Our Subaru EG33 is a "normally
aspirated" and fuel
injected 3.5L engine (stock displacement is 3.3L but we installed larger
diameter cylinder barrels during the build). The engine requires some sort of
Engine Control Unit (ECU) to manage the ignition, fuel and cooling systems. The engine's previous
owner had used a "Motec M48" to serve those functions and a custom made
"Sakata" wiring
harness for the M48 came with the engine. Unfortunately, the actual
ECU wasn't included with the engine. We found a used M48 on EBay for a
reasonable price and had it on hand a few days later. We had no idea
what it had been used for previously but were fairly certain that it wasn't
programmed for our engine type; our wiring harness would connect to it
perfectly but without proper programming, the engine wasn't going to
run...
Programming an ECU is not one of our
strong points and the EG33 is a bit unusual. Also, the M48 is an
"older" Motec ECU and there wasn't a ready made "tune" for our engine
available. DanZio Performance
Engineering is in the
business of building and tuning engines for off-road cars; they were an obvious
choice for our ECU programming needs. We worked with Chris at DanZio
on two occasions - the first to just get the engine running and then later
to "tune" the engine on the dynamometer. Everyone at DanZio was great
and we're very happy with the results - we highly recommend them!
Finally in the shop for ECU programming With the car mechanically complete, we brought it to DanZio for ECU
programming. In addition to actually controlling
ignition and fuel delivery, the ECU also controls the radiator
fans. Initially, we'll run the engine "open loop" but will add an O2
sensor to run "closed loop" as soon as we adapt the sensor and wiring
harness to work with each other...
Chris checking things over Chris was a pleasure to work with and was very complimentary of how we
built the car. That was nice validation from someone who really knows
off-road race cars...
On the "Dyno" for final tuning "White knuckle" time for us! Happy to report that aside from a
couple of very minor issues (a couple of "iffy" plug wires and a leaky fuel
rail "O" ring) that were
easily resolved, the tuning session went perfectly.
Power Curve Analysis display Chris' tablet showing results for the current "pull"
Final "Pull" on the Dyno
Power Evaluation Sheet The final evaluation sheet shows "at the wheels" numbers of 231.5 hp and
217.9 ft-lbs running on 91 octane "pump gas". Chris estimated a 25%
power loss between the engine and the wheels due to axle angle and other
driveline losses. That translates to an "at the flywheel" power output
of about 309 hp - a 79 hp (34%) increase over a stock Subaru EG33 engine.
Those numbers are in line with our expectations and should result in plenty
of reliable power for our "light weight" pre-runner.
