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Info: Intercooler
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Old 14 Jul 2006, 10:42 AM   #1 (permalink)
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Info: Intercooler

Intercooler

An intercooler is a heat exchanger. That means there are two or more fluids or gasís that don't physically touch each other but a transfer heat or energy takes place between them.

How does an intercooler work?

Air flows in through the air intake/filter and then through tubes inside the intercooler. The air transfers heat to the tubes, warming the tubes and cooling the air. Outside air (or water) passes over the tubes and between fins that are attached to the tubes. Heat is transferred from the hot tubes and fins to the cool outside air. This heats the outside air while cooling the tubes.


Positioning the intercooler

There are two main locations an intercooler is normally fixed, on the top of an engine, aka top mount, or in the lower front bumper, aka front mount.

Top mount

The top mount is the standard location used on an Impreza,






The top mount allows short lengths of pipe work to be used between the cooler and the manifold preventing heat from transferring back to the air, this also however has disadvantages. Being sat right on top of the engine means that itís in probably the hottest part of the car and this reduces efficiency.



Front mount

To move the intercooler away from the heat of the engine bay it is often moved to the lower front bumper, directly in the airflow as the car moves.






Although a front mounted intercooler will be much more effective than a top mount, it does have disadvantages. The main one is increasing turbo lag (the time it takes the turbo to gain pressure). Due to the larger volume of the front mount it takes longer for the air to fill and then start to flow through. This sudden drop in airflow also affects sensor reading such as air/fuel mixture, which will spike rich, and also exhaust temps will be affected.

The problems can be corrected by adjusting the map (see ecu section) to take these factors into account.

Imprezaís have as standard top mount intercoolers, fitting a front mount will cost approx £800, not including remap or map adjustment.

few additions thanks to Bob

The lag can be easily sorted by keeping the Dump valve recircÖSo it dumps back into the system so keeping the lines under more pressureÖ

The front mount will also require the removal of the air box for the pipe work so induction kit is required.. Induction kit required is oil free as to not coat the maf.




Water Injection

The theory of water injection has existed for about 50 years and revolves around controling the burn of fuel in the piston. A fine mist of water is sprayed into the fuel and air mixture.

The water has two main affects,
firstly it cools the air coming into the air system, increasing the oxygen density which helps to keep bost levels high.
secondly it creates a dampening affect on the fuel and air mixture burning, which sounds like a bad point, however, the wate content isn't high enough to prevent the full mixture burning, but it is enough to prevent uneaven burn and varying detination which can cause major engine damage.

water injection systems range from anywhere around £300 upwards

but in truth they are only realy worth while on high powered cars (running over 500bhp)
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Last edited by skylight; 07 Nov 2006 at 09:55 AM.
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Old 20 Dec 2006, 11:30 AM   #2 (permalink)
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further to this is the attached article





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Old 02 Aug 2007, 09:19 PM   #3 (permalink)
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water injection is also independant of ambient temps and will keep the motor cool whilst stationary in traffic or waiting to go up the strip
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Old 03 Aug 2007, 11:22 AM   #4 (permalink)
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Quote:
Originally Posted by ScoobyAbuser View Post
water injection is also independant of ambient temps and will keep the motor cool whilst stationary in traffic or waiting to go up the strip
yep, but you can run out of water lol, plus if the water jets fook up you could need a new engine
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Old 03 Aug 2007, 12:58 PM   #5 (permalink)
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true but use a proper water tank with a level indicator, and at 150 psi, the jets very rarely block up
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Old 06 Aug 2007, 11:44 AM   #6 (permalink)
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Quote:
Originally Posted by ScoobyAbuser View Post
true but use a proper water tank with a level indicator, and at 150 psi, the jets very rarely block up

yeah set up right they are good, i question how usefull they are unless your going silly power where it will make the difference
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Old 21 Feb 2010, 09:18 AM   #7 (permalink)
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Re: Info: Intercooler

hi guys, im torn between fmi and upgrading initially to version 3/4 sti tmi. Firstly will the version 3/4 sti intercooler fit my 94 import wrx? Or cld u recommend a good upgrade tmi for my early classic? Any advice wld be appreciated. thanks Gareth
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Old 21 Feb 2010, 11:07 AM   #8 (permalink)
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Re: Info: Intercooler

i think that most people go to a fmic from the slanty type tmic but a remap will be needed
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Old 21 Feb 2010, 11:48 AM   #9 (permalink)
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Re: Info: Intercooler

As above, for and early impreza definately a front mount. You can get a Hybrid GT FMIC for £300 these days brand new. but a remap of your ecu will be needed as said above.
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Old 21 Feb 2010, 12:48 PM   #10 (permalink)
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Re: Info: Intercooler

I understand that the fmic is a big job and can take some time. Having spoken to a few people on the early classics some of the fmic's dont fit properly either. I have easy access to the v 3/4 sti tmic will this improve my setup at all?
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Old 21 Feb 2010, 01:09 PM   #11 (permalink)
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Re: Info: Intercooler

yep i think it will be better for the car but its getting it to fit. any fmic will have probs id say. like getting extra silicone hose incase u have to cut pipes. ive never converted slanty to straight so couldnt say what u need
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Old 22 Feb 2010, 01:25 PM   #12 (permalink)
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Re: Info: Intercooler

To fit a front mount you haev to cut some of the inner wing, remove some of the bumper and fit an induction kit, then map it.

however it will reduce heat issues and also if you sit in traffic for a while and give it welly straight away with a top mount it can be heat soaked and wipe out your engine. Front mounts are by far the best way to go on all models once you hit 300bhp.
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Old 22 Feb 2010, 01:39 PM   #13 (permalink)
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Re: Info: Intercooler

What about a bigger scoop to improve air flow on to a tmi and replace it with a STI V4 intercooler. Also is a ZERO SPORT INTERCOOLER AIR INTAKE unit which fits inside the scoop worth the money. Also what about replacing the little vents with a scoop too increase the air flow into the engine bay to cool it.
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Old 23 Feb 2010, 12:58 PM   #14 (permalink)
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Re: Info: Intercooler

Quote:
Originally Posted by GTSTr32 View Post
What about a bigger scoop to improve air flow on to a tmi and replace it with a STI V4 intercooler. Also is a ZERO SPORT INTERCOOLER AIR INTAKE unit which fits inside the scoop worth the money. Also what about replacing the little vents with a scoop too increase the air flow into the engine bay to cool it.

helps a bit when moving, but not when sat in traffic, heat rises stright into the intercooler.

the shape of the front actualy baloons the air up and over alot of the scoop, raising the scoop does help a bit, but your still talking a very small area of air going through to it.

simply put, above the engine is a crap place to put anything trying to take heat away from anything to do with the engine.
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Old 23 Feb 2010, 02:18 PM   #15 (permalink)
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Re: Info: Intercooler

Ok so on top is not a good place. I'm only slightly moding mine at the moment. Exhaust, green, filter, forge rec dump valve. I will get a bigger scoop and the vent thing. Whats next is it the ecu as mine is a uk model what issues do I have with the ecu I have herd you can not remap it. As with the mods, it will need a remap. As the car is a 98 2000 turbo can i use a ecu out of another model. Best price and where get it from any ideas would be great.

At what point do you get to the 300bhp mark with the mods normaly before I have to go fmi.

Thanks for your help.

Last edited by GTSTr32; 23 Feb 2010 at 02:20 PM.
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