K&Ns, etc

[Jeff Kyle <jkyle1 at x]

I just picked up a pair of K&N filters for my Elan S2 - has anyone
else here installed them?

I'll definitely need a new throttle linkage, however my mechanic is
concerned that the thickness (1.75" is the only one available) isn't
enough to provide good airflow... The car tends to run rich normally
and he's afraid that this will make it run even richer. The other
problem is the horns on the carb - is it "ok" to just remove them and
leave the holes wide open? If they have to stay on, then the filter
element just isn't deep enough and it doesn't appear that K&N sells a
thicker one. It would probably be possible to "stack" two elements but
that seems like a bit of a hack.

Anyone have any thoughts?

[paul_adamson]

The original installation gets cool air to engine and (according to Miles
Wilkins Twin Cam Book) should be fine for engines producing upto about
150bhp.

Removing the horns from the carbs doesn't sound like a good idea either.
The radius on the horn (trumpets) smoothes the flow of air (which is a good
thing) and
I am led to understand that the lengths of the horns provide a degree of
resonance which is also beneficial.

I would leave it standard.

Having said that, other members on the list suggest moving the air cleaner
canister to improve air flow through the radiator - which does sound like a
good idea.

["Peter Boegli"]

I bow to the expertise of Miles Wilkins (and others), but it might be of
interest what I measured a number of years ago on my Elan Sprint using
Webers (numbers are from memory = approx.):

The original air trunking reduced the peak power by some 4 bhp compared to
no free breathing trumpets.
A couple of Warneford foam air filters (something like the K&Ns) did not
reduce power by any measurable amount. I used (and still do) the deepest
variant with 105mm depth. Iwas told that the original air box is too
shallow, especially at cylinder 4, i.e. the airbox cover is too close to the
opening of the trumpet. This means that the induction pressure pulses get
reflected back into the trumpet with detrimental effect. As a rule of thumb
the distance measured from the trumpet end to the closest wall measured in
axial direction should not be less than the trumpet mouth opeing diameter.
Removing the trumpets made for quite a ragged torque curve over the engine
speed range. Peak power dropped by some 2 bhp and torque in the middle range
was lower by several percent. At some specific engine speeds there was a
slight improvement.
Mounting shorter trumpets as used with the DCOE2 series made the torque
curve somewhat less ragged, but still was inferior to the original trumpet
length.

The "official" school of thought says that K&N style filters are worse that
the original trunking because they make the engine breathe warm air = less
desity. Sounds plausible. My measurement were taken with the car standing
ond bonnet/hood removed = cold air.

Peter


----- Original Message -----
From: Paul Adamson <[email protected]>
To: <[email protected]>
Sent: Thursday, September 09, 1999 10:08 AM
Subject: Re: [lotuselan] K&Ns, etc

[rodbean]

Peter Boegli wrote:


I would make an air box or modify the existing one, to be as far from the
trumpet ends as allowed by the space available, then put a good K & N (or other
good free-flow air filter) down in the nose where the stock one is.

Rod

[Stevie-Heathie]

IIRC the airbox protects the GRP in the engine bay from getting soaked
in the petrol being blown back through the Webers' trumpets, and is
therefore an important fire avoidance device.

Stephen
1970 Plus 2S

[Jeff Kyle <jkyle1 at x]

On Thu, 9 Sep 1999 12:53:26 +0200, you wrote:


Supposedly my car has the "short" trumpets - I have others in a box
but haven't compared lengths.


We were planning on keeping the hose and mounting one end to the
grille and the other to right in front of the air cleaners to
hopefully get cool air when moving... Of course this probably
wouldn't help the rear carb much.

Main reason I was planning on going this route was that the original
air cleaner system is not quite all there - I have the air box, the
hose, and a cylinder filter stuck to the end of that, and I fear that
it's just not enough filter. Sounds like I should return the K&Ns,
read the manual, and figure out how it all originally went together...

