Is the Ford Modular 3 valve more efficient than Honda’s K20A? The answer might surprise you.

First lets start with how everyone seems to think import’s engines are so much more efficient. It seems to be the first thing the owners and lovers of these cars seem to spout when talking about an American V8. Most of the time the larger engine makes more power, so they fall back into the stance of , “but my car is more efficient”, “I make 100 HP per L”.

Lets take a step back and define efficiency. HP per Liter is such a false representation of efficiency. If you want to measure efficiency, define some better rules. Volume that the engine takes up, not combustion volume, but the physical outside dimensions. Maybe fuel efficiency, which can be affected by all things outside the realm of the engine (weight, driver, gears, transmission, wind resistance). Manufacturing costs, dependability, etc…

There are alot of better ways that efficiency could be measured, but they don’t. Why? It’s an easy defense of why their car is better. It’s an ego thing. Nobody wants to hear they made a bad choice. I’m not saying that buying an import is a bad choice, but no one wants to hear that their investment is not perfect or the best thing on the road. The thing that gets me though, is even in this definition of efficiency - it fails.

What 111 HP per L really means.

I’m using the Japan spec Civic type R engine for the example. 2.0L engine 222HP @ 8000RPM = 111 HP per Liter. If you think about it, the engine isn’t really pumping just 2.0 Liters of air to reach 222 HP. It needs to spin to 8000 to reach that goal. So with that in mind and the fact that it’s a four stroke engine it’s really using 8000 / 2 / 222 Liters of air per horsepower. In other words about 36 Liters per horsepower.

Let’s break down that formula. The first number, 8000, is for the RPM required for peak horsepower. We divide the RPM by two because for every two rpms the engine fires all it’s cylinders. The last number, 222, is the peak horsepower for this engine.

Let’s apply this to the 3 valve Mustang GT engine. 5750 / 2 / 300 or 34.5 Liters per HP. Seems a little more efficient to me.

Of course this is only peak HP numbers. We haven’t even touched torque or power under the curve. I’ll leave that for another rant.