496 Drag Test REDO.............

[vortecpro]

Larry has certainly contributed to my program that's for sure.

[maxracesoftware]

Larry,
What are you using for Cd and FA?
I long time ago I found somewhere on the internet. 70 Chevelle .42 Cd 25.52 FA
Stan

i did a very quick Simulation for Mark's 650 HP ... i didn't fine-tune it or nit-pick it
however, i came out pretty close to reality

VortecPro_DragCoefficient_FrontalArea.png

 

[Rick!]

For the OP, here's a screenshot from an ET Predictor based on Pat Hale's Performance Racing Atmosphere calculations. (a modified version of SAE J1349) I believe Larry's program uses Pat's CF calculations. I also use some formulas off of epi-eng.com for water vapor calcs and such.
The screenshot has the one day's CF for your first Texas runs, another for the "23.7" Baro and the bottom line is for the theoretical -475ft DA.
All it uses is Temp, Baro and Humidity and calculates DA to within a few feet of airdensityonline. airdensityonline is useful for looking backwards a day but doesn't keep up hour to hour for track days in my experience. I usually have to find a nearby weather station to the track to get data so I can predict my brother's ET remotely.
If you're feeling really froggy, I've attached the spreadsheet that does the work.

[Stan Weiss]

Larry,
What are you using for Cd and FA?
I long time ago I found somewhere on the internet. 70 Chevelle .42 Cd 25.52 FA
Stan

i did a very quick Simulation for Mark's 650 HP ... i didn't fine-tune it or nit-pick it
however, i came out pretty close to reality

VortecPro_DragCoefficient_FrontalArea.png

 

Larry,
Thanks. That does make a small difference in what I would get.

Stan

[maxracesoftware]

by Rick! » Tue Apr 16, 2024 7:52 am
For the OP, here's a screenshot from an ET Predictor based on Pat Hale's Performance Racing Atmosphere calculations. (a modified version of SAE J1349) I believe Larry's program uses Pat's CF calculations. I also use some formulas off of epi-eng.com for water vapor calcs and such.

"I believe Larry's program uses Pat's CF calculations."

hi Rick ,
i'm not using any of Pat's equations ... instead i discovered that my equations + SuperFlow's Friction Factors
are byfar the most accurate combination to use ! ... tested up to 36,000 Feet Density Altitude for accuracy ! ( i know no one Races in that Range )
Once you start passing about 10,000 to 12,000 Feet Density Altitude , all SAE equations cause progressively increasing HP Correction errors !

Basically, HP Weather Corrections Factors accuracy Order :
1st Best highest accuracy = SAE J-607 STP or SAE J1349 along with SuperFlow Engine Friction Factors is byfar highest HP Correction accuracy
2nd Best accuracy = SAE J-607 STP or SAE J1349 along with 85.0% Mechanical Efficiency %
3rd Best accuracy = is SAE J-607 STP , what some HP Correction softwares use , is 3rd place

Hale_Density_Software.png

Rick_XLS_Correlations.png

Outside_Weather.png

 

[Qtrhrse23]

Nice to see a fellow Texan doing some TNT. My local dragstrip got closed(Hallsville and Texas Raceway).

[maxracesoftware]

SuperFlow_Friction_Factors_accuracy examples :

SuperFlow_Friction_Factors_accuracy.png

 

[BP758]

Larry has certainly contributed to my program that's for sure.

The last 496 you built was stout! Told Steven I can put it in for a run or two....
I'll be on the pump next week and call you.

[Stan Weiss]

Larry has certainly contributed to my program that's for sure.

The last 496 you built was stout! Told Steven I can put it in for a run or two....
I'll be on the pump next week and call you.

Barry,
How light can you be, if you don't have to be class legal?

Stan

[vortecpro]

Larry has certainly contributed to my program that's for sure.

The last 496 you built was stout! Told Steven I can put it in for a run or two....
I'll be on the pump next week and call you.

There you go! I'd love to see that............................I don't think they realize what they have there, when I Get 635 HP measured you can bet its gonna be quick.