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King of Smart Gadgetry
1,075 Posts
Discussion Starter #1
Now if you drive a 451, have you ever wondered just how big your engine is? Well the engine is pretty well buried under that engine cover that you have to remove to check your oil. You can kind of see it down in there, or at least a portion of the valve cover.
Now you have probably heard me say on the forum before that if you are driving up a hill in your Fortwo and a Harley Davidson motorcycle passes you, don't be offended because he has a larger engine than you do, and that is a fact. Later model Harley Davidson motorcycles come with 2 different series of "V" twin engines, the 88B and the 96B engine. In very general and vague terms a Harley engine can range from 82 cubic inches(1,340 cc) to a 110 cubic inch (1,801 cc). So okay how does this relate to my Fortwo engine? Well the Mitsubishi 3B21 series engine in our Fortwo is considered a 1 litre engine. A litre = 1,000 cc's or 61 cubic inches. The Smart is actually 999 cc's so it's just under 61 cubic inches or just under a litre. So when you compare it to the Harley, you see that the smallest Harley modern day engine is 82 cubic inches to the Fortwo's 61 cubic inches or in other terms the Harley's smallest engine is 1,340 cc's to the Smarts 999 cc's. The largest Harley engine is 110 cubic inches to the Smart's 61 cubic inches or 1,801 cc's to 999 cc's. So the large Harley engine is almost twice the size of your Fortwo engine in displacement. Or another way of looking at it is, the Fortwo engine is only 74% of the size of the smallest Harley engine.
Now lets look at the comparison of vehicle weight. The Fortwo weighs in at roughly in the 1,800 pound range. A basic Harley Davidson "superlow" weighs in at 540 pounds. A Heritage Softtail weighs in about 730 pounds and a CVO Road Glide Ultra weighs 905 pounds. So the lightest Harley weighs a 3rd of what the Fortwo weighs and even the heaviest full dress Harley weighs half what the Fortwo does.
So you can see that if a motrocycle like a Harley weighs substantially less and has an engine substantially more than the 451 does, it's no wonder the car may seem underpowered. Plus the engine has to run the air conditioning compressor when the passengers need cooled off or the defroster is turned on. Even with the air conditioner off the engine still has to turn the pulley and belt. Then the engine has to turn a 90 amp alternator and also the water pump to circulate the coolant through the engine and through piping to the radiator at the front of the car and back to the engine again.
Now down in that engine bay it's hard to tell how big (or small) the physical dimensions of the engine is because towards the rear of the car is the exhaust manifold, catalytic converter and muffler. Towards the front side of the car the engine has the intake manifold on it. Towards the driver side of the engine is the bellhousing with the clutch inside if it and the GetRag Transmission. All of that bellhousing and tranny is hidden under that big black airbox. Towards the passenger side of the engine is 2 belts and pulleys for the Air conditioner compressor, water pump and alternator.
The entire engine was designed by Mitsubishi to not stand up straight. The engine is slanted like one side of the letter "V". They did this so that the engine would sit under the floor in the rear of the car and still leave some room for cargo.
So to put it into actual size dimensions, we'll take a look at the head gasket and that will give you an idea of the size of the actual engine, the size of the cylinders and the size of the pistons that are in each cylinder.

Since the engine sits sideways in the chassis, the front of the engine faces the passenger rear wheel and the rear of the engine faces the driver side rear wheel. So you can see from the picture that the engine itself is 11 inches long (27.94cm). So it's less than a ruler and is about the size of the length of a sheet of standard notebook paper.

Now the width of the engine is about 6 inches (15.24cm). Now a standard #2 pencil with an eraser and unsharpened is 7.5 inches (19.05cm). So the width of your Fortow engine is less than a new pencil.

Now the diameter of the cylinder is about 2 3/4 inches (6.98cm). Now the diameter of a standard pop can is 2.6 inches (6.6 cm), so a soda can would sit down inside of one of the cylinders with 3/20th of an inch (.38 cm) left on the sides to flop around in there.

So the piston moves up and down in the cylinder, but how far? If we measure the piston at it's lowest point (bottom dead center) BDC, and then let it go to the very top of it's travel, even with the top of the engine block (top dead center) TDC the piston moved 3.22 inches (81.8mm). So that's 1.61 inches less the the height of a soda can. So your piston is moving up and down 2/3 the height of a soda can. So if you take the displacement of all 3 cylinders and combine them together, you are running in the displacement of air equal to 2 pop cans.

So I hope this puts it all in perspective in simple everyday terms. The next time you complain about the lack of power in acceleration of your Smart, remember what a minscule amount of displacement is moving you along down the interstae at 75 mph, pulling a hill, with the A/C on, a passenger in the passenger seat, a weeks worth of groceries in the cargo area, and an outside hot July day temp of 100 degrees. DCO:laugh:

He's not mine
9,617 Posts
DCO, it's just big enough to fit....:)
Big enough to get the job done. And deliver a fun ride if you want it to.

But yeah, 999cc, that's why I didn't buy the chromed lettering stating 1L, for my overly verbose rear end, it's not accurate.
On the other hand, if an item costs $9.99, most people would say it costs ten dollars (myself included).

844 Posts
Don't forget the "Sportys".....883cc and 1000cc.....
it's funny, the 883 sportster weighs the 540 he listed as the low weight (dry, 562 lbs "wet"). i still carry a "class m" license but haven't ridden a bike in 30 years. then there's the newer little "500" that weighs 489 lbs...


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