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That is a good question. At one time all we had were American numerals to designate engine size. Basically if you were to call for a used engine before metric equivalents took over, you might ask for a 350 ‘cubic inch’ (CID) Chevy engine for a 1978 Camaro.

Now they call the same engine a 5.7 liter engine. Essentially, manufacturers and mechanics too have started to use metrics to Identify engines. I’m sure you noticed how many metric tools are used now in the auto repair field, compared to hardly any 20 years ago.

Say we have a good used engine marked 350 cubic inches. One liter has 61.5 cubic inches in it. So, 61.5 cubic inches X 5.7 Liters = 350.55 cubic inches, rounding it off, we get 350 CID.

If we wanted to convert a 350 cubic inch engine to centimeters, as some engines use to display size, then 1 cubic inch = 16.387 064 cubic centimeters. So, 350 cubic inches X 16.387 = 5735.45 CC’s or 5735 rounded off. Or 1 liter = 1 000 cubic centimeters, thus 5.7 liters ( 350 cubic inches) X 1000 = 5700 CC’s. Works out perfectly.

Last equation to consider is that 1 cubic centimeter = 0.061 023 744 095 cubic inchs. Therefore 5700CC X .061 = 349.5 cubic inches, rounded off to 350 CID.

That is my lesson today on deciding what size a used engine may be in either American or Metric designations. It is sort of confusing at first, I know this stuff instinctively because I have been a mechanic (and guitar player) for my whole life, literally.

In reality, we, my mechanics and I talked and interchanged terms all the time. But you should not be fooled by not knowing the differences in how to calculate engine size, especially if you are going to purchase a good used engine. Only a hand full of used engine suppliers understand this dynamic. It is quite helpful to deal with a salesperson who knows their stuff.

By reading the GotEngines.com blog, expect to learn undisclosed and misunderstood terms and equations such as the ones in this article, and many more. Enjoy sifting through our pages and feel free to comment, ask questions or sign up for a free subscription today..