iv had my furby vrs for 3 months and lately since the weather has got hotter my car seems a bit slower. i dont know if its me gettin used to the power or the heat is killing my performance? is it to do with cold air bein more dense?? :confused:

Yes you do get used to it and yes warm air is less dense meaning with the poor design of the intercooler and it's location, you will get a noticable heatsoak effect in the warmer weather.

Solutions to this are getting an FMIC, Water spray kit or doing the Pikey Mod

Check this out;

http://www.briskoda.net/forums/fabia/pikey-mod-no-2-intercooler-has-airflow/47646/

Yep, as per Decron.

Heatsoak is particularly noticeable on PD130 engines, where all the intercoolers are in concealed locations, and quite small in size. :(

Expect reduced performance, expecially after sustained thrashing, more smoke, worse fuel economy etc. Its even worse on remapped cars. :(

oh right, that explains why the performance its naff and it smokes a bit more. i will have to invent some kind of vacum from the intercooler taking all the hot air out of the engine bay. thanks for your help.

It happens to all cars though to a degree, regardless of IC location and size.

The IC can only do so much. 2 cars both with FMIC's but with differing intake temps will perform differently, the cooler air temp one performing better.

Warm air is, as above, less dense and thus there is less of it going into the cylinders. With there being less air going in, there's less fuel being injected too (the air to fuel ratio has to remain pretty constant) on MAF equipped engines (as they know the incoming air mass/ temp) and this results in less power.

It shouldn't smoke more as the ECU should reduce the injector pulse width to reduce the amount of fuel injected based upon its MAF readings. This wasn't so on old diesels where they had no idea how hot/ dense the air was and just injected the same amount regardless.

EDIT: By the way, I'm talking about volumetric efficiency here, not heat soak.

Density has a lot to do with it.

Running the aircon makes it worse still, the IC being bathed in warm air from the aircon rad while it is on. I am looking at ways to partition off the IC and feed it with cooler air.

Chris

anyone tried a chargecooler? I used to have one of these for my old fiat uno turbo, it had its own little radiator to cool its own water, and used the water to cool the chargecooler... should keep it cold no matter what its doing outside......

note: I reccon my furby lost a good 10-20 hp when it got to 30 celcius outside!

remember the AutoCar 0-60 of 7.2 seconds? done with an outside temp of freezing!!

I am looking at ways to partition off the IC and feed it with cooler air.

Feeding the i/c cooler air won't be particularly effective. The i/c is acting as a heatsink, like the fins on the back of an amplifier. The aluminium absorbs heat quickly from the turbocharged intake air, and releases it slowly to the atmosphere. The aluminium is acting as a temporary heat store, and the more aluminium there is, the more heat it can absorb. The flow of cooling air over the aluminium dissipates the heat only slowly (even if aided with a water spray) compared to the rate at which the i/c heats up. The only solution is more aluminium, not more air. (Isn't that right, Mr. Forge?)

Whilst the Fabia may be down on power due to heat soak, I find my Octy much

better on fuel economy as the ambient temp increases

decron with the mod you did does it get any problems with mud blocking it or road debris damage?

Feeding the i/c cooler air won't be particularly effective. The i/c is acting as a heatsink, like the fins on the back of an amplifier. The aluminium absorbs heat quickly from the turbocharged intake air, and releases it slowly to the atmosphere. The aluminium is acting as a temporary heat store, and the more aluminium there is, the more heat it can absorb. The flow of cooling air over the aluminium dissipates the heat only slowly (even if aided with a water spray) compared to the rate at which the i/c heats up. The only solution is more aluminium, not more air. (Isn't that right, Mr. Forge?)

Well it is sort of an idea, but in principle, the IC will get to equilibrium (a temperature at which it will stay give or take a few degrees) after a short while. A bigger lump of aluminium will take a few more minutes to get to equilibrium. If what you say above were correct, then the IC (or amplifier) would continue to heat up until it melted.

Hot air from boost travels through the IC and the heat from the air is absorbed by the aluminium. From cold, the aluminium will absorb heat and its temperature will rise. As its temperature rises, it will absorb less heat from the boosted air and dissipate more heat to the airflow over the exterior of the IC. At some stage, not long into warm up, the rate at which the IC absorbs and dissipates heat will reach a stage where it is the same. The temperature will then be relatively stable.

