Change to ST 1-4 & SU line 7.2.3 to not penalize small displacement forced induction motors

[Alan_Wolfe]

Purpose of present rule:  To not allow competitors to use forced induction to create a torque curve which translates to a flat HP curve.  The rules allow this to be done with large displacement NA motors, but for some reason competitors using forced induction to do this is frowned upon.  Anybody want to explain this to me?

Purpose of proposed change to 7.2.3:  To allow competitors to use forced induction to create a higher typical shaped dyno HP curve without penalty.  Where typical shaped is defined as an ever increasing HP curve with one peak at Max HP.

Change:

Add " with Max Tq > Max HP" to the end of 7.2.3 first sentence

New sentence:

7.2.3  For vehicles with a maximum RPM less than 6000 rpm, and all Forced Induction vehicles with Max Tq > Max HP:

Discussion:

This proposed rule change will allow small displacement forced induction motors which produce typical shaped dyno curves to compete without penalty just as a large displacement motors making the same dyno curve are allowed.  It will still penalize competitors using forced induction to create a torque curve which translates to a flat HP curve.

Alan

[Alan_Wolfe]

Excerpt from 3/27/23 email to @Greg G. :

"The rule as presently written not only doesn't do a good job of deterring people (that can) from creating a flat HP Dyno curve, it penalizes the people with a typical dyno curve the most!  A vehicle with a flat dyno curve will get exactly the same Avg HP whether 4, 6, or 8 points are averaged.  The more sloped the HP dyno curve is the more this rule will penalize the vehicle.  Exactly the opposite of the stated purpose of 7.2.3.  Rule 7.2.3 requires all forced induction vehicles to create a flat HP dyno curve to be competitive.
I think what happened is whoever came up with this rule had the implicit assumption that all vehicles with forced induction can and will create a flat HP dyno curve.  Not only is this assumption False, the rule does not test to validate this assumption.  And thus my added test for 7.2.3.
Let's get this fixed."

 

[Tansar_Motorsports]

I like it.  I would want to see the math on high rpm + turbo engines, to make sure that a turbo K24 couldn't still do a big power plateau at 5000-8000 rpm (for example) without trq exceeding power.

 

Assuming that math works out, why not just remove "forced induction" from the wording all together.

7.2.3  For vehicles with a maximum RPM less than 6000 rpm, and all vehicles with Max Tq > Max HP

Maybe we dont even need the 6000 RPM note.  

 

[Alan_Wolfe]

Thanks for the endorsement!

Excellent (and valid) concern.  Since HP=Torque(lb-ft) @ 5252 RPM, it absolutely IS possible for a forced induction car with good boost control to make a flat HP curve above 5252 RPM and Not exceed Max Tq > Max HP.  

JDM K24a3/K20Z3 40º limiter in gear. TSX cams. 

https://www.k20a.org/threads/dyno-results-and-concerns.227360/

 

I also think it would be possible for an NA "VTEC / VNOS" car to do this as well.  

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I absolutely agree with your suggestion to remove "forced induction" from the wording all together.  This will cause heartburn for more than a few people running big displacement NA motors though.  There are at least 2 ST4 competitors with "CURRENT" ST/TT Compliance Submissions that will get penalized.

 

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But that gets me back to my original point that 7.2.3 doesn't really penalize flat HP dyno curves.  If your HP curve is flat for 2000 RPMs you get nearly the same answer whether you average over 4, 6, or 8 data points.  

 

 

[Alan_Wolfe]

Maybe more like this:

7.2.3  For vehicles with a maximum RPM less than 6000 rpm or greater than 7252, and all vehicles with Max Tq > Max HP

 

[Alan_Wolfe]

Hey @Firouz H., this is the second thread I mentioned in the email I sent you 2 days ago.