SOHC vs DOHC

[zaza.altis]

good day gurus. i was visiting honda show room yesterday and noticed 2 variants SOHC and DOHC . which of the two will translate to more power? how about fuel efficiency? and how do they work in layman's term. thanks and more power.

[washburn]

mahirap explain pero basta
SOHC ang matipid sa gas DOHC ang more power

[1D4LV]

SOHC means that there is only one camshaft per header. Inline engines will contain one camshaft. V-type and/or flat will contain 2 camshafts. For a SOHC engine there are usually 2 valves per cylinder but there can be more with the addition of cams for each valve.

DOHC have2 camshafts per header. So in an inline there are 2 camshafts because there is only one header, but there is 4 in a V-type or flat engine. These DOHC engines usually have 4 valves. One camshaft for the exhaust valves and the other for the intake valves.

Advantages to having a DOHC engine over a SOHC is that the engine has twice as many intake and exhaust valves as a SOHC motor. This makes the engine run cooler and more smoothly, quietly, and efficiently. But the downfall is that DOHC engines cost more for repairs.

[zaza.altis]

thank you sirs for the quick reply. more power!

[nameless411]

typically po, in terms of percentages -

re power - example po would you say that DOHC engines are 40% more powerful than DOHC?

re fuel consumption - would you say po that DOHC engines consume 25% more fuel?

kahit po ballpark figures ok na ok na po, para lang may idea kami...

thanks!

[XTO]

SOHC Engines Vs. DOHC Engines

Difference

SOHC stands for Single Overhead Camshaft. That means that there is only one camshaft per header. Inline engines will contain one camshaft. V-type and/or flat will contain 2 camshafts. For a SOHC engine there are usually 2 valves per cylinder but there can be more with the addition of cams for each valve.

DOHC stands for Double Overhead Camshaft. Now there are 2 camshafts per header. So in an inline there are 2 camshafts because there is only one header, but there is 4 in a V-type or flat engine. These DOHC engines usually have 4 valves. One camshaft for the exhaust valves and the other for the intake valves.

Advantages to having a DOHC engine over a SOHC is that the engine has twice as many intake and exhaust valves as a SOHC motor. This makes the engine run cooler and more smoothly, quietly, and efficiently. But the downfall is that DOHC engines cost more for repairs. To ensure against expensive engine repairs, make sure you change your engine's timing belt about every 60,000 miles.

http://www.angelfire.com/hiphop3/ppddaiddddyy/SOHC.html

[v6dreamer]

The difference are two letter......The S and D.

Peace!!! By the way, Ill let someone else do the big answer, here is the short one. SOHC develops a little less power than its DOHC brother, but it develops more of its power earlier and is therefore more flexible and generally more economical. The DOHCs rev much harder and higher, and at mid to top revs develop much more power for the same displacement engine, making them ideal for racing or performance vehicles. And if the DOHC is a V-engine, like a V6 or V8, it could be called a Quad-cam.

[mbeige]

SOHC and DOHC simply mean that the SOHC has a Single OverHead Camshaft, while a DOHC means Double OverHead Camshaft. The power and fuel efficiency really depend on what kind of tuning the engines were designed for, because there are cars that have DOHC engines but are meant for fuel economy, while on the other hand there are cars that have SOHC engines that can be tuned for much more power.

In stock form, typically the DOHC will have more power gains due to better control of the valves, since there are two camshafts. More power results in increased fuel consumption, but a better (meaning, lower) overall fuel consumption for DOHC engines can be attained by maximizing the power band and transmission/differential gearing. What this means is, since it has more power on tap, one can easily accelerate to a desired speed with less effort, so less fuel is consumed. But this is primarily dependent on driver skill already.

Also as mentioned earlier, DOHC engines typically have more valves per head, than its corresponding SOHC variant. With that, the DOHC takes full advantage of valve train control to attain optimum power or fuel economy, again this is dependent on the design of the engine.

There are inline engines that have either SOHC or DOHC. On the other hand, there are non-inline engines (either V shaped or boxer engines) that can have either as well. Some V6 engines, for example, have one camshaft per side so the right bank of three cylinders has one camshaft, while the other side has another one. There can also be two camshafts per side, so that effectively makes it four camshafts in total.

[niky]

Actually... the only real difference is in the number of camshafts.

A SOHC engine can also have 4 valves per cylinder, like a DOHC engine. The Honda Jazz and City only have SOHC motors. Yet despite both 1.3 and 1.5 liter variants being SOHC, the 1.5 liter version has 4 valves per cylinder, while the 1.3 liter only has three (because the secondary spark plug take up the space where the fourth valve would be).

Typically, it's easier to design a 4-valve per cylinder engine using two camshafts, and a 5-valve per cylinder (such as on the Toyota 20-valve 4AGE "Blacktop" motor) probably requires DOHC to work... but SOHC engines can be built in this configuration, also.

It's possible that you can be more flexible in variable valve timing with a DOHC head, and it's possible that DOHC heads may have more power potential, but Honda's SOHC R-engines (Honda Civic 1.8 and Honda CR-V 2.0) just blow that theory out of the water. Those two engines are at the top of their classes in terms of specific power output and fuel economy, and have one of the most advanced variable valve systems on the market today. They're much better day-to-day engines than the old K-series engines they're replacing, with comparable torque and horsepower with much better economy.

