Thread: First Time On the Dyno

Originally Posted by hockeybawler

Very nice numbers man! I am getting ready to install my meth kit as well(putting it in within the next week or so, currently sitting in my room lol). I thought the meth couldnt be shot in the air intake tube?

Why wouldn't you be able to spray it through the intake tube? Just curious. I had to order a piece for the the rubber intake so it would seal correctly, but other than that I don't see why you couldn't.

I know a lot of people hate on ZZP's PCM's, but my tuner said that they actually did a very good job with it.

Very nice numbers. I've had my Devils Own kit on for a couple weeks now, what size nozzle are you using?

Originally Posted by CapnBreakAlot

Very nice numbers. I've had my Devils Own kit on for a couple weeks now, what size nozzle are you using?

D05, they sent me a D07 as well.

Any difference between the two pulls other than the meth kit install? Was the tune the same?

Originally Posted by CapnBreakAlot

Any difference between the two pulls other than the meth kit install? Was the tune the same?

Well the car made 240/280 on the first pull with the mods in my sig. Then when the meth came on for next pull it made 262/387. The tune was tweaked and forgot how much timing was added. The guy that tuned it took off $300 because there wasn't much to to tune and he said it was very easy.

Something is not right. The horsepower and torque should ALWAYS cross at 5,252 no matter what. Torque can be measured, but Horsepower is calculated with Torque and RPM. The formula for Horsepower is torque X RPM/5252. Not really understanding what was done, but it seems the numbers are skewed.

Jeff

edit: the second graph looks correct.

Originally Posted by J57ltr

Something is not right. The horsepower and torque should ALWAYS cross at 5,252 no matter what. Torque can be measured, but Horsepower is calculated with Torque and RPM. The formula for Horsepower is torque X RPM/5252. Not really understanding what was done, but it seems the numbers are skewed.

Jeff

edit: the second graph looks correct.

I argued this with some experienced guys... technically correct but it doesn't always show up exactly on the dyno sheet that way. Strange but true.

How? Horsepower is a calculation not a measurable quantity as I understand the formulas and how Horsepower is derived. Not arguing just I don't understand this.

the only way I can see this happen is if the car spins the tires on the dyno.

Jeff

Horsepower is being measured on the dyno. Torque is calculated. Some of my dyno sheets don't even have a torque curve, because the dyno shop couldn't pick up spark signal.

No, Horsepower is not being measured by the dyno. It is being calculated by torque and RPM pure and simple. If the dyno only displays horsepower and not torque then it's because the operator didn't select it to graph. Look up horsepower, and it's defination. Horsepower is work done over time. It is calculated either using eddy currents and converted from electrical HP or its calculated on the time it takes to spin a large drum, but the calculation is always the same 5252 is the standard established based on something like 33000 foot lbs per minute. If the dyno lines do not cross at 5252 something went wrong and it is an invalid pull. When I dynoed my Tbird and Diablo back in the day if the dyno didn't cross at 5252 then we redid the pull. I was always told "mmm, something didn't go right." And the setup would be checked again and usually they would snug down the straps. When I was in school and studied power we went over and over this. We had to be able to convert all kinds of power numbers, Dynes,Watts, HP, Torque/Time/ BTU's all that junk, and the one thing I always asked is how do you measure HP, my professors always said "HP isn't measured, it's calculated."

Jeff

not to take away from the OP, accomplishments, but something wasn't t correct on the first pull. It's not possible to have torque and HP not cross at 5252 rpm.


Math does not lie

Originally Posted by J57ltr

How? Horsepower is a calculation not a measurable quantity as I understand the formulas and how Horsepower is derived. Not arguing just I don't understand this.

the only way I can see this happen is if the car spins the tires on the dyno.

Jeff

Thats pretty much it, real-world variation. There are different kinds of dynos and the info is best used in comparison to other tests run on that same dyno setup. Look at enough readouts and you'll see that the intersection is never far from 5252 but rarely falls exactly on it. Drive-on dyno numbers must be less consistent than flywheel due to all the added machinery between the powerplant and the dyno. Its not an exact science, but the math is.

