"performance Air Filters"

[Thunderchild]

I recently changed my air filter, probably a bit later than I should have. I have noticed reduced fuel consumption (the plugs were a little black) and better acceleration. Clearly this is all because I am now drawing in enough air to burn all of the fuel properly. So i wonder, do the so called performance air filters actually make any difference ? is it worth fitting one ? I saw one claiming that it allows twice the air flow - I assume they mean half the pressure drop across the filter for the same air flow bearing in mind that at twice the airflow you have 4 times the pressure drop etc.

Any thoughts ?

[tonyav]

(the plugs were a little black)

They should not be Black, usually a sign of running rich.

[Thunderchild]

Indeed, I expect because I was not getting enough air in to burn all of the fuel forcing a rich mixture. My first car despite having being repaired for a head gasket had not had the air filter changed, it was probably blown out with an air gun, the result was that the can stalled whenever the engine was at low revs as it was starved of air but at higher revs was just managing to drag some air in. I changed the filter and all was fixed.

[tonyav]

So i wonder, do the so called performance air filters actually make any difference ?

I think not, because they are usually drawing in much warmer air than a factory system would.

[tonyav]

Have you tried disconnecting the car battery for around 20 mins / half hour. This will reset the ECU.

[Thunderchild]

Why do you say that, they sit in the same airbox, In winter due to my short journeys I would prefer warm air actually but that is another story.

[Thunderchild]

Well the car is performing very well now with a new stock air filter so I guess the ECU has adjusted itself.

[Thunderchild]

This is an example of what I can buy. But I don't know if the claims are BS or not, I know how to test them but don't have the time or equipment.

[Thunderchild]

Sorry, this is the link:

http://www.ebay.co.uk/itm/Ford-Fiesta-MK6-1-25-1-4-16V-1-6-TDCI-K-N-Air-Filter-/142039968295?_trksid=p2349526.m2548.l4275

[Ryzen]

You will notice little or no difference if you fit a hi flow air filter to a stock engine with a clean air filter.However if you tune the engine it may need more fuel and more air so a non standard filter may be required.

[Thunderchild]

I was considering getting someone to tune it as at pull-away it was bad but now is quite good if you turn the air con off ;)

[tonyav]

Right then, you mean one of these things then.
https://www.knfilters.com/images/l/33-2167.jpg

And not one of these.
https://cdn.mishimoto.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/M/M/MMAF-2756S_1_3.png

And cold air = better performance ( ie better acceleration ).

[Thunderchild]

Yes quite, Yes I know that the air needs to be cold as it will be denser. But I also suspect that unless your having to floor it all the time you are nowhere near running out of "volumetric capacity". In winter I drive 6.5 miles to work, the engine is hardly warm by the time i get there and very inefficient.

[tonyav]

In winter I drive 6.5 miles to work, the engine is hardly warm by the time i get there and very inefficient.

That has nothing to do with the temp of the air being drawn into the fuel system.
Probably a dodgy thermostat.

[Thunderchild]

Well I'm just saying that if it's freezing cold out warmer air will not try to cool the already cold engine as much. I don't know how long it takes for a modern engine to warm up, this is a 7 year old fiesta

[tonyav]

A small engine like that should only take a few miles to warm up.
I'd change the thermostat if I were you, easy to do and not very expensive.

[Thunderchild]

yes, will I suppose it is warm after a couple of miles but you don't get much warm air out of it until about 4 or 5 by which time I am there, do you think it will have broken after 7 years / 35000 miles ? I really don't know why they have not yet been replaced with a solenoid.

[tonyav]

do you think it will have broken after 7 years / 35000 miles ?

Maybe / maybe not, could just be the nature of the thermostat that is fitted at the factory.

[RobNorth]

Generally speaking, these various gadgets offer no advantage over the OEM parts but often carry some penalty, in this case perhaps a shorter life or increased noise - the car manufacturers/OEM suppliers have enormous R&D budgets to ensure the best possible match and performance from properly specified parts, plus reputations to keep - which is the only reason why they urge us to use OEM parts - BMW or Ford are unlikely to go under if we buy replacement filters from elsewhere.....
The warm air in winter comment is interesting but only if you have an A35 or something similar, which could suffer from icing on the carburettor venturi at certain temperatures/flow rates and a lot of cars with simple carbs had two positions for the air cleaner intake, with
one near the exhaust manifold for winter.
But...as Tonyav says, cold air = dense air = more oxygen = more fire

[Thunderchild]

Yes cold air means more dense but if you don't need to floor it and it's damn cold why not allow warmer air ? if your only using 20-30% throttle what is wrong with warmer air that helps the engine warm up quicker even if it means running 40-50% throttle? I generally never have to push all of the way especially now I've changed the filter.

[tonyav]

what is wrong with warmer air that helps the engine warm up quicker even if it means running 40-50% throttle?

As I said before, it is how soon or not your thermostat opens that determines how quickly your engine warms up ( unless it's Artic temperatures outside ).