Of course, it's doubtful whether Honda can make an R-series engine as powerful as the Civic Type-R K20 (220 hp), as the R-series is an undersquare design not fit for the extra high revs that the K20 can develop, but in the real world, at least as far as Honda non-Type-R products are concerned, SOHC or DOHC is a moot point. Honda's SOHC engines can kick anyone else's DOHC blocks anyday...

[hondaesi]

Actually... the only real difference is in the number of camshafts.

A SOHC engine can also have 4 valves per cylinder, like a DOHC engine. The Honda Jazz and City only have SOHC motors. Yet despite both 1.3 and 1.5 liter variants being SOHC, the 1.5 liter version has 4 valves per cylinder, while the 1.3 liter only has three (because the secondary spark plug take up the space where the fourth valve would be).

Typically, it's easier to design a 4-valve per cylinder engine using two camshafts, and a 5-valve per cylinder (such as on the Toyota 20-valve 4AGE "Blacktop" motor) probably requires DOHC to work... but SOHC engines can be built in this configuration, also.

It's possible that you can be more flexible in variable valve timing with a DOHC head, and it's possible that DOHC heads may have more power potential, but Honda's SOHC R-engines (Honda Civic 1.8 and Honda CR-V 2.0) just blow that theory out of the water. Those two engines are at the top of their classes in terms of specific power output and fuel economy, and have one of the most advanced variable valve systems on the market today. They're much better day-to-day engines than the old K-series engines they're replacing, with comparable torque and horsepower with much better economy.

Of course, it's doubtful whether Honda can make an R-series engine as powerful as the Civic Type-R K20 (220 hp), as the R-series is an undersquare design not fit for the extra high revs that the K20 can develop, but in the real world, at least as far as Honda non-Type-R products are concerned, SOHC or DOHC is a moot point. Honda's SOHC engines can kick anyone else's DOHC blocks anyday...

yup i've done this with a mazda 3 car na

just my 2 cent

[RC-V]

advantage ng CR-V gen3 to gen2 fuel efficient lang? gen2-dohc gen3-sohc engine.

when overtaking need pa ng gen2 ng mid to high rpm para maovertake yung gen3?

[p_borj]

2.0 SOHC vs 1.5 DOHC Variable Valve Timing engine on a short sprint?

Marami akong kilala, ang sabi matulin talaga ang vios so tumatak sa isip ko itong bagay na ito hehe. One time, may nakatapat ako sa stoplight, gold Vios 1.5, ready to race so I gave it a shot kung ano ba ang ibubuga ng stock 1.5 DOHC VVT vs 2.0 SOHC. (Advie vs. Vios) (Paalala, street racing is dangerous and prohibited) Stoplight to stoplight lang kami so short burst sprint lang ang nangyari. To make the long story short, inungusan ko lang ang loko hehe, nasa 90km/hr na ako nung nag-brakes ako.

Dati kasi, ang pagkakaalam ko basta DOHC at VVT, eh tatalunin ka talaga sa heads on sprint pero hindi ganoon ang nangyari. I don't know baka dahil mas malaki ang displacement ng engine nung SOHC kaya baka nanalo. Baka kako pinagbigyan lang ako (but this happened 4 times pa and same result), so nagresearch na ako regarding SOHC vs. DOHC.

http://paultan.org/2005/06/22/sohc-vs-dohc-valvetrains/

"So to sum it all up, SOHC has better low-end power, DOHC has better high-end power and overall maximum power. 4 valves per cylinder is much better than 2 valves per cylinder and it doesn’t matter whether 4-valves is achieved via SOHC or DOHC."

After reading from this site, now I know bakit nanalo ako. Kung nasa highway kami, tatalunin niya ako kapag nasa 100km/hr na dahil mas nagpro-produce na nang mas more power ang DOHC kontra SOHC hehe. Sorry, short sprint lang mga nakalaban ko hehe.

[Type 100]

If you don't modify your engines SOHC vs. DOHC doesn't matter.

Like Niky mentioned, the R18A1 1.8L engine in the FD1 Civic is a SOHC four-banger with four valves per cylinder, hence a 16-valve design. Yet Honda managed to bang out an even 140 HP at the crankshaft from what is supposed to be a second-fiddle engine to its DOHC big brother, the K20A/K20Z 2.0L engine - with none-too-shabby torque delivery too. In non-Type R applications, as in the FD2 Civic and RE5 CR-V, the K20 is good for just 155 HP at the crank.

This just goes to show that for most purposes, the number of camshafts doesn't really matter. Such is the state of engine technology today.

Now if you were to go racing the normally-aspirated way...a twin-cam cylinder head would certainly help as an engine tuner could more effectively control the "breathing" of the engine. Having a dedicated camshaft each for intake and exhaust makes it easier to tune, in practice. For 90% of us however, the number of camshafts is a moot point.

[Type 100]

Double post, laggy forum

[Type 100]

Triple post, laggy forum