The secret to why this happens is thermal gradient. When the IC is stone cold, the temperature difference between it and the boosted air is large, so it will pull lots of heat from the boosted air. At the same time, the aluminium is cold, so the amount of energy it transmits to the cooling air is minimal. As it heats up to equilibrium, it gets to a point where the heat input (from the boosted air) falls and heat output (to the cooling air) rises until the temperature stays constant.

The system is however not dealing with temperature, but with energy. A larger IC will be able to transmit more heat to the passing air than a smaller one, as well as being able to absorb more heat from the boosted air. This is because it has a larger surface area for the heat to transfer across. Paradoxically, because the IC does not get as hot, its efficiency per unit area is actually reduced, but not by as much as its area improves things, so you get lower intake temperatures.

If the stock IC is running hot, the only way to improve it will be to improve the thermal gradient on the cooling side. If the air on the cooling side can be dropped by a useful temperature, the IC will work more efficiently. The differences may not be huge, but it must help to shroud off heat from the radiator and AC pump and double or treble the flow of ambient air over the IC.

Big ICs also suffer from increasing inlet volume so increasing lag.

Chris

Well it is sort of an idea, but in principle, the IC will get to equilibrium (a temperature at which it will stay give or take a few degrees) after a short while. A bigger lump of aluminium will take a few more minutes to get to equilibrium. If what you say above were correct, then the IC (or amplifier) would continue to heat up until it melted.

Hot air from boost travels through the IC and the heat from the air is absorbed by the aluminium. From cold, the aluminium will absorb heat and its temperature will rise. As its temperature rises, it will absorb less heat from the boosted air and dissipate more heat to the airflow over the exterior of the IC. At some stage, not long into warm up, the rate at which the IC absorbs and dissipates heat will reach a stage where it is the same. The temperature will then be relatively stable.

The secret to why this happens is thermal gradient. When the IC is stone cold, the temperature difference between it and the boosted air is large, so it will pull lots of heat from the boosted air. At the same time, the aluminium is cold, so the amount of energy it transmits to the cooling air is minimal. As it heats up to equilibrium, it gets to a point where the heat input (from the boosted air) falls and heat output (to the cooling air) rises until the temperature stays constant.

The system is however not dealing with temperature, but with energy. A larger IC will be able to transmit more heat to the passing air than a smaller one, as well as being able to absorb more heat from the boosted air. This is because it has a larger surface area for the heat to transfer across. Paradoxically, because the IC does not get as hot, its efficiency per unit area is actually reduced, but not by as much as its area improves things, so you get lower intake temperatures.

If the stock IC is running hot, the only way to improve it will be to improve the thermal gradient on the cooling side. If the air on the cooling side can be dropped by a useful temperature, the IC will work more efficiently. The differences may not be huge, but it must help to shroud off heat from the radiator and AC pump and double or treble the flow of ambient air over the IC.

Big ICs also suffer from increasing inlet volume so increasing lag.

Chris

Yeah, what he said...

decron with the mod you did does it get any problems with mud blocking it or road debris damage?

No, none at all in 50k

The vent has discoloured a bit but thats it.

Well it is sort of an idea, but in principle, the IC will get to equilibrium (a temperature at which it will stay give or take a few degrees) after a short while. A bigger lump of aluminium will take a few more minutes to get to equilibrium. If what you say above were correct, then the IC (or amplifier) would continue to heat up until it melted.

...

The system is however not dealing with temperature, but with energy. A larger IC will be able to transmit more heat to the passing air than a smaller one, as well as being able to absorb more heat from the boosted air. This is because it has a larger surface area for the heat to transfer across. Paradoxically, because the IC does not get as hot, its efficiency per unit area is actually reduced, but not by as much as its area improves things, so you get lower intake temperatures.

I was assuming the i/c was already at equilibrium, and describing what happens when a pulse of hot air from an acceleration event goes through it. At that point, the extra energy is absorbed by the metal first, then dissipated to the atmosphere over a period of time. A larger mass of metal is better able to smooth out this peak than a small mass.

Well it is sort of an idea, but in principle, the IC will get to equilibrium (a temperature at which it will stay give or take a few degrees) after a short while. A bigger lump of aluminium will take a few more minutes to get to equilibrium. If what you say above were correct, then the IC (or amplifier) would continue to heat up until it melted.

