Low torque #'s on the dyno

Eham · 04-15-2021, 03:47 PM

Any dyno experts in here? What could cause abnormally low torque #'s? I know there are many variables that can affect dyno readings but i'd think they would apply to both HP and T. Torque looks to be about 60ft.lbs lower than what i've typically seen from a ZL1:

LT1ornothing · 04-15-2021, 04:11 PM

Hey there! No expert but I've been tuned before on other cars. I saw your thread with the dyno number and agree with the guys that said the torque is low.

Was the pull done on 93 octane? Was it really hot? There are a number of factors that can trigger the ecu to decrease timing and lower torque output to prevent engine or clutch damage. This is why on manual cars it is better to have both torque management and clutch protection turned off.

Hope you get it sorted out soon.

Eham · 04-15-2021, 05:37 PM

Hey. Yes there was about a half tank of 93 and wasn't that hot. I guess i am trying to figure out if it was actually the car reducing torque, the dyno operator, or just the dyno? I dont believe he turned any of the nannies off and i think he ran it in touring mode, if that makes any difference.

LT1ornothing · 04-15-2021, 05:54 PM

Quote:

Originally Posted by Eham

Hey. Yes there was about a half tank of 93 and wasn't that hot. I guess i am trying to figure out if it was actually the car reducing torque, the dyno operator, or just the dyno? I dont believe he turned any of the nannies off and i think he ran it in touring mode, if that makes any difference.

I'm no ZL1 owner, but that very well may have been the issue. I believe the nannies should be off to make a clean pull. I'd have the car dyno'd again with the nannies off to rule that out and go from there.

95 imp · 04-15-2021, 11:08 PM

Were you tripping the KS?

Doc Oc · 04-16-2021, 09:17 AM

I work part time at a dyno shop. According to our dyno operator the nannies don't need to be turned off, as the car recognizes it's on rollers and shuts everything off at a particular speed anyway. It kind of gives a wiggle when it happens and hasn't seemed to affect my results. Take that for what it's worth.

Could improper tq management tuning be at work?

Sometimes when our torque numbers are off it's due to a bad rpm connection but the graph doesn't look that smooth when it happens so I doubt that's the reason. We also spray belt dressing on the tires of any higher hp cars to prevent slippage which can lead to low #'s. However our dyno is old and the rollers worn, so I'm not sure how necessary that is elsewhere. Also, your operator should see that on the graph if it was happening.

Eham · 04-16-2021, 09:40 AM

Help me out here...KS? If you're talking about the knock sensor then i wouldnt think so since the first run was completely stock and still low torque. The second run was after a 30 min cool down and Roto-fab install only (no tune). I also thought that maybe there was some wheel slip going on but wouldnt that show up on the HP as well?

04-15-2021, 03:47 PM	#1
Eham Drives: 2021 ZL1 1LE Join Date: Oct 2020 Location: Charleston, SC Posts: 103	Low torque #'s on the dyno Any dyno experts in here? What could cause abnormally low torque #'s? I know there are many variables that can affect dyno readings but i'd think they would apply to both HP and T. Torque looks to be about 60ft.lbs lower than what i've typically seen from a ZL1: Attached Images

04-15-2021, 11:08 PM	#5
95 imp Dumb Ass Deluxe Drives: A Tricked Out Mountain Bike Join Date: Jun 2019 Location: Arizona Posts: 1,959	Were you tripping the KS? __________________

04-16-2021, 09:17 AM	#6
Doc Oc Drives: 2017 Camaro 2SS Join Date: Jul 2016 Location: SC Posts: 185	I work part time at a dyno shop. According to our dyno operator the nannies don't need to be turned off, as the car recognizes it's on rollers and shuts everything off at a particular speed anyway. It kind of gives a wiggle when it happens and hasn't seemed to affect my results. Take that for what it's worth. Could improper tq management tuning be at work? Sometimes when our torque numbers are off it's due to a bad rpm connection but the graph doesn't look that smooth when it happens so I doubt that's the reason. We also spray belt dressing on the tires of any higher hp cars to prevent slippage which can lead to low #'s. However our dyno is old and the rollers worn, so I'm not sure how necessary that is elsewhere. Also, your operator should see that on the graph if it was happening. __________________ 2017 2SS A8 TSP LT's, ported msd/95 mm, e85

04-15-2021, 04:11 PM	#2
LT1ornothing Drives: 2020 LT1 M6 Join Date: Jan 2016 Location: South, the DEEP south Posts: 1,114	Hey there! No expert but I've been tuned before on other cars. I saw your thread with the dyno number and agree with the guys that said the torque is low. Was the pull done on 93 octane? Was it really hot? There are a number of factors that can trigger the ecu to decrease timing and lower torque output to prevent engine or clutch damage. This is why on manual cars it is better to have both torque management and clutch protection turned off. Hope you get it sorted out soon.

04-15-2021, 05:37 PM	#3
Eham Drives: 2021 ZL1 1LE Join Date: Oct 2020 Location: Charleston, SC Posts: 103	Hey. Yes there was about a half tank of 93 and wasn't that hot. I guess i am trying to figure out if it was actually the car reducing torque, the dyno operator, or just the dyno? I dont believe he turned any of the nannies off and i think he ran it in touring mode, if that makes any difference.

04-16-2021, 09:40 AM	#7
Eham Drives: 2021 ZL1 1LE Join Date: Oct 2020 Location: Charleston, SC Posts: 103	Help me out here...KS? If you're talking about the knock sensor then i wouldnt think so since the first run was completely stock and still low torque. The second run was after a 30 min cool down and Roto-fab install only (no tune). I also thought that maybe there was some wheel slip going on but wouldnt that show up on the HP as well?

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