Ess G3 Dyno Dip Question

[Austin8341]

Good catch. Something is off.

From this article:
https://www.enginelabs.com/engine-t...y-does-a-dyno-graph-always-cross-at-5252-rpm/

If you’ve seen a dyno graph more than once in your life, you’ve likely noticed that horsepower and torque always seem to cross around 5,200 rpm, regardless of combination or engine type. That’s not some fluke, because horsepower and torque do, in fact, cross at exactly 5,252 rpm. It’s not magic or witchcraft, but rather simple math. We’ll explain.

The mathematical equation for horsepower is torque times RPM, divided by 5,252. If you are familiar with algebraic expressions, you have probably already picked up why the lines of the dyno graph cross at 5,252 rpm. In the horsepower equation, when RPM equals 5,252, dividing it by the constant gives us a value of 1. So simplifying that equation for that specific RPM means that at 5,252 rpm, horsepower equals torque. (If you’re a pedantic math nerd, it actually means that horsepower equals torque, times 1, divided by one.)


So, we’ve answered why they always cross, but you might have picked up on something else… why is there an equation for horsepower? Aren’t we measuring it on the dyno? The answer to that question might surprise you. No, we aren’t directly measuring horsepower on the dyno. We are directly measuring torque, and then calculating horsepower using the torque measurement and engine RPM.


That leads us further down the mathematical rabbit hole. If all that is true, then below 5,252 rpm torque will always be greater than horsepower, and above 5,252 rpm, horsepower will always be greater than torque. But, again, why? That all comes down to the variable of time.

That’s great information.
I actually ended up drawing out the torque curve by hand scaled on the hp curve and it does intersect at 5300 not 5600. I about had a stroke trying to do it with two different scales.

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[cbrtrx]

On a dynojet it can be auto scaled or force scaled. It's just the way the dyno operator set it up. When x and y axis are the same it will always cross at 5252.

 

[Austin8341]

Just curious. Isn't tq and hp suppose to intersect at 5250 rpm. Is something off with the graph?

Here's my whipple car for reference.

Which pulley and how much boost are you seeing? Just curious. I’m on the 120mm which is rated at 8 psi at 7200. I think it’s around 10 psi at 8000.

 

[Lonniesgt]

Which pulley and how much boost are you seeing? Just curious. I’m on the 120mm which is rated at 8 psi at 7200. I think it’s around 10 psi at 8000.

On my whipple I run a 3.75 pulley. My boost gauge shows around 11.5 psi at around 7k rpms.

 

[jpjr501]

We have basically the same stuff (head unit different of course), same pulley, fuel system and mine does not drop off.

Procharger D-1X (120MM Pulley)
Fore Innovations Fuel System / id1050x Injectors / E85
Long Tubes / No Cats / Stock Resonator / Stock Catback

Untitled by jpjr50, on Flickr

 

[Austin8341]

We have basically the same stuff (head unit different of course), same pulley, fuel system and mine does not drop off.

Procharger D-1X (120MM Pulley)
Fore Innovations Fuel System / id1050x Injectors / E85
Long Tubes / No Cats / Stock Resonator / Stock Catback

Untitled by jpjr50, on Flickr

That’s awesome. I would be very happy with a 740+ because I can see the potential. I am hoping to get this back on a dyno soon and give an update. What gear was your pull done in?

 

[jpjr501]

That’s awesome. I would be very happy with a 740+ because I can see the potential. I am hoping to get this back on a dyno soon and give an update. What gear was your pull done in?

The torque number can't be right on your chart. Must have had issues with the dyno. Centri blowers usually intersect between 5000-6000rpm.

Did you have an air filter on it? Mine had a Bellmouth but for the street I have run a filter.

 

[Austin8341]

The torque number can't be right on your chart. Must have had issues with the dyno. Centri blowers usually intersect between 5000-6000rpm.

Did you have an air filter on it? Mine had a Bellmouth but for the street I have run a filter.

Yes it was with the filter. The torque is correct. The torque is on a different scale on the right side of the graph. They intersect at about 5300.

 

[jpjr501]

Yes it was with the filter. The torque is correct. The torque is on a different scale on the right side of the graph. They intersect at about 5300.

Got it! Drop off has to be the filter, choked it out. Your power is fine then. Probably would have made 740 without it.

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