M O D I F I C A T I O N S :   A i r f i l t e r s

many, many thanks to MG enthusiast magazine

Read the article, have a look at the charts and pics:

MG enthusiast magazine
May 1999, Volume 24, No 2

 

F I L T E R   F A C T S

The main purpose of an air filter is to provide an engine with clean air. Wheter you're using a supercharger, carburettor or fuel injection system, dead flies, grit and the occasional loose bolt won't ignite very well in an engine. Traditional paper air filters are effective at filtering the air of any dirt and delivering clean air to the engine. However, the paper filter also restricts the flow of air, more so if it becomes clogged with dirt. Literature from K&N promises that by "installing a K&N Filtercharger in place of an original equipment or aftermarket paper filter removes the restrictions which then allows the engine to inhale all of the air it can physically use."
The aftermarket filters on test should all in theory promise such characteristics . The results are more power, as the K&N information explains, "Increasing the amount of air available to the engine promotes performance since oxygen in the air is the necessairy ingredient for combustion."
It could be argued therefore, that the ellimination of an air filter would be the best set up for maximum performance. K&N disagree commenting that, "Dyno tests and track tests carried out by leading race teams including Williams/Honda, Benetton/Cosworth and Jaguar/TWR have proved beyond doubt that with K&N filters fitted the engines showed no loss of power over open intakes. In some instances power was increased due to a reduction in turbulence over the intakes and a more even distribution of air..."

Getting the air into the engine is very important and the theory on the subject is that cone filters are more effective than panel filters (check the K&N site). Visually, there are less obstacles in a cone filter to restrict air flow into the engine and so the power output of the engine should be greater. The temperature of the air entering the air filter and eventually entering the engine is critical for performance.The standard set up of the MGF allows air drawn from the rear  of the engine bayto be used. However the cone kits from K&N and Ramair come with a couple of intake tubes which deliver air from underneath the 'F.

R O A D  W O R K

Test driving the filters provided a variety of impressions. Pipercross seemed to get the best vote for noise and growl. "After driving a standard car, fitting a Pipercross Vector can come as something as a surprise," says Rob Bell. "Instead of the mundane hum of a car manufactured to pass drive-by noise regulations, one is confronted by the his and burble of intake noise, which increases in volume when the throttle is depressed, egging on the driver with a sporty roar. This sound is the closest one can get to the sound of a Weber carburettor whithout actually fitting one. It is enormously intoxicating. Throttle response too is terrific. Whilst the power gain is modest with this filter, one can detect that one's braking points have changed slightly to compensate for the emproved engine performance.In conclusion this is one of the cheapest cone filters on the market that provides the owner with a lot of smiles. Ultimate performance fails to match the other filters in this class, however."

Richard Eaton fitted a K&N on test day. His impressions were as follows. "The K&N Cone seems to have transformed the car in terms of both performance and noise! Flooring the accelerator now treats your ears to a throaty growl that quickly turns into an almighty roar wich has you grasping for another gear before you bounce off the rev limiter. When accelerating, the sound inside the cabin gives the impression that a loud high performance exhaust has been fitted, but to the outside world there is hardly any increase; quite a bonus when trying not to attact unwanted attention! While you may think that an increase in cabin noise might become an annoyance, the beauty is that it's only there when you want it to be -when you are accelerating hard. When the car is sat at constant revs -like on the motorway- it's as quiet as before, it's only when you floor itthat the growl appears along with a huge grin on your face!"
"The car is also much more responsive than before. It seemed to have some kind of lag when you floored it at low revs before, now it accelerates instantly. Initially I thought that the filter had only an effect at low revs, but after driving it a few more miles I now think it feels quicker across the whole rev range. It seems to rev much more freely and has you changing gear more often and quicker than before. The car now feels faster and is so eager to accelerate, you find yourself constantly overtaking slower moving cars and making rapid progress."

 

  Standard air filter K&N panel Jamex Panel Ramair Panel Pipercross PX Cone Ramair Cone K&N
Cone
Pipercross Vector Cone
  MGF 1.8i
  BHP at flywheel
118.1
@5635rpm
120.7
@5540rpm
119.5
@5700rpm
119.7
@5635rpm
120.9
@5600rpm
124.1
@5600rpm
125.3
5700rpm
121.4
@5750rpm
  MGF 1.8i
  Power tail off to
102
@6500rpm
102
@6500rpm
104
@6500rpm
103
@6500rpm
108
@6500rpm
110
@6500rpm
110
@6500rpm
108
@6500rpm
  MGF VVC
  BHP at flywheel
140.3
@6500rpm
143.6
@6500rpm
140.7
@6500rpm
142.1
@6500rpm
150.4
@7000rpm
155.9
@7000rpm
156.1
@6500rpm
153.9
@7000rpm
  Prices - 31.71 28.78 27.35 23.74 170.38 82.25 -
98.66
37.60

MG enthusiast magazine (May 1999, Volume 24, No 2)

Graeme Bishko had used a Moto-Build exhaust and Pipercross cone air filter. The filter had been bolted directly onto the throttle body which as Graeme explained, "the whole thing was a bit too loud. It was especially painful at between 3000 and 4000rpm when it droned (70-85mph in 5th) so it was a bit of a pain on the motorway. I took off the Pipercross cone and replaced it with a K&N panel filter in a standard air box. There was a slight drop in power from the cone, but much nicer to live with. I then replaced the Rover air box  and K&N panel with a K&N cone kit. Nice noise again but not so much drone on motorway as Pipercross.
Ramair also seem to give the driver a bit of ear bashing. Despite its highperformance output, the cone in particular was viewed as being excessively noisy. Outside the test panel, Malcolm Gammons feels that the Ramair is good for the track, but not for the road. At cruising speeds the Ramair cone is fine, but under acceleration Malcolm feels that the noise is too much from a filter that is merely inches from your ears.However, Paul Sharpe feels that the Ramair is less noisy than the K&N and Pipercross under acceleration. He's also experimented with mounting the K&N cone Pipercross cone direct onto the throttle body and feels that this produces a meatier noise with a better throttle response.

 

A N D   T H E   W I N N E R   I S . . .

Well have a look at the MG enthusiast magazine (volume 24, No 2 of May 1999) and you can read many more details about air filters and which one you defenetly need to buy.

 

A D D I T I O N A L

Have a look at my page about the K&N 75i kit and a K&N heat shield.
The Mike Satur Vader kit installed in my MGF.