MKCPerformance.com

Tonight I had the pleasure of Open Source tuning a very nice 2005 Subaru Imprezza WRX with stage 2 modifications and a street tune. First we rolled her on the dyno to get a baseline of where it’s at, and then started to dial in the tune even more. After just a few pulls on the dyno she was dialed in for the current setup. Injector duty cycle’s were in the low 90 percentile and boost was at 14.5psi peak, tapering to 12psi at redline.

The car tuned out very well and picked up 14 peak HP and 5 peak LB/FT of torque. In the meat of the graph it picked up as much as 20-25 HP and 8-12 LB/FT of torque. This was all from dialing in the AFR’s and Ignition Timing on the same amount of boost. I would have went higher if there was adequate fueling.

After coming back from the street tune, the customer and I had the opportunity to discuss what avenue to pursue next as far as modifications are concerned. Ultimately, the car needs more fuel to increase the boost.

Since this car is a daily driver, I suggested a mod path we did for another local 2004 WRX. This consisted of a 2007 WRX STI Topfeed fuel rail setup, STI Injectors, STI Topmount, and VF43 Turbo; along with a Walbro 255lph fuel pump and Re-Tune. Here is a comparison of the graph after tonight’s tune vs. the 2004 WRX with the 2007 mods mentioned above. The 2004 was on 18psi as well.

If you would like to check out the customers page with more pictures of the car, please Click Here

The owner of this car came to us a while back after returning from military leave. The car wasn’t building oil pressure, and he wasn’t sure what the problem was, so we meticulously looked over the car and tore it down for a re-build. We sent the block and cylinder head out to a local machine shop. The cylinder head was sent out for a pressure check and to make sure the surface was not warped. Some valves were bent and subsequently replaced. The block was also sent out for a pressure check, along with a check for sunk sleeves, and hot tank to clean out any foreign material from the oil passages.

When putting everything back together some area’s of the build were of concern for us that we wanted to update. For one, the intercooler piping was made from stainless steel and some of the bends and welds weren’t very well thought out. Second, some of the old pipes bends were very abrupt that would hinder flow compared to the new piping.

We have since updated this section of piping with new mandrel bent aluminum piping that we use in all of our turbo builds here at MKC. Here’s a comparison of the old cold side intercooler piping vs. the new aluminum pieces.

And here is the hot side of the intercooler piping, this one had a large section that was smashed flat to clear the steering rack; which it was actually resting on. The new piping clears the rack very nicely now and flows better as the integrity of the tubing wasn’t sacrificed for clearance.

Here’s is the culmination of the build and tuning, putting out over 500whp on 91 octane and 16psi; and over 600whp on Q16 and 25psi. This is all on a single walbro High Pressure 255lph fuel pump and PTE 1000cc injectors.

If you look closer, later in the graph in the upper RPM’s it started to lean out as the fuel pump was done flowing. We turned the boost down for the Q16 tune for a much safer tune on the current fuel system. The customer will be returning for a new fuel and ignition system upgrade for more power very soon, as he is currently getting the transmission and rear end taken care of.