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Torque = 5,252 x hp / RPM Bob 


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Hp = rpm x torque/5,252 Conversely, to calculate torque the equation is: Torque = 5,252 x hp/Rpm If you know either the hp or the tq, you can calculate the other. 


I guess I didn't explain very well what I was looking for.
I don't want to know what the torque is at the peak hp rpm. I want to know what the peak torque @ rpm estimated from the peak HP @ rpm data. For example, a 454 making 300hp at 4500 rpm makes about 450 ftlb of torque at 2500 rpm. Or a 283 making 300hp at 6000 rpm makes about 300ftlb of torque at 4000 rpms. I know there is some kind of "peak torque @ rpm" estimate that can be made from the peak HP @ rpm. Years ago I had a program that did that. 


Maybe this will help you:
www.rbracingrsr.com/runnertorquecalc.html There are many variables involved in caculating what you desire, but you may be able to get an appx. estimate. 


[QUOTE=454C10]I guess I didn't explain very well what I was looking for.
Seems to me that the formula works for all variables of horsepower and RPM whether "peak" or not. If you know the horsepower at any RPM, you can find the torque with that formula. Graphing the torque curve would then be an exercise in deriving the torque from several known values of power and RPM and plotting them, no? Bob 


Yes, that formula would work great if I knew the hp at the peak torque. But, all I know is peak hp @ rpm.
Knowing the peak HP @ rpm, it is possible to estimate a hp curve, and from there estimate a torque curve. 


[QUOTE=bobscogin]
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The program that he mentioned earlier most likely figured in part selections and calculated the answer based on the inputs. On the other hand, it seems that there was a program called "Engine Analyzer" or something like that which was availabe for free download. I think it was on a thread here a ways back...maybe if he could find that it would help. 


To many variables. Dependent on the combination and the camshaft as to how broad the powerband is going to be. Some engines are designed with a very narrow powerband (Pro Stock) some engines are designed for a very broad powerband, (marine engines). You peak torque rpm will very.



If you have only one known data point it's impossible to solve for another data point when only that one variable is know. If we know peak HP is 300 at 5000 RPM all we really know is peak torque is going to occur at a lower RPM, as it always does. Where is another matter. Unless you know the HP at the peak torque RPM point you can't calculate peak torque.
Engine analyzer calculates a torque curve based on engine modeling then assigns a HP number to the torque curve via mathamatical calculations as was shown earlier. In other words it's an engine simulation program. It's quite accurate if all the data is input correctly. I am sure you can write an equation which might get you in the ballpark but whether it's in the left field of the ballpark or the right field I have no idea. I guess surrounded by a Cam Doctor machine, two flow benchs and a real live dyno week to week I'm not used to swagging things or put much stock in the results. 


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Obviously real world testing is a far better way to go about this, but it still can be done...just too much work for me. 

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