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Discussion Starter · #1 ·
Hi,

I just fit my new 52mm throttlz body on my 1.8i and put my KN cone air filter directly after.

I have read somewhere that it's not a good idea.

Could you please explain me why ? Is there a thread talking about that ?

What is the best fitting for the KN air filter ?

Thanks

Karistep
 

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if its an open cone then it will suck in hot air from the engine bay which is less dense and therefore carrys less oxygen, thus reducing power.
 

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karistep said:
Could you please explain me why ? Is there a thread talking about that ?
There is loads of threads on here discussing what is the best general idea, just search on here for induction kits. It is mainly though that a good panel filter (K&N or ITG) in the OE airbox is pretty much just as good as an induction kit as long as both are enclosed, ie not open filter and they have a cold air feed run from the front of the car into them.

Hope this helps

Tom
 

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Discussion Starter · #4 ·
Thanks but

I understand the problem of cold air but what I do not understand is what I do not have to fit the air filter directly on the throttle body.

Thanks for your help

Karistêp
 

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no, you can but youll need a cool air feed going straight too it, and you will lose power at slow speeds. if you use an enclosed kit or panel filter you wont. like i didnt....
 

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closer to the tb means more noise from it, ive run a k+n cone filter on a 2.5 v6 omega without any shileding and it made no loss of power even with the heat generated in the very tight engine bay. Try it if it fits, everyone has their own opinion on this matter but if it works for you then why not do it. If you really wanted to, remove the airbox and run a length of ducting from the o/e cold air feed upto the cone.
 

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kev25v6 said:
If you really wanted to, remove the airbox and run a length of ducting from the o/e cold air feed upto the cone.
That won't help at all. A bit pointless really.
 

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everybody does have there own opinion but its simple science not what a person 'thinks' will give/reduce power.
btw adding the cone aswell wont really help much.
 

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ashy said:
That won't help at all. A bit pointless really.
why not, it still has the cold air feed being directed straight to where it needs to be. Everyone says to have a direct cold feed to the air box so why not make use of the original one?
 

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dac said:
everybody does have there own opinion but its simple science not what a person 'thinks' will give/reduce power.
btw adding the cone aswell wont really help much.
It may be science that shows power gains/losses but most people wont notice the minimal difference a cone will make. It is mainly in the mind that when you hear the cone 'growl' you think you are going faster.
 

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kev25v6 said:
It may be science that shows power gains/losses but most people wont notice the minimal difference a cone will make. It is mainly in the mind that when you hear the cone 'growl' you think you are going faster.
so, running a cone on hot air in a v6 will make it faster because it sounds faster?...
 

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dac said:
so, running a cone on hot air in a v6 will make it faster because it sounds faster?...
Im not saying it actually makes the car faster but the noise of it makes you think you are going faster, just like putting a 6'' exhaust on a 1.0L nova,it sounds like it is going faster even though it isnt.
 

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kev25v6 said:
why not, it still has the cold air feed being directed straight to where it needs to be. Everyone says to have a direct cold feed to the air box so why not make use of the original one?
The OE cold air feed will do nothing for an open cone for 2 reasons:
One is that the OE CAF goes down into stale air behind the bumper, so no forced air into the feed.
Second the OE air feed only works when it is sealed within it's airbox as the engine sucks the air it requires through it. An open cone is not sealed and therefore will not be able to suck any air through the feed.

A CAF for an open cone needs to be forward facing at the front of the car to scoop air into it.
 

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ashy said:
The OE cold air feed will do nothing for an open cone for 2 reasons:
One is that the OE CAF goes down into stale air behind the bumper, so no forced air into the feed.
Second the OE air feed only works when it is sealed within it's airbox as the engine sucks the air it requires through it. An open cone is not sealed and therefore will not be able to suck any air through the feed.

A CAF for an open cone needs to be forward facing at the front of the car to scoop air into it.
with no air box, just a pipe onto the o/e caf leading upto the cone filter will still have some effect. If the stale air from behind the bumper does nothing, why bother having it there in the first place. It may not be as good as a great hole cut into the bumper for the air to enter from but at least it can suck some cooler air from the pipe than from what is in the engine bay. From looking into the engine bay it is not easy to route a caf from the bumper due to the battery being in the way.
 

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kev25v6 said:
with no air box, just a pipe onto the o/e caf leading upto the cone filter will still have some effect. If the stale air from behind the bumper does nothing, why bother having it there in the first place. It may not be as good as a great hole cut into the bumper for the air to enter from but at least it can suck some cooler air from the pipe than from what is in the engine bay. From looking into the engine bay it is not easy to route a caf from the bumper due to the battery being in the way.
It will have nil effect.
You obviously didn't read or understand my post.
The cone will suck air from wherever there is the least resistance I.E. from the area surrounding it (hot engine bay air).
The OE cold air feed leads through some quite tight angled bends down into, as said before, stale air.
The open cone will not suck or benefit from this feed. Try it, get a large tube and put your mouth about 2 inches away from it, put your hand at the other end then suck up. Can you feel any suction? I think not.

However if you put the tube to your lips and suck then you will get suction through it, as you have made a sealed system, just as the OE feed would if it was still connected and sealed within the airbox with the pistons creating the suction force instead of your mouth.

Now do you understand?
 

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kev25v6 said:
with no air box, just a pipe onto the o/e caf leading upto the cone filter will still have some effect. If the stale air from behind the bumper does nothing, why bother having it there in the first place. It may not be as good as a great hole cut into the bumper for the air to enter from but at least it can suck some cooler air from the pipe than from what is in the engine bay. From looking into the engine bay it is not easy to route a caf from the bumper due to the battery being in the way.
to reduce noise, thats why it goes into a big resonator box to stop the induction roar you are trying to create.

you need cold air from as close to the ground as you can get away with, covering the shortest distance to the filter as far away from a heat source as you can manage.

it will sound nice bolted onto the end of the TB but you WILL LOSE POWER
 

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Discussion Starter · #18 ·
I heard something about wave ram air effect that will not works if if fit the cone air filter directly on the throttle body. They talk about a minimu of 6 inches between the filter and the throtlle.

What do you think about that ?

http://www.mgf.ultimatemg.com/group2/air_filters/ramair.htm

Engines are reciprocal air pumps. Air tends to enter the engine in pulses- at both high and low pressures concomitant with the induction, compression, ignition and exhaust cycles of the engine. Thus, like a musical air instrument, the inlet path can be tuned. Instead of tuning for musical pitch, the inlet tract can be tuned to actively encourage air movement into the engine.
Some air filters have been fitted directly to the throttle body on the MGF. This is bad for the harmonics of the air intake- not only does it make the system louder, it also detrimental to power output. More developed systems have a spacer tube between the throttle body and the filter- which makes the installation more refined, but is beneficial to power outputs at particular engine speeds.The trick involves ensuring that the low pressure pulse in the inlet tract coincides with the intake cycle of the four stroke engine, thus encouraging more air to enter the engine by effectively sucking it in. The length of the tube determines which engine speeds benefit most- approximately 6 inches has been found to benefit the top end power production of the 1.8 K series most.
Some manufacturers have developed variable induction length manifolds- to benefit not only high output at high speeds (short inlet tract) but also low end torque (pulling power) at low engine speeds (long inlet tract). Sadly, MG/ Rover have yet to adopt this technology.



Thanks for your answer

Karistep
 
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