You can reach me at phinishline@yahoo.com for comments, questions, and suggestions.To make the calculations for the dyno you must know a few things:
Once you can identify all of the above factors you are ready to make your calculations. What you will need is a chart so that when you do the dyno runs you can record your data. You will need to record Motor RPM and pressure at several different points to make your graph (and pump flow if you use a flow gauge).
To do the simple HP calculation all you have to do is:
In this calculation you have to know pump gpm. The way to get pump gpm is:
To get pump size it should be on the pump or you may have to call pump manufacturer with model number and get pump info. To get pump rpm you just divide the motor rpm by the gear ratio. Example - 6200(motor rpm) divided by gear ratio of 3.625 (16 engine gear 58 axle gear) = 1710 axle / pump RPM.
The way this system is set up you get your HP readings first. Then you punch the HP numbers into a formula to get your Torque. Here it is:
That was simple enough!
Very important question. No, you don't have to correct for weather factors but if you do it doesn't matter if you do the dyno reading in December or July you can correct the readings for the weather factors and still come up with a usable reading. There is a way to correct the dyno readings for weather factors but it is to long to put on this page. The only way I can tell you to get it is to go to my Excel Calculations spread sheet and do the calculations there. It took me about 3 days to put all the numbers into a spread sheet. It is a very long and drawn out process. I got the table and factors from John Copeland, he posted the numbers and chart in National Kart News Magazine. You can still order the back issues from them I believe. If you are using a spreadsheet program other then Microsoft Excel let me know and I may be able to convert the file for you. Hope this clears up all the questions everyone has had about getting the calculations from the dyno.
I have been getting a lot of questions of how I came up with the numbers used in the formula's. Well, I'll be the first to admit I don't have a clue. Somewhere in time I'm sure several engineer's and R&D teams came up with the formulas through years of testing. What I can do is point you to some very good articles that explains it MUCH better than I ever could. To see the formulas that I use and many others that will be helpful to you at sometime look at the webpage by Ram Industries Inc. To get an idea where the "1714" comes from in the in the HP formula take a look at the webpage by Westlands Water District. A very well written article. For more info on where the 5252 comes from in the Torque formula take a look at the page by Westech Performance Group, Inc. Very good info!
Jamie Webb
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You can reach me at phinishline@yahoo.com for comments, questions, and suggestions.