| August 31, 2011 was an
important day for me. Following my initial settings performed in the
garage, I drove a 204 mile round trip (in rain) to Sportti-Auto, in
order to tune the engine on a Dyno Dynamics 4-wheel chassis dyno and
find the perfect settings for each parameter of the Vi-PEC V88
ECU. Interestingly,
they had never dyno tested anything with such a long (129")
wheelbase! |
 Here's the patient and the doctor, Jean Niemi of Sportti-Auto, seeking the perfect injector timing in order to make the A/F ratios equal between adjacent cylinders sharing an intake port. We had wideband lambda sensors connected to # 5 & 6 primary header pipes to compare the A/F ratios. Jean has the headset connected to a knock sensor. During the morning session, Jean was able to find the optimum injector timing for the majority of rpm/load conditions. Then we had a lunch break. After our break, Jean continued to find the optimum injector timing for the rest of the fuel table, but he couldn't, and none of the earlier values gave satisfactory results, either. No matter what we tried, there was always deviation between cylinders. Obviously something happened while we had our break, but what it was, remains a mystery. We had spent a full day on the dyno, and frustrated as we were, we left the adjustments to the best setting we could find. To prevent detonation in the "lean" cylinders 2/5/7/4, Jean left the overall mixture relatively rich. |
 To wrap up the day, Jean made three full dyno pulls. Here are the first two. Something went wrong with the first pull, but the second one yielded 131.7 kW, and the third one 131.9 kW = 180 HP @ 3500 rpm. The torque curve seems flat at approx. 420 Nm (310 lbft). This is "crankshaft" power, as the dyno sofware uses a certain drivetrain loss factor to convert wheel horsepower to engine horsepower. Typically it's around 15-18% for manual trans and 18-22% for automatic trans cars. In 1942, the factory claimed 165 HP @ 3600 rpm. This was the dual-carb dual-exhaust manifold engine, and gross HP without any of the peripherals (water pump, fan, generator) or exhaust pipes. My numbers are "net HP" with full exhaust and the p/s pump, water pump, alternator and electric fan running. Not bad for a 7.6:1 compression, stock cam and nearly-stock head engine! |
 mounted the Innovate MTX-L wideband gauge under the dash, where it's rather "stealth" looking in all-black, until ignition is turned on. The A/F ratio shows rich, as this photo was taken during warm-up enrichment. The Sun Super mini-tach is mounted on the steering column. The old tach didn't work with the low-level signal from the ECU. I spent a moment trying to figure out how to replace Buick's gas pedal starter function, now that I don't have the carbs anymore. The factory cranking system activates when gas pedal is depressed and a switch in the carburetor engages, and deactivates when there's vacuum or the generator starts charging. I cannot use vacuum as a "vital sign" of a running engine because of the supercharger that will be installed later. Luckily there are other "vital signs", and I was able to retain that neat Buick feature. I configured one of the Vi-PEC ECU digital outputs to ground a relay when these conditions are met: 1. Engine RPM is less than 350 2. Throttle is opened more than 20% (TPS sensor) 3. There is no oil pressure. I have installed an oil pressure warning light switch earlier, and could use that as a "digital input". When there is no oil pressure, the switch grounds the warning light, hence the input = "0". When the engine is running, the light turns off and the input sees 12 V = "1" The ECU allows a combination of three conditions maximum. It doesn't allow the use of battery voltage as a condition, though. |