Peak Hp on Dyno Chart Question

[liche]

Regarding Dyno Charts, how do you typically specify what the peak HP point of the chart is? Is there a standard which specifies which "peak" to use if there are multiple peaks?

I understand complely how to "read" the chart, but when someone refers to Peak HP, what exactly does that mean?

My question in particular is the chart enclosed:

On this chart, there is a inflection point at 340HP @ 5600RPM, however, hp starts ramping up again around 5800RPM and continues to do so. The car continues to create increasing positive boost up through 6500RPM, so power continues to increase.

Not sure why the tuner only set the x-axis to 6000RPM max, but if you interpolate the chart out to 6500RPM, it appears it would easily hit a peak HP of at least 380HP.

What are your thoughts?
Thanks

[rbm g35]

I see your point. Did he determine what happened at 5600rpm? (possible knock that would decrease spark more than what is stated in the main map(different map I believe addresses knock reduction inwhich it would slowly recover giving you the increase you see after). What was a/f ratio at that point? food for thought

[GreenGoblin]

Peak hp should be at the point where the power was the highest. That dyno chart print out is pretty useless IMO. especially since you can not see readline.

[ttrank]

+1

That looks like a dynapack dyno and you set those up of when to end the run. In this case the run ended at that point. They have always asked me when I want to end it or done a few runs to see where the power started to drop off and ended right as it went down.

We ran my car up to 7500rpm but power started to drop off before that.

[Tollboothwilley]

Peak signifies the HIGHEST point that it travels to.

[liche]

Originally Posted by Tollboothwilley

Peak signifies the HIGHEST point that it travels to.

Not necessarily.

The only real measurement being taken with a Dyno is torque. Horsepower is not a measurement and only derived from the instrumentation through a mathematical relationship:

where HP = Torque*EngineSpeed (RPM) / 5252

Therefore, since HP is a function of both Torque and EngineSpeed it may make more sense (or perhaps this is how they do it and thats my question) to specify the peak HP as the point where Torque is at its maximum.

[DaveB]

Originally Posted by liche

Therefore, since HP is a function of both Torque and EngineSpeed it may make more sense (or perhaps this is how they do it and thats my question) to specify the peak HP as the point where Torque is at its maximum.

It doesn't work that way. On most cars, peak torque occurs around 3000 to 4500rpms. The longer the torque curve is sustained in relation to rpm, the more HP is made and the higher the peak HP number.

[liche]

So when an auto manufactuer states Car X has 300HP, what exactly does that mean?

Does it simply mean thats the absolute peak HP (flywheel) across the operational RPM range of the vehicle?

Is there an industry standard that defines the way this is specified, or does it just differ from manufacturer to manufacturer, driven more by marketing which is why i assume they use flywheel vs. rwhp.

Thanks

[Tollboothwilley]

Originally Posted by Tollboothwilley

Peak signifies the HIGHEST point that it travels to.

I'm quoting myself because this is true.

You are correct in that HP is a quantitative number of work performed BASED on TORQUE but the highest number that the HP curve attains is called PEAK HP.

[Tollboothwilley]

Originally Posted by liche

So when an auto manufactuer states Car X has 300HP, what exactly does that mean?

Does it simply mean thats the absolute peak HP (flywheel) across the operational RPM range of the vehicle?

Is there an industry standard that defines the way this is specified, or does it just differ from manufacturer to manufacturer, driven more by marketing which is why i assume they use flywheel vs. rwhp.

Thanks

see above ^^

When a manufacturer says a vehicle has 300 HP they are going off of flywheel.

The industry standards come in for how the dyno's calculate the numbers. Every manufacturer will post up slightly different numbers from different locations, altitudes, corrections and their dyno. Magazines that revue vehicles always differ on the calculations that they come up with.

[pfarmer]

Originally Posted by liche

Not necessarily.

The only real measurement being taken with a Dyno is torque. Horsepower is not a measurement and only derived from the instrumentation through a mathematical relationship:

where HP = Torque*EngineSpeed (RPM) / 5252

Therefore, since HP is a function of both Torque and EngineSpeed it may make more sense (or perhaps this is how they do it and thats my question) to specify the peak HP as the point where Torque is at its maximum.

Or maybe specify it as an average over the torque curve. In that way the sooner torque comes up and the longer it is substained then the higher the average number which would be a better comparison between different makes and models of autos.