Impreza WRX STi intercooler "booster"?

[Egg Nog]

Here's a direct quote from an article in the Vancouver Sun newspaper that reviewed the new WRX STi:

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"The intercooler is larger than that on the WRX and, during hard acceleration, the driver can spray cool water on to it via a dash-mounted button, giving the car an instant 30 per cent power boost"
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Has anyone else heard of this? It's a neat idea, and kinda mimics the whole racer-boy nitrous oxide button. So now comes the question in my mind, is the claimed 30% true, does that mean that without this water spray the real output is 225hp? Or does it mean that with the spray it puts out 390? It sounds mighty unrealistic to me...

[crisis]

I have heard of this before. The quoted power increase seems optimistic but it would be related to the size of the intercooler and the amount of boost. All it does is enhance the amount of cooling applied to the incoming air. The cooler the air the more dense etc etc. So you can wind the boost up higher because you can cool the air more effectively.With a huge intercooler, lots of boost and heaps of water who knows the upper limit of added power.

[motormaniac]

Originally posted by Egg Nog
Here's a direct quote from an article in the Vancouver Sun newspaper that reviewed the new WRX STi:

-------------
"The intercooler is larger than that on the WRX and, during hard acceleration, the driver can spray cool water on to it via a dash-mounted button, giving the car an instant 30 per cent power boost"
-------------

Has anyone else heard of this? It's a neat idea, and kinda mimics the whole racer-boy nitrous oxide button. So now comes the question in my mind, is the claimed 30% true, does that mean that without this water spray the real output is 225hp? Or does it mean that with the spray it puts out 390? It sounds mighty unrealistic to me...

that's damn cool

[guyt_x]

A year or ago I read an article where in the UK the had a track day inviting what they thought where the 11 fastest Subaru's.

They had a broad selection from foresters to 22b's to a limited addition STi VI type R which with a few mods and a water spray
got from 0 to 60 mph in 3.7 seconds !!!
They did mention that it took a deft touch between gear changes by the driver.

So my personal opinon is that std the new WRX STi should put the quoted hp and depending on the drivers personal skill will depend on the extra hp benefits the water spray can give.

I just like to add subaru's rule and just get the job done better than any other car out there.

[Kudosdude]

For all those that don't know the whys and wherefores here goes;

Air is compressed by Turbocharger which is run from exhaust gases;
Exhaust is very hot; therefore intake air that is compressed by turbo heats up (also the simple act of compression raises temperature slightly).

Now you ideally want the intake air to be cold because colder air is denser (therefore you can squeeze more air into the cylinder and burn more fuel).

A pipe takes the now hot air (compressed by the turbo), to the intercooler, which attempts to cool the air.

This air is now fed to the engine.

Now, running high levels of boost can heat up the air so much that the intercooler can't really cope (by this I mean it cannot reduce the amount of heat in the air by a high enough percentage). This means that the air is still quite hot as it enters the engine (cylinders). It is not as dense and therefore less power is produced as a result. (remember we wanted the air to be as cool as we could get it).

Adding a water spray makes the intercooler MUCH more efficient, therefore cooling the air down more. The air then becomes denser and power increases again.

The only time water spray would reduce the power by as much as stated it is if the air got VERY hot and the intercooler wasn't really big enough. This can occur when boost settings are turned up for a considerable time period.

Do not get intercooler spray mixed up with water injection which is totally different, and also used on many turbocharged cars

[guyt_x]

we are talking about the incar button you can use to minipulate the intercooler spray

but thanks for the info

[Wouter Melissen]

That spray is fitted on my friend's EVO 6 as well. It makes a small but noticable difference.

[Kudosdude]

we are talking about the incar button you can use to minipulate the intercooler spray

Sorry, what do you mean? The user has the option of spraying the water, hence the button; but to be honest it would be better to rig up a heat sensor and do it automatically . . . but then no-one would notice. Buttons are great at showing off features.

[guyt_x]

the point is it is controllable, when driving around you dont want it going off. only when you want to push the car.
hence the button.

[Kudosdude]

But guyt_x -

As an analogy you don't go round turning your cars radiator fan on manually when your water temperature gets too hot do you?

The fact is your radiator fan is run off a sensor, just like the water cooling would be.

Water is free, the petrol you are wasting, while you're engine intake air isn't as dense as it could be, is.

[guyt_x]

the reason of the button like I stated last time is:
to give the driver more control over there driving experiance.

I still dont understand why people make performance cars that are automatic... eg merc's I mean really if I had to pay a small fortune for a sports car that all you can do is push the loud pedal and turn the wheel.

like with the water spray it gives the driver the ability to drive the car how he wants not just letting a computer have all the fun.
then u might as well take the bus.

sports cars are ment to be driven, they arent suposed to drive you.

[motorhead]

Originally posted by guyt_x
the reason of the button like I stated last time is:
to give the driver more control over there driving experiance.

I still dont understand why people make performance cars that are automatic... eg merc's I mean really if I had to pay a small fortune for a sports car that all you can do is push the loud pedal and turn the wheel.

like with the water spray it gives the driver the ability to drive the car how he wants not just letting a computer have all the fun.
then u might as well take the bus.

sports cars are ment to be driven, they arent suposed to drive you.

good point though but there are bloody stupid lazy people in this world perhaps they should make both types eh - what do you propose

[motormaniac]

gd point

u r supposed to drive a sports car

it's not meant to drive u around

like the sl55 amg

[motorhead]

the sl55 is a up to you kind of car - you can perform it - which is the good thing to do and you can treat it like a s-class - it has all the technological gagets and gizmos of the s-class - its a lazy mans car but its also a car which can make you work very hard

[guyt_x]

make you work hard at keeping its fat ass on the road.