Induction kits

Get a panel filer for original air box

K&N Panel filters

Flow better than any filter

Clean the air better than any filter

Need cleaning regularly

I'd recommend them!

On my last car changed the air filter once in 5 years - cleaned it every 6 months

Two things here!

A) Induction Kits

B) Better filtration

A) can lower power through hot air intake

B) Usually means a little more power but mainly a filter you clean rather than throw away, which is more efficient

I'm wondering about this a bit. Cold air is denser, no error there, but the fuel computer takes air mass into account when adding the petrol via the injectors.

At part throttle, you're holding the pedal in a position that achieves the power necessary to maintain speed. If you have warm air, this means your pedal is slightly further to the floor, but you're using no more fuel than with cold air and a higher pedal. In fact, you'd be drawing in exactly the same mass of air whatever the temperature, and injecting the same mass of fuel per cycle.

The density could mean the mixture is slightly more spread out in the cylinder, so flame front would be slightly slower propagating, however that means, surely, you could run a slightly higher compression ratio and not knock.

At higher engine speeds, my gut feel is the engine will have less air in it and that means less power, but as a long ducting will cause a higher manifold vacuum, I'm not sure this would have a real effect at all, without doing some practical tests.

There must be some reason why this isn't how it works, because modern cars all seem to take their feed from the cooler air next to the radiator, and they've tested this extensively, right?

"part throttle" is the operative phrase in your statement.

At full throttle, the cooler the air, the denser it is, so the more air you can fit in there, so the more fuel can be injected, so the more power you make.

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Why? What are their benefits? You'd listed a few attributes, but it's not clear than they are advantageous.

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Frankly, the kind of kids who drive around at full throttle are exactly the sort that these toys are designed to seperate from their money.

The OEM cold air intake is usually the most restrictive part of the inlet system. Often just punching holes (using a nice neat tank cutter) in the inlet side of the air filter housing will give a performance improvement, even though it results in hot air induction. The higher inlet temp increases the possibility of detonation so higher octane petrol is needed if the car is to run safely at max power with a heat soaked engine and under bonnet space - thrashing from cold not recommended.

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And f**k up the tuned inlet tract.

K&N make decent filters, to be fair. I wouldn't have a problem putting one in, although I wouldn't expect much difference over the paper element, except of course the longer life and option to clean the filter.

If you modify the car, though, the airflow arrangements are almost certainly not up to the increased airflow the modified engine will demand, what with us being in rec.car.mods among other places.

Easiest way to do this is take off the trunking from the MAF upwards and put a conical filter on it. It's unlikely your car manufacturer sells a filter for when you do this, but K&N will.

That's normally post the air filter though :-)

At full throttle less air into the engine = less power

Remove smaller particles - possible engine benefits.

Flow better - more power or more economy

Washable - better for environment

in terms of filtering dirt from intake air, the kn and cheapo foam type filters often work less well than paper element type filters.

unless you have the abilty to make an efficient air box enclosure, with ducted cold air intake, then these silly induction kits are likely to result in loss of power, and other than that only other results will be more noise and increased engine wear!

TBH, I don't regard K&N filters as silly induction kits.

In comparasons I have seen K&N usually win

Here's a typical one.

This chap has done tests with various filters and none at all. The inlet and air box alone without a filter gave close to 80% of the losses he got with the worst filter installed.

You do have to be careful with tuned length inlet tracts. I fitted a pair of S&B filters (cone K&N look a likes but a lot cheaper - don't seem to supply UK car market) to a Honda 250. When fitted directly to the carbs just like every man and his dog had them, it was crap, about

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Yes but they're normally ones published by K&N to some 1970's filtration standard nobody else can remember.