Dyno results
10-21-2019, 07:42 PM
#141
I stick to the easy stuff for me to understand ...the heads are supposed to be the same as the C7...the cam timing has not been revealed to my knowledge but I really doubt it is extreme ...the compression, dry sump, headers ,taller intake manifold ,and less drivetrain loss are good things...but they still do not add up IMHO to those rwhp#s.
10-21-2019, 07:50 PM
#142
Le Mans Master
Of course it's what they should do. It's not what they're going to do, though. They even told us what they're going to do: put another C8 on the same dyno in the coming months. I suspect that by then, the dyno operator will have figured out his error and the resulting numbers will be quite a bit lower. Just imagine the resulting article? "Proof that GM gave us a pre-production ringer!"
10-21-2019, 07:56 PM
#143
Melting Slicks
I don’t know if anybody has brought this up this up before but I’ll give you my input. The article is worthless.
I’m disappointed with the Motor Trend editors not the reporters.
The reason I say that is if article authors were getting numbers that don’t make any sense, why didn’t they find another dyno to run the same test. GM said the SAE test was 495 hp and the 123 mph 1/4 mile was consistent with 495 hp. So they should have run it on another 1 or 2 other Dynos to either confirm or refute the original Dyno numbers.
I don’t blame the reporters. I blame the editors for allowing this article to go out without some common sense testing on a different dyno. This is plain and simple failed editor review. It’s their job to do that.
I’m disappointed with the Motor Trend editors not the reporters.
The reason I say that is if article authors were getting numbers that don’t make any sense, why didn’t they find another dyno to run the same test. GM said the SAE test was 495 hp and the 123 mph 1/4 mile was consistent with 495 hp. So they should have run it on another 1 or 2 other Dynos to either confirm or refute the original Dyno numbers.
I don’t blame the reporters. I blame the editors for allowing this article to go out without some common sense testing on a different dyno. This is plain and simple failed editor review. It’s their job to do that.
Last edited by RussM05; 10-21-2019 at 07:57 PM.
10-21-2019, 08:06 PM
#144
Race Director
Blame common sense. Because they obviously are lacking in common sense math.
How did thwy not call in to question the dyno it was on and the settings? A simple Google search would have solved it for them.
Like this explanation by a tuner I found on Tech.
Kind of makes it easier to understand if you have the time to read it.
How did thwy not call in to question the dyno it was on and the settings? A simple Google search would have solved it for them.
Like this explanation by a tuner I found on Tech.
. I have written pages and pages of posts on this topic on various forums. Here's a little write up I did a few monthss ago. . .
DynoJets are inertia dynos, and have been around for years, much longer than any type of load cell dyno. Inertia dyno's work on the principle of the acceleration of a known mass over time. Their rollers are the known mass. Weighing in at over 2500lbs or so. Your car gets strapped down to the machine, and the dyno collects it's data. It is able to calculate horsepower by measuring the acceleration in rpm of the rollers in regards to RPM. This is why gearing can affect the dyno results, more on that in a bit. Now that the dyno has recorded the horsepower curve, it can take the integral of that curve and get the torque curve. Since the dyno’s power calculations are based on the acceleration of mass over time in regards to RPM, gearing is very important. Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).
Now we go to Mustang dyno’s and other loaded dyno’s. Our Mustang MD-1100SE dyno’s rollers weigh 2560lbs. That is the actual mass of the rollers, much like the DynoJet. That’s about where all the similarities end. When we get a car on our dyno, we enter two constants for the dyno’s algorithms. One being the vehicle weight, the other being what’s called “Horsepower At 50mph”. This is a number that represents how much horsepower it takes for the vehicle to push the air to maintain 50mph. This is used as the aerodynamic force. Mustang dyno’s are also equipped with a eddy currant load cell. Think of a magnetic brake from a freight train. This magnetic brake can apply enough resistance to stall a big rig. Off one side of the eddy currant load cell, there is a cantilever with a 5volt reference load sensor (strain gage). As the rollers are spinning this load sensor is measuring the actual torque being applied. So as the rollers spin, the load sensor is measuring the force being applied, sending that information to the dyno computer, taking into account the two constants entered earlier, computing the amount of resistance needed to be applied to the rollers to load the car so that the force of the rollers resistance is as close to the force the car sees on the street. The dyno is then able to calculate the total force being applied to the rollers in torque, and then taking the derivative of that torque curve to arrive at the horsepower curve. Since torque is an actual force of nature, like gravity and electricity, it can be directly measured. Horsepower is an idea that was thought up by man, and cannot be directly measured, only calculated.
I like to state it like this. . . I start by asking how much your car weighs, lets say 3500lbs. Now you take your car and you make a make a WOT rip in your tallest non overdrive gear, how much mass is your engine working against? 3500lbs right? Now you strap your car on a DynoJet and you make a WOT in the same gear, how much mass is your engine working against? 2500lbs right? Now you strap your car on a Mustang dyno, how much mass is your engine working against? 2500lbs. Plus the resistance being applied by the eddy current generator. We’ve seen anywhere for 470lbs of resistance to over 700lbs of resistance as measured in PAU force in the data logs. So which one is more accurate? Well they their both accurate. If a DynoJet dyno says you made 460rwhp, then you made 460rwhp. If a Mustang dyno says you made 460rwhp, you also made 460rwhp. Now which one of those numbers best represents what your car is doing when its on the street. That’s a different question.
