Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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Do you mean a calc that tells you what cam to run? If so keep reading, if not then please ignore me completely.
If you want to use a comp cam go to there website and and download camquest. You put in your setup and it gives you several cams that would work for you. It is just meant to be a guide though. If you posted your setup someone might be able to help you out on these boards.
I think Cam quest will give you what you are looking for. If you what I still have the setup file and will email it to you if you like. It will give you choices depending on motor, heads, type of intake manifold, weight, power added, exhaust, fuel delivery, and rpm range. It even gives you a projected power curve If you don't want a comp cam then you would at least get a idea of the duration, lsa, and lift you need to look for.
Ok well maybe it isn't on here, but on a forum, and I thought it was this one, there is a set of equations that help figure the best lift and duration configuration for a said set of motor specifications.
well there kinda is some math that can choose the proper camshaft for a given motor but i dont have that math. Custom cam grinders i'm sure have this knowledge I know there are engine simulation programs in the 300-500 dollar range that you can play with a ton of variables to analyze how the motor will make power and flow air.
I can imagine its extensive. To develop a camshaft, one needs to analyze flow dynamics of the intake manifold and heads. You will need to know the flow numbers they produce and lift range of the heads. You need alot of information such as wave harmonics calculations for your intake, and velocity the air charge carries into the ports.
You will need to know basic information such as cubic inches, possibly rod length, bore size, static compression ratio, vehicle weight/gearing etc, and generaly performance goals you have in mind. This will be used to determine camshaft characteristics to best suit your needs for your particular combo.
Once you know how the motor will be flowing air, you can calculate optimum valve events and duration the cam will need. Lift is basically pretty easy, you want to keep it near peak lift of the head if not alittle higher than peak flow. The intake opening poing and closing point both will help determine duration of the cam and where the powerband will be. Exhaust opening and closing point need to coincide with those numbers to keep cylinder pressure at its highest point and help expel spent exhaust gases from the cylinder based on the heads port flow rates and the exhaust sytem you will be running.
Intake opening and exhaust closing will help determine camshaft overlap. Higher rpm power goals will need more overlap, and hence tighter LSA.
I TOO am eager to find these equations and to better my knowledge of camshaft design. I went custom cam for my HSR 383 build and I'm looking into how the grinder may have came up with the specs. If i dont like this cam or want more power later, i want to beable to make my own grind
Ok well maybe it isn't on here, but on a forum, and I thought it was this one, there is a set of equations that help figure the best lift and duration configuration for a said set of motor specifications.
What you're looking for doesn't really exist. You could use systems of dozens of equations to model the engine and then optimize chosen variables including cam timing, or you could use off-the-shelf software to do it for you. Unless you're planning on having a custom grind done, it's a lot easier to pick a cam out of the catalog.
I know there are engine simulation programs in the 300-500 dollar range that you can play with a ton of variables to analyze how the motor will make power and flow air.
