Ford Ka Induction

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he standard Ford Ka induction system is reputed to be rather restrictive, but I personally do not subscribe to this point of view. The standard Ka induction is designed to promote low down torque and low noise levels, which is entirely in keeping with the Endura-E engine’s standard tuning.

In the case of a standard Ka, the air intake sits in front of the radiator and condenser package (part of the air conditioning system), shown below. The intake points down, and leads to the airbox via a bit of black tubing. The airbox itself is a rather large affair (I’m sure it could be drilled for extra noise) with a curved bit of piping to reach the engine.

Indeed, Ford have deliberately engineered the Ka’s induction system to be quiet...

Airbox Temperature

Spooky and I have been having some discussion regarding the induction set up on a standard Ka – specifically, how hot it gets.

As a refresher, engines produce power by burning fuel and oxygen, thus releasing the energy. If you can get more oxygen into the engine, you can burn more fuel, and thus increase the power. Alternatively, if you can get more oxygen in for a given volume of air, you’ll be able to burn more fuel, and increase the power.

If we assume that the induction system can suck in a given quantity of air at a given speed, the only way we can increase the oxygen is by cooling it, or at least, keeping it cool. This is because colder air is more dense, and the denser it is, the more oxygen you’ll get in a given volume.

Unfortunately, the Ka’s airbox sits at the front of the engine bay, and is coloured in matt black, where it can absorb lots of heat from the engine, thus increasing the temperature of ingested air, which in turn makes it less dense, and that in turn means that you’re burning less oxygen, and so producing less power. This is one of the reasons why cars feel more powerful when the engine is cold, on a cool, moist morning. It’s not you, it is happening!

We need to ascertain the temperature of the airbox, and the temperature of the air inside the box of course. It may be that, on the move, there is very little difference in the air temperature, but I would expect that at low speed, or in stationary traffic, the air box temperature would rise. Perhaps painting it dazzling white, or using bacofoil, would help keep the temperature down? I discuss the problem in more detail here.

Other Solutions

Within the Ka Klub, there are a number of different solutions to the problems of a restrictive induction system. The most dramatic to look at is simply cutting a hole in the bonnet of the Ka, just above the air intake.

This offers the shortest possible amount of space between “fresh air” and “air filter” – it’s almost two inches! The owner of this Ka has reported that he has had no difficulties with snow, ice, or water and the intake.

Whilst it might seem a little crude (“just cut a hole in the bonnet, bosh in some mesh, and you’re done!”) it’s certainly effective.

Another solution, and one that is rather more subtle and perhaps even more effective, is FART – Fresh Air Ram Technology, shown here. The owner of this particular Ka, Andy T, comments: “the Viper airfilter got my attention, using vehicle speed to feed cool air directly into the enclosed airfilter and force it into the engine under pressure, without taking in warm air from the engine bay. But I ain’t spending £250 on an air filter, not in this lifetime. Even if claims are made for massive power gains. A Saxo VTS only gets an extra 10 bhp. Don’t know what to expect from a Ka! So for those of us who have a more modest budget to play with, there is an alternative to the Viper. It called Twister, made by Green Filters, and its £70. Its the same as the Viper, just not carbon fibre. It works exactly the same. It’s a fully enclosed filter with a 80mm feed mouth, you connect some ducting to it, and away you go.

Here is a photo of how it is on my Ka. Ignore the colour of the ducting, it’s all I could get in the short time I had to do this. It’ll get replaced later with something more pretty. I’m still experimenting with where the best place to feed air from is, at the moment it’s from behind the grill, but I’m thinking maybe a scoop from behind the lower grill opening might be even better.

As you can see, it’s a tight fit. The air temperature sensor will need relocating properly (those with newer Ka’s need not worry, ‘cos their’s are in a different place anyway). But I’m happy to say it feels like it’s working correctly. I might jump on the dyno to see for definite. It’s quieter than my previous K&N 57i, I do miss the noise from that. But if this feels better and is proven to increase power/response then I’ll be happy.” Note that I can’t be responsible for Andy’s opinions or comments.

Another way to introduce more air into the airbox is to add another cold air feed – as shown here. This particular Ka has an auxiliary cold air feed, fed from the grill and via a black flexible pipe. It’s a relatively simple modification to make, it’s very subtle, and it may even be reasonably effective, too!

This final picture shows the more usual technique of a few cold air pipes pointing towards the cone filter induction kit arrangement. The biggest drawback to this approach is that, inevitably, some warm air from the engine bay will find its way into the air filter. However, when moving forward, this should make up a minute proportion of the ingested air.

If you’re looking for a loud induction note, this is the way simplest forward!

Andy T’s revised FART (picture taken at Fiesta in the Park, May 2003) illustrates how he’s finished off the tubing. This picture shows the induction tubing as it loops under the manifold heat shield – the tubing double backs onto itself and the intake is at the bottom of the lower grill.

There will be no more pictures of FART for a few reasons, like Andy changing engine to the 1·7 litre Zetec-SE from the Puma, heh. But see here for my custom induction article.