make any discernable difference in performance.

This keeps cropping up for both combustion and cooling. There are several attempts in the archives including a description and photographs of a fully ducted Seven.

It looks very likely to me that both could be improved. But it never seems to catch on, and there are usually good reasons for that...

Jonathan

[SLR No.77]

There were a couple of mods that were the norm for the 1400 Supersports with the forward facing throttle body ...

1. To reduce the intake temperature fashion a simple ally plate that will direct air over the radiator to the air filter, I've not got any pictures and not sure whether you'll understand my description ... it's a simple angled plate, the horizontal part at the bottom sits over the radiator and passes far enough back to tuck under the filter, the angle forms a 90 degree vertical section that passes up the engine side of the filter and forward again over the radiator, adding some rigidity. Trim the top of the vertical section so that it's close but doesn't touch the nose cone. Hope that makes sense!

2. If you remove the air filter and open the throttle fully, unless it's already been modified you'll notice the butterfly doesn't open fully because there's a limit to the cable travel due to a fixed stop. Most people file the stop away slightly to allow the butterfly to open fully.

3. The air filter is a bespoke part - the rubber mounting face is angled slightly to orientate the filter correctly. It would be unusual for a K&N filter to be beyond service life, is it so bad that it can't just be cleaned properly and re-oiled?

Stu.

[Toby S]

Cheers for the suggestions guys

I think at this stage I do a clean and re-oil and see how I get on

Stu - I saw a similar thing (home made air box) on Alcester racing sevens website 
http://www.alcester-racing-sevens.com/heat_management.htm
which sound pretty similar to what you were saying and agree it  might be worth thinking about, although I'm not sure there is that much clearance between the radiator and the nose cone, and their's seemed to stop at the radiator (I'd thought you'd need to do a hump back bridge effect over the radiator with the aluminium to get any real ait scoop effect). Alternative I suppose would be to enclose and either side vent through the side of the nose cone behind the radiator or do an air scoop out the top  behind the radiator, I suppose - I've seen a couple of air scoop bolt on mods on a few performance sites but there not that cheap - key I suppose is deciding whether it will make a significant diff to performance before spending the cash

Your point on the butterfly in the throttle body is a good one - did that a couple of years ago and it made a noticeable difference at full throttle so  to anyone who hasn't done that already.

RJ - Like your thinking - which went through my mind when I was typing the original query 

Regards