Yeah - I need to talk to Dynapack today and figure out what is going on…I’m sure it is just a setting somewhere. Either way - good power for a fairly mild SR setup.
I have a feeling these numbers will soon be crushed.
if your running stock injectors i strongly recommend not to boost higher then 12psi. nice numbers but i dont forsee your engine lasting too long like that.
Thanks for the warning Mr 240sx… and your right on stock injectors this engine would have blown long ago. I have been running 14 psi since last season. My AFR’s are all with-in spec.
Good warning for anyone who sees this and thinks turning the boost to 14PSI will instantly net them these sort of #'s. Anything over 12PSI (and even I think that is high, 10 is the only 100% safe in all conditions boost level) will max out your stock injectors. It may read 95% on your SAFC or what ever but anything over ~80% is potentially unsafe.
But the graph shows the peak 260hp and the 5252 crossover…
If the RPM on the graph is wrong then the lb-ft @ XXXX RPM is wrong making HP (rpm * torque / 5252) wrong…
If the RPM on the graph doesn’t match what your actual engine speed was then HP cannot be accurate…
Not saying you made less hp or anything, infact if the rpm shown is LOWER than it was then you probably made MORE horsepower than 260…
Max,
Dan would be the best to explain this clearly but a dynapack dyno was only plotting incorrectly, not calculating. At least that was my understanding based on what Dan said.
However, taking a second glance at the chart the cross-over at 5252 does seem to line up to the chart which concerns me… hrm…
//edit// the only thing i can think of that would allow the 5252 to still line up would be that instead of the rpm reading being offset by “x” rpm throughout the entire range, the actual ratio from start to finish is not 1:1 and the 5252 is where starts from as a 1:1. I don’t see this being a possibility however…
I don’t see how it can calculate HP without knowing the car’s RPM.
I know that you don’t need to input final drive information for the DYnapack to measure torque accurately (some Dyno’s you do have to enter it)
Anyway… Horsepower is a calculation of WORK, to get an accurate measurement for work you need to take into account Force, Distance, Time.
The number 5252 is the result of several other calculations put together
1 hp is 550 foot pounds per second. meaning the force that can move 550 lbs of say… rocks 1 foot OR 1 lb of rocks 550 feet in one second.
since work is calculated using distance we need to turn rpm into distance.
1 revolution is 360 degrees
The circumference of a circle is 2 x pi x radius, we already know the radius… it’s 1 foot (cause it’s lb-ft torque) so 2 x pi x 1 = 2 x pi
(pi is 3.14159265)
so 2 x 3.14159265 = 6.2831853
Since we need distance per SECOND and not minute (m in rpm is minute) we divide that number by 60
= 0.1047198
Now divide 550 lb-ft by 0.1047198
= 5252.1
so near as needed 5252.
