9 replies to this topic

[danny_]

I was recently browsing this forum where i came across a PDF file on how to change your Fuel injected mini into a cold air intake mini by blocking some breather hole or something smiler.
I have recently bought a K&N filter and just wondering if someone could point me in the right direction of this PDF file as i have not been able to find it again!

Danke.

[jamesmpi]

That sounds bizzar...all cars have a cold air in take. modern cars use plastic ducts to feed cold air from the grille via a plastic unit containing the air filter and then on into the engine.

Most mpi owners use flexible tubing to feed the cold air from the grille to the filter, such as a k&n which it bolted to the throttle body. However you can make you own unique ducting with a bit of large diameter silicon hose and some aluminium tubing. You can bolt a cone filter on one end (which is then located behind the grille) mean while bolt the other end on to the throttle body.

You'll have to watch what size hose / tubing you buy as there isn't much space between the brake servo and the rocket cover! Lol

[danny_]

Well someone told me and i read somewhere the inlet housing has a heater to heat up the air or something? I must of just been drunk at the time if its wrong....

[jamesmpi]

I didn't say you were wrong lol maybe I misunderstood your post....

[Bungle]

it always makes me laugh when i read about people thinking that if they put a pipe from the front grill to the air filter that the air will magically get cold as it passes through the tube

[northy]

I think the idea is that it doesnt get hot, not that it gets cooler.
Since without a cold air intake the air is drawn from the area behind the engine where the exhaust manifold is, it makes sense if you think about it for more than 20 seconds.

[jaydee]

The inlet manifold is heated, by blanking off the heater pipes the inlets run cooler, i doubt you'll see a noticeable gain from it.

Edited by jaydee, 18 December 2012 - 12:21 AM.

[northy]

blanking off the inlets run cooler

?

[jaydee]

Sorry, missing part added ;)

[northy]

I've seen articles from Calver which would suggest otherwise. He reckons the reason that the regular airbox with a K&N element is more efficient is because it draws air from the front of the engine, where the air is cooler, and therefor more dense. Assuming the air over the exhaust manifold is around 60 degrees C, which is quite conservative, and the air coming in at the grill is around 15 degrees C, we can see from the graph below that the density is reduced by a quarter. That means that there is a quarter less oxygen. Now if we had a quarter less fuel, which is the other chemical ingredient for ignition, we would obviously see a difference, so explain how we would not see a difference with 1/4 less oxygen?

Also if the temperature of the intake air was not relevant, why would rover have put an air intake temperature sensor in the intake which contributes (according to sprocket) about 20% of the data for the fuel mix?

People are too quick to dismiss things like cold air intakes, if they didn't make a difference, why would all modern production cars come with them?!

EDIT: I forgot to put the graph in...

Edited by northy, 18 December 2012 - 06:07 PM.