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I have this integra with DOHC that produces 140hp.

The newer Civics (2006 onward) have SDHC and 140hp Suppose these Civics are DOHC, would they produce more power?

Other thing when they already have VTEC engine, why don’t they make it standard? They already developed and therefore there is no additional R&D cost. Ford is cutting on R&D cost by going for global models.

Not necessarily. It has more to do with the engineering then the number of cams. Wouldn’t it make sense to design a motor that performed as well with fewer moving parts and less drag ? Same with VTEC. Some of their motors perform within the parameters they have set without it…why bother.

To me, it’s like stereo buffs talking about their speakers having titanium tweeters as a selling point when what really matters is the sound, regardless of how it is produce. In cars, it 's the performance.

Honda’s very clever at getting 99% of the benefits of DOHC with SOHC. Might there be a few more hp? Yes, but at higher cost. For a given cost I’m pretty sure Honda designed the best engine they could.

The number of cams used is only one of many variables that determine how much power a given displacement engine can produce. DOHCs have the advantage of allowing multiple valves to be placed on each side of the chamber, enlarging the amount of flow that can be accomplished in & out of the cylinder, but depending on the configuration of the piston top and the cylinder head that may or may not be beneficiel when one is also considering gas mileage as a goal, especially with the proliferation of forced air devices. And with direct injection becoming common, one has to find room for the injectors in the cylinder heads as well as the spark plugs. Two valves might be able to provide for the engine’s need just as well as three, yet still leave room for the injector.

CAFE requirements and emissions requirements have taken over as the primary drivers for engine design. Yes, designers try to eek out power when they can, but mostly they try to move closer to 54 mpg and zero emsissions. Putting the injectors directly in the cylinders allows more complete combustion, even if it does reduce the space available for valve area.

Actually, TSMB, the Honda SOHC has 4 valves/cylinder. Like I said, Honda is very clever.

Honda has made quite a few SOHC 4 valve-per-cylinder engines, including ones with VTEC. My Odyssey has one, as did my Civic. Other manufacturers have, too. The SOHC Neon was a 16 valve inline 4.

Four valves it is. Yeah, it’s really only a question of having rocker arms on both sides of the camshaft. I guess I really messed that explanation up!

DOHC gives more freedom to configure the valve angles: how the stems/heads are tilted.
Plus smaller, straighter rocker arms, or no rockers at all.

And greater head angles means more area to put bigger valves.

I gues it all gets back to the opint that there’s more than just SOHC vs. DOHC invlolved in making horspower. And there definitely is.