12valve

hI
I need urgent help, I have to make a simple program for tomorrow, and wanna make it about

HP calculation. Hasnt to be very exact! So any formulas?
and torque-HP calculation. I forgot where i left that formula.

thanks in advance!

here are some usefull calculators, You can hit menu view-view source code...
just i dont really know which formula it is and how it works!
PS http://thedieselgarage.com/projects/...c/tirecalc.htm

RustyJC

HP = (Torque x RPM)/5252
Torque = (5252 x HP)/RPM

OR:

HP = (P x L x A x N)/33000

Where:
P = mean effective pressure (PSI)
L = length of stroke (feet)
A = area of piston (square inches)
N = number of power strokes per minute (all cylinders combined)

Rusty

12valve

THANKS A LOT!

Any Hp calculation from trap speed and or ET time?

Ph4tty

I haven't seen this before. Can you plug the numbers for a ctd and explain mean effective pressure?? We might need Hohn for this one

RustyJC

This is Watt's original equation used to determine horsepower of his steam engines. It is based in a linear frame of reference versus a rotational frame of reference for HP = (Torque x RPM) / 5252. The latter equation can be easily derived from the former - in fact, 5252 is just 33,000 lb-ft/min (the definition of 1 HP) divided by 2 x pi radians per revolution.

OK, let's take my engine back when it was in stock condition (245 BHP @ 2700 RPM) and solve for P, which in this case since we're using brake horsepower will be brake mean effective pressure (BMEP).

The equation becomes:

P = (BHP x 33000) / (L x A x N)

P = (245 x 33000) / ([4.72"/12] x [2.01^2 x 3.14159) x [{2700 / 2} x 6])

P = (8085000) / (0.3933 x 12.6923 x 8100)

P = 8085000 / 40434.24

P = 199.95 PSI

Mean effective pressure is the theoretical average pressure of the gas pushing down on the crown of the piston during the power stroke. It is used by engine designers as an indicator of engine "loading" (it ultimately determines torque in the familiar HP = Torque x RPM / 5252 equation) and is useful because it can be compared between engines of differing displacements or numbers of cylinders.

Rusty

Ph4tty

Thanks. I must be a geek since I enjoy the math threads- you've just been promoted to Hohn ^ 2 in my book

Good stuff. I'm going to bookmark this thread for future reference

RustyJC

From an engine design perspective, it's pretty clear that the engineers at Cummins designed the 2002 HO as a "200 BMEP" engine (at peak BHP) and let the ratings flow from that. Such is pretty typical - our company's KSV nuclear standby diesels (the last line of defense to power the cooling water pumps at nuclear power plants) are 250 PSIG BMEP 13" bore x 16" stroke, 600 RPM, V-12, V-16 or V-20 diesel engines.

Rusty