Where is this please, i assume it's around the bumper area somewhere presumably lurking behind one of the presumably removeable black inserts. If it is, are the inserts easy to get out as I want to know how to do so before the cold weatherr arrives.

Isn't it the big open bit below the number plate?

On mine there are NO removeable bits!

Correct - that's where the intercooler is. But why would you want to cover it up as it's not like the radiator with water in. The intercooler only "cools" the air (no water) going into the cylinders and has nothing to do with cooling the engine like a radiator does. In fact, I assume that by restricting the cool air, you will get a slight power loss. Turbocharged cars always perform better in cold weather because as the air is cooler and denser which = more power. I stand to be corrected on this, so perhaps one of the "performance" members would care to comment

Well my Yeti was performing very well yesterday in the cool wet weather......

Correct - that's where the intercooler is. But why would you want to cover it up as it's not like the radiator with water in. The intercooler only "cools" the air (no water) going into the cylinders and has nothing to do with cooling the engine like a radiator does. In fact, I assume that by restricting the cool air, you will get a slight power loss. Turbocharged cars always perform better in cold weather because as the air is cooler and denser which = more power. I stand to be corrected on this, so perhaps one of the "performance" members would care to comment

You're right, that's what the intercooler is for. Blocking it off in cold weather would be a senseless exercise and more than likely do more harm than good. I'm man enough to admit if I'm wrong but that has always been my understanding 'denser the better'!

Perhaps Octman could explain exactly what he is trying to do?

It's a diesel not petrol, and the incoming air should not be overcoolled. The inlet trunking to the manifold should be very slightly warm to the touch, and in winter the intercooller is not really needed.

Hmmm.. I can understand owners wishing to personalise their cars but I have to admit I struggle when owners attempt to alter the functionality of a fundamental piece of equipment that the manufacturer has produced. I thought all manufacturers these days tested their cars everywhere from the Nevada desert to Siberian wastelands to cover every eventuality, isn't that good enough in good old blighty? If someone wants to remap or run a panel filter to extract more power or economy I get that - you want to make the car perform better in a tangible way, but blanking intercoolers and such like because the weather too hot/too cold, sorry I just don't get that!

If it's good enough for VAG engineers it's good enough for me. Now, how is Shark and that CR170 remap via OBD coming along

Edited 19 July, 201213 yr by GJay

Hmmm.. I can understand owners wishing to personalise their cars but I have to admit I struggle when owners attempt to alter the functionality of a fundamental piece of equipment that the manufacturer has produced. I thought all manufacturers these days tested their cars everywhere from the Nevada desert to Siberian wastelands to cover every eventuality, isn't that good enough in good old blighty? If someone wants to remap or run a panel filter to extract more power or economy I get that - you want to make the car perform better in a tangible way, but blanking intercoolers and such like because the weather too hot/too cold, sorry I just don't get that!

If it's good enough for VAG engineers it's good enough for me. Now, how is Shark and that CR170 remap via OBD coming along

Agree 100% - why does the intercooler function differ from petrol to diesel? My advise - leave well alone - period!

I'm kind of seeing the argument here. The need for denser air in a petrol is because a petrol engine runs most effectively at stoichiometry, which is approximately 14:1 air to fuel ratio. To get more power you can add more air, which means you can add more fuel which means you get more power from more energy released.

With a diesel though, they don't run stoichiometrically. They run with a massive excess of air, with power being controlled by how much fuel you inject. Therefore having 'more' air is largely redundant because you already have an excess of air anyway. You will get a small improvement from thermal expansion of the denser air, but this is likely to be minimal. I suppose extra air would also have a dilution effect on emissions and a cooler combustion would help keep NOx down (at the expense of increased particulates).

I'd guess most effects will be marginal.

Thinking about it more, air that is too cold in the intake will reduce the atomisation of the injected fuel (by increasing the fuel's viscosity) potentially reducing power and increasing smoke. In a high pressure CR engine this is probably not a issue in reality though.

Too many posts by people that know nothing about engineering and are using information that is googled.

I'm kind of seeing the argument here. The need for denser air in a petrol is because a petrol engine runs most effectively at stoichiometry, which is approximately 14:1 air to fuel ratio. To get more power you can add more air, which means you can add more fuel which means you get more power from more energy released.

With a diesel though, they don't run stoichiometrically. They run with a massive excess of air, with power being controlled by how much fuel you inject. Therefore having 'more' air is largely redundant because you already have an excess of air anyway. You will get a small improvement from thermal expansion of the denser air, but this is likely to be minimal. I suppose extra air would also have a dilution effect on emissions and a cooler combustion would help keep NOx down (at the expense of increased particulates).

I'd guess most effects will be marginal.

So would one have to ask why they bother fitting intercoolers and turbos to diesels? Not being funny, just that it seems from your very detailed explanation that more air isn't needed. Just interested :think:

It's all kind of irrelevant anyhow. You can't block air to the interocooler as it sits in between the air con condenser and the water radiator. To block one would block them all.

Too many posts by people that know nothing about engineering and are using information that is googled.

Enlighten us...

Agree 100% - why does the intercooler function differ from petrol to diesel? My advise - leave well alone - period!

