Performance Graphs - horsepower/torque

[PerfAdv]

http://www.rototest.com

This site has a large collection of graphs and details about engine output and real wheel hp, as measured by their equiptment. Great resource for researching engines.

Click "performance graphs" >> "graphs"

[derekthetree]

wow pretty cool. cheers for sharing it!

[hightower99]

I found that site alittle while ago. They use some of the most accurate dynos in the world and they show outputs at the crank and at the wheels. Helped me alot researching motors.

[Azon]

Great web-site but it only has the modern models.

I found that site alittle while ago. They use some of the most accurate dynos in the world and they show outputs at the crank and at the wheels. Helped me alot researching motors.

Read your signature and was wondering why are porting and polishing bad in your opinion?

[hightower99]

Well that question will probably cause a big arguement but the truth is that polishing is a flawed concept that in the real world leads to losses due to increased friction (however don't mix polishing up with smoothing which is normally benificial) Porting is normally not going to work for the better on it's own because it too is a misunderstood concept. To tune 4 stroke engines you must realise that there are 8 phases that need to be taken into account. The classical intake phase you read about in text books actually is made up of 3 different phases in real life. Intake overlap, Intake flow, and Intake charging. Porting noramlly increases the volume of the intake ports which allows for higher flow rates but lowers the velocity seen by the engine. The velocity is crucial in the last and most important phase of intake namely Intake charging (the point where the piston is passing BDC and for a short time travels upwards before the intake valve closes). To increase the amount of air closed into the cylinder is how you make more power, and therefore you have to make sure that in the intake charging phase the most air possible is being crammed into the cylinder. To increase the velocity you can remove the "dead space" that is in most intake ports this will increase velocity without lowering flow.

The whole subject was talked about in another thread so try a search. This is just a short snippet.

[Matra et Alpine]

The whole subject was talked about in another thread so try a search. This is just a short snippet.

Shame you decided to put only the one ( largely erroneous ) point of view, ht.

Polishing and porting DOES help, but it's NOT simple ( which is what ht was rightly saying can do little ).

Polishing and porting is NOT about making it BIGGER but makgin it BETTER

Recommend you search and read the various threads we've had on porting and polishing and glean teh benefits, techniques and warnings from those.

[Cyco]

hightower99, we are still waiting to see your dyno graphs that you have been promising for sevearl months now on this.

[Matra et Alpine]

hightower99, we are still waiting to see your dyno graphs that you have been promising for sevearl months now on this.

But PLEASE do it in the threads where it was asked

[Sid447]

Please be aware,

This is a hub dyno and so doesn't measure rear wheel hp.
The highest transmission loss is in the wheels/tyres. Hence the low loss with the Audi RS4 of only 20% from measured hub power to flywheel for 4wd, and only approx 8% for the V10 M5.

quote:-
........"ROTOTEST Chassis dyno
The test has been conducted using a ROTOTEST Chassis Dynamometer. The dynamometer is in reality a supreme engine dynamometer fitted to each drive wheel. The Rototest dyno is of hub-type design (in contrast to roller-type, or rolling road) and is being used by many of the auto manufacturers around the world in their research and development and quality assurance."

[KnifeEdge_2K1]

sid's right on the money there, sorta

the wheel/tyres dont really rob horsepower in the same way as the transmission because tranny losses are due to friction, losses from the wheels is due to inertia, it takes torque to spin the heavy wheel and tyre and this "robs" horsepower, because the torque used to spin up the wheel and tyre wont be measured by a roller type dyno, the losses due to inertia arre proportional to the rate of acceleration, so at high speeds where acceleration is slow the loss due to the tyre and wheel weight is minimal

[Alastor]

sid's right on the money there, sorta

the wheel/tyres dont really rob horsepower in the same way as the transmission because tranny losses are due to friction, losses from the wheels is due to inertia, it takes torque to spin the heavy wheel and tyre and this "robs" horsepower, because the torque used to spin up the wheel and tyre wont be measured by a roller type dyno, the losses due to inertia arre proportional to the rate of acceleration, so at high speeds where acceleration is slow the loss due to the tyre and wheel weight is minimal

Damping in the tire sidewall could be consider a frictional loss.

As well, isn’t power independent of acceleration? So any inertial affects shouldn’t change the steady state power generated by the engine.