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In talking with Cobb Tuning, regardless of the mods you do (turbo boost, exhaust, etc.), you are defeating the purpose if you do not adjust/replace the ECU chip. The stock computer will compensate for the increased performance via a negative reduction one way or the other. Just something to think about for the new WRX owners looking to modify.
 

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Put a boost controller on it and set it for 14.5 which is about peak factory boost. You will know it when you are running in 1st and 2nd gear. And you aren't hurting anything yet. They have aftermarket items that will let you control fuel or what ever and its no problem, however an ECU is a middle level mod, meaning, minor gains across the board that can be compensated for with other devices if you want. Did I make sense or am I rambling?
 

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My thought on the ECU is that its real usefullness will come into play whan you have the mods. The OEM ECU is designed to get the best performance from the stock car but when you add turbo backs, turbos FMIC and such that is when you need to take advantage of your new setup.

If i'm wrong let me know :)
 

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Out of curiousity, are you people resetting your ECUS after heavy mods or just plug and play? I think most ECUs have to relearn the new power curve of the car if you mod heavily. ECU is just a computer, it's like having to restart your pc when you install certain programs at rely heavily on dll files(btw, I'm not a computer expert, so I could be totally off target). And how come no one ever responds to my topics??? Oh well.
 

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Oh yeah and Root, the fuel controllers are needed if you plan to run high boost levels so that your engine doesn't run lean(detonation...yikes!). There are plenty of them out there, I think the easiest one is HKS VPC(vein pressure converter) that gets readings from your O2 sensor to adjust fuel levels and you don't need to really push any special buttons or anything, it's just a module. Apexi has the sexiest one(apparently works well and looks mighty swell), but takes time to adjust from what I heard, I've never tried it.
 

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WRX44 is right on the money. If you do not replace the ECU or get a 'piggyback' ECU your mods will be for nothing. There is an article on www.autospeed.com where they put on a APS Stage 1 kit on the new Rex, but instead of putting everything on, they put things on individually, and at every increment, they put it back on the Dyno. Stock, it produced 93kw at the wheels. They added the full 3-inch exhaust system, and the peak power stayed the same! They then added the air filter, same result! After that they added the intercooler and the peak power stayed the same. Bottom end was improved by about 15% but peak power was the same. When they added the ECU last, power jumped frok 93kw at the wheels to a massive 135kw at the wheels!!! If you add mods to increase boost, different story, but beware of turbo longevity. But if you add a exhaust, don't expect more power, just noise. I can post this article for you guys as you need a membership to read it. For some reason, subaru have re-programmed their ECU's to not except mods with a power increase. On the old model, by adding just an exhaust, power jumped by 30-40hp!! I think subaru know most people don't want to change the ECU, so they did this to their ECU's to put people off modifying their cars.
Just a thought....
 

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I hear what your saying, but to my way of thinking when they put on the ECU they need to tune it to your car. If this is the case than you would want your mods in place already. If the new ECU is already in than any mod you add will require an ECU ajustment to get the benifit out of it :confused:
 

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I think some of the results are a little misleading. Remember that puny turbo is maxed out so even thogh you can do mods to the car peak power is difficult to increase past a certain point. True the ECU dumps fuel like nobody's business but still top end is just limited by the turbo sizing and flow rate. If you stay with stock turbo you will increase area under the curve and midrange power with most mods. Not that this is bad, it's what you want for street but I think you can not look at just peak numbers when dealing with modification. You have to look at the entire curve and read mirange data as well. Even if I gain 0 hp peak a mod is well worth it if I can get 10 ft lbs in the midrange.
 

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I have to agree with Dan. Peak power is not the issue with our cars, it is bottom end / midrange. The WRX makes very little torque below 2700 rpm. If you can fatten up the power curve with more low end torque, the car will be faster and more drivable.

As for the stock ECU, it is there to protect the stock (smallish) turbocharger and keep the car running with low emissions. A bigger turbo needs an ECU to take advantage of the greater flow.

Anybody know what JUST changing the ECU on a stock WRX would do for power across the RPM range? (Besides full boost in 1st and 2nd.)

-Jim
 

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Anyone heard of the Apexi Power FC? I think it's an ECU to replace the factory one. You can buy seperate control to change the fuel and ignition maps. They are made vehicle specific so maybe we should lobby Apexi to make one for the Rex?
 

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I've used the Power FC myself personally and I love it. Unfortunately it is not available for the GDA WRX. Only the older models. THey are working on it but Apexi USA is extremely unlikely to released it here in the US. I import all my Power FC's from Japan directly. Once it is released I will most likely order one but if not out soon I'll probably just go with the Autronic ROM board upgrade. A little more expensive but it is self learning which is nice and simply replaces your stock ECU rom board. Plug and play just like the FC.
 

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I personally have never seen the FC in real life but that thing is so cool. That hand held controller allows you to adjust just about anything(including boost). But it isn't a cheap unit, don't they average at about $1000-1200? Then again, if you buy an EBC, AFC, ECU, etc...it'll come to be the same. Hopefully they have one for the north american Rex.
 

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Another thing to keep in mind, is that the ecu takes some time to learn the new mods. The ecu is constantly changing and learning, so putting a 3" turbo back exhaust on, and then going straight to the dyno without any driving time for the ecu to learn the new air flow rates is not going to gain a whole bunch. Remember when the car was brand new (no miles), compared to now (over 1000 miles), you should have a lot better responding car due to the ecu learning. Like wise, you take a car that has only been drivin out in Colorado, and then you driv it down to sea level, it is not going to run he same, it is going to take some time to relearn the air pressure differences. Just a couple of other things to think about.


Russ
 

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Power FC will not be avaiable for the USDM WRX but should be for the JDM spec model. Also, I spoke with HKS and they mentioned that the F-Con V S will be available shortly. It is piggyback though. I was hoping they releaase the incredible F-Con V Pro which is a standalone and pretty remarkable. No plans on that though.
 
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You guys might want to check the latest article in Sport Compact Car. SPO Motorsports Stage 1 mods increase power by 35hp at the wheels without a turbo or ecu swap.

[ August 31, 2001: Message edited by: Bear ]
 
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Your right, the number is at the wheels. The gragh in the article showed substantial increase in torque and horsepower throughout the entire powerband. The 35hp was the increase in PEAK hp.If you have less resistance before and after the turbo you can increase performance without a turbo swap. They changed the intercooler, the exhaust, the air filter, and the boost controller. If the exhaust and/or the intake size remains the same you may not be able to see an increase without the swap. The most impressive part of the mods were an increase in low end that carried all the through to the upper revs. A turbo swap alone will increase the top end because of increased pressure, but as I understand it the stock injectors may not be up to the task.

[ August 31, 2001: Message edited by: Bear ]
 

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Yeah, the new issue of SCC is pretty cool with basically the whole issue being Subies. Did anyone read that article on the 900hp Golf AWD(nicknamed the RSI).....sick in the head! Flared arches with 19X10 wheels all around!
 
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