["Craig Hill" &l]

Jeff K&N makes a filter that will fit inside the factory filter housing.Also
the factory recomended a modification to the filter housing that involved
cutting about a 3/4" hole in the bottom to allow water to drain out. I found
the hole also inproved airflow at high RPM.
----- Original Message -----
From: Jeff Kyle <[email protected]>
To: <[email protected]>
Sent: Wednesday, September 08, 1999 9:28 PM
Subject: [lotuselan] K&Ns, etc

["Peter Boegli"]

----- Original Message -----
From: Steve Heath <[email protected]>
To: <[email protected]>
Sent: Thursday, September 09, 1999 2:16 PM
Subject: RE: [lotuselan] K&Ns, etc




Sure true! I did not mean to advocate using neither airbox nor K&N-style
filters.

Peter

[Jeff Kyle <jkyle1 at x]

On Thu, 9 Sep 1999 07:33:17 -0700, you wrote:


Well, my car has no factory filter housing... The filter that's
currently on there is just a tube one stuck on the end of the hose.
Needless to say I want to get something better in there.

[gobw2]

Jeff - original air cleaner on mine had a small element with a big clunky round
case with two long horns. This contraption sat right in front of the radiator,
blocking a lot of it. Also, the airhorns were at right angles to the airflow.
I went to the boneyard and found a base off a large 4 barrel carb from a large
v8 engine. I picked one that had a small diameter and was very deep. the outlet
was the same size as the flex hose. I used a flat aluminum plate for the top,
and air cleaner for the v8 engine. Today, I would look for the the flat air
cleaner as used in the Ford Mustang V8's. It is compact, and would allow a
straight airflow with no turns until you got to the engine airbox. Restriction
should be low, as it is designed for a 302 high output engine and the elan
engine would only flow a fraction fo the CFM.George.
[email protected]

Jeff Kyle wrote:

[rodney]

Jeff at 12:28 AM 9/9/99 -0400, you wrote:

One thing that no one else has mentioned is the fact that the trumpets
actually hold the venturi in place. Removing the trumpet would allow the
venturi to move which could have disasterous effects on the flow of petrol
from the mains through the venturi to the air stream.


Rodney Stevens

Email: [email protected]

Work Phone: 61 2 97106701
Work Fax: 61 2 97106789
Email: [email protected]

Elan SS s/e 45/7616
http://sites.netscape.net/rodjohnstevens/homepage

[Sking06]

Jeff....

I think you have all the fixin's for a reasonable good filter system. Use
the original airbox / hose and mount a single K&N at the end up against the
grille. Go to K&N's web site http://www.knfilters.com/affacts.htm and look
at the section on air filter selection to figure out what size filter you
need.

[saarhus]

I recall reading somewhere (Dave Bean catalog, probably) that the trumpets
for the TC Webers were a special length, tailored specifically for the TC
intake runner length. Supposedly only available in that length from Lotus.
The filter housing clearance problem for #4 is very plausible, and would go
a long way towards explaining my crispy #4 exhaust valve. I agree that cold
air is important and that retaining but modifying the cold air box is the
best idea. I have used the recycled V8 air cleaner with good success.
Stan

-----Original Message-----
From: Rodney Stevens <[email protected]>
To: [email protected] <[email protected]>
Date: Thursday, September 09, 1999 6:25 PM
Subject: Re: [lotuselan] K&Ns, etc

[Phillip Babcock <phill]

Well here is my two cents worth:

On our Dynojet chassis dyno with a 150 hp (at flywheel) eng.

I installed a K&N filter charger at the end of the hose, in the nose on the
car. Bought from Ken at Dave Bean, I don't know the part number. Picked up
about 4hp.

Now for the big gain, the org (on mine) air box is too shallow, trumpets too
close to the box. When enlarged, made deeper, I picked up 8hp & 10 lbs of
torque.

Don't run them breathing under the hood the hot air produces a 6-8hp loss.

Phil Babcock
72 Sprint Vintage Racer

The Dyno Shop
http://www.the dynoshop.net

[elancoupe]

:



Very interesting!
I have seen photos of the Dell'orto airbox , it appears to be "deeper" than
the Weber. Can anyone comment on this? Is it interchangable with the Weber
backing plate? Perhaps someone with a UK model?

Mike B