There's a trash-talking DSM owner in my area that swares that a HP figure a dyno gives you incorporates the weight of your vehicle. Here is a quote: "Have you ever gone to a dyno with your car before? One of the first things they do is find out how much your car weighs so that it can accurately determine your HP..."

Now, I have never personally gone to a dyno, but I sounds to me like this is one of the most rediculous things I've heard all month. I just wanted to confirm this so that I can slap it in his face.

 

He is so.... right.

 

so, a heavier car has less hp simply becasue its heavier? That would mean that a hp rating is actually a sort of HP/weight ratio? explain


[Modified by servion, 12:00 PM 8/20/2002]

 

BS. Weight would only affect your HP if it was creating a HEAP more load on the tyres. Weight doesnt have enough affect to even worry about!!!

 

That is the stupidest thing I have ever heard. They don't factor in weight to your horsepower. If they did why would people figure out power to weight ratio. Their would be no need. Go ahead and give you friend a

 

That was my thought exactly. Do they ask for your vehicle weight at the dyno? If so, why?

 

Somebody can correct me if I'm wrong.
But it is my understanding that the high-end roller dynos have to ability to adjust the weight of the roller (via water). The weight of the roller is adjusted to mimic the effect of the rolling weight of your car as if you were on a track. This would give you a more accurate "HP to the ground".


[Modified by mrlegoman, 1:36 PM 8/20/2002]

 

that makes sense..... its not increasing/reducing your hp rating due to the fact that your car weighs xxx pounds... it is rather 'adjusting' the way the dyno will read your car to allow for an accurate hp rating... sound right?

 

yes dyno is short for dynamometer which is an entity used to measure force among other things with sensors. the weight of your car is part of the normal force, so it would be needed for the calculation. Right?

 

ive been to 4 different dynos here in s cali. dynamic, import builders, aebs, and harves. all dont ask for the weight of your car. hp has nothing to do with your weight. the only time weight is a different is ONLY when your racing. thats when weight comes to play. you friend doesnt know what hes talkin about

 

Bingo

Because it takes time. And time is money, especially running a dyno.

Most dyno software will take into account the weight of the vehicle. What it actually does with this, it all depends on what spec your looking for. If your looking at hp at the crank, or hp at the hub, weight will not be a factor. But hp at the wheel is another story.

 

So, how does the weight of the whole vehicle affect the WHP

 

Weight x speed = force , or some crap like that... I dont know the math, but its a pretty simple theory that to figure out the power of a moving object you have to know (or should know) its weight for a proper measurement. It just makes sense. Whethere people do or don't (as is shown in this thread) seems to be your real issue/question... I think YES they should, but NO they dont. In fact, go buy a dash mount dyno (not the real name) and it forces you to tell it the car weight w/ you in it. My corvette freak of a friend has a dash dyno and we had to go weigh it to use it... its the reason I havent used it in my car yet....