VTEC, DOHC, SOHC and Rotary Engines
-
Is there any websites to clearly explain what are the differences between these engines? I am still quite fuzzy about the concepts of how these engines work . Would appreciate if any one here knows about it and explain
-
http://www.streetracersonline.com/articles/camshafts/3.php
http://auto.howstuffworks.com/rotary-engine.htm
http://www.mycarforum.com/forum/gforum.cgi?post=273681;search_string=vtec;#273681
VTEC is a technology found in Honda engines. So it is more of a feature than a engine as compared to DOHC and SOHC and Rotary.
The technical aspects of VTEC is quite hard to explain..but what i can do to help u understand it to explain to you how it feels.
The older generation of Civics basically has a 2 band VTEC engine. This means that below a certain RPM (for eg, 5500) your car is basically more like a tame tiger. Once you reach 5500, the VTEC kicks in. You can hear the distinct VTEC sound from your engine...when VTEC kicks in, it would SEEM as if all of a sudden you are running on Racing cams....you car will have improved power and torque. Needless to say, your fuel consmption will go up to.
DOHC stands for Double OverHead Cams and SOHC stands for Single. There isnt much to explain over here that you cant already deduce from the two terms. DOHC engines generate more power as two cams are used to deliver power and torque over the entire RPM range while the SOHC uses only 1 cam.
With that i do not mean that SOHC engines are slow...properly tuned and with VTEC, they can even trash my stock TwinCam 4A-GE engine.
Lastly, Rotary engines. They work totally different from Electronic Fuel Injection(EFI) and Carb engines. I am not too sure how it works too but i have attached a link above for you to read up more.
the last link that i posted have alot of pple who are very good at the the mechanics of a car and the details of tuning a car. maybe you can find more help there. -
rotary engines operate in a world w/o cylinders nor pistons... how the triangular rotar spins creating the traditional combustion process, you gotta see the graphic motion to understand haha...
-
so which type of engine is better?
how about the V6, V8, V10 or the W12 engine? -
V6- six cylinders, V positionOriginally posted by heynsl:so which type of engine is better?
how about the V6, V8, V10 or the W12 engine?
V8- eight cylinders, V position
V10- ten cylinders, V position
W12- 12 cylinders, W position (eg. Continental GT, Bugatti Veyron)
-
those dudes very smart hor... those who invented the rotary engine...Originally posted by Theatre Of Dreams:rotary engines operate in a world w/o cylinders nor pistons... how the triangular rotar spins creating the traditional combustion process, you gotta see the graphic motion to understand haha... -
Read the Renesis Engine (Rotary Engine) under Mazda RX-8Originally posted by seizure_:Is there any websites to clearly explain what are the differences between these engines? I am still quite fuzzy about the concepts of how these engines work . Would appreciate if any one here knows about it and explain
http://autozine.kyul.net/html/Mazda3.htm#RX8
Kudos to Mazda for keeping the Rotary Engine Evolution alive!
-
Heh.... now if only they could make the fuel consumption better as well...Originally posted by TwinTurbo_Supra:those dudes very smart hor... those who invented the rotary engine... -
for the question of an engine size, the whole deciding factor is the aims of the designer. A V12 has more cylinders, hence the gap timing between each of the cylinders' firing order is smaller, hence it is smoother. But there are so many factors to consider.Originally posted by TwinTurbo_Supra:V6- six cylinders, V position
V8- eight cylinders, V position
V10- ten cylinders, V position
W12- 12 cylinders, W position (eg. Continental GT, Bugatti Veyron)
In terms of more cylinders, 12 vs 10 vs 8, in general more cylinders means more valve area, so u can in theory get more airflow in an engine per revolution. More cylinders also tend to have lighter pieces for a given capacity, so u r often able to run them to a higher RPM. And both of these things mean more airflow, to which you put more fuel, and that means you add more base power.