Hot air from boost travels through the IC and the heat from the air is absorbed by the aluminium. From cold, the aluminium will absorb heat and its temperature will rise. As its temperature rises, it will absorb less heat from the boosted air and dissipate more heat to the airflow over the exterior of the IC. At some stage, not long into warm up, the rate at which the IC absorbs and dissipates heat will reach a stage where it is the same. The temperature will then be relatively stable.

The secret to why this happens is thermal gradient. When the IC is stone cold, the temperature difference between it and the boosted air is large, so it will pull lots of heat from the boosted air. At the same time, the aluminium is cold, so the amount of energy it transmits to the cooling air is minimal. As it heats up to equilibrium, it gets to a point where the heat input (from the boosted air) falls and heat output (to the cooling air) rises until the temperature stays constant.

The system is however not dealing with temperature, but with energy. A larger IC will be able to transmit more heat to the passing air than a smaller one, as well as being able to absorb more heat from the boosted air. This is because it has a larger surface area for the heat to transfer across. Paradoxically, because the IC does not get as hot, its efficiency per unit area is actually reduced, but not by as much as its area improves things, so you get lower intake temperatures.

If the stock IC is running hot, the only way to improve it will be to improve the thermal gradient on the cooling side. If the air on the cooling side can be dropped by a useful temperature, the IC will work more efficiently. The differences may not be huge, but it must help to shroud off heat from the radiator and AC pump and double or treble the flow of ambient air over the IC.

Big ICs also suffer from increasing inlet volume so increasing lag.

Chris

Hot damn what an answer!

Drive you car in Dubai at 12-1 PM, it'll be useless, my car is 1-2 secs faster to 100 in cold/winter days in dubai !!!!

Was reading a copy of fast ford over christmas (sorry!) and they were doing a comparison of different air intakes to the engine of a 2.0L Duratec engines in the Fiesta ST and I think they stated that for every 1 deg C decrease you could obtain in air intake temp, the powetr would increase by approx. 1hp.

The air intake of the Fiesta is so poorly designed that a good induction kit can produce gains of 12-15hp... not sure if this was bad design or to limit the power tho.

A good cold air induction kit should increase power by providing a colder air flow to the engine, thus increasing power however on v. hot days the power will obviously be lower no matter what engine or set up your running.

That's why you have to isolate the induction kit from the heat of the engine bay, usually through the use of a carbon fibre box or something similar. Just sucking in ambient engine bay air would more than likely reduce power.

Just piping a tube to the front of it that feeds cold air is not enough.

Edit: Like this: Davef induction kits

yesbit really does - less fun in summer here 42-45 deg C. No heatsoak tho thanks to the FMIC

That's why you have to isolate the induction kit from the heat of the engine bay, usually through the use of a carbon fibre box or something similar. Just sucking in ambient engine bay air would more than likely reduce power.

Just piping a tube to the front of it that feeds cold air is not enough.

Edit: Like this: Davef induction kits

This is why fitting an induction kit to the VRS is not as good as people think. The stadard airbox and PD160 pipe offer one of the most efficient forms of induction you will need. The air comes straight in off the front!

This is the thing....'most' air OEM air boxes provide more than enough volume for an engines requirements. The only restriction on the Fabia is the initial intake pipe which everyone replaces with the PD160 pipe as you say. On the BMW's it was the same......if you're gonna do anything, just get a panel filter and save yourself some wasted cash.

This is however until you start really fiddling with things. High lift cams, ported and polished intakes, throttle bodies, free flowing exhausts.....all can potentially increase an engines need for air over what the standard airbox can provide, and so only at this point does an induction kit become necessary. That is unless the standard one is as rubbish as people say the Fiesta ST's is.

Don't forget reducing air intake temps helps preserve the engine life too. It's not just a performance mod. Also having a nice short FMIC to intake manifold section helps keep the cooler air. Mine takes a unique path through the engine bay to minimise the distance the air travels. The IC is also 95% vented to oncoming air to keep the metal nice and cool.

So reading about this Pikey mod -thing and now wondering what the TT liner actually is (or the Ibiza liner). Is the whole wheel arch liner or just a smaller thing that you install to wheel arch behind the intercooler. Yes, I'm stupid... :eek:

SORRY GUYS! After posting this, I found the Pikey mod thread with all answers I was looking... So thanks anyway...

was idly thinking of covering PD160 intake with reflective insulation to see if that makes any difference. Suppose it could be done proper with logged air intake temps before and after but cant be bothered....