You can hold back, and not be able to measure; you can not measure without being able to hold back.

A torque arm sunk into a block of concrete may hold a motor back, but it's not measuring anything.

Due to the method of acceleration of a nitomethane motor, and the load application of this and any other dyno's of sufficient capacity, the motor would self destruct long before peak power or load were applied.

The dyno can hold it back, but it can't measure it.

 

Dang, I am continually amazed that anyone can get so stuck on sematics. I don't care if you call it load, hold back whatever you care to call it.

If you are worrried about loading the nitro-methane motor during acceleration just put an inertia on it and provide additional loading with the water brake.

This has nothing to do with the way a nitro motor accelerates. Heck even an inertia can load the motor so that motor can provide full load. There is no majic to a nitro motor. It is just a high HP motor.

Yes, a dyno measures torque. And given that you measure speed, HP is just the product of torque and RPMs divided by a constant.

Once again, I ask you: what makes you think this dyno won't work?? Either chit or get off the pot!!

 

It continually amazes me how you overlook critical items so that you can continue to claim your correct!

Please get it right, I'm not disputing load vs. hold back. I'm disputing measure vs. hold back. I never said a thing about a dyno not being able to hold it back, I said it couldn't measure it.

You again show your true ignorance when you state that this has nothing to do with how a nitromethane motor accelerates. Do you realize that if sufficient load is supplied to slow the nitromethane motors acceleration (and that is what is required to find the limit), then it's fuel will extinguish the ignition? If that were to happen to just one cylinder, the results would be useless. It would likely happen to all cylinders.

I wouldn't call a nitro motor "majic", but I would call it touchy. It must opporate in a particular way and any diviation from that will cause it to self destruct. Too much load slows the motor, causing too much fuel, causing failure. It's fuel system is only designed to work under certain "narrow" parameters. Essentially- Idle, burn-out, and full throttle.

Now the dyno you chose is an engine dyno, not a chassis dyno. If we use it directly to the engine, the load can not be controled quickly or accuratly enough to achieve a measurement. If we use it as a chassis dyno to take advantage of the clutch system, bolting it to an axle(to eliminate tire slippage), then we can not put the entire load of the engine through one axle without it shearing. We can not use one on each axle because the dyno you chose is not reversable. The dyno you chose is for diesel and turbine engines, specificly. Both of these motors (diesel and turbine) produce huge amounts of power, but are not qiuck accelerating. What more needs to be shown to you before you admitt that it's not capable? How about you show us were it says that it can be used for a nitromethane motor. [I would mention the futility in proving a negative, like you continually ask me to do, but it would likely start you on another obsquere tangent] Like I said originally, show me an exact HP figure that demonstrates that someone has been able to do this.

I thought you were starting to learn, but I over estimated you. "What you don't know; you are too ignorate to realize"- done in my best Yoda voice

Ok, I'm done with the thread again, I hope, probably, maybe, please let me be.

As for "chit or get off the pot"- you are proving to be the expert on chit, I'll give you that.

 

I am going to take a guess at what is bothering you knutz. I think the concept of inertia is not clear. When the fueler is on the drag strip, the only thing that holds the engine torque back at the starting line is the inertia (weight, mass) of the vehicle. The engine can only accelerate the dragster as fast as the torque supplied by the engine can accelerate the mass (assuming the tires do not spin). So if we want to make a dynamometer accelerate like the vehicle, we add inertia (mass) to the rotating dyno to a value that is equivalent to the dragster. Then when you apply full engine torque to the inertia, the inertia will accelerate just like the vehicle. If we left it as that, we would just have an inertial dyno. However, if we want to simulate aerodynamic drag, we must add an additional load to the inertia using the water brake. In addition, if we want to hold the engine at a fixed speed, we need the water dyno to supply a load equivalent to the maximum engine torque. So by using a water brake and an inertia, we get a dyno that can simulate the acceleration of the dragster, but also a water brake that can provide a fixed load at a constant speed. The dyno I cite has enough torque to almost stall the nitro-methane engine at full torque. With a 4:1 gear box, this dyno can absorb 20,000 Nm of torque at the crank (80,000 Nm at the dyno), yet the engine can only generate 6000 Nm of torque at the crank or 24,000 Nm at the dyno. The measuring device is a load cell, but an inline torque transducer would have to be added to measure the torque between the engine and the dyno/inertia. Funny thing is, this dyno is about the same size (in volume) as the nitro-methane engine.

