New Vortech supercharged dyno sheet posted....
06-27-2002, 09:23 AM
#62
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HP = TQ * RPM/5252
So, yes. The magnitude of Torque [lb-ft] = HP at 5252 rpm. It must. No questions.
As to Mustang vs. Dynojet vs. whatever. I'll take an SF 901 over all of them. It takes the drivetrain and tires out of the equation. It may not be the best dyno out there, but it's a hard package be beat for under $50K.
So, yes. The magnitude of Torque [lb-ft] = HP at 5252 rpm. It must. No questions.
As to Mustang vs. Dynojet vs. whatever. I'll take an SF 901 over all of them. It takes the drivetrain and tires out of the equation. It may not be the best dyno out there, but it's a hard package be beat for under $50K.
06-27-2002, 09:43 AM
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Also, I'm pretty sure that a dynojet is pretty accurate when measuring torque, since torque is the force exerted by a rotating mass on another object. So, I think that a wheel spinning up another cylinder, not counting the loss caused by the flex of the tires, is pretty accurate.
Not to mention that I'm pretty sure the calculations going from the length it takes to spin through an RPM range converted to torque are basic physics calculations. If the dynojets work like you say, dongerguy, you're measuring the actual the rate of change of the speed of the cylinder at each RPM (ROC being acceleration). Take the acceleration, the weight of the cylinder, maybe the moment of inertia, and a few other components, and I'm sure there is an equation or two that will give you the torque. Those equations will ALWAYS work. The only thing that can throw them off is the inaccuracy of the data going into those equations.
Blake
Not to mention that I'm pretty sure the calculations going from the length it takes to spin through an RPM range converted to torque are basic physics calculations. If the dynojets work like you say, dongerguy, you're measuring the actual the rate of change of the speed of the cylinder at each RPM (ROC being acceleration). Take the acceleration, the weight of the cylinder, maybe the moment of inertia, and a few other components, and I'm sure there is an equation or two that will give you the torque. Those equations will ALWAYS work. The only thing that can throw them off is the inaccuracy of the data going into those equations.
Blake
06-27-2002, 10:36 AM
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s2kpdx01, what part of the equation posted by Phaco don't you understand? Oh wait, I didn't catch that your one of dem dere 'puter Engineers. I must be wrong. 
Go ahead and respond all you want because you are now on my ignore list.
Dongerguy and KAMcDonald - Sorry if I'm a pessimist when it comes to vendors hyping their wares, but I've been around the import performance scene for longer than I'd care to admit and have seen more than my share of bogus vendor dynos. I don't think it's too much to ask of a company selling $5K FI systems to post a dyno chart that is technically accurate. Basic Excel skills would allow anyone to make a table with the actual torque numbers, enter one formula to calculate the HP and create a graph that is more accurate than the one Vortech posted.
I'm done and so is this post until an actual customer posts a dyno.
Cheers,
Jimbo
Go ahead and respond all you want because you are now on my ignore list.Dongerguy and KAMcDonald - Sorry if I'm a pessimist when it comes to vendors hyping their wares, but I've been around the import performance scene for longer than I'd care to admit and have seen more than my share of bogus vendor dynos. I don't think it's too much to ask of a company selling $5K FI systems to post a dyno chart that is technically accurate. Basic Excel skills would allow anyone to make a table with the actual torque numbers, enter one formula to calculate the HP and create a graph that is more accurate than the one Vortech posted.
I'm done and so is this post until an actual customer posts a dyno.
Cheers,
Jimbo
06-27-2002, 11:58 AM
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Originally posted by infinitebass
Take the acceleration, the weight of the cylinder, maybe the moment of inertia, and a few other components, and I'm sure there is an equation or two that will give you the torque.
Take the acceleration, the weight of the cylinder, maybe the moment of inertia, and a few other components, and I'm sure there is an equation or two that will give you the torque.
T=I*alpha.
T = torque (3x1 matrix)
I = mass inertia matrix (3x3 matrix, 3 diagonals are moments of inertia, 6 off-diagonals are symmetric cross-products of inertia)
alpha = angular acceleration (3x1 matrix)
The inertia matrix should not change unless the drum is liquid filled (I would hope it is a solid, calibrated mass). The faster you accelerate; the more torque you generate. Looking at it from the car's perspective: the more torque you generate, the faster you accelerate.
PS: When have you ever met an engineer that could spell without a spell checker? Not I.
06-27-2002, 01:18 PM
#68
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thank you jimbo...i do understand the equation. the whole problem is i'm saying that the dyno is not made up or fabricated. I looked at the dyno. If you can say that it isn't crossing at 5252 then whatever...the stock one is off....I will give you that. why it is off..i don't know. The S/C dyno looks right though, again why is it different then the stock one in that regard I don't know. All i'm saying is vortech didn't make this dyno with crayons...it just didn't happen.
06-28-2002, 05:08 AM
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I don't know about Mustang dynos, but the way the data acquisition works on the dynos I have used would not permit an offset; ie crossover must occur at 5252 rpm. Therefore, the graph posted was clearly a cut and paste job. If the x axis was offset, why should I assume the y axis is accurately represented?
06-29-2002, 08:03 AM
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Hmmm I don't know too much about where the HP and TQ are supposed to cross but here are some observations...
The Comptech SC vs NA graph both cross at the exact same point. Looks like the 5252 RPM everyone agrees on.
Why doesn't the Vortech SC vs NA graph cross at the same point? (I don't know)
I really want the Vortech graph to be true and real since I am seriously considering to buy it. Looking at the graph now gives me some doubts of its objectiveness...
Has anyone contacted Vortech about their chart??
The Comptech SC vs NA graph both cross at the exact same point. Looks like the 5252 RPM everyone agrees on.
Why doesn't the Vortech SC vs NA graph cross at the same point? (I don't know)
I really want the Vortech graph to be true and real since I am seriously considering to buy it. Looking at the graph now gives me some doubts of its objectiveness...
Has anyone contacted Vortech about their chart??