I was just trying to be funny. I get all that. We usually have 20003000+ corrected air here during the season, sometimes over 4000, maybe in the late fall, we get a day where it's around 1200 or something corrected da, that's stellar. 1200 feet measured altitude.skinny z wrote: ↑Tue Nov 22, 2022 8:55 amAnd now you can see why I don't bother correcting a negative DA pass!Bigchief632 wrote: ↑Tue Nov 22, 2022 8:45 amIf your best pass was ar 100 da, that's like running 100 feet below sea level, corrected, so running at a sea level track it would go slower,skinny z wrote: ↑Mon Nov 21, 2022 1:25 pm
No sir. 1.891.85.
That pass, with a minus 100' DA ( beautiful fall racing weather at the old track in Ontario). 60's were at their worst. Foot brake to 2200. RPMs fell to below 4000 on the shifts despite carrying to 6500 on the 12.
I think with that same engine, the new converter and transmission plus tires, I should see that 12 teen.
Best was 1.7 flat with a different rear gear and tire. If I get that back, it might make the difference.
11's are the goal but I'll have to go to the sea level track on the coast for a sniff of that.
Seriously though, while I keep a record of all of my time slips (which by the way, after ten years or so the slips themselves sort of fade to the point of being unreadable) I also check the DA on the day and record that too. If for nothing other than being able to compare different runs on different days. Or years for that matter.
Case in point was the back to back, spread 6 months apart, 2500 miles east to west and 1500+' up runs I did when I moved. I wanted 12 second slips (yeah, not great I know) from opposite sides of the country. Well, I got that, legitimately and uncorrected, but using the DA compensation, the runs were exactly the same.
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How will you go faster?
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Re: How will you go faster?
Maximum power using simple logic and common sense
Re: How will you go faster?
I got your humour!Bigchief632 wrote: ↑Tue Nov 22, 2022 9:25 amI was just trying to be funny. I get all that. We usually have 20003000+ corrected air here during the season, sometimes over 4000, maybe in the late fall, we get a day where it's around 1200 or something corrected da, that's stellar. 1200 feet measured altitude.skinny z wrote: ↑Tue Nov 22, 2022 8:55 amAnd now you can see why I don't bother correcting a negative DA pass!Bigchief632 wrote: ↑Tue Nov 22, 2022 8:45 am
If your best pass was ar 100 da, that's like running 100 feet below sea level, corrected, so running at a sea level track it would go slower,
Seriously though, while I keep a record of all of my time slips (which by the way, after ten years or so the slips themselves sort of fade to the point of being unreadable) I also check the DA on the day and record that too. If for nothing other than being able to compare different runs on different days. Or years for that matter.
Case in point was the back to back, spread 6 months apart, 2500 miles east to west and 1500+' up runs I did when I moved. I wanted 12 second slips (yeah, not great I know) from opposite sides of the country. Well, I got that, legitimately and uncorrected, but using the DA compensation, the runs were exactly the same.
I miss the old track.
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Re: How will you go faster?
Perfect.David,
See if this helps.
Stan
1000 246.5
1100 260.5
1200 273.5
1300 285.5
1400 296.5
1500 306.5
1600 316
1700 325
1800 333.5
1900 341
2000 348
2100 354.5
2200 359
2300 363
2400 367
2500 370.9
2600 374.7
2700 378.5
2800 382.3
2900 386
3000 389.9
3100 393.7
3200 397.5
3300 401.0
3400 407.2
Thanks Stan
Re: How will you go faster?
No,. you may be crazy if you use the corrected to standard dyno number at sea level to input to know the actual in car performanve at a elevation and DA other than the sea level standard .. Like track @ 3000' elevationClassAct wrote: ↑Mon Nov 21, 2022 10:32 pmYou’re crazy if you use observed numbers for sure.Stan Weiss wrote: ↑Mon Nov 21, 2022 6:13 pmSo when someone asks you how much HP did your engine make on the dyno. Do tell them that or the corrected HP?
Stan
and typical dayily D/A much higher too 4500'5000'
in say Calgary..
Never promise what your engine cannot deliver.
The tested HP @the wheel in car is always a very modest looking number. You have to know the true weight of the car + driver.
If you do not know the weight you only get a power to weight ratio number. You can plug that into any known weight. You can correct to sea level dry air condition if you know the weather @ the test, if you want.

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Re: How will you go faster?
Ambient weather conditions have an effect on performance.
Consider a baseline at SAE J1349 (29.23inHg, 77F, 0RH), and the temperature goes up to 97F.
We would lose 3.6% engine power; even after a jetting correction.
But the reduced air density would also reduce aero drag forces; required power at 100mph would fall from 54.9hp to 52.9hp.
The tradeoff becomes apparent which is why aero drag is often ignored, except for turbo
engines which are unaffected by density and might go fast enough to worry about drag.
Why is DA still used when actual density values are easily available?
Consider a baseline at SAE J1349 (29.23inHg, 77F, 0RH), and the temperature goes up to 97F.
We would lose 3.6% engine power; even after a jetting correction.
