Dyno-Tune!

It was a big milestone event yesterday in the Bugeye's life: its first dyno session and professional tune. Woot!

As I may have mentioned in a previous post, the engine for the car came out of a custom Model A (!) driven by an elderly gentleman. The builders of that car were worried he was going to hurt himself driving the high-power/low-weight vehicle, so they had the ECU purposely de-tuned, boost limited to 5psi, and the engine rev-limited to 5K rpm--primarily to give everyone a little peace of mind when the customer took possession of the car.

Fast forward to now. The engine and transmission eventually found their way into my car, including the de-tuned ECU and the 5psi-limited turbocharger. A few months ago, we got the car on the road, but it was clearly in need of a proper tune. I also wanted (needed!) the rev limiter removed. Plus I wanted to up the boost a bit.

This week I took the car into a tuner friend of Joe's. We originally planned to use the tuner's hub dynos, so I purchased some wheel adapters and brought them to the shop. Unfortunately, the wheel adapters weren't machined properly and wouldn't bolt on properly. Argh. Fortunately, the tuner also had a traditional Mustang roller dyno that worked out. In the end, we spent more than 3 hours on the dyno, getting the entire air-fuel and ignition maps setup. Here's a short clip of Steve Cole (tuner) making one of a dozen pulls on the dyno:

The goal of the session was not to maximize performance--far from it, in fact--but to create a base, reliable, safe tune with good, crisp performance throughout the rev range and boost limited to 5psi. We also wanted to "poke at" some higher boost (10psi) to foreshadow a future dyno session.

So, here are the tabulated summary results of the best 5psi pull and the one aborted 10psi pull:

And one of the 5psi money shots:

Nice, fairly flat torque curve with a noticable upward slope change when the turbo kicks in at 3K rpm. Horsepower just builds pretty linearly throughout the rev range.

From the table, you'll note that the one 10psi run we tried was aborted at around 5,500rpm because of the injectors saturating at 100% duty cycle. Assuming I buy/install larger injectors, advance the timing a bit, and run it up to the current redline 7K, I extrapolate max torque and horsepower to be around 220lbf-ft and 250hp, respectively, at the wheels. This would mean approximately 260lb-ft and 300hp at the crank, which is backed up by other people's results with this same type of engine. Sounds pretty promising to me, especially for a car that weighs just 1850lbs.  And what if I crank to boost to 15psi, which these engines have been shown to handle with ease? And what if, what if....

Sigh.

I have to pause and just enjoy the car as-is. I'm not planning said larger injectors, increased boost, or further tuning, etc. any time soon. Instead, the goal is to get a thousand or more miles on the drivetrain and work out some of the various gremlins and issues that have arisen in these first few hundred miles of shake-and-bake driving. I have some nasty sheet metal buzz at certain rpm levels, for example, that requires attention. Plus sway bars to figure out, a parking brake to design, various electrical tweaks, etc., etc., etc.....  Only then will I start to think about bringing the car back for round 2 of testing for more performance.

For now, the drivability of the car is greatly improved. Like night and day improved. Smoother idle, very crisp throttle, and very strong freight-train pulling throughout the entire rev range, etc... Not to mention no 5.5K rpm rev limit! The bottom line is I could not be happier with this first step toward full performance of the car. Woot!