Can anyone tell me what's these different?

Hi,
I checked the engine types of my fried's car and mine. One is "2.3L I-4 SFI SOHC;" ------------(2000 Accord DX) The other is "3.0L V6 EFI SOHC VTEC." --(2000 Accord EX)
Can anyone tell me what's the differences between these engines? Thanks.
Cuthbert
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one is a 4 cylinder I 4 inline 4, the other V6 6 cylinder.
Tom

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cc I-4 is an inline four cylinder engine design; V6 is a V-shaped six cylinder version with three cylinders on each side of the V SFI is Sequential Fuel Injection, where fuel is injected to each cylinder just in time to be sucked in; EFI is Electronic Fuel Injection... same thing basically, but the fuel is injected to all cylinders in the bank at one time. (SFI is a special form of EFI) SOHC is single overhead cam - one camshaft operates intake and exhaust valves. The alternative is DOHC (Dual Overhead Cam), with separate camshafts for intake and for exhaust valves. Older engines often had camshafts in the crankcase instead of above the head (overhead), and used pushrods to make the valves work. Pushrod engines didn't rev very freely. VTEC is Valve Timing Electronically Controlled. At normal engine speeds the camshaft sits in a position where the cams don't allow much "overlap" (times when both the intake and exhaust valves are open at the same time when the exhaust stroke transitions to the intake stroke.) This allows for steady idle and adequate power for tooling around. Engine tuners call it a "mild" cam. At a certain rpm, the camshaft is shifted by electronic command to use what is known as a "hot" cam; the intake valves open well before the exhaust stroke is finished and the exhaust valves stay open well into the beginning of the intake stroke. This improves both the intake charge and the exhaust scavenging. Using this cam all the time would produce a characteristically rough idle (you may have seen race cars shaking at idle... that's why), but at high rpm where breathing is hard for engines the effect is dramatic, increasing high end engine power as much as low pressure turbos do, and extending the maximum rpm (red line). Hoo-yah!
Mike
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