Project Mileage Motor
Part 5: On the dyno... and wow!

BY BRUCE SIMURDA

If you've been following our Project Mileage Motor for the last four months then you know the goal of this undertaking was building an engine that will power a stock trim Beetle down the highway at 70mph, and deliver somewhere in the neighborhood of 35-40mpg. To reach our lofty goal we have talked to a variety of people in the industry, and used their feedback to design and build an engine that will hopefully provide the type of performance (as in mileage performance) we're looking for. Remember, at this point in the game we're not guaranteed that this project engine will actually produce the kind of fuel economy we're looking for! Only after we install it in a car, fire it up, and drive it down the highway will we know for sure how well our combination works. We will also be testing other items on this engine in the future, such as fuel injection, to help reach our goal.

Last month we left off with our engine "almost" assembled. The only thing left was the exhaust system, which was not completed in time for that segment. For our unique engine, the crew at CB Performance was having a special merged system built to properly match the components of our 1745cc (76mm stroke x 85.5mm bore) engine, especially the 33mm intake valves. This system was constructed with small 1-3/8-inch merging tubes and a 1-5/8-inch collector, which connected to a turbo-style muffler. One look at this unit proved that it was a quality piece, as the inside of the merged collector was a well shaped and clean as the outside, which was ceramic coated.

While installing the muffler, we also added a Bugpack billet remote filter bracket and adapter. After connecting the filter adapter to the pump and case via AN-8 fittings and braided stainless steel lines, we were ready for the dyno.

As we were fast approaching the busy holiday season, we were glad when Jack Sacchette of JayCee Enterprises in Huntington Beach, California was more than happy to squeeze our engine in. After the wild VW Engine Builder Showdown he had at his shop the month prior, putting our mild Mileage Motor through a run seemed like a snap. So after we arrived, Jack and his crew, including David Stark and Steve, bolted our engine to the Stuska dyno, and proceeded to hook everything up. Before spinning on the new Fram PH8A filter, David filled it with oil to facilitate a quick priming of the system. By the way, we were using Shell's 20W-40 Rotella T, a diesel oil with high sulfur content to provide maximum lubrication during the break-in process.

After the fuel lines were connected from our stock fuel pump to a fuel can filled with premium grade pump gas, and the timing checked, it was time to fire our engine up for the very first time. Once the float bowls in the Weber ICT carbs filled, the engine barked to life without hesitation. Jack immediately held the speed to 2,500 rpm, as he checked vitals like the oil pressure (a solid 55 psi), then allowed the cam to break-in. After about five minutes the engine was permitted to idle as ignition timing was again checked and set at 28° full advance, and the carbs adjusted. With the small single-barrel Webers, it idled like a kitten, although there was a bit of noise from the valvetrain. At this point the engine was allowed to cool, before Jack fired it up and ran it at 2,500 rpm for another five minutes. The break-in procedure continued as the engine was run, allowed to cooled down, then run again, before it was allowed to cool completely for a valve adjustment.

At this point the engine was ready for testing. Once fired we noticed that the valvetrain noise had disappeared (due to the adjustment), oil pressure was still strong, and Jack was ready for a dyno pull. But what we were about to see shocked even us! Remembering that our goal was high mileage, not performance, we were more than a little suprised when the 1745cc engine made 57.5 horsepower at 2,500 rpm, and a whopping 92.5 at 5,000! Even more impressive was the torque readings with 120.8 ft.-lbs. at 2,500 rpm dropping only 19.6% to 97.17 ft.-lbs. at 5,000 rpm. With so much torque at a low rpm, we should be able to gear down our transaxle to take advantage of the strong powerband.

To us, the excellent powerband and crisp throttle repsonse proved that you don't necessarily have to go big to produce a good running engine. With the exception of the CB 76mm stroker crank, all of our components were on the small size - cam, heads, exhaust - but they were all properly matched, so they worked efficiently together. And efficiently means performance, and hopefully that will result in a good fuel economy as well.

At this point we're ready to install project Mileage Motor into an actual Bug and do some testing... but that will have to wait 'till next month!