Engine dyno sweep RPM

[ClassAct]

What is the best (or correct) RPM/second sweep rate when testing an engine on the dyno? I know some use 300 RPM, others use 600 and maybe there are higher sweep speeds. What sweep rate is the most accurate and how do you decide which rate to use?

[dynoflo]

I have a old go power dyno converted to strain gauge with manual water control valve and I use 300 rpm per second. I have never used anything other than 300 rpm per second.I have noticed that when rpms get a little bit ahead on speed it reads higher. My data aquisition is about as old as dyno. Maybe some of the big money dyno operators would chime in.

[maxracesoftware]

both 300 or 600 RPM/Second Rates are good to use .
i use 600 RPM/Second Rate just about for every type Engine , and especially for all DragRace Engines
most DragStrip Engines will be on average around 600 RPM/Second in hi-gear at last half of the DragStrip

660 FT to 1320 FT distance average :
if your Car is around 10.000 second ET or faster , you might be around 500+ RPM/Second Rate or faster
if you are slower than 11.000 second ET , you are probably closer to 300 RPM/Second Rate

600 RPM/Second Rate gives accurate enough correlation to Dragstrip Runs
so that i feel using 300 RPM/Second Rate just wears out your Dyno and test engine twice as fast , just for the same basic information .

[ClassAct]

Thank you Larry. My next question would be is what about low gear rpm/second? Is that a factor? I would think any decent 400-425 horse engine would accelerate at closer to 600 rpm/second in low gear. Does what an engine does in low gear matter regarding dyno testing. Thanks in advance.

[maxracesoftware]

Thank you Larry. My next question would be is what about low gear rpm/second? Is that a factor? I would think any decent 400-425 horse engine would accelerate at closer to 600 rpm/second in low gear. Does what an engine does in low gear matter regarding dyno testing. Thanks in advance.

425 HP in 3330 Lbs 1968 Camaro
4.10 rear gears , 4000 Stall Converter,
30" Slicks , 2-Speed PowerGlide 1.82:1 1st , 1900Ft DA
Feet ET MPH RPM GForce Gear
0 -0.2219 6.1149 4000 1.2105 1
60 1.6703 39.4673 4000 0.6874 1
330 4.7919 76.3648 6752 0.4349 1
660 7.4123 92.4118 4547 0.2766 2
1000 9.7141 107.3490 5186 0.2543 2
1320 11.6523 116.6368 5668 0.2270 2

2-Speed PowerGlide 1.82:1 1st
1094 RPM/Second -to- 882 in 1st Gear ( 882 RPM/SEC @ Shift , and 297 feet out )
297 RPM/Second -to- 238 in 2nd Gear ( 238 RPM/SEC @ 1320 Feet )

_________________________________________________________________________


3-Speed Turbo 350 Trans 2.52,1.52,1.00
Feet ET MPH RPM GForce Gear
0 -0.1887 7.1520 4000 1.6251 1
60 1.5223 41.2033 5065 0.7359 1
330 4.6263 75.0422 5543 0.4402 2
660 7.2518 92.6551 4559 0.2763 3
1000 9.5488 107.5357 5194 0.2538 3
1320 11.4841 116.7887 5675 0.2265 3

3-Speed Turbo 350 Trans 2.52,1.52,1.00
2002 RPM/SEC -to- 1667 in 1st Gear ( 1667 RPM/SEC @ Shift , and 114 Feet out )
749 RPM/SEC -to- 591 in 2nd Gear ( 591 RPM/SEC @ Shift , and 506 Feet out )
294 RPM/SEC -to 233 RPM/SEC in 3rd Gear ( 233 RPM/SEC at 1320 Feet out )

2850 Feet out = 119 RPM/SEC , 19.2820ET 146.6828MPH 7016RPM

[ClassAct]

Thank you Larry. My next question would be is what about low gear rpm/second? Is that a factor? I would think any decent 400-425 horse engine would accelerate at closer to 600 rpm/second in low gear. Does what an engine does in low gear matter regarding dyno testing. Thanks in advance.

