Zen and the search for more power - Turbo Phase 3 – Realization ver 2

Zen and the search for more power - Turbo Phase 2 – Realization

It’s been 3 years and a bit since the last article. This Legacy GT has been turbo’d since
February 2003, and 2 days following the build and tuning, it participated in the Wosca winter AutoSlalom. No rest for the wicked, and from there, the car new that it was going to live a pampered but harsh life.

Back in 2003 when I wrote the “Turbo Phase 1” article, I mentioned a phrase:

I've gone as far as I wanted to go without dismantling my engine completely, and the thirst for more thrust is ever present. My mind wanders and wallows in thought "will it ever end", I ask myself. The answer, "I don't care"!!!

Once you've reached that point, it's downhill from here.

Boy, isn’t that the truth! Just to backtrack for a few moments and recap the history of the car, it’s always fun to see where it came from and where it is now. Jumping to the present, the car is currently getting a new block with forged 10:1 compression Arias pistons and Tomei STI rods (longer rods), to get as much “rod to stroke” ratio as possible to minimize the sideloads on the cylinders. But I’ll save that for later, and let’s go back a few years to recap.

Purchased the car from Trento back in December 1999, waited for its arrival in January, it stayed stock for all of 1 year, since there were no suspension mods available. Fall of 2000 started looking for power mods to make the car perform better and went through the efforts in the first series of Zen Articles. Settled on Cams by Yoshio and never looked back.

Was happy running it NA participating in the CASC-OR Autoslalom Championships, and managed to maintain top spots in my class for over 5 years with the Legacy. But there must be more, so we turbo’d the car. OMG, that had to be the best learning experience “ever” as far as learning the in’s and out’s of making it last. How long do Normally Aspirated engines last when turbo’d? Before answering that, remember that this car is used in the Autoslalom championships and spends lots of time at the redline, bouncing off the rev limiter. It’s has done so since new, and continued to do so for a number of years until late 2005 (explanations later in this article).

So let’s continue on with Phase 2 – Realization

The quest for more power resulted in the culmination of parts, and the relentless scavenging for cost effective parts from the 4 corners of North America. Nasioc turned out to be one of the best resources. Injectors came from a tuner somewhere in the south, along with the Forester intercooler. Headers were brand new from Maxim works, cross member from Japan Auto Parts, wiring was all done by me using 2 manuals. Service manual courtesy of the internet, and the Autronic ECU documentation.

I originally created an adapter harness using pieces from a dead ECU and a donor harness for the ECU plugs. Wiring each one straight through and testing them on the car, after it was completed to make sure the car ran, and there were no check engine lights. This took a whole 2 weeks to do, using a soldering iron, flux and fine solder. This was backbreaking work, soldering each wire to each contact. This was just the first part, because I didn’t want to cut the OEM harness on the car, so that “just in case” I wanted to put things back to stock (yeah right). That was the easy part!!

Documentation was what required the most concentration, creating the wiring map, checking it twice, going to the car and measuring voltages, making sure that it was correct. Another 3 weeks of wiring and testing passes, since the first step was to get the ECU wired and working.

Aaah, segway to the ECU, it’s an Autronic SMD/SMC ecu with a pre-production chip version 2.0. After numerous communications with Ray Hall of Autronic and sending in the crank trigger and cam trigger configuration (yes, Subaru does use different types, on an EJ25), they finally created the custom chip to work with the stock Legacy triggers.

Note: I used as much OEM as possible in order to make availability of components accessible anywhere in North America. The main thrust of this search for power is “reliability”, more on that later too.

After the harness was plugged into the car, and used as a bridge to bypass the stock ECU for all engine management duties, the time came to plug it in and start the car.

“Realization” Part II

This is a brand new installation and there are no data points to follow from a previous install. This is when the learning began, setting up all the parameters for the Autronic ecu, things that we take for granted on a stock car.

• Base ignition timing on a 16X16 3d grid
• Base fuel delivery
• Base engine setup, injector types, pulse types, injector fire type, number of cylinders, cylinder offsets, etc. etc.
• Throttle enrichment multiplier
• Dashpot multiplier
• Timing acceleration limits
• TPS limits
• Cold Start Maps
• Warm Start maps
• Warm start enrichment multipliers
• Temperature compensation maps
• Barometric compensation maps
• Fuel modification maps
• Timing modification maps
• Injection end angles
• IAC Maps

And the list goes on and on, without the proper settings, or if any settings were wrong, or out of spec, there would be countless hours spent figuring out the problem. Problems can result in flooding during start up, to engine dieing for no reason, then starting up again.

Wow “realization” = knowing that you don’t know ½ as much as you thought you knew before embarking on this project. That’s history now, and the future is now. Having worked on the solution for many of the setup parameters, I documented every process and wiring maps, and forwarded them to my friend in the USA who was doing the exact thing I was doing to my car. In hopes of having someone benefit from the hardships I had already lived through. Ben aka PHATsuby found them beneficial and successfully turbo’d his car.

Of course, the master of tuning himself “Yoshio Kinoshita” of Japanese Automotive was crucial to creating a startup map, which enabled the base for which the car was to be tuned. With all that done, Yoshio asked how much power I was looking for, and I explained to Yoshio, that all I was looking for was a “Safe” amount of power since the car would have to live a life of competition.

So the marching order for Yoshio was, “Safe” please. At that time, I asked Yoshio what the stock internals could take when turbo’d. He said, you are the first one with an EJ25 with all this equipment, so I don’t know, was his answer. I followed up with “how long do you think it’ll last”? Same answer. That didn’t leave me with any level of comfort, but never the less, remembering the statement in the 2nd paragraph of this article, I didn’t care. Let’s see how long it’ll last while being able to use it as a daily driver.

Recap: Phase 2 SOHC stock internals with bolt on everything to it, and WRX injectors.

The results:
Dynapac Dyno: 269 Hp and 267 Lbs ft of torque at the wheels @ 7psi.
Car was tuned up to 10 Psi.

Now back to the question of “how long will it last”. Let’s qualify that, this car was driven hard from day 1, firstly as a cammed NA 2.5L with Maxim Works headers high flow cat and a 2.25” exhaust. Raced every weekend, with countless number of track days.

Then turbocharged using the same internals, same cams, new headers, new metal core cat, and 2.5” exhaust system and the best engine management system at the time, that money could buy. To add to that, the car was daily driven and is still being driven on a daily basis up to today. So how reliable is it? What did break, when it broke?

As far as the engine is concerned, it was stock for 20K km, turbocharged when the car had 40K on the clock, ran with a TD04 turbo until it was changed to a VF23 and had more power until 2005 when I finally broke a ring land. By that time the engine had 125K Km on it.

What I broke was not engine parts during it’s lifetime with the stock EJ25, it was the following:

1 front right drive axle
1 TY75 Transmission (OEM), lasted for 4 years.
1 TY75 Transmission with 4.44 RA gear set, lasted for 1 season of racing, 3rd gear shattered (VF23 in the car)
2 sets of STI 6 speed R180 rear axles

Engine was always reliable.

Looking back, is there anything I would change, answer “no”. This Subaru has always lived up to its expectations, and the engines are bulletproof.

What’s the secret? Tuning, Tuning, Tuning by an experienced tuner.

Next article: Zen and the search for more power – Part 4 – No Holds Barred!!