threekidss

heya,
working on a custom project and need to know how the rollers on a dyno are set up..do they have any resistance and if so how much and how is it applied.....also wondering how the hp is measured.......basically how do the rollers simulate pavement. this is a related topic and will clue you in when the project is done.thanks
mark

bler

hahaha ROFL, you may try the 'physics' forums !! good luck getting any help here..

also, if your seriously doing this, try contacting Dyno yourself, I'm sure they will be more then willing to help you out with a project (as long as it's not mfg'ing dyno's for sale to compete with them)

Brett256

It depends on what type of Dyno your talking about..

You've got 2 choices..

1st is a water brake-type dyno also known as Hydrualic-type dyno. This is old school ****. The dyno uses applied resistance (a fluid) to put different loads on a motor at a given rpm. This is good for measuring power under different circumstances (ex. half throttle or full throttle). These dynos are sometimes drum or can be setup to measure directly at the crankshaft (this requires the motor out of the vehicle of course). In the end though water-brake dyno's suck *** because they are giving analog readings and tuning a car properly will take days and $$$$$$ since you can only do one rpm point at a time. They are also hard on a motor.

Now... on to modern technology..

Next is an inertial-type dyno This dyno measures how fast you are accelerating a given mass (drums). Since this is a PC based system doing the calculations you will get full graphical displays of horespower and torque at all rpm's. The only downfall is it's for full throttle tuning only.

I used to operate a Dynojet Dynamometer at a performance shop here in town. It was an inertial-type dyno. You basically were setting a car atop 2 drums with a combined weight of 2400lbs. Runs were performed in whatever gear was closest to a 1:1 ratio. Manual car (4th gear) Automatic (3rd gear usually). A sensor on the drums measures how fast the drums were being accelerated and basically time taken to reach speed measured in fps (feet per second) . With this information sent to the PC it is basically calculating :

horespower = weight(drums) x acceleration x speed / 375

So your getting exact horsepower outputs down to 1/10th hp across the rpm range.

Torque is also calculated since torque can be derived from HP :

torque = 5,252 x HP / RPM

RPM info is sent to the PC through a tach sensor hooked directly to a spark plug wire.

What is so interesting that most people don't realize is your torque and horsepower are always EXACTLY the same numbers at 5,252 rpm's..... doesn't matter if its a Toyota Tercel, Ferrari F50, or a John Deer Riding Mower.... HP and TQ will always intersect at 5,252 rpms...
weird huh?

Hope this helps...im tired of talkin nerdy

bler

what a math GEEK !

Brett256

word!

MikeM

Say what you want but I'm impressed.

bler

haha I was messin with him wish I knew all that..

one of my friends is studying math, and always goes off on algorithms and equations, and I just sit there and are like 'yah, mmm huh, ok.... mm huh.. ok' I barley passed algebra

Brett256

I barely passed algebra too I just know this junk becuase I operated the dyno for a couple years and I used to be into the making a car fast thing.

Yep.. Dynamometer Technician was definitly the coolest job I ever had. The title alone had a cool ring to it :YEAH

Robbie

I think bler is the only f'n nerd/geek or what ever you want to call it on this board.
1st the dumbass says in this thread that no one would know here...with in minutes someone does...ur such a dumbass bler. funny part...i have read everyone of ur dumbass posts...its so nice when ur gone.

ok ..im done with this dipshit again.