Date registered: Mar 2005
Vehicle: '01-E320 & 02-ST2
Location: John 15:18-19
Mentioned: 0 Post(s)
Quoted: 35 Post(s)
Originally Posted by theboss
sorry this topic does not concern cars but engines only.
Im trying to adopt a vehicle engine into gen set use and would need its peak power at 1500rpm. Can anyone tell me what kind of cam adjustments i need here. I dont have a dynometer available otherwise it would be much easier.
The cam opens wide at piston BDC after power stroke and begins to close as piston is rising upwards and stays open until TDC. Then as piston begans to travel downwards for intake stroke, Intake valves begins to open while exhaust valve begins to close. There is a slight valve overlap here..So fresh air charge will push out any remaining exhaust gases. As piston reaches BDC, wide open intake valve will close much faster to hold as much charge as possible keeps backflow as low as possible.
cam lift should be kept low and duration longer for improving air velocity to aid engine breathing. Attached is a not so perfet picture of cam lobe shape i feel most appropiate. the flat side of the egg is what keeps valve open longer at constant height.
Just curious, why not use a diesel, which are designed to give peak torque early and run at lower rpms?
Be that as it may, some of your basic assumptions are skewed. Longer duration and overlap are required as RPMs increase (less time for the mixtures to move in and out of the CC), but at lower RPMS (which 1,500 certainly is for a conventional gasoline engine) you'd need less overlap and duration. Big valves and appreciable lift (since you don't have lots of mixture velocity at lower RPMs) are other things that would boost power at low RPM. Moreover, the design configuration of the combustion chamber is also a significant component here.
That said, your question is one that vehicle engineers tangle with on an ongoing basis and they have the aid of supercomputers to help them do the calculations and permutations necessary for the best cam design and static timing. A generic post in an automotive forum likely isn't going to yield you anything more than generalities and hypothetical guesses.
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy; its inherent virtue is the equal sharing of misery. (Winston Churchill)