But the reduced air density would also reduce aero drag forces; required power at 100mph would fall from 54.9hp to 52.9hp.
The tradeoff becomes apparent which is why aero drag is often ignored, except for turbo
engines which are unaffected by density and might go fast enough to worry about drag.
Why is DA still used when actual density values are easily available?
Re: How will you go faster?
Accessibility.David Redszus wrote: ↑Tue Nov 22, 2022 2:31 pm Why is DA still used when actual density values are easily available?
Even long after the fact.
https://www.dragtimes.com/dadensityal ... ulator.php
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Re: How will you go faster?
As you know, a torque curve consists of torque vs rpm. From which horsepower is derived. Conversely, from a power curve vs rpm, torque can quickly be determined. There should be no disagreement on that subject.A power curve is more relevant than a torque curve.
Yes it is, the units being lb ft. When the torque at the drive wheel is divided by the wheel radius in feet, the result is lbs of force propelling the vehicle. The same is true under braking. In neither case is power a factor.Torque is a twisting force.
.Yes, it is. So when we multiply wheel torque by wheel rpm, the result is wheel horsepower. Which could be considerably less than engine power.Power is a (rate of) measurment of getting work done / time
Yes, work is force x distance, but it is not power until we include a measure of time.Getting a car down a ¼ mile track from a standing start is getting work done.
For a lengthy distance, MPH is the result of power and aero drag (and some rolling resistance). Think Bonnevile.How fast (MPH) at the end is a good measure...
If distance is limited (1/4 mile), acceleration becomes the critical factor. And since F = M * A, and A = F / M, force and mass are determining factors, horsepower is AWOL.How fast (quick(er) is too.
A torque curve already contains rpm by definition. There is no need to calculate the power curve since it is not part of the F = M * A eqution.The only way a torque curve can be used to maximize performance is if you add the rpm component in the spreadsheet  so you can calculate the power curve and know what to optimize in the drivetrain.
That was the original intent. After the selection of a torque (or power) curve, what parameters should be changed in order to improve performance?Some of us are trying to help with the original intent of the thread to examine the effect of various parameters that influence drag race performance which will hopefully bust a few myths and provide useful insight that is helpful to racers.
Gearing, rear end, tires (size & grip), aero, weight, aero?
Re: How will you go faster?
I know you don’t like thinking outside the box with equations butDavid Redszus wrote: ↑Tue Nov 22, 2022 3:08 pmAs you know, a torque curve consists of torque vs rpm. From which horsepower is derived. Conversely, from a power curve vs rpm, torque can quickly be determined. There should be no disagreement on that subject.A power curve is more relevant than a torque curve.
Yes it is, the units being lb ft. When the torque at the drive wheel is divided by the wheel radius in feet, the result is lbs of force propelling the vehicle. The same is true under braking. In neither case is power a factor.Torque is a twisting force.
.Yes, it is. So when we multiply wheel torque by wheel rpm, the result is wheel horsepower. Which could be considerably less than engine power.Power is a (rate of) measurment of getting work done / time
Yes, work is force x distance, but it is not power until we include a measure of time.Getting a car down a ¼ mile track from a standing start is getting work done.
For a lengthy distance, MPH is the result of power and aero drag (and some rolling resistance). Think Bonnevile.How fast (MPH) at the end is a good measure...
If distance is limited (1/4 mile), acceleration becomes the critical factor. And since F = M * A, and A = F / M, force and mass are determining factors, horsepower is AWOL.How fast (quick(er) is too.
A torque curve already contains rpm by definition. There is no need to calculate the power curve since it is not part of the F = M * A eqution.The only way a torque curve can be used to maximize performance is if you add the rpm component in the spreadsheet  so you can calculate the power curve and know what to optimize in the drivetrain.
That was the original intent. After the selection of a torque (or power) curve, what parameters should be changed in order to improve performance?Some of us are trying to help with the original intent of the thread to examine the effect of various parameters that influence drag race performance which will hopefully bust a few myths and provide useful insight that is helpful to racers.
Gearing, rear end, tires (size & grip), aero, weight, aero?
Tractive effort force = wheel power / velocity
So 400 hp (298,000 watts) at a speed of 60 mph (28.7m/s) will generate a tractive effort force = 10,383N (22,800lb)

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Re: How will you go faster?
You are quite right; I am stuck deep within the physics box, never to escape.I know you don’t like thinking outside the box with equations but
But wheel power is lb ft/sTractive effort force = wheel power / velocity
and velocity is ft/s, so...
Tractive force = lb ft/s / ft /s, and since ft and s will cancel each other, we are left with:
Tractive force = Force (lbs)
and since F = M * A, and A = F / M, then
A = Force (lbs)/ Weight (lbs), and
if F = 3000 lbs, and
if M = 2000 lbs, then
3000 (lbs)/ 2000 (lbs) = 1.5 G.
And since we can directly measure acceleration using data logging accelerometers,
we need simply to multiply the G force x vehicle weight to determine the traction
force at the drive wheels.