425 HP in 3330 Lbs 1968 Camaro
4.10 rear gears , 4000 Stall Converter,
30" Slicks , 2-Speed PowerGlide 1.82:1 1st , 1900Ft DA
Feet ET MPH RPM GForce Gear
0 -0.2219 6.1149 4000 1.2105 1
60 1.6703 39.4673 4000 0.6874 1
330 4.7919 76.3648 6752 0.4349 1
660 7.4123 92.4118 4547 0.2766 2
1000 9.7141 107.3490 5186 0.2543 2
1320 11.6523 116.6368 5668 0.2270 2

2-Speed PowerGlide 1.82:1 1st
1094 RPM/Second -to- 882 in 1st Gear ( 882 RPM/SEC @ Shift , and 297 feet out )
297 RPM/Second -to- 238 in 2nd Gear ( 238 RPM/SEC @ 1320 Feet )

_________________________________________________________________________


3-Speed Turbo 350 Trans 2.52,1.52,1.00
Feet ET MPH RPM GForce Gear
0 -0.1887 7.1520 4000 1.6251 1
60 1.5223 41.2033 5065 0.7359 1
330 4.6263 75.0422 5543 0.4402 2
660 7.2518 92.6551 4559 0.2763 3
1000 9.5488 107.5357 5194 0.2538 3
1320 11.4841 116.7887 5675 0.2265 3

3-Speed Turbo 350 Trans 2.52,1.52,1.00
2002 RPM/SEC -to- 1667 in 1st Gear ( 1667 RPM/SEC @ Shift , and 114 Feet out )
749 RPM/SEC -to- 591 in 2nd Gear ( 591 RPM/SEC @ Shift , and 506 Feet out )
294 RPM/SEC -to 233 RPM/SEC in 3rd Gear ( 233 RPM/SEC at 1320 Feet out )

2850 Feet out = 119 RPM/SEC , 19.2820ET 146.6828MPH 7016RPM

AWESOME Larry. Thank You.

[MELWAY]

What is the best (or correct) RPM/second sweep rate when testing an engine on the dyno? I know some use 300 RPM, others use 600 and maybe there are higher sweep speeds. What sweep rate is the most accurate and how do you decide which rate to use?

I feel on a superflow it’s a little application specific.
I test all drag engines and most street engines at 600/ sec
I have seen with heavy rotating assembly that the slower the
Test. There is a slight increase in numbers
I have built and dyno tested some endurance boat engines
And to get a good tune up and plug readings and build heat in chamber and engine I have tested them at 100/ sec

[ClassAct]

What is the best (or correct) RPM/second sweep rate when testing an engine on the dyno? I know some use 300 RPM, others use 600 and maybe there are higher sweep speeds. What sweep rate is the most accurate and how do you decide which rate to use?

I feel on a superflow it’s a little application specific.
I test all drag engines and most street engines at 600/ sec
I have seen with heavy rotating assembly that the slower the
Test. There is a slight increase in numbers
I have built and dyno tested some endurance boat engines
And to get a good tune up and plug readings and build heat in chamber and engine I have tested them at 100/ sec

When testing at 100 RPM per second did you make the sweep time (rather than pulling from say 3500 to 7000) less (like 5000 to 7000) to decrease the time the engine is being loaded for the pull?

[MELWAY]

What is the best (or correct) RPM/second sweep rate when testing an engine on the dyno? I know some use 300 RPM, others use 600 and maybe there are higher sweep speeds. What sweep rate is the most accurate and how do you decide which rate to use?

I feel on a superflow it’s a little application specific.
I test all drag engines and most street engines at 600/ sec
I have seen with heavy rotating assembly that the slower the
Test. There is a slight increase in numbers
I have built and dyno tested some endurance boat engines
And to get a good tune up and plug readings and build heat in chamber and engine I have tested them at 100/ sec

When testing at 100 RPM per second did you make the sweep time (rather than pulling from say 3500 to 7000) less (like 5000 to 7000) to decrease the time the engine is being loaded for the pull?

Not really. I usually only pull an engine just below Pk Tq
A high comp engine that peaks at 7000 or more is not going to be happy being fully loaded at 3500
A good torcher test on a boat engine is to run test to say 7200
Then set return engine speed to 7000 and leave it at WOT for a few minets

[BobbyB]

Thank you Larry. My next question would be is what about low gear rpm/second? Is that a factor? I would think any decent 400-425 horse engine would accelerate at closer to 600 rpm/second in low gear. Does what an engine does in low gear matter regarding dyno testing. Thanks in advance.

