SOHC vs DOHC
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what are the disadvantages and advantages of the sohc engine over the dohc engine?
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http://auto.howstuffworks.com/camshaft3.htm
Try this web. It explains how SOHC works and very basic advantages of DOHC. -
double overhead cams seperates the intake valve timing control from that of the exhaust valves. one cam for intake,one for exhaust. crucial for variable timing operation. 2 cams allows you to play with the valve timing, so as to achieve the best torque/economy characteristics. this is only a simplistic exp.Originally posted by TVaddict:what are the disadvantages and advantages of the sohc engine over the dohc engine? -
hey thanks guys... so generally speaking, dohc is more fuel efficient than sohc...
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valve timing can be implemented on SOHC.. exp. the SOHC VTEC on current civic and also the new 1.8 litre i-VTEC SOHC powerplant coming soon from Honda, spec at 140ps and will be as fuel efficient as a typical 1.5 litre engine.
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WaahOriginally posted by RSKeisuke:valve timing can be implemented on SOHC.. exp. the SOHC VTEC on current civic and also the new 1.8 litre i-VTEC SOHC powerplant coming soon from Honda, spec at 140ps and will be as fuel efficient as a typical 1.5 litre engine.
, i want the post 2000 civics back!
1.6 litre, 175 horsepower and its a normal sedan. -
how? 2 camshafts but only 2 valves per cylinder? how to alternate?Originally posted by RSKeisuke:valve timing can be implemented on SOHC.. exp. the SOHC VTEC on current civic and also the new 1.8 litre i-VTEC SOHC powerplant coming soon from Honda, spec at 140ps and will be as fuel efficient as a typical 1.5 litre engine.
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http://world.honda.com/HDTV/news/2005-4050705a/
TOKYO, Japan, July 5, 2005 - Honda Motor Co., Ltd. today announced that it has developed a new 1.8l i-VTEC engine to be introduced this fall in the new Civic that achieves both more powerful performance and improved fuel economy. The engine employs an intelligent VTEC system that switches the valve timing for maximum efficiency during startup and acceleration to achieve powerful, torquey performance, then delays intake valve closure timing during cruising and other low-load conditions for improved fuel economy. Use of the valve timing control system results in off-the-line acceleration performance equivalent to a 2.0-liter engine, fuel economy approximately 6% better than the current 1.7-liter Civic engine, making it one of the worldÂ’s most efficient 1.8-liter engine designs. During cruising, the new engine achieves particularly high fuel economy, on a par with that of a 1.5-liter engine.
Under low-load conditions on conventional engine, the throttle valve is normally partly closed to control the intake volume of the fuel-air mixture. During this time, pumping losses are incurred due to intake resistance, and this is one factor that leads to reduced engine efficiency. With the i-VTEC engine, however, intake valve closure timing is delayed to control the intake volume of the air-fuel mixture, allowing the throttle valve to remain wide open even under low-load conditions for a major reduction in pumping losses of up to 16%. Combined with comprehensive friction-reducing measures, this results in a significant increase in fuel efficiency for the engine itself.
A DBW (Drive By Wire) system provides high-precision control over the throttle valve while the valve timing is being changed over, ensuring smooth driving performance that leaves the driver unaware of any torque fluctuations. Other innovations include a variable-length intake manifold that delivers optimum inertia effectto further improve intake efficiency and piston oil jets that cool the pistons to suppress engine knock, for powerful torque even atrpm ranges typical in normal driving. The new engine delivers a high level of performance, with maximum output of 103kW (140PS) and maximum torque of 174N·m (17.7kg·m). It also delivers cleaner emission performance, employing a 2-bed catalytic converter positioned immediately after the manifold and high-precision air-fuel ratio control to achieve emission levels 75% below 2005 Japanese government standards (based on Honda in-house testing).
In addition, lower block construction resulting in a more rigid engine frame, aluminum rocker arms, high-strength cracked connecting rods, a narrow, silent cam chain, and other innovations make the engine more compact and lightweight. It is both lighter and shorter overall than the current Civic 1.7l engine, and quieter as well. -
sounding like a big backlash on toyota
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sounds like the Altis, Sunny and Mazda will be peeing in their pants now.
Only thing is 1.8L engine may cost a lot more. Unless Honda manifacture in Thailand like the City. -
SOHC and DOHC does not means power....
ppl use to believe that DOHC is better thats why all the powerful cars are DOHCs..... -
but it does affects the power and torque rite? since it can control the intake and exhaust separately...Originally posted by ceecookie:SOHC and DOHC does not means power....
ppl use to believe that DOHC is better thats why all the powerful cars are DOHCs..... -
The key is that it is easier to tune a DOHC engine to bring out the engines performance. Or else why they invent this engine. But of course with some work on the engineering side, a SOHC engine can be as powerful but it is just harder to achieve.Originally posted by ceecookie:SOHC and DOHC does not means power....
ppl use to believe that DOHC is better thats why all the powerful cars are DOHCs..... -
say as good as dun say.Originally posted by ceecookie:SOHC and DOHC does not means power....
ppl use to believe that DOHC is better thats why all the powerful cars are DOHCs.....
u obviously have no inkling of wat u are saying kid.... -
Heh ... no sweat to Toyota ba ....
Have you heard of a 1GZ-FE(if remembered correctly) 1.8L DOHC Dual VVTi engine block?
hahahaha .... fierce competition from both company ... but its still Fuel over power ....
*$1.927 for RON 98 ....