Originally Posted by J57ltr

No, Horsepower is not being measured by the dyno. It is being calculated by torque and RPM pure and simple. If the dyno only displays horsepower and not torque then it's because the operator didn't select it to graph. Look up horsepower, and it's defination. Horsepower is work done over time. It is calculated either using eddy currents and converted from electrical HP or its calculated on the time it takes to spin a large drum, but the calculation is always the same 5252 is the standard established based on something like 33000 foot lbs per minute. If the dyno lines do not cross at 5252 something went wrong and it is an invalid pull. When I dynoed my Tbird and Diablo back in the day if the dyno didn't cross at 5252 then we redid the pull. I was always told "mmm, something didn't go right." And the setup would be checked again and usually they would snug down the straps. When I was in school and studied power we went over and over this. We had to be able to convert all kinds of power numbers, Dynes,Watts, HP, Torque/Time/ BTU's all that junk, and the one thing I always asked is how do you measure HP, my professors always said "HP isn't measured, it's calculated."

Jeff

not to take away from the OP, accomplishments, but something wasn't t correct on the first pull. It's not possible to have torque and HP not cross at 5252 rpm.


Math does not lie

On an inertia dyno, horsepower is measured, and torque is calculated via spark signal. If you are not able to pick up spark, you will not get a torque curve.

Actually on an inertial dyno torque is measured and horsepower is calculated. It's calculated by the time it takes to accelerate the mass (roller) over time. Again look at the way horsepower is calculated, it's work done over time.

Now I have seen a lot of dyno sheets both chassis dyno from Mustang the eddy current to the Superflow inertial. Every time I have had a run come out weird, either I or the guy running the dyno said it was a bad run and we ran it again and threw out that run because it wasn't correct. Personally I haven't had an issue picking up spark, but I have been turn d away because the dyno was not able to pick up ignition rpm because of one reason or another. As far as being "real world" unless dyno manufacturers have sat on their hands for more than 10 years and haven't improved their products, or people are using equipment that is not fit for proper measurement then everything should be spot on. I work in the weights and measures industry. I manufacture in-motion scales we weigh most everything you have ever come in contact with, be it food, concrete, C4 (yes the explosive kind), salt (table, rock and water softener), Bacon.... Basically the list is endless. Now the scale industry (among others) is heavily regulated by Weights and Measures. I don't recall seeing anything on dynos (octane and fuel, yes) but I'll check and see if there are any NIST standards for them but I don't think they are covered. Most of this looks like sloppy work of the operator. To me if someone tells you some stuff about phase of the moon or some overly complicated explaination they are not dazzling you with brilliance, they are baffling you with BS.

One instance of a company doing a half ass job of making a piece of machinery is some of the golfball dispensers. We had a company come to us to be able to fill golfball a into a bag based on weight. Well that's a problem since not every one weighs the same. We decided counting them would be better since that's what they were going for anyway. None of the manufacturers were able to hold a very good tolerance +/- 2-3 balls per fill. We said we could do 99%.

If you go into Walmart or Academy and are into golf chances are you have bought a bag or bucket of used balls under the Reload or Hunter name or any other used golfballs, they were done on the filler we designed. We are able to fill anywhere from 12-100 balls per package with 99.8% accuracy over the last 5 years in operation.

Now if our company can make a machine that we have no experience in counting golfballs at high speed. Why can't a dyno manufacturer get their crap together? I don't think it's the dyno I think it has more to do with the operator.

The math vs real world doesn't fly anymore. They may not be exact, but they will be within a couple of percent, if not something is wrong.

Jeff

No. A brake style dyno measures torque and horsepower is calculated. An inertia style dyno measures horsepower and torque is calculated.

Show me a the formula, and I'll stand corrected, but I have never seen a measurement of horsepower that was not calculated from Torque and RPM or work done over time.

In an inertial dyno the mass of the drum is known as well as its RPM so it's still calculated with no other inputs.

Jeff

I don't have a formula.

But horsepower is calculated by timing the acceleration of a known amount of inertia from one rpm to another. (Work/time, lb ft/sec, or power)

Knowing engine rpm, torque can then be calculated.

Originally Posted by GTPpower

I don't have a formula.

But horsepower is calculated by timing the acceleration of a known amount of inertia from one rpm to another. (Work/time, lb ft/sec, or power)

Knowing engine rpm, torque can then be calculated.

by your own words. Calculated. Ft/lbs per second is a measurement of Torque. Not a calculation.

But we're off track if the graph doesn't cross at 5252 then something went wrong. Believe me I am doing measurement all the time and you will get erroneous readings here and there. Sometimes you know what caused it others you don't. But the operator should know to throw that out.

Jeff

Originally Posted by J57ltr

by your own words. Calculated. Ft/lbs per second is a measurement of Torque. Not a calculation.

Jeff

I didn't make the rules on how an inertia style dyno works.