Top Speed ?

What is a technical way of testing the top speed of a car ? Beside flooring it on the highway ? :)

a dyno?

um read motor trend or something??

Check around on the net, do some searches. There will idiots out there saying "I did 170 in my car, stock!) but you can get a good idea of what you can achieve. There is also a mathematical formula, although i have no idea what it is. But if you take your max revs, final gear ratio and tire size into consideration then you can figure it out some how, but good luck with that. Sorry i couldn't help.
Jake

Well to figure out top speed of a vehical requires several variables, such as.

Horsepower, drivetrane powerloss, RPM redline, Gearing, Tire size, Areodynamic coefficient of the car body, slope of the surface your to driving over.

but Basically with enough Horsepower RPM range with the proper gearing and tires you can get to any high speed, but you might kill your self if its a boxy unareodynamic vehicle.

Thanks for the info guys. Can you do it on a dyno ?

The short answer is no - well with one exception.

The only way you are going to get the actual top speed of a vehicle is to drive it along a flat piece of road until it accelerates no more. This can take a loooong time. And it presumes you can find a straight enough piece of road without altitude changes and that your tires sustain the heat and pressure. Even a loop like Nardi presents significant issues over drag caused by the slight bend and also the heat generated on sustained high speed runs...

It will also be influenced by the climatic conditions such as ambient temperature, barometric pressure (incl altitude), tire inflation pressures etc etc - which may mean the top speed could vary a lot.

Unless you knew exactly how much drag would be presented at a certain speed by the shape of the car and all the other variables - no you couldn't find out on a dyno...

For instance, drag rises fourfold with a twofold increase in velocity...

There is one exception - a lot of cars have engine management systems that impose a speed limiter including Japanese domestic vehicles which are limited to 180 km/h and German domestic vehicles that are mainly limited to no more than 250 km/h.

Now, presuming the vehicle in question could actually reach that speed in a real world situation (some cars won't get there in any case not being sufficiently powerful to accelerate to that speed) when the engine figures that you have reached its speed limit - it will intervene and do some things to the ignition timing or fuel flow and prevent further acceleration...

I'm asking because I had my car put on a Dyno. And they told me my car top out at 150 mph. I told someone this and they said it can't be done on a Dyno.
Jessica

Well, you can test the top speed of a car on a dyno by simulating the load so it is identical with the load otherwise caused by the drag. But an approximate top speed can quite easy be calculated if the coefficient of drag, frontal area, power curve and gearing is known.

If they say that they top out the car at 150 mph at the dyno it is likely that this was the maximum speed of the wheels.

Thanks ;)

dyno testing top speed is like driving without wind resistance. just go floor it on the highway, thats my style. if gotten a ford escort 99 SE to go 120mph and Ford says the top speed is 105mph, and got a 2004 Sebring 2.7 V6 to 125+mph, near manufacturers 130mph guestimate.

Well thats what I did and I buried the needle. ;) I have a Superchip in it so it removes the gov. I guess people fing it hard to believe because its only a V6 Mustang. ;)