Analysis of my dyno runs as compared to my drag strip results.
Nov 11, 2009, 04:09 PM
#1
Analysis of my dyno runs as compared to my drag strip results.
Every dyno is different, the data in this post partains to the AMS dynojet dyno... that dyno only, not any other dynojet, dynapack dyno, mustang dyno or dyno dynamics dynometer.
IF you take the stock dyno results of the AMS shop car of 195.78 wheel HP 213.39 wheel torque compared to the advertised 237 HP and 253 lb/ft of torque of the Ralliart, you come up with a correction factor of 82.61% for crank HP and 84.34% for crank torque. For these rough estimates and for ease of calculation we can use 83% correction factor for both. This assumes that the dyno operators are competent and not fudging the numbers (accuse AMS at your own risk) and that the advertised HP and torque of the car in question are accurate as well (take that one up with Mitsubishi). Just for clarity, let me state that AMS does not provide or endorse this correction factor in any way.... it is derived from the results of a stock RA on their dyno using SAE correction.
Using this correction factor, you take the measured wheel HP and torque values and divide them by 83% to get the estimated crank HP and estimated crank torque. In my case, those numbers are as follows:
SAE corrected figures:
259.61 wheel HP => 312.78 crank HP. Gain over a stock RA 75.78 crank HP
283.66 wheel torque => 341.76 crank torque. Gain over a stock RA 88.76 crank lb/ft of torque.
Hmmmm, where have I seen numbers like that before…. Oh yeah, my estimated HP based on my drag strip runs was 306 by the ET method and 317 by the trap speed method…. I always go by the trap speed method because there is less variation due to driver error than there is in the ET method. So, less than 5 HP difference between the drag strip estimate of crank HP and the Dyno derived estimate of crank HP…. What do you know!
When I made a claim of gaining APPROXIMATLY 71 crank HP I was told repeatedly that there was no possibility of making those kinds of gains on my setup…. Well, that person was correct! It was a 75.78 crank hp gain!
I expect this thread to devolve into a “you can’t estimate crank HP from dyno results” bickering match. I will NOT be participating in the bickering, and would appreciate the mods monitoring the thread and locking it if needed… but please don’t delete it.
Keith
IF you take the stock dyno results of the AMS shop car of 195.78 wheel HP 213.39 wheel torque compared to the advertised 237 HP and 253 lb/ft of torque of the Ralliart, you come up with a correction factor of 82.61% for crank HP and 84.34% for crank torque. For these rough estimates and for ease of calculation we can use 83% correction factor for both. This assumes that the dyno operators are competent and not fudging the numbers (accuse AMS at your own risk) and that the advertised HP and torque of the car in question are accurate as well (take that one up with Mitsubishi). Just for clarity, let me state that AMS does not provide or endorse this correction factor in any way.... it is derived from the results of a stock RA on their dyno using SAE correction.
Using this correction factor, you take the measured wheel HP and torque values and divide them by 83% to get the estimated crank HP and estimated crank torque. In my case, those numbers are as follows:
SAE corrected figures:
259.61 wheel HP => 312.78 crank HP. Gain over a stock RA 75.78 crank HP
283.66 wheel torque => 341.76 crank torque. Gain over a stock RA 88.76 crank lb/ft of torque.
Hmmmm, where have I seen numbers like that before…. Oh yeah, my estimated HP based on my drag strip runs was 306 by the ET method and 317 by the trap speed method…. I always go by the trap speed method because there is less variation due to driver error than there is in the ET method. So, less than 5 HP difference between the drag strip estimate of crank HP and the Dyno derived estimate of crank HP…. What do you know!
When I made a claim of gaining APPROXIMATLY 71 crank HP I was told repeatedly that there was no possibility of making those kinds of gains on my setup…. Well, that person was correct! It was a 75.78 crank hp gain!
I expect this thread to devolve into a “you can’t estimate crank HP from dyno results” bickering match. I will NOT be participating in the bickering, and would appreciate the mods monitoring the thread and locking it if needed… but please don’t delete it.
Keith
Nov 11, 2009, 04:41 PM
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You can’t estimate crank HP from dyno results.
Okay, so these are some interesting numbers. A 17% drivetrain loss seems about right for an AWD car. I think DSport used an 18% estimate for drivetrain loss when they were dynoing the Ralliart and EVOs.
Okay, so these are some interesting numbers. A 17% drivetrain loss seems about right for an AWD car. I think DSport used an 18% estimate for drivetrain loss when they were dynoing the Ralliart and EVOs.
Nov 11, 2009, 10:37 PM
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Keith,
I think your observations are pretty spot on.
I passed thru the showroom today and said whats up, but I had a lot on my plate today and little time to stop and chat. I'm sure you'll be back around sometime soon and we'll have a chat!
Regards,
Eric Jones
I think your observations are pretty spot on.
I passed thru the showroom today and said whats up, but I had a lot on my plate today and little time to stop and chat. I'm sure you'll be back around sometime soon and we'll have a chat!
Regards,
Eric Jones
Nov 12, 2009, 06:03 AM
#6
My road tune resulted in almost matching your orange shop RA's stock turbo HP, but you guys made a $hitload more torque than I did.... I am running about 12.5 to 1 A/F for spool up, are you guys a lot leaner or is your timing very aggressive in the low RPM's? Not asking for specifics... just your general philosophy
Keith
Nov 12, 2009, 08:15 PM
#7
Hey Eric,
My road tune resulted in almost matching your orange shop RA's stock turbo HP, but you guys made a $hitload more torque than I did.... I am running about 12.5 to 1 A/F for spool up, are you guys a lot leaner or is your timing very aggressive in the low RPM's? Not asking for specifics... just your general philosophy
Keith
My road tune resulted in almost matching your orange shop RA's stock turbo HP, but you guys made a $hitload more torque than I did.... I am running about 12.5 to 1 A/F for spool up, are you guys a lot leaner or is your timing very aggressive in the low RPM's? Not asking for specifics... just your general philosophy
Keith
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Nov 13, 2009, 03:41 PM
#8
I started out with the GST base flash that Bryan offers up for free. It is a great starting point! I then re-scaled both the RPM and Load axis on the fuel maps to give high resolution from 5000 RPM and up (250 RPM increments) and on the load scale from load of 100 up to 270 in increments of 10. From there I just did load of runs on the street while data logging, and then tweaking the map where ever I saw a need for change. I made a few small changes to the timing map to get ride of knock at certain RPM / Load points.
Keith
Nov 14, 2009, 03:47 PM
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Pardon my ignorance, but crank HP is before losses? Is this the same as braking HP?
By the way, well done. You sound like you know what you are doing... and doing it well.
By the way, well done. You sound like you know what you are doing... and doing it well.
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