 

Lok down to the next page, this dyno is reversible by using the two direction version. Down rated from 80,000 Nm to 70,000 Nm. And if we use twin dynos (one on each wheel) we can use the next size smaller dyno the 3600. Water dynos are used as engine dynos, chassis dynos and power train dynos. Still don't see a problem here.

 

There is no problem with measurement. If you want the fastest torque measurement device, you will buy a standard inline torque transducer. These have a dynamic response much faster than any nitro-methane engine that you could possible build. Is a frequency response of 1000Hz good enough for you? This transducer will be so good, you will be able to see the individual torque pulses of the cylinders firing. If that is not good enough, you are had to please.

 

Acceleration explained.


* One Top Fuel dragster outfitted with a 500 cubic-inch replica Dodge (actually Keith Black, etc) Hemi engine makes more horsepower (8,000 HP) than the first 4 rows at NASCAR's Daytona 500.

* Under full throttle, a dragster engine will consume 11.2 gallons of nitro methane per second; a fully loaded Boeing 747 consumes jet fuel at the same rate but with 25% less energy being produced.

* A stock Dodge Hemi V8 engine cannot produce enough power to merely drive the dragster's supercharger.

* With 3000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. Cylinders run on the verge of hydraulic lockup at full throttle.



* At the stoichio metric 1.7:1 air/fuel mixture for nitro methane the flame front temperature measures 7050 degrees F.

* Nitro methane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

* Dual magnetos supply 44 amps to each spark plug. Which is typically the output of an electric arc welder in each cylinder.

* Spark plug electrodes are totally consumed during a pass. After 1/2 way thru the run, the engine is 'dieseling' from compression and the glow of the exhaust valves at 1400 degrees F. The engine can only be shut down by cutting the fuel flow.

* If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with enough sufficient force to blow the cylinder heads off the block in pieces or split the block in half !!

* Dragsters reach over 300 MPH +... before you have completed reading this sentence.

* In order to exceed 300 MPH in 4.5 seconds, a dragster must accelerate an average of over 4 G's. In order to reach 200 MPH well before reaching half-track, at launch the acceleration approaches 8 G's.

* Top Fuel engines turn approximately 540 revolutions from light to light!

* Including the burnout, the engine must only survive 900 revolutions under load.

* The redline is actually quite high at 9500 RPM.

* THE BOTTOM LINE: Assuming all the equipment is paid for, the pit crew is working for free, & NOTHING BLOWS UP, each run will cost an estimated $1,000 per second.

0 to 100 MPH in .8 seconds (the first 60 feet of t he run)
0 to 200 MPH in 2.2 seconds (the first 350 feet of the run)
6 g-forces at the starting line (nothing accelerates faster on land)
6 negative g-forces upon deployment of twin 'chutes at 300 MPH



An NHRA Top Fuel Dragster accelerates quicker than any other land vehicle on earth . . quicker than a jet fighter plane . . . quicker than the space shuttle....or snapping your fingers !!

The current Top Fuel dragster elapsed time record is 4.420 seconds for the quarter-mile (2004, Doug Kalitta). The top speed record is 337.58 MPH as measured over the last 66' of the run (2005, Tony Schumacher).

Let's now put this all into perspective:

Imagine this...........You are driving a new $140,000 Lingenfelter twin-turbo powered Corvette Z-06. Over a mile up the road, a Top Fuel dragster is staged & ready to 'launch' down a quarter-mile s trip as you pass. You have the advantage of a flying start. You run the 'Vette hard, on up through the gears and blast across the starting line & pass the dragster at an honest 200 MPH.... The 'tree' goes green for both of you at that exact moment.



The dragster departs & starts after you. You keep your foot buried hard to the floor, and suddenly you hear an incredibly brutally screaming whine that seares and pummels your eardrums & within a mere 3 seconds the dragster effortlessly catches & passes you. He beats you to the finish line, a quarter-mile away from where you just passed him. Think about it - from a standing start, the dragster had spotted you 200 MPH.....and it not only caught, but nearly blasted you off the planet when he passed you within a mere 1320 foot long race !!!!

That, my friends.....is acceleration.

 

Math heads? Oh, never mind.