Competition How do I dyno

[jeff95]

Last weekend I dynoed my 95 Ram. It was a dynojet with a 4500 lb roller and no load. How much should I load up? This was my first time on a dyno and the person running it is used to gas vehicles. Thanks for your help

Jeff

 

[PKozlowski]

What do you mean How much should I load up?

 

[johncameron]

The more you load it, your torque numbers will be higher because of faster spool-up VS RPM. Think of it this way, free refing your engine will not allow much boost but if you are towing 12K up a hill and you floor it, the boost will come up much faster than your RPM.



John

 

[PKozlowski]

I guess it also depends on what you want to know.

You can do an accelleration test or a pull down test.

I do the pull down myself. This of it has hitting a really big hill at

80 mph and bringing down the rpms to about 1600 in about 20 seconds

Or you could do the accelleration test like alot of guys seem to do.

I personally don't care how fast I can get there, I want to know what I have

when I hit the mountain.

 

[robertyoke]

I guess it also depends on what you want to know.

You can do an accelleration test or a pull down test.

I do the pull down myself. This of it has hitting a really big hill at

80 mph and bringing down the rpms to about 1600 in about 20 seconds

Or you could do the accelleration test like alot of guys seem to do.

I personally don't care how fast I can get there, I want to know what I have

when I hit the mountain.

you can't load an inerta type dyno, well unless you use your service brakes.



only load type dynos can do pull down/lug down.



you wont see full boost if the load cells/rollers are just 4500 lbs.

-robert

 

[DavidTD]

Last weekend I dynoed my 95 Ram. It was a dynojet with a 4500 lb roller and no load. How much should I load up? This was my first time on a dyno and the person running it is used to gas vehicles. Thanks for your help

Jeff

Tell the dyno operator your truck should be run in OD with the converter locked. Depending on how your valvebody is set-up will determine when you can nail full throttle. At the very least, by 70 mph or around 2k rpm you can be full tilt on the throttle.



The load vs inertia thing will go on forever and that is ok with me. I will though say that boost CAN be made on the inertia machine, and ARE made by those that can tune. This is not a slam, just fact. Over charge (way too big) and take away the response of the engine, and you will not make a big number on a dyno jet unless you spray it. But when I have seen well over 100 psi with big turbo's and over 1000hp on a dyno jet without the use of nitrous this should tell everyone it can be done.



HP by definition is the ability to travel distance over time. That is acceleration.