Free Flow Filters

[jammyk]

Afternoon all! Newbie owner of an S4, needing some advice on the replacing the OE airbox and throttle return spring mounting with K&N airfilters.

I have a part supplied by Paul Matty Cars that provides the bottom bracket mounting for the retun spring & throttle cable, but the way that its fitted means that there is no movement in the throttle linkage - this is due to the spring fouling on the back plate of the k&N air filter.

Has anyone fitted K&N's succesfully?
Is there a trick to getting everything back in place?

Any help/advice would be much appreciated....

Gav.

[worzel]

Hi

I'm sorry to say but I'd stick with the original system- it's worked fine on thousands of cars and I suspect the manufactures know what they're doing

John

[jammyk]

old addage... if it aint broke, dont fix it.... frustrating none the less, as there has to be a simple way of changing what is, in essence, a simple thing....

The issue with the air box is the way in which i'm restricted in access to the fluids. At the moment it concerns me - the faff to check things before a run on an unknown car means much check/setup time before i get out and drive the thing!

Is there a worakround to the latter if K&N's arent the way to go?

[BillGavin]

I, too, would advise keeping the original air box setup. My car is LHD, so I don't have problems reaching my master cylinders.

It's fairly easy to modify the airbox securing bolt so it's easy to remove without tools: this may solve your access problem. I can reach my distributor and oil filter fairly easily with the airbox removed, but the backplate still in place.

It's also pretty common to fit remote reservoirs to the master cylinders, especially in race cars. Tony Thompson fits these to some of his cars, I think there are pictures on his web site.

I fitted a Pertronix Ignitor electronic ignition to my engine, so I rarely need to get to the distributor.

[worzel]

I know the caps under the carbs are sometimes (always) difficult to remove- I just wind on a jubilee clip and then turn the lid- or get one of those thingies that act as a strap wrench (they're made of nylon) and use that to grip.

John

[mike+2s130]

keep to original air box.keep the original trunking.get a k n cone filter with neck size about 82mm and connect to trunking.place filter near griil intake .that way the filter can drag in colder denser air.if you fit k n filters directly to carbs you will be drawing in hot air from the engine that is why the original filter is fitted where it is hope this is some help bye

[paros]

I agree with keeping the elephants trunk pipework for cool air HOWEVER replace the tin Ford filter box with a conical modern filter - I used Pipercross, dead easy to fit as it has a neck of same diameter as the trunking. I have seen dyno figures showing loss of bhp with standard small filer but replacing with Pipercross etc style liberates something like 10 bhp

Richard

[steveww]

The standard air box robs the rear chokes of air, TTR sells a better air box. The hot air intake with filters directly on the carbs argument is just that - hot air. I have measured the intake temps and their is no difference. When the car is moving at 50mph there is enough air swirling round the engine bay to provide enough ambient air. Additionally the airbox and trunking heat up and transfer this heat to the ambient air drawn in from the front.

The biggest restriction of the intake system is the tiny filter box in the nose, this needs replacing with a better breathing unit. Either a cone filter on the pipe or a domed air filter on the carbs. Avoid pancake filters on the carbs as there is not enough space to have sufficient gap between the trumpet and filter top plate. Filters directly on the carbs will give you more inlet roar.

All this will only be noticed at high rpm

[jammyk]

Many thanks for all this. Begun the road of trouble shooting:

1) had carbs reset to sprint specs to match the head & thoroughly cleaned (should have been my first thought)
2) had the carbs balanced to actually feed the engine properly & ingition slightly retarded to fire correctly
3) Will be purchasing a cone filter to mate to the end of the std intake hose
4) will be advertising two 40mm K&n pancake filters asap.
5) looking to get the new airbox ordered - this advice also mirrored by Roy at Paul matty cars...

Upshot of the carb work is a fine response, top end power restored, usable torque across all of the rev range and a big smile on my face as i blow past unsuspecting elise drivers
Now to sort out the cam timing...grrr

[rickf]

I bought two nice chrome mesh and foam dome shaped filters from Victoria British LTD in the US. They're called Longflow and they come it oval and round styles. They're actually for a TR6, but they bolt right on Strombergs. They even have holes and fittings for hooking up the crankcase vent, if you want to (I don't). $33.95 US ea. They'll tell you they don't have parts for Lotus, but just assure them you know what you're doing and you want the ones for a 175CD.

I use open velocity stacks for autocross, where the helmet muffles the noise, but I switch to these on the street. Still makes quite a roar, but keeps it below the level for brain damage. I have an oversized aluminum radiator and the original air trunk can't go around it.

One thing: Don't put the gaskets they give you on backwards, or they'll block the vent from the carb and the car won't start. Don't ask how I know this, but let's just say it proves I can't afford any brain damage.