Why is it that none of the dyno sheets that we see on a daily basis have a time listed to show how quick the pull made it from say 2000 rpm to 6000 rpm..? Wouldn't that be a true indicator to the power made.. Sure my motor made good power but how long did it take to get there? I think it would be a cool feature to truly judge the power of a motor.. I mean look at all the car manufacturer's out there that state 0-60 in 3.2 seconds or 4.7 seconds.. I think the software in these dyno's should state that fact because everyone knows it's not really about how much power you make but how quick you get there... Like running quarter or eighth mile.. We could have the same power but my 10 sec. run will most likely beat an 11 sec. run.. Anyways didn't any of you guys ever think about this?

 

From my understanding of how dynos work, they measure the amount of time it takes to get the drum, with its known weight, to a certain speed to determine the torque, and the horsepower is derived, using a formula, from the measured torque. Not sure how showing the time on the sheet would be of any real world use, but I guess it would be neat to see the raw numbers.

Cheers!

 

That's exactly how they work.

Performance numbers can be estimated out of hp and torque numbers but there's more to it than just engine performance. Specifically, machine weight and rider performance. If the rider weighs 300 lbs and takes lunch between shifts the 1/4 mile will be crap.

 

Actually it's the other way around. Drum type dynos measure the the power applied to the drum for it to accelerate. As the drum accelerates they measure the time between ticks on a disk on the drum to get the power applied. They get the torque by the usual HP formula in reverse and reading the RPMs from a sensor clipped on a spark plug.

You can plot time on the X axis if so desired but it really don't mean much. First gear would be smokin' fast and 5th/6th gear much slower.

 

You can get a fair estimate of peak HP from a formula based on engine speed through the traps in the 1/4 mile.

 

The dyno operator does see how fast it spools up. If they start telling you your buddy made 120HP in 3 seconds while your bike made 120HP in 4 seconds you're going to be mad. If he tells you that you both made 120HP then everybody's happy. There's a lot of information available to the tuner but for most people all they care about is the final #.

 

Years ago, Bob Wood called us after he had his 5" stroke wheels lightened, and said he did not witness any increase in power.
I told him to click on the time feature and see any difference....he did, and it did.
True story.
Scott

 

That's just it most don't know and only care about peak numbers.. I never did... That's why I had Bob Wood grind me a cam from the W8 grind with a little different duration to help the power band spool the motor quicker,,, I always cared about elapsed time because it's not that your motor makes more power it's that it applies it to the ground quicker hence I beat your ***... LOL...

Absolutely... Horse power to weight ratio...

 

Eh, permit me to disagree. Nitro bikes and alcohol funny cars have similar ET's but vastly different HP outputs.

 

First off, I did not write ET's, I wrote vehicle speed. The formula includes vehicle weight.

https://www.ajdesigner.com/fl_horsep...trap_speed.php