Factory Airbox

Is the standard airbox a restriction at standard or moderate power levels? Has anyone tested it properly?

I have a drilled air box and an extra inlet pipe.On my tuned 20vt. I seem to remember my tuner saying I might gain 5 or 10 hp if I change to a cone filter etc.
Others on here should know more about than me though.

There was a time when I used to think that if you sorted out a better flow of induction, this would make good gains. This is not the case. Others on here have tested various options & bottom line is it makes no real difference, just messing around with the air flow.

I seem to recall Flea saying that there was no measurable difference between the factory airbox and a pod filter but I can't remember for what power level.

For a standard or moderately tuned car, I would say that the stock airbox is best. A cone filter only gives poorer low down response.

K&N filter did make a difference on my 20V N/A VIS.

I bought my VIS with a K&N but read an article saying your insurance company should be told as its a modification C.I.S insurance underwriter said they will not insure it with a K&N filter so put original airbox back

The only difference by just putting in a K&N filter in, will be the sound.
Placebo factor may affect things as well.

Hey Makkadiamond,

So are you saying: you could perceive a roll-off in performance, when you reverted to the standard box?

Yes I did perceive more performance but I have a n/a and its a VIS.

I put the K&N back and on as a test it makes a noticeable difference.

A friend of mine tested the engine with original airbox and an Apexi cone filter.

Run 1, 2 and 3 was with original airbox.
4 and 5 with Apexi.

As you can see he gained 13 HP (268 - 255) on the wheels.

Mods: FMIC, GT28R, 2.5" exhaust, FC Performance chip etc.

He had a good result then

Interesting vid:

https://www.youtube.com/watch?v=PAIxeQUSg-Q

And another re: Cold air intake:

https://www.youtube.com/watch?v=gCi2yo4UqPI

Mightycarmods great channel