[Eldi Z]

Raising the question to those who have a real-world experience in this comparison.

Given all hardware elements, engine, sensors, Etc. are are healthy and functioning as they should, using a proper WB measurement tool (I.E. Ballenger AF500 + Bosch / NTK sensor) / PROLInk into HP Tuners.

How close is the correlation of the logged data and the actual dyno results of Power and Torque?
When calculating by the formula of:

Engine Torque (taken from "Delivered Engine Torque" or "Engine Torque" VCM channels) x RPM / 5252 (constant #) = CHP
Then applying the Drivetrain loss depending on Transmission type, Auto / Manual to get the R-WHP/TQ

Does the result of the calculation come close to the actual dyno numbers?

[RobZL1]

In my opinion, it's much closer to use MAF airflow in lb/min * 10 as a representation of crankshaft hp. If your torque model is correct, then the other way should be close, too.

[SOCAL.M6.ZLE]

Great question that I get asked alot also... I will check my recent DYNO log and report back soon...

[SOCAL.M6.ZLE]

Alright, quick check on both recommendations...

ROB, on the graph below, but peak RWHP was around 6,100rpm... MAF airflow in lb/min = 86.69 * 10 as a representation of crankshaft hp would equal 866hp at the fly which seems pretty far off... seems alot closer to WHP... thoughts?

Now testing; Engine Torque (taken from "Delivered Engine Torque" or "Engine Torque" VCM channels) x RPM / 5252 (constant #) = CHP
Then applying the Drivetrain loss depending on Transmission type, Auto / Manual to get the R-WHP/TQ...

Peak torque is at 4,500 rpm... Delivered was 640ftlb and Engine torque was 878ftlb...

Using your model...
Delivered 640 x 4,500rpm / 5252 = 548hp
Engine Torque 878 x 4,500 / 5252 =752hp

Seems like all of these are off... unless I am doing something wrong...
Thoughts?

[RobZL1]

Originally Posted by SOCAL.M6.ZLE

Alright, quick check on both recommendations...

ROB, on the graph below, but peak RWHP was around 6,100rpm... MAF airflow in lb/min = 86.69 * 10 as a representation of crankshaft hp would equal 866hp at the fly which seems pretty far off... seems alot closer to WHP... thoughts?

Now testing; Engine Torque (taken from "Delivered Engine Torque" or "Engine Torque" VCM channels) x RPM / 5252 (constant #) = CHP
Then applying the Drivetrain loss depending on Transmission type, Auto / Manual to get the R-WHP/TQ...

Peak torque is at 4,500 rpm... Delivered was 640ftlb and Engine torque was 878ftlb...

Using your model...
Delivered 640 x 4,500rpm / 5252 = 548hp
Engine Torque 878 x 4,500 / 5252 =752hp

Seems like all of these are off... unless I am doing something wrong...
Thoughts?

You have to look at dynamic airflow. MAF tops out at that number in the PID's. Dynamic keeps going. What is the peak lb/min of dynamic airflow during the log of that pull (not necessarily at 6100 exactly)? I would expect 95-96lb/min.

[Eldi Z]

In terms of the Torque PID, I think that the correct one to use in the formula is simply "Engine Torque" and not the "Delivered Engine Torque" Channel.

Maybe calibrators can chime in and correct this information / provide some insights for the audience.

[RobZL1]

For what it's worth, engine torque is indeed the one I've used in the past. I've also made huge physics-based math parameters for calculated horsepower based on acceleration rate during a pull, including drag coefficient, frontal area, weight, etc. At the end of the day, I think the dynamic airflow is the easiest estimate (or engine torque for that matter if your virtual torque model is good)

[SOCAL.M6.ZLE]

Originally Posted by RobZL1

You have to look at dynamic airflow. MAF tops out at that number in the PID's. Dynamic keeps going. What is the peak lb/min of dynamic airflow during the log of that pull (not necessarily at 6100 exactly)? I would expect 95-96lb/min.

The log look weird now that you mention it...
MAF (SAE) climbs to 86.69 at 5,700rpm, and stays there till redline...
While the MAF Hz goes from 9,925 to 10,498 during the same time...

[SOCAL.M6.ZLE]

Cylinder airmass peaked at 1.74g at 5,230rpm and dropped to 1.68g at 6,850 rpm
Which was lower than my street data logs, I believe due to the 93F ambient temps and belt slip (I was logging 1 psi less than my earlier data logs)

My first data log with this combo had a cylinder mass of 1.77g during that same RPM spread with a peak of 1.81g

[Joshinator99]

Originally Posted by RobZL1

In my opinion, it's much closer to use MAF airflow in lb/min * 10 as a representation of crankshaft hp. If your torque model is correct, then the other way should be close, too.

Originally Posted by RobZL1

You have to look at dynamic airflow. MAF tops out at that number in the PID's. Dynamic keeps going. What is the peak lb/min of dynamic airflow during the log of that pull (not necessarily at 6100 exactly)? I would expect 95-96lb/min.