But what u do is u take off some things too. More cylinders give u greater losses thru friction. Though u are theoratically producing more power, because there are more moving parts so it takes more power for them to move, so in theory u get a situation where a 12 vs 10 vs 8, will each respectively have more power but a lot more losses, so that the actual bhp is different.
But there is obviously a lot more to it, because of the losses. More cylinders are less efficient, so you have to use much more fuel. In the end u've got a lot of things going against much more cylinders and only a few going for them.
Also considering the bore and stroke, in a V8, it has a large bore, which is god for generating power, and a short stroke, which is also good for boosting revs because the piston has less dist to travel, It has good torque. For a V12 though, the capacity must be much larger, because in any case, if u compare a V8 and a V12 both with the same capacity, the V12 is going to get better top end power because of the lighter pistons moving up n down, but it lacks low end torque.
Another problem is packaging. In designing a car, u have to decide how to package the engine. A V12, though more powerful, is longer and heavier, used more fuel, and its crankcase was so much longer that it is fundamentally less torsionally stiff. There are also more exhaust pipes to package. Also, operating with more friction, it is less heat efficient, which would imply that larger radiators are needed, which presented more packaging problems. This would also lead to increased drag, which could be undesirable for the want of a slightly superior top end power. -
...and to that may I add - Vroom!!! Vroom!!!Originally posted by HENG@:for the question of an engine size, the whole deciding factor is the aims of the designer. A V12 has more cylinders, hence the gap timing between each of the cylinders' firing order is smaller, hence it is smoother. But there are so many factors to consider.
In terms of more cylinders, 12 vs 10 vs 8, in general more cylinders means more valve area, so u can in theory get more airflow in an engine per revolution. More cylinders also tend to have lighter pieces for a given capacity, so u r often able to run them to a higher RPM. And both of these things mean more airflow, to which you put more fuel, and that means you add more base power.
But what u do is u take off some things too. More cylinders give u greater losses thru friction. Though u are theoratically producing more power, because there are more moving parts so it takes more power for them to move, so in theory u get a situation where a 12 vs 10 vs 8, will each respectively have more power but a lot more losses, so that the actual bhp is different.
But there is obviously a lot more to it, because of the losses. More cylinders are less efficient, so you have to use much more fuel. In the end u've got a lot of things going against much more cylinders and only a few going for them.
Also considering the bore and stroke, in a V8, it has a large bore, which is god for generating power, and a short stroke, which is also good for boosting revs because the piston has less dist to travel, It has good torque. For a V12 though, the capacity must be much larger, because in any case, if u compare a V8 and a V12 both with the same capacity, the V12 is going to get better top end power because of the lighter pistons moving up n down, but it lacks low end torque.
Another problem is packaging. In designing a car, u have to decide how to package the engine. A V12, though more powerful, is longer and heavier, used more fuel, and its crankcase was so much longer that it is fundamentally less torsionally stiff. There are also more exhaust pipes to package. Also, operating with more friction, it is less heat efficient, which would imply that larger radiators are needed, which presented more packaging problems. This would also lead to increased drag, which could be undesirable for the want of a slightly superior top end power.
-
V engine is more smooth than inline 4.
V8 more smooth than V6 especially on high speed and high rpm.... you wont feel too much jerky compare to less cylinder like V6. -
sound of inline-6 is da best!!!
eg. car in my nick -
so it is to say that V6, V8, V10 and W12 kind of engines enven though can have high performance but very fuel hunger?
those normal type of engine such as DOHC are more balanced in their performance as compare to fuel compsumtion? -
in-line 6 is the best! wish i had one. n u find it in cars that i can never get: skyline GTR (especially R32!) and supra. but of coz, twin rotor is still the god of engines
going to dream abt them.... again... -
yes of course. the reason why most family cars use in-line 4s, even the higher capacity onesOriginally posted by heynsl:so it is to say that V6, V8, V10 and W12 kind of engines enven though can have high performance but very fuel hunger?
those normal type of engine such as DOHC are more balanced in their performance as compare to fuel compsumtion?