425 HP in 3330 Lbs 1968 Camaro
4.10 rear gears , 4000 Stall Converter,
30" Slicks , 2-Speed PowerGlide 1.82:1 1st , 1900Ft DA
Feet ET MPH RPM GForce Gear
0 -0.2219 6.1149 4000 1.2105 1
60 1.6703 39.4673 4000 0.6874 1
330 4.7919 76.3648 6752 0.4349 1
660 7.4123 92.4118 4547 0.2766 2
1000 9.7141 107.3490 5186 0.2543 2
1320 11.6523 116.6368 5668 0.2270 2

2-Speed PowerGlide 1.82:1 1st
1094 RPM/Second -to- 882 in 1st Gear ( 882 RPM/SEC @ Shift , and 297 feet out )
297 RPM/Second -to- 238 in 2nd Gear ( 238 RPM/SEC @ 1320 Feet )

_________________________________________________________________________


3-Speed Turbo 350 Trans 2.52,1.52,1.00
Feet ET MPH RPM GForce Gear
0 -0.1887 7.1520 4000 1.6251 1
60 1.5223 41.2033 5065 0.7359 1
330 4.6263 75.0422 5543 0.4402 2
660 7.2518 92.6551 4559 0.2763 3
1000 9.5488 107.5357 5194 0.2538 3
1320 11.4841 116.7887 5675 0.2265 3

3-Speed Turbo 350 Trans 2.52,1.52,1.00
2002 RPM/SEC -to- 1667 in 1st Gear ( 1667 RPM/SEC @ Shift , and 114 Feet out )
749 RPM/SEC -to- 591 in 2nd Gear ( 591 RPM/SEC @ Shift , and 506 Feet out )
294 RPM/SEC -to 233 RPM/SEC in 3rd Gear ( 233 RPM/SEC at 1320 Feet out )

2850 Feet out = 119 RPM/SEC , 19.2820ET 146.6828MPH 7016RPM

Great Info!

How are you obtaining, or determining the GFORCE in each gear?

Thanks,

[maxracesoftware]

by BobbyB » Mon Sep 27, 2021 10:31 am

Great Info!

How are you obtaining, or determining the GFORCE in each gear?

Thanks,

with my old ETA v1.00 version Software
here's Pictures of how i did it :

ETA1.jpg

ETA2.jpg

ETA3.jpg

ETA4.jpg

ETA5.jpg

ETA6.jpg

[CamKing]

To me, it looks like the slower you go on a superflow, the less the numbers are inflated, but that's just what I have seen.

When I started working around a dyno, there were no computer controls.
It was a H.F. dyno, the operator would bring it to a given RPM, load the brake, and hold it there, monitoring temps and pressures, while one person reads the laminar air flow meter for CFM, another person reads fuel flow, and another person may be reading exhaust temps, boost, or something else. When everyone has their reading, and the controller has read the torque reading on the Toledo scale, he backs the engine down, writes down all the readings, and goes to the next step in RPM to do it all over again.

Here's an old sheet from what looks like a wastegate spring test on a turbo Cosworth Indycar engine

dyno sheet.jpg

[Stan Weiss]

Thank you Larry. My next question would be is what about low gear rpm/second? Is that a factor? I would think any decent 400-425 horse engine would accelerate at closer to 600 rpm/second in low gear. Does what an engine does in low gear matter regarding dyno testing. Thanks in advance.

425 HP in 3330 Lbs 1968 Camaro
4.10 rear gears , 4000 Stall Converter,
30" Slicks , 2-Speed PowerGlide 1.82:1 1st , 1900Ft DA
Feet ET MPH RPM GForce Gear
0 -0.2219 6.1149 4000 1.2105 1
60 1.6703 39.4673 4000 0.6874 1
330 4.7919 76.3648 6752 0.4349 1
660 7.4123 92.4118 4547 0.2766 2
1000 9.7141 107.3490 5186 0.2543 2
1320 11.6523 116.6368 5668 0.2270 2

2-Speed PowerGlide 1.82:1 1st
1094 RPM/Second -to- 882 in 1st Gear ( 882 RPM/SEC @ Shift , and 297 feet out )
297 RPM/Second -to- 238 in 2nd Gear ( 238 RPM/SEC @ 1320 Feet )

_________________________________________________________________________


3-Speed Turbo 350 Trans 2.52,1.52,1.00
Feet ET MPH RPM GForce Gear
0 -0.1887 7.1520 4000 1.6251 1
60 1.5223 41.2033 5065 0.7359 1
330 4.6263 75.0422 5543 0.4402 2
660 7.2518 92.6551 4559 0.2763 3
1000 9.5488 107.5357 5194 0.2538 3
1320 11.4841 116.7887 5675 0.2265 3

