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MG MGF Technical - k&n accelerate ??

since I have put the K&N filter on,
I think that my f does not accelerate like before.
is this possible?


After fitting the K&N to mine I really couldn't detect an increase in accelation, but I did notice that it was slower to pick up from low revs, for example after crossing a speed bump. This was probably because the air ducts supplying air form undernneath the car to the K&N didn't work well at low speeds, which meant the engine was drawing in warm air from the engine bay.

If you fit any sort of filter enclosure (current evidence shows little difference between the cheapest and most expensive versions)and ensure inlet trunking draws in cold air, such as from the left hand dummy air vent, the engine will accelerate better.


is the left hand vent only a dummy???

The K&N shouldn't make the car feel like it accelerates any slower. In fact, it should make it *feel* like it accelerates faster - tho' if this is a real effect, or simply that the car accelereates more smoothly, I don't know.

Are the air intake pipes directed onto the filter - they should be about 10 cm away (converted to metric for our friends on the mainland!). Are the ends of the pipes under the car pointing forward?

Does the engine still idle at about 8-900rpm when warm? Occasionally, overtightening the clip on a plastic throttle body can cause it to stick.
David Bainbridge

Daniel, I think that David is right. If you have the 57i kit it is *essential* that the cold air ducts are properly installed, otherwise the engine bay temperatures are such that you LOSE power with the installation of a K&N filter! :o(

I met a couple of German MGF owners who have reported similar problems. Because of the TUV, many leave the lower half of the standard airbox insitu. This restricts airflow around the filter, and also makes installing the air ducts pretty much impossible.

If the TUV inspection makes the 57i kit impossible to install properly, then I'd recommend a K&N panel filter in the standard airbox, but with a cold air feed from the left hand airvent.

GC, to answer your question, the vent performs little function in terms of cooling; there is very little airflow through it :o( In fact, when Andy, Tom, Paul and I stuck some streamers around the area of the vent, their movement suggested that air flow was non-existant through that vent at 50 mph. Actually, that is perfectly okay for enclosed filter systems - and why the 820 filter mod uses this intake - see
Rob Bell

Quite so.

Sorry nothing else constructive to add except to say Iím quite old and had lots of cars and motorbikes and I married into the travel industry.

Fred Oldman

Is Fred Oldman supposed to be a parody of Ted Newman because I didn't get it.

Sorry - I thought they meant palindrome!

Your correct. There would be no air flow thru the lhs air duct as the pressure inside the engine bay will be greater than outside and a little like when you open the window at speed any cigarette smoke is drawn out of the car not into it!
Correct positioning of the duct tubes underneath the car pointing forward should provide a very small amount of ram air but only slightly.
R Baker

>>>should provide a very small amount of ram air but only slightly

I think it's more a question of creating a 'puddle' of cold air around the filter than actually forcing air into it.
David Bainbridge

Quite so.
Sorry nothing else constructive to add except to say Iím quite old and had lots of cars and motorbikes and I married into the travel industry.
Fred Oldman

David, yes you are right. If can get a "puddle" of pressurized air around the filter, then this is perfect. Sometimes forcing air is not a great solution. It depends, only with tests you can get there.
Cheers, Valter.

I have just installed the K&N 57i kit on my 1.8i and can only say it certainly feels like its accelerating faster. Before the engine seemed to run out of breath at around 4,500rpm but now its revving like crazy!

Quick, but probably also dumb, question for you. I've recently got myself a K&Ni and will be fitting it on the first available dry day.

It seems that some of you have your intake pipes under the car, but what's to stop the worst from happening if you happen to drive through a deep puddle or something??? I imagine a quick suck of muddy water probably won't do tooo much good.

Is the LH air intake vent a dummy then? Would this be a better site to situation the pipe?


This thread was discussed between 19/12/2002 and 22/12/2002

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