Engine Horsepower

Engine horsepower, abbreviated as EHP, is the estimate of engine horsepower after a quarter mile run using the trap speed.

 

Engine Horsepower formulas

\(\large{ EHP = W \; \left( \frac{ v }{ 234 } \right) ^3   }\)
\(\large{ EHP = \frac{ W }{ \left( \frac{ ET }{ 5.825 }   \right) ^3 }  }\)	(elapsed time)
\(\large{ EHP = W \; \left( \frac{ s }{ 234 } \right) ^3  }\)	(trap-speed)
\(\large{ EHP = \frac{ \tau \;\; s \;(RPM) }{ 5252 }  }\)	(rotating horsepower)
\(\large{ EHP_{change} = W \; \left( \frac{ v_2 }{ 234 } \right) ^3  \;-\; W \; \left( \frac{ v_1 }{ 234 } \right) ^3  }\)	(determine increase in horsepower)
\(\large{ EHP_{change} = \frac{ W }{ \left( \frac{ ET_2 }{ 5.825 }   \right) ^3 }  \;-\;  \frac{ W }{ \left( \frac{ ET_1 }{ 5.825 }   \right) ^3 }  }\)	(determine increase in horsepower with ET)

Where:

Units	English	Metric
\(\large{EHP}\) = engine horsepower	\(\large{\frac{lbf-ft}{sec}}\)	\(\large{\frac{Btu}{s}}\)
\(\large{ET}\) = elapsed time (time to finish quarter mile)	\(\large{sec}\)	\(\large{s}\)
\(\large{ET_1}\) = initial elapsed time (time to finish quarter mile)	\(\large{sec}\)	\(\large{s}\)
\(\large{ET_2}\) = final elapsed time (time to finish quarter mile)	\(\large{sec}\)	\(\large{s}\)
\(\large{s}\) = speed	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)
\(\large{ \tau }\)  (Greek symbol tau) = torque	\(\large{lbf-ft}\)	\(\large{N-m}\)
\(\large{v}\) = velocity	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)
\(\large{v_1}\) = initial velocity	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)
\(\large{v_2}\) = final velocity	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)