3-Speed Turbo 350 Trans 2.52,1.52,1.00
2002 RPM/SEC -to- 1667 in 1st Gear ( 1667 RPM/SEC @ Shift , and 114 Feet out )
749 RPM/SEC -to- 591 in 2nd Gear ( 591 RPM/SEC @ Shift , and 506 Feet out )
294 RPM/SEC -to 233 RPM/SEC in 3rd Gear ( 233 RPM/SEC at 1320 Feet out )

2850 Feet out = 119 RPM/SEC , 19.2820ET 146.6828MPH 7016RPM

Great Info!

How are you obtaining, or determining the GFORCE in each gear?

Thanks,

How I do it.

You take 2 MPH and their time points.

You convert MPH to velocity in feet per second.

You subtract the first Velocity from the second velocity.

You subtract the first time from the second time.

You divide the results of the time difference in the results of the velocity difference.

You then divide that answer by gravity.

Stan

[ClassAct]

425 HP in 3330 Lbs 1968 Camaro
4.10 rear gears , 4000 Stall Converter,
30" Slicks , 2-Speed PowerGlide 1.82:1 1st , 1900Ft DA
Feet ET MPH RPM GForce Gear
0 -0.2219 6.1149 4000 1.2105 1
60 1.6703 39.4673 4000 0.6874 1
330 4.7919 76.3648 6752 0.4349 1
660 7.4123 92.4118 4547 0.2766 2
1000 9.7141 107.3490 5186 0.2543 2
1320 11.6523 116.6368 5668 0.2270 2

2-Speed PowerGlide 1.82:1 1st
1094 RPM/Second -to- 882 in 1st Gear ( 882 RPM/SEC @ Shift , and 297 feet out )
297 RPM/Second -to- 238 in 2nd Gear ( 238 RPM/SEC @ 1320 Feet )

_________________________________________________________________________


3-Speed Turbo 350 Trans 2.52,1.52,1.00
Feet ET MPH RPM GForce Gear
0 -0.1887 7.1520 4000 1.6251 1
60 1.5223 41.2033 5065 0.7359 1
330 4.6263 75.0422 5543 0.4402 2
660 7.2518 92.6551 4559 0.2763 3
1000 9.5488 107.5357 5194 0.2538 3
1320 11.4841 116.7887 5675 0.2265 3

3-Speed Turbo 350 Trans 2.52,1.52,1.00
2002 RPM/SEC -to- 1667 in 1st Gear ( 1667 RPM/SEC @ Shift , and 114 Feet out )
749 RPM/SEC -to- 591 in 2nd Gear ( 591 RPM/SEC @ Shift , and 506 Feet out )
294 RPM/SEC -to 233 RPM/SEC in 3rd Gear ( 233 RPM/SEC at 1320 Feet out )

2850 Feet out = 119 RPM/SEC , 19.2820ET 146.6828MPH 7016RPM

Great Info!

How are you obtaining, or determining the GFORCE in each gear?

Thanks,

How I do it.

You take 2 MPH and their time points.

You convert MPH to velocity in feet per second.

You subtract the first Velocity from the second velocity.

You subtract the first time from the second time.

You divide the results of the time difference in the results of the velocity difference.

You then divide that answer by gravity.

Stan

I’m interested in this. What points on the time slip would you start with? 60 to 330 feet 330 to 660 or 660 to 1320?

I’m learning from this thread and it’s interesting.

[Stan Weiss]

Great Info!

How are you obtaining, or determining the GFORCE in each gear?

Thanks,

How I do it.

You take 2 MPH and their time points.

You convert MPH to velocity in feet per second.

You subtract the first Velocity from the second velocity.

You subtract the first time from the second time.

You divide the results of the time difference in the results of the velocity difference.

You then divide that answer by gravity.

Stan

I’m interested in this. What points on the time slip would you start with? 60 to 330 feet 330 to 660 or 660 to 1320?

I’m learning from this thread and it’s interesting.

What I posted uses MPH / Velocity. The time slips that I have seen only have 1/8 mile and quarter mile MPH. 60 to 330 feet 330 to 660 or 660 to 1320 would be time and distance which would be a difference set of formulas.

Stan