How do I determine diesel starting requirements?
How do I determine diesel starting requirements?
(OP)
I'm working on a weight reduction contract for a 2kW military generator. The generator uses a 4.7hp Yanmar Diesel (211cc single, air cooled).
This engine has an electric starter on it (although it is almost never used, they like the option). I believe this starter is overkill because they also use it on a 400cc diesel - and it weighs 7-8lbs. I know I can save several lbs with a gear reduction starter. My question is how do I determine the starting requirements of the engine, minimum torque/rpm, etc. I would also like to know how flywheel inertia effects starting requirements.
Any suggestions are greatly appreciated.





RE: How do I determine diesel starting requirements?
Why not measure the current during a start and see what proportion of the starter's capacity you are using?
I'd guess, when starting a diesel, that a big flywheel helps to reduce the peak draw on the motor, leastways when hand cranking one I'd much rather have a big flywheel.
You need to size the starter to cope with arctic starts at a guess.
When an engine is running much of the friction is from the piston rings and valve gear - neither of which will be much smaller in a 200 cc than 400cc engine, at a rough guess.
Cheers
Greg Locock
RE: How do I determine diesel starting requirements?
Take the engine, bring it up against compression in a cold, not having been run in a while (no lubrication up in the engine,) and put a torque wrench on the engine, and see how much torque it takes to break it loose.
That may give you an indication of the range you are working in.
The flywheel inertia helps you with the starting situation. Once you get the engine spinning, the flywheel trys to keep it spinning, putting less strain on the starter. However, the starter has to overcome all the friction and inertia to get it spinning.
RPM, I would just measure the rpm of the current starter, and pick a replacement starter to match that RPM. Someone who put that large starter on it put one to produce that many rpm for a reason.
I hope these comments aid you in your quest.
rmw
RE: How do I determine diesel starting requirements?
PJGD
RE: How do I determine diesel starting requirements?