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Engine Terminology

Sun Apr 14, 2002 5:27 am

A quick question for you,

Lately, I've been wondering what the 2.0 litres or 2.2 litres means when refering to an engine. For example my engine is a 2.0L DOHC 150HP.


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RE: Engine Terminology

Sun Apr 14, 2002 5:47 am

2.0 liters - The capacity of the cylinders in the engine.

DOHC - Double overhead camshaft . This is the device that lets the valves move which lets the fuel in and the exhaust out. And there are two of them.

150HP - The engine creates the equivalent power that would take 150 horses to generate.
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RE: Engine Terminology

Sun Apr 14, 2002 5:50 am

Its the displacement. The amount of empty space in all your cylinders when they are at the bottom of their stroke.

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RE: Engine Terminology

Sun Apr 14, 2002 6:04 am

2000 cubic centimetres or the nearest displacement to it...eg 1998cc
in general a bigger naturally aspirated engine can produce more power...but there are always exceptions..
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RE: Engine Terminology

Sun Apr 14, 2002 6:32 am

You may also hear displacement written as cubic inches. About 61 cubic inches = 1 liter. So, you engine is also about 122 cubic inches.
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RE: Engine Terminology

Sun Apr 14, 2002 7:56 am

And if you want to get real technical, displacement is the bore * stroke * # of cylinders. Bore is the inside diameter of the cylinder, and stroke is the distance that the piston travels during one revolution. A larger engine will produce more torque for a given RPM, but there are ways to get more power out of a small normally asperated engine. These generally involve winding them to a real high RPM.

Indy cars manage 800hp out of a 1.9L engine. Of course, they're turbocharged and running on pure ethenol. And turning at around 14,000 rpm.

Interestingly, horsepower is a fabricated number that Watt came up with based on how much coal he thought a mine Mule could haul in a givin time- 33,000 lb-ft/minute. An interesting site for questions like this is How Stuff Works-

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RE: Engine Terminology

Sun Apr 14, 2002 11:44 am

Not quite right Illini_152, you left out pi. Displacement is a volume, so the formula is ((1/2 bore)squared x pi) x stroke x number of cylinders. And the more, the merrier!  Big thumbs up
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RE: Engine Terminology

Sun Apr 14, 2002 5:03 pm

Righto 'Fordlover' on the displacement calcultion...and I agree there's no replacement for displacement- in a pragmatic sense anyway. It should be noted that advertised Horsepower and Torque specs do not always tell the full story- They're just a "snapshot" at the peak of a curve and may not be indicative of the shape of the curve and how much usable power is available in most driving conditions. Generally, an engine with a broader powerband will be more satisfying to drive than one with a more "peaky" powerband. As the old hotrod adage goes: "Horsepower sells cars - Torque wins races". Horespower IS torque...but it depends on how effectively it is applied.
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RE: Engine Terminology

Mon Apr 15, 2002 3:10 am

Whoops- shows me to proofread these things before I post them; think one think, type another. Talk about the brain fart, I was thinking area x bore, and you are correct about the area being pi R^2.

Couldn't agree with you more about displacement; give me a P&W R4360 Wasp Major. he he he; biggest piston engine ever built. 28 cylinders, 5.75" bore, 6" stroke. Some put out as much as 4500 hp.
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RE: Engine Terminology

Mon Apr 15, 2002 5:41 am

Thanks guys for all the infos

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