I've heard that the JDM AND EUR cars run about 15psi boost from the factory and the US only about 13.5 due to many states haveing no higher than 92 octane whereas the rest of the world has access to 94. Since these cars are supposedly mechanically identical how the heck is it that tuners can sell you a chip or ECU to let you run 15 psi AND maintain SAFETY for your engine? Is it just through putting a greater volume of fuel to the cylinder? Can the stock fuel system provide enough fuel to match 15 psi of boost? Will a stock ECU fire bigger (sti) injectors. Will the stock fuel rails and pump be enough to feed these bigger injectors. I'd really like to take advantage of all my turbo has to offer but washington only has 92 octane and tolulene is a pain! Any knowledge you can impart would be hlpful.

Thanks,

Travis

 

Detonation and high boost = bad. That said, you can safely run 15 in your WRX.

Aftermarket ECU's do a number of things to increase performance. It is more than just increasing boost - the also advance timing and add more fuel.

The stock fuel system can supply plenty of fuel to run 15 and even up to 16PSI of boost. The injector duty cycle on a stock WRX is realitively low.

The stock ECU will not fire larger injectors properly as you will be spraying alot more fuel than you desire. If you get larger injectors, you should get larger fuel rails (the perrin is good), a larger fuel pump (the walbro 255l is the most popular), and a aftermarket ECU to fire them properly. You won't reach a nead for this until you have completed your exhaust and go to a bigger turbo.

You will not be able to run as agressive a timing map on 92 octane as someone running 93. But you could be like me and only get 91 octane petrol water. Check out the UTEC (TurboXS)and the EXEED (Vishnu tuning). These will give you plenty of flexability to properly tune your car for your enviornment.

 

So in short I probably can attain 15 psi with 92 Octane at the cost of a little bit of fuel economy. That's fine with me I'm getting as good of mileae from my WRX as I do from my ZX2 (which could really use a tune up). Thanks for the advice.

Travis

 

The fuel economy question is a little bit tricky. True you will burn a little more gas, but on the otherhand you will make more power at that point as well. It could actually go either way.

 

I'm just rying to figure out why subaru didn't map it for a bit more HP. After all they had to remap it for the US market. They could've gone all out. Maybe emissins has something to do with it also. At any rate if I get an ECU it will definetly some means of installing a disconnect switch for the whole damn thing so the factory map can take over.

 

The UTEC does that. You can get a switch that will allow you to switch between various maps that you define. Then you just select the factory map either through your laptop or the remote switch. Much easier than trying to wire a bypass,or removing the ECU to run stock settings.

 

I think I will eventually go with the UTEC. For right now I'm probably gonna stick with rims, tires, and an STi suspension until my piggy bank has a bit more in it. Thanks for the advice.

Travis

 

If funds are tight you might want to wait until KYB releases the AGX for the WRX. That and some ground control coilovers (or similar) would set you back less than the STI suspension. You would get adjustability that way as well.

 

I've never even worked on suspension components much less tried to tune them. It sounds too involved for me. I've never heard complaints about the STi suspension and I might be able to convince my dealer to warranty it. What kind of savings are we talking here. My auto mechanic skills pretty much stop at external components (alternators, waterpumps, thermostats, brakes). I'm fairly handy with a wrench though I'm a shipboard electrician by trade. I just wonder what the learning curve is on something like that.

 

They haven't released pricing yet, but I am sure that this setup would cost you several hundred dollars less depending on how much you could pick up the STI setup for. The AGX's will probably range in the 250-400 dollar range for all 4 and throw in 250-350 for the ground controls. Total cost somewhere in the 500-750 range. I watched an install with this setup on a miata and it wasn't bad at all.