performance air induction filters v fuel economy

Barr

I have recently installed a K&N high-flow air filter to replace the standard one that came with my car.
The performance has improved slightly , not a huge amout tho.
But one thing I have noticed is my fuel economy is after disimproving from when I first bought the car bout six months ago.Year is 1997 by the way.
I was getting bout 100 km fo €10 now it seems to work out at 80km for €10.
I know petrol prices have gone up recently and this may partly be to blame :mad:
But could an induction filter really make fuel economy worse , or may there be some other related culprit at work?

JohnCleary

Yup its your K&N thats doing the damage. Chances are that the induction filter is soaking in hot air (heatsoak), and infact is not improving your performance at all, you just think it is because of the louder noise.

Its a known fact that induction kits decrease your MPG

IrishRover

What JohnCleary says is often the case. It may be less fuel efficient until the engine warms up though.

However, a tenner @95cents used to get 10.53 litres.
Last time I looked it was about 108 cents.
So now 10 euro only gets 9.26 litres.
If you can get 100km on 10.53 litres, you'll only do 88km on what a tenner buys you at the increased price.

So buy by the litre, not the euro.

fletch

I put a K&N in my car and actually noticed my fuel economy improving....can't say I noticed a huge difference in performance though.
Did your's come with a heat shielded pipe you run to the front air intake?

Barr

fletch wrote:

I put a K&N in my car and actually noticed my fuel economy improving..

It did actually say on the box that fuel economy would improve , something to do with more cold air getting into engine, resulting in increased "combustion efficiency" But from my experience I find it hard to believe.
There is no pipe running to the front air intake , its just like a conical shaped filter which I attached the air flow meter.
I think it is workin as it should tho , as when i rev the engine i can feel it workin and suckin in air.

Barr

JohnCleary wrote:

Yup its your K&N thats doing the damage. Chances are that the induction filter is soaking in hot air (heatsoak), and infact is not improving your performance at all

Is there a way of counteracting this ? , thought it was to induct cold air not to soak hot air ,

fletch

Think maybe I'm improvin fuel consumption cause I'm not as throttle happy cause I actually find the noise quite embarassin so I find myself upshiftin earlier and not applyin full throttle

stratos

You didn't say if your car was fuel injected or carb. In a carb car the kand n filter will cause more air to enter the engine, this will cause more fuel to be sucked into the engine too, Giving higher performance and more fuel consumption. It may also weaken the mixture causing some rough running. The other problem is if you improve flow into the engine your next blockage is the exhaust. Usually induction systems should be installed with larger exhaust and new jets.
I am not sure the affects on an injection system, I presume to some extent the ecu should adapt to the more dense air flow and compensate.

IrishRover

Barr wrote:

Is there a way of counteracting this ? , thought it was to induct cold air not to soak hot air ,

You mount it at the front of the engine bay, as far away from the engine as possible. Enclose it if possible and run a cold air feed to it.

JohnCleary

Barr wrote:

Is there a way of counteracting this ? , thought it was to induct cold air not to soak hot air ,

Do it Irish style... Get a big piece of tinfoil and stick it between your cone and the engine block. Then get a piece of 50-70mm flexi-pipe and get it to direct cold air from the front of the car to the cone

unkel

stratos wrote:

You didn't say if your car was fuel injected or carb

Surely all '97 and newer cars would be injection?

fletch wrote:

Think maybe I'm improvin fuel consumption cause I'm not as throttle happy cause I actually find the noise quite embarassin so I find myself upshiftin earlier and not applyin full throttle

LOL

greglo23

legally all cars in Ireland have to be fuel injected from 94 on. basically your problem is the increase in fuel prices and the fact you give it more shoe because of the nice induction sound you're getting !! fill the tank to the brim and drive 300 miles. brim it again and divide the litres by 4.54 to get gallons, divide the miles by the resulting figure and you've got you're mpg !!

Seth Brundle

re - soaking in hot air - this will only really happen whilst in slow moving traffic. On the open road the induction kit will be taking in air which is cold. You can make a heatshield but as I said this will only be of use in rush hour traffic where your mpg will be crap anyway.

Ernie Ball

A heatshield is a double-edged sword in this case: it'll keep intake from getting hot, but once the intake is hot, it'll keep it from cooling off as fast.