Lotus Elan

K&N filters (sensations and question)

PostPost by: LotusEngineeringBuff » Mon Jul 09, 2018 1:45 pm

First let me tell you that I bought my Elan (Plus2) in 2010 or 2011 before a long dark era of my life forced my to sideline the car.
Last year I unearth it and started work to put it back on the road. Among other things I installed a pair of thick (3 inches) K&N filters directly on the DelOrto's. A few week ago I got to the point of starting to drive the Elan again :-) :-) I loved it even if driving without an interior and with the K+N was ... kind of noisy; but with so few Elan's on the roads in Switzerland I had nothing to compare to. And with almost 7 years without driving even for short distances I did not remember how it sounded originally. I did tell myself however that with that level of noise it was surprising Lotus was aiming at the upscale market with the +2 back in the days.

When I tied to pass MOT the 1st time early last month, I failed for some non-existent spring/damper problem I might talk about some day. Anyway, the technician added that next time he would submit the car to a noise test. I got scared and told myself I'd stand a better chance of passing the test with the original filter. So I did put it back in.

What as difference! I am really into enjoying my Lotus as a sports car, driving hard and fast. But it is so much more comfortable with the original filter. Maybe there's not this grunt that makes you believe your driving a racing car but there is still plenty of engine noise to enjoy and the level is quite acceptable. I am not going back to those K&N unless I start racing (in which case I will change the car around the filter(s) to a baby Elan).

I remember seeing a conical filter that attaches directly to the air box somewhere on a picture. Has anyone tried one of those ones out?

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PostPost by: prezoom » Mon Jul 09, 2018 3:25 pm

I have both my S2 and the Plus2 utilizing cone shaped filters. However, they are attached at the end of the air trunking in the nose. My S2 came with K&N filters attached to the carbs, and the induction noise was quite loud compared to when I went to the standard back plate and cover with trunking to the nose. The only appreciable noise now is from the exhaust. When noise restrictions started with racing here in the US, many cars were unable to reach the mandated db requirement without applying as much effort to the intake as to the exhaust.
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PostPost by: Davidb » Mon Jul 09, 2018 4:44 pm

I am of the opinion that K&N are a triumph of marketing over filtration...

However, I replaced the two K&N filters fitted directly to the Webers on my Elan with a cold air box and a cone shaped filter (K&N :oops: ) in the nose and the car is so much nicer to drive now.
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PostPost by: pauljones » Mon Jul 09, 2018 7:36 pm

I have the k&Ns..wicked noise. I love it.
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PostPost by: Chancer » Mon Jul 09, 2018 8:30 pm

Davidb wrote:I am of the opinion that K&N are a triumph of marketing over filtration...

Aint that the truth, it may not look as sexy, may not sound as rorty but there is nothing that can touch a bog standard correctly sized paper filter for filtration and flow, neither oiled cotton, nor foam.
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PostPost by: MikeB » Tue Jul 10, 2018 2:50 pm

Apart from the greater induction noise, with the filters fitted onto the carbs you are also drawing warm air from the engine bay, whereas, the std air box with the hose to the filter in front of the radiator draws colder denser air with more oxygen in it, which is good.

Unless you are running a high performance engine and always in the upper end of the Rev range, the std setup is more than adequate for road use.

The other one to watch out for are individual sock filters on each trumpet, as these can get sucked into the carb.

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PostPost by: pereirac » Sat Jul 14, 2018 10:52 am

I remember reading (somewhere) that K&N Filters are great when new and clean but when they get dirty they are actually more restrictive than paper filters?


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PostPost by: Chancer » Sat Jul 14, 2018 11:48 am

Exponentially worse after a very short number of breaths.
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PostPost by: The Veg » Wed Jul 18, 2018 1:34 am

Which also means less consistent during the time between cleanings.
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