Engine Basics, Spark
#12
#13
Engine Basics, Spark
If you see a torque and horsepower graph, and they dont cross at 5250, then its wrong.Horsepower is just a computation of torque and rpm, they have to cross at 5250.
Some motors, fire at every top dead center, they usually have the spark tigger on the crank. The more advanced types have the spark tigged by the cam, which only fires on the top of the compression stroke. It doesnt hurt anything to fire at the top of the exhaust stroke.
If you havent gone to www.howthingswork.com, yet....its a good place to learn some engine basics.
how things work
Some motors, fire at every top dead center, they usually have the spark tigger on the crank. The more advanced types have the spark tigged by the cam, which only fires on the top of the compression stroke. It doesnt hurt anything to fire at the top of the exhaust stroke.
If you havent gone to www.howthingswork.com, yet....its a good place to learn some engine basics.
how things work
#14
#16
Engine Basics, Spark
Yeh Hondabuster. What I meant to say is I've seen incorrect dyno curves (because the HP and Torque crossed at an RPM other than 5250). Correct, HP is a calculation of Torque and RPM.
Bigger - Maybe Sandaholic and I aren't explaining it correctly i.e. 180 degrees apart. What we are meaning is is you take your cams off when they are in the exhaust stroke TDC and THEN you re-install them facing out (at the same TDC - without rotating the engine) the engine will fire without a problem when you put everything back together. The spark system fires every TDC regardless of weather the cams are open or shut.
Bigger - Maybe Sandaholic and I aren't explaining it correctly i.e. 180 degrees apart. What we are meaning is is you take your cams off when they are in the exhaust stroke TDC and THEN you re-install them facing out (at the same TDC - without rotating the engine) the engine will fire without a problem when you put everything back together. The spark system fires every TDC regardless of weather the cams are open or shut.
#17
Engine Basics, Spark
Bigger - Maybe Sandaholic and I aren't explaining it correctly i.e. 180 degrees apart. What we are meaning is is you take your cams off when they are in the exhaust stroke TDC and THEN you re-install them facing out (at the same TDC - without rotating the engine) the engine will fire without a problem when you put everything back together. The spark system fires every TDC regardless of weather the cams are open or shut.
What I trying to say is, the notch in your crank is thier so you will be sure to get the cams in the right position(face outwards fom eachother). that way, the intake valves will be opening ,when the piston starts to drop. Remember the cams turn half as fast as the piston(2 rotations of the crank ,to one rotation on the cams). So on its upstroke the valves will be closed again and the spark plug will fire at TDC(again) igniting the comressed fuel. If the cams were 180 out, that could not happen.
Bigger.
#18
#20
Engine Basics, Spark
Originally posted by: biggerisbetter
Yes the spark plug will fire, But because the cams turn clock-wise(if looking at the sprockets), The exhaust vavles will now be opening when the piston is on its way down, therefore you will be drawing air through the exhaust into the combustion chamber instead of fuel and air.
What I trying to say is, the notch in your crank is thier so you will be sure to get the cams in the right position(face outwards fom eachother). that way, the intake valves will be opening ,when the piston starts to drop. Remember the cams turn half as fast as the piston(2 rotations of the crank ,to one rotation on the cams). So on its upstroke the valves will be closed again and the spark plug will fire at TDC(again) igniting the comressed fuel. If the cams were 180 out, that could not happen.
Bigger.
Yes the spark plug will fire, But because the cams turn clock-wise(if looking at the sprockets), The exhaust vavles will now be opening when the piston is on its way down, therefore you will be drawing air through the exhaust into the combustion chamber instead of fuel and air.
What I trying to say is, the notch in your crank is thier so you will be sure to get the cams in the right position(face outwards fom eachother). that way, the intake valves will be opening ,when the piston starts to drop. Remember the cams turn half as fast as the piston(2 rotations of the crank ,to one rotation on the cams). So on its upstroke the valves will be closed again and the spark plug will fire at TDC(again) igniting the comressed fuel. If the cams were 180 out, that could not happen.
Bigger.
Isn't this exactly what you described above, Crank at TDC, cams facing towards each other = drawing air through the exhaust into the combustion chamber instead of fuel and air.