Okay here is my dilema, I've come across some aluminum heads that I can get for free so if I could use them I would like to. The heads are 54 cc and I am trying to figure out what dished pistons I could use to acheive the lower compression ratio I would prefer.

So basically I have two concerns one is if somebody could explain a simpler way in doing the math to figure out what compression a motor would yield if i know the gasket thickness, head size, and the - cc of the dished pison...


I tried a search and mostly came up with nonsense i couldnt put together .. I do have a somewhat understanding so I am just hoping for a lamens terms simplification if it is possible.


My second concern which I may need to address to the power adder board is if I may encounter any problems running a dished piston with a supercharger, I wouldnt imagine there would be but it never hurts to ask for my own self satisfaction.....thanks for any help you can give on either situation.


If I cant use the heads for my planned forced induction then I guess I cant I can always save them for another application later because mostly what ive foudn is i probobly cant get the compression down but I didnt know if my calculations were wrong...just wanted tp see what others thought.....

 

There is no simpler way; it's already about 4th grade simple.

It is commonplace to run dished pistons with blowers, turbos, or nitrous, or N/A for that matter, to get the desired CR. It is felt by most knowledgeable engine builders that a small-chamber head and a dished (or reverse dome) piston is a superior configuration to a large chamber and a domed piston.

 

It can't get much easier than this:

Engine Calculator.xls

 

whats 4th grade simple theres nothin posted but thanks for the actual tech help on the other situation



btw thanks to you also vader

 

Whether you posted it or not, the calculation method is extremely simple.

Compression ratio is nothing more than the ratio of the total cyl volume with the piston at BDC, to the cyl volume with the piston at TDC.

So all you have to do is to add up the volume of the chamber, the volume inside the head gasket, the volume in the deck clearance, and the volume of a dish or dome (add the dish volume to the others, subtract the dome volume); that's the volume with the piston at TDC. Then add the displacement of the cyl to come up with the volume at BDC. Then divide the one by the other.

Lots of places on the Net have Excel spreadsheets or HTML calculators posted, that you can just use; or you can write your own; or do what we all did for all those years before the Net, and just calculate it.

 

thankyou thats exactly the kind of definiton i was looking for i appreciate it.