American car sound versus European car sound QUESTION #2
Asked by StevenWicked Jan 25, 2022 at 09:41 AM about the 2021 Porsche 718 Cayman GT4 RWD
Question type: General
A couple of days ago I asked why American race cars sound different from from European race cars. Ed92626 it extremely well. He said that European engines run a little out of balace but they rev higher. I was wondering why?
4 Answers
European engines favor crankshafts that are of a single-plane design. Basically, they’re movement is linear, with half their pistons moving up while half are moving down; it’s a light weight design that allows for quick acceleration. But the connecting rod journals are moving rotationally, which causes lateral movement. This out-of-line movement causes a vibration that those designers didn’t consider large enough to address. It’s funny to drive a “55 V8 Chevy, then get into a “55 Volkswagen and feel all that shaking at low RPMs….. American V8s with cross-plane crankshafts started out with the same vibration problem. But where Europe was in the Automotive Dark Ages, American engineers strove to correct this. What they did was add counter weights/balances to the crankshafts that absorbed vibrations and created the smooth-running engines that American cars are known for. But there was a price to pay for that smoothness. Those counterweights take up engine power to turn: their mass resists movement and this causes those engines to accelerate slower and to achieve lower top speeds, and this also causes poorer fuel economy….. Being aware of these differences, in the late 1960s, I was building a racing engine for a GTO. The first build was around 430 ci with 700 hp. It turned out well and did the quarter in about 11.5 seconds. A year later, we were into the second build and I proposed a change to the car’s owner to cut down the crankshaft counterweights, as the car was just used for racing. We used a good machine shop and they were able to put the crank on a lathe and shave off a lot of that weight; albeit expensively. That engine build increased power a bit, but the engine accelerated much quicker and the shift speeds were a thousand RPM higher. After that, the GTO was hitting 10.5 seconds in the quarter.
European engines favor crankshafts that are of a single-plane design. Basically, they’re movement is linear, with half their pistons moving up while half are moving down; it’s a light weight design that allows for quick acceleration. But the connecting rod journals are moving rotationally, which causes lateral movement. This out-of-line movement causes a vibration that those designers didn’t consider large enough to address. It’s funny to drive a “55 V8 Chevy, then get into a “55 Volkswagen and feel all that shaking at low RPMs….. American V8s with cross-plane crankshafts started out with the same vibration problem. But where Europe was in the Automotive Dark Ages, American engineers strove to correct this. What they did was add counter weights/balances to the crankshafts that absorbed vibrations and created the smooth-running engines that American cars are known for. But there was a price to pay for that smoothness. Those counterweights take up engine power to turn: their mass resists movement and this causes those engines to accelerate slower and to achieve lower top speeds, and this also causes poorer fuel economy….. Being aware of these differences, in the late 1960s, I was building a racing engine for a GTO. The first build was around 430 ci with 700 hp. It turned out well and did the quarter in about 11.5 seconds. A year later, we were into the second build and I proposed a change to the car’s owner to cut down the crankshaft counterweights, as the car was just used for racing. We used a good machine shop and they were able to put the crank on a lathe and shave off a lot of that weight; albeit expensively. That engine build increased power a bit, but the engine
StevenWicked answered 2 years ago
Thanks for all the professional answers. If you're an example of the CarGurus site, its something I can rely on.
StevenWicked answered 2 years ago
Just went to a race and now I can tell the difference between a Porsche and a Corvette just by the sound. Ed92626 YOU ROCK.