Actually, our data loggers can be programmed to graph traction force for every foot of track,
or every 0.001 seconds. And then overlay the traces to see exactly where the differences are.
When we do so, we see that traction force is not smooth and steady, but is
rather jumpy and irregular.
Did someone earlier mention shocks and wheel hop?
Re: How will you go faster?
Of course the units cancel out when you do a dimensional analysis they are supposed to……. This method is the power curve alternative to using torque curveDavid Redszus wrote: ↑Tue Nov 22, 2022 5:28 pmYou are quite right; I am stuck deep within the physics box, never to escape.I know you don’t like thinking outside the box with equations butBut wheel power is lb ft/sTractive effort force = wheel power / velocity
and velocity is ft/s, so...
Tractive force = lb ft/s / ft /s, and since ft and s will cancel each other, we are left with:
Tractive force = Force (lbs)
and since F = M * A, and A = F / M, then
A = Force (lbs)/ Weight (lbs), and
if F = 3000 lbs, and
if M = 2000 lbs, then
3000 (lbs)/ 2000 (lbs) = 1.5 G.
And since we can directly measure acceleration using data logging accelerometers,
we need simply to multiply the G force x vehicle weight to determine the traction
force at the drive wheels.
Actually, our data loggers can be programmed to graph traction force for every foot of track,
or every 0.001 seconds. And then overlay the traces to see exactly where the differences are.
When we do so, we see that traction force is not smooth and steady, but is
rather jumpy and irregular.
Did someone earlier mention shocks and wheel hop?
Re: How will you go faster?
If distance is limited (1/4 mile), acceleration becomes the critical factor. And since F = M * A, and A = F / M, force and mass are determining factors, horsepower is AWOL.How fast (quick(er) is too.
A torque curve already contains rpm by definition. There is no need to calculate the power curve since it is not part of the F = M * A eqution.The only way a torque curve can be used to maximize performance is if you add the rpm component in the spreadsheet  so you can calculate the power curve and know what to optimize in the drivetrain.
[/quote]
David your own simulation data proves these statements incorrect. How is it possible your better calculated performance is with the lower of your chosen input parameters if there is not something more to be learned?
Re: How will you go faster?
David your own simulation data proves these statements incorrect. How is it possible your better calculated performance is with the lower of your chosen input parameters if there is not something more to be learned?parkman wrote: ↑Tue Nov 22, 2022 7:57 pmIf distance is limited (1/4 mile), acceleration becomes the critical factor. And since F = M * A, and A = F / M, force and mass are determining factors, horsepower is AWOL.How fast (quick(er) is too.
A torque curve already contains rpm by definition. There is no need to calculate the power curve since it is not part of the F = M * A eqution.The only way a torque curve can be used to maximize performance is if you add the rpm component in the spreadsheet  so you can calculate the power curve and know what to optimize in the drivetrain.
[/quote]
He isn’t wrong but don’t bother arguing as he hasnt figured out that maximising the force in F=MA is also achieved by maximising available power to the wheels at any instant . Multiple ways to skin the cat.

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Re: How will you go faster?
He isn’t wrong but don’t bother arguing as he hasnt figured out that maximising the force in F=MA is also achieved by maximising available power to the wheels at any instant .
To my esteemed fellow racers.
Given F=MA, and A=F/M, where is the horsepower factor?
Is it to be found within the Force parameter, or the Weight parameter? I think not. Both have units of lbs.
Then where?
Currently, we are examining the performance of racing snowmobiles with CVT transmissions.
Since the rpms and torque are held constant, so is the horsepower.
Yet, the sled will accelerate quite quickly at constant horsepower. How is this possible?
Re: How will you go faster?
Only until it hits the wall, aerodynamic wall, gradient wall, CVT has no more gearing increase wall.David Redszus wrote: ↑Tue Nov 22, 2022 11:32 pmHe isn’t wrong but don’t bother arguing as he hasnt figured out that maximising the force in F=MA is also achieved by maximising available power to the wheels at any instant .
To my esteemed fellow racers.
Given F=MA, and A=F/M, where is the horsepower factor?
Is it to be found within the Force parameter, or the Weight parameter? I think not. Both have units of lbs.
Then where?
Currently, we are examining the performance of racing snowmobiles with CVT transmissions.
Since the rpms and torque are held constant, so is the horsepower.
Yet, the sled will accelerate quite quickly at constant horsepower. How is this possible?

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Re: How will you go faster?
It does nothing of the sort. What do you feel is incorrect? Could you please provide a concrete example with real numbers?David your own simulation data proves these statements incorrect.
There is a great deal more to be learned; we have just begun. The changes in calculated performance were never intended to optimize performance; only that as various parameters change, so does performance.How is it possible your better calculated performance is with the lower of your chosen input parameters if there is not something more to be learned?
The shape of the torque curve and the gear sets used can produce substantial differences in performance.
A short first gear will produce a very quick 60ft time and high G force.
But, if the remaining gears are incorrect, the total 1/4 mile elapsed time will be slow.
Given a specific torque curve, it is important to find the right combination of rear end ratio, gear ratios, and tire diameter.