The function of an intercooler is to reduce the air temp, so I'm not sure it matters what fuel is at the end of the process.

I'm kind of seeing the argument here. The need for denser air in a petrol is because a petrol engine runs most effectively at stoichiometry, which is approximately 14:1 air to fuel ratio. To get more power you can add more air, which means you can add more fuel which means you get more power from more energy released.

With a diesel though, they don't run stoichiometrically. They run with a massive excess of air, with power being controlled by how much fuel you inject. Therefore having 'more' air is largely redundant because you already have an excess of air anyway. You will get a small improvement from thermal expansion of the denser air, but this is likely to be minimal. I suppose extra air would also have a dilution effect on emissions and a cooler combustion would help keep NOx down (at the expense of increased particulates).

I'd guess most effects will be marginal.

I'm not sure you are right.

Thinking about it more, air that is too cold in the intake will reduce the atomisation of the injected fuel (by increasing the fuel's viscosity) potentially reducing power and increasing smoke. In a high pressure CR engine this is probably not a issue in reality though.

Will it ever be that cold? Even when external temperature is below freezing, like last winter, it doesn't stop atomisation of diesel.

So would one have to ask why they bother fitting intercoolers and turbos to diesels? Not being funny, just that it seems from your very detailed explanation that more air isn't needed. Just interested :think:

Intercoolers are fitted because air that is cooled appears to "hold" more 02 molecules, so ignition of either fuel is improved. I can't explain scientifically why, but I know that when temps are at a certain range and when it is slightly damp my Yeti, and all my previous turbo diesels, seemed to have better performance and fuel consumption.

I'm sure that if you Google "why intercool a diesel" there will be lots of answers. Some cr@p, some better.

The physics is simple density. Colder air is denser than warm air. Denser mean more molecules per unit of volume. Since air is 22-odd percent oxygen, then colder air contains more oxygen per unit volume than warm air. Engines are volumetric devices so this is a positive thing.

The chemistry bit comes next. The power if an engine comes from the force exerted by a rapidly expanding reaction between hydrocarbon (fuel) and oxygen. In this reaction, known as combustion, liquid fuel reacts with gaseous oxygen to create gaseous water and CO2 plus a whole heap of heat. This increases the pressure in the combustion chamber, which pushes the piston down, which goes on to turn the wheels.

The fundamental difference between petrol and diesel is what I said. Petrol engines run at a fixed air/fuel ratio (with some variance) and to increase engine power you simply add more air (open the throttle) which means more fuel needs to be added (to maintain the stoichiometric ratio) so you get a bigger bang and more power.

With a diesel there is no throttle. The engine is running on full air all the time. To adjust power you simply add or remove more fuel to this air for a bigger or smaller bang.

These are the fundamentals of it. Thinking fundamentally, there is more reasons why a petrol engine will benefit from a cooled air charge than a diesel. That's not to say a diesel won't benefit, but I can see why a diesel

might not want over-cooled air. However I don't think that there is any need to restrict cooling to the intercooler as the effect will likely be neglible.

Where is this please, i assume it's around the bumper area somewhere presumably lurking behind one of the presumably removeable black inserts. If it is, are the inserts easy to get out as I want to know how to do so before the cold weatherr arrives.

Why do you want to know? Is it because of the risk of water ingestion, or dirt, or something else?

Certainly a lot of cars have low air intakes, presumeably in an effort to get cooler air, but the risk of major trouble can be high though in some circumstances.

I thought it would create a bit of a discussion. I raised the question as I did restrict the intercooller inlet in my Fabia Tdi in the winter. Easily done by removing the off side black panel surrounding the fog light. Afriend of mine who lives in France was a professional diesel engineer, he has a Golf GTD and he reckons you should stop the intercooler working in the winter, and has even fabricated a moveable engine air intake so that the engine air can be taken from the rear of the engine when it gets really cold.

Diesel fuel needs the hot, compressed air to ignite, so why cool it down in winter to a point where it is too cool? The compression by the turbo warms the air up but hardly enough to need to cool it down again especially if a lot of the plumbing is exposed to the blast of cold winter air coming through the radiator and other vents in the front of the car.

But having said all of that, if I can't get to the air intake on the Yeti the problem doesn't arise.

Case closed.....!

Check out the Superskoda "Winter protective grill covers."

I've thought about fitting them myself when they throw grit and salt all over the roads in the cold weather.

Better performance on cold damp days a combustion byproduct is producer gas which also burns with a bang thus giving a bit more ummmmpphhhhhhh!

Not as obvious when there is plenty of damp stuff about!

Better performance on cold damp days a combustion byproduct is producer gas which also burns with a bang thus giving a bit more ummmmpphhhhhhh!

Not as obvious when there is plenty of damp stuff about!

I noticed it the other day. Car was positively flying :lol:

Interesting coming home from work this morning at 0530.

Temperature was around 6 degrees with a light mist, and the car seemed really "oomphie". Pick-up was brisk, and the fuel consumption improved, and I wasn't hanging about; I wanted my bed!!

Thinking about it, with the extra H2O in the atmosphere, plus the coolness of the air increased the amount of O2 available.

Exactement!!!