Agree with Rob 100%

[RobZL1]

Originally Posted by SOCAL.M6.ZLE

Cylinder airmass peaked at 1.74g at 5,230rpm and dropped to 1.68g at 6,850 rpm
Which was lower than my street data logs, I believe due to the 93F ambient temps and belt slip (I was logging 1 psi less than my earlier data logs)

My first data log with this combo had a cylinder mass of 1.77g during that same RPM spread with a peak of 1.81g

Originally Posted by Joshinator99

Agree with Rob 100%

Gabe, do you have Dynamic Airflow in your channels? That's ultimately what the ECU uses for it's final airflow. It's a combination of some parts MAF and some parts VVE until over 4000rpm, where in all GM ECU's I've dealt with, it then equals filtered MAF data, regardless of how you set the dynamic RPM switchover point.

So basically anywhere above 4000rpm, and especially at WOT, the Dynamic Airflow channel IS the MAF airflow. That would be the lb/min to use for this HP estimation.

[SOCAL.M6.ZLE]

Originally Posted by RobZL1

Gabe, do you have Dynamic Airflow in your channels? That's ultimately what the ECU uses for it's final airflow. It's a combination of some parts MAF and some parts VVE until over 4000rpm, where in all GM ECU's I've dealt with, it then equals filtered MAF data, regardless of how you set the dynamic RPM switchover point.

So basically anywhere above 4000rpm, and especially at WOT, the Dynamic Airflow channel IS the MAF airflow. That would be the lb/min to use for this HP estimation.

Thanks for the clarification Rob! That said, here are the revised calculation...

peak RWHP was around 6,100rpm... Dynamic Airflow was 5,600 lb/hr or 93.3 lb/min = * 10 as a representation of crankshaft hp would equal 933hp at the fly . At 838rwhp x 1.18 = 988bhp so it looks like a 6% difference so far?

Now... checking at 6,950rpm... Dynamic Airflow was 6,114 lb/hr or 101.9 lb/min = * 10 as a representation of crankshaft hp would equal 1,019bhp...

Am I doing this right?

[RobZL1]

Originally Posted by SOCAL.M6.ZLE

Thanks for the clarification Rob! That said, here are the revised calculation...

peak RWHP was around 6,100rpm... Dynamic Airflow was 5,600 lb/hr or 93.3 lb/min = * 10 as a representation of crankshaft hp would equal 933hp at the fly . At 838rwhp x 1.18 = 988bhp so it looks like a 6% difference so far?

Now... checking at 6,950rpm... Dynamic Airflow was 6,114 lb/hr or 101.9 lb/min = * 10 as a representation of crankshaft hp would equal 1,019bhp...

Am I doing this right?

There you have it. I'd say you are in the ballpark.

I think most people find that the M6's lose about 12-13%, so

933*0.87 or 0.88 = 812 to 821rwhp

There is also an odd bump in the dyno around 6100 where you had your peak. If that was flattened out, it looks like peak would still be about 835-840 but around 6300rpm. I'd wager that your lb/min at 6300rpm, times 10, times 0.875 would be about 840.

The higher airflow numbers you see near 7000rpm where the power doesn't match, is where the engine is dropping off. It might (or might not!) be able to take some more timing as the engine gets less efficient in that last 800-900rpm approaching 7000rpm. If it could take more timing, then your HP peak would push higher toward the 880+rwhp range (1019*0.87 or 0.88).

In any case, I think the Dyn Air estimation works pretty well here. It's just an estimation, and assumes you are using that air the the best of it's ability.

With the old design Terminator cam, I think that might be what's holding back the last 1000rpm or so. I believe that cam is smaller than his current design. I think Ted added duration and widened the lsa on the newer ones, which would make that thing pull to 7000+. You can see it in the boost curve here. Above 6000, it ramps up the boost because it can't get it out of the cylinder.

This is just my opinion. I'm no expert here!

[SOCAL.M6.ZLE]

Originally Posted by RobZL1

There you have it. I'd say you are in the ballpark.

I think most people find that the M6's lose about 12-13%, so

933*0.87 or 0.88 = 812 to 821rwhp

There is also an odd bump in the dyno around 6100 where you had your peak. If that was flattened out, it looks like peak would still be about 835-840 but around 6300rpm. I'd wager that your lb/min at 6300rpm, times 10, times 0.875 would be about 840.

The higher airflow numbers you see near 7000rpm where the power doesn't match, is where the engine is dropping off. It might (or might not!) be able to take some more timing as the engine gets less efficient in that last 800-900rpm approaching 7000rpm. If it could take more timing, then your HP peak would push higher toward the 880+rwhp range (1019*0.87 or 0.88).

In any case, I think the Dyn Air estimation works pretty well here. It's just an estimation, and assumes you are using that air the the best of it's ability.

With the old design Terminator cam, I think that might be what's holding back the last 1000rpm or so. I believe that cam is smaller than his current design. I think Ted added duration and widened the lsa on the newer ones, which would make that thing pull to 7000+. You can see it in the boost curve here. Above 6000, it ramps up the boost because it can't get it out of the cylinder.

This is just my opinion. I'm no expert here!

My man! I agree with your analysis... Feels like the exhaust duration is a little light on the current cam, and would benefit from more in the higher RPMs for sure. I plan to go back in late November once the new clutch is installed, now that I have the belt slip fixed also... with better air, just interested as what the delta will be, and what the true standard to X port gains are.

RobZL1 you are far more than a novice my friend, you are a stud for sure, and this was a fun exercise.