I ran a k&n in my turbo mondeo and high octane petrol definately feel the difference.
My boxster i have kept the stock filter because i live in a dusty area and the oiling issue with the maf. I have a fvd exhaust and noticed a bit of performance also when i run better gas.

Been messing around with cars since I was 15 so 40 years, in all cases more air in, and more air out equals increased performance! The higher octane too. So I am sure you feel a boost! :D

Thankyou, love Mondeos, been through all the ST's

[QUOTE=Cunningr;604197]I ran a k&n in my turbo mondeo and high octane petrol definately feel the difference.
My boxster i have kept the stock filter because i live in a dusty area and the oiling issue with the maf. I have a fvd exhaust and noticed a bit of performance also when i run better gas.

Been messing around with cars since I was 15 so 40 years, in all cases more air in, and more air out equals increased performance! The higher octane too. So I am sure you feel a boost! :D[/QU

Sorry more air in and more air out does not equal performance gains "in all cases"

[QUOTE=blue62;604209] You can argue that eventually you'll have diminishing returns, but when does more air in and more air out NOT result in increased performance?

[QUOTE=piper6909;604213] well lets look at one possibility: more air in and more air out creates more heat: more heat "possibly" could create ping or pre detonation. Picked up by the knock sensor when read by the ECU the ECU will retard timing to eliminate knock. retarded timing=.loss of power

or lets say you port and polish your intake: In theory increases flow (more air in more air out). but if you eliminate to much of the turbulence (make the runners to smooth).
Fuel particles drop out of the air: you have more air (and fuel) coming in and going out but your fuel air ratio is all messed up and you get a performance loss.

The OP stated that "IN ALL CASES" more air in and more air out increases performance.
I am not trying to start an argument.
I point out that the statement is not true because:

Many young people with limited automotive knowledge get their ideas on how to mod their cars from forums just like this one. They read a thread that says more air in and more air out "in all cases" increases performance.

So They run out and buy something like a high flow air filter for a ridiculous price.
Slap it on the engine and think they have increased performance.
When in most cases they have added intake noise and nothing else.
Except a fouled MAF sensor that causes the engine to run rich equaling a loss in power. and possibly over time a plugged up catalytic converter.

Yes in theory more air (and fuel) in and more air out build power. But it is not that simple. And it is not true "in all cases"

Blue62, I think you're just being purposely contrary.
Which person with "limited automotive knowledge" is going to port and polish an intake, but do it improperly, because they read this forum?

And your whole knock sensor scenario is full of holes as well. Heat is the enemy, but more air in / more air out doesn't generate more heat "in a vacuum". It generates more heat because you're (hopefully) increasing cylinder pressure. That increased cylinder pressure equals more more power. If you're getting detonation, you need better fuel, not less air.

Yes: more air in / more air out DOES equal more power.

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There certainly are alot more contributing factors, I once took my ST mondeo to a rolling with a performance cone filter on and was down on power, rolling road guy told me to put original airbox back on with a decent filter which I actually still had in the boot of my car, I put it on and went back on the rolling road and performance went up. So yes a performance filter can have the opposite effect.

One key factor with the more air statement is "cold air"

I watch alot and I mean a lot of American mod programs and I cringe every time I see a beautifully modified car with a cone filter added into the engine bay sucking in lots of hot air

You're right, but it's the same thing. Cold air is more dense than hot air, and that's why it matters. If you've got a liter of hot air, it has less oxygen than a liter of cold air. Less oxygen = lower cylinder pressure.

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Sounds good M9G....Mine will arrive in a couple days and I will drive it awhile then do some easy mods to start with.

Good point but the engine ecu needs to be tuned in for the mods in many cases, plus if you have more air flowing in and did nothing to the exhaust to get the air out more efficiently.

There certainly is more to it than throwing on air filters and loose exhaust but more air in more air out is the basis of developing more power. Idea is to increase combustion and evacuate gases more efficiently. Hot rodding 101!

I gotta say I am in the skeptical camp here until I see some before and after dyno data. I have been looking at these mods since 2005 and the desnork/hi flow cone filter typically return about 1hp measured. Not enough to feel with the "butt dyno" and likely below the margin of error with a typical Mustang dyno.

Where the placebo effect comes in is by altering the intake and exhaust the car is significantly louder and "seems" a lot faster. Put it on the dyno to test it objectively... bupkis.

Subjective sensation: Louder feels a LOT faster. :D
Objective before and after dyno test: 1hp maybe :o

I believe in keeping an open mind so if you want to support a subjective "butt dyno" sensation of power, get her on a real dyno and look at the objective data.