The most important thing to remember is that a dyno is a testing tool. If the numbers keep increasing, then you’re doing the right thing. We try to look over at NET gain, instead of Peak HP numbers. A 30rwhp increase is a 30rwhp increase regardless of what dyno it is on.
Now I can address how to calculate the difference between one type of dyno and another. Simply put, you can’t. Because Mustang dyno’s have so many more variables, it’s not a simple percentage difference. We’ve had cars that made 422rwhp on our Dyno, two days later make 458rwhp on a DynoJet the next day. We’ve also had cars that made 550rwhp on our dyno, make 650+rwhp on a DynoJet a few days later at another shops Dyno Day. For instance, my 2002 Z28 with a forged internal LS6 Heads/Cam/Intake, makes 460rwhp on our dyno. I thought that was a little low, since I’ve had cam only LS6 Z06 vettes make 450rwhp. So I overlaid the dyno graphs. Guess what, the PAU force for my car was almost 200lbs more than the C5Z06 that made 450rwhp with cam only. So I entered the weight and horsepower at 50 number for a C5Z06 and did another horsepower rip with my car. The only reason I did that was to compare Apples to Apples. This time my car made 490rwhp, no other changes. Now I don’t go around saying my car made 490rwhp, I say what it actually did with the correct information entered into the computer. It made 460rwhp. Now if I ever get a chance to take it on a DynoJet (which I plan to in the spring), I have no doubts it’ll be over 500rwhp. I know this based on airflow and fuel consumption on the data logs.
But since we’re asked this question constantly we're fairly conservative, and hence tell our customers that the difference is closer to 6-7%, but as you make more power, and the more your car weighs, the difference increases as well. You must remember, Dyno's regardless of the type are tuning tools, and are in no means meant to tell people how fast their car is. Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalactic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coefficient, and you race on a planet called Earth, then use a Mustang Dyno.
DynoJets are inertia dynos, and have been around for years, much longer than any type of load cell dyno. Inertia dyno's work on the principle of the acceleration of a known mass over time. Their rollers are the known mass. Weighing in at over 2500lbs or so. Your car gets strapped down to the machine, and the dyno collects it's data. It is able to calculate horsepower by measuring the acceleration in rpm of the rollers in regards to RPM. This is why gearing can affect the dyno results, more on that in a bit. Now that the dyno has recorded the horsepower curve, it can take the integral of that curve and get the torque curve. Since the dyno’s power calculations are based on the acceleration of mass over time in regards to RPM, gearing is very important. Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).
Now we go to Mustang dyno’s and other loaded dyno’s. Our Mustang MD-1100SE dyno’s rollers weigh 2560lbs. That is the actual mass of the rollers, much like the DynoJet. That’s about where all the similarities end. When we get a car on our dyno, we enter two constants for the dyno’s algorithms. One being the vehicle weight, the other being what’s called “Horsepower At 50mph”. This is a number that represents how much horsepower it takes for the vehicle to push the air to maintain 50mph. This is used as the aerodynamic force. Mustang dyno’s are also equipped with a eddy currant load cell. Think of a magnetic brake from a freight train. This magnetic brake can apply enough resistance to stall a big rig. Off one side of the eddy currant load cell, there is a cantilever with a 5volt reference load sensor (strain gage). As the rollers are spinning this load sensor is measuring the actual torque being applied. So as the rollers spin, the load sensor is measuring the force being applied, sending that information to the dyno computer, taking into account the two constants entered earlier, computing the amount of resistance needed to be applied to the rollers to load the car so that the force of the rollers resistance is as close to the force the car sees on the street. The dyno is then able to calculate the total force being applied to the rollers in torque, and then taking the derivative of that torque curve to arrive at the horsepower curve. Since torque is an actual force of nature, like gravity and electricity, it can be directly measured. Horsepower is an idea that was thought up by man, and cannot be directly measured, only calculated.
I like to state it like this. . . I start by asking how much your car weighs, lets say 3500lbs. Now you take your car and you make a make a WOT rip in your tallest non overdrive gear, how much mass is your engine working against? 3500lbs right? Now you strap your car on a DynoJet and you make a WOT in the same gear, how much mass is your engine working against? 2500lbs right? Now you strap your car on a Mustang dyno, how much mass is your engine working against? 2500lbs. Plus the resistance being applied by the eddy current generator. We’ve seen anywhere for 470lbs of resistance to over 700lbs of resistance as measured in PAU force in the data logs. So which one is more accurate? Well they their both accurate. If a DynoJet dyno says you made 460rwhp, then you made 460rwhp. If a Mustang dyno says you made 460rwhp, you also made 460rwhp. Now which one of those numbers best represents what your car is doing when its on the street. That’s a different question.
The most important thing to remember is that a dyno is a testing tool. If the numbers keep increasing, then you’re doing the right thing. We try to look over at NET gain, instead of Peak HP numbers. A 30rwhp increase is a 30rwhp increase regardless of what dyno it is on.
Now I can address how to calculate the difference between one type of dyno and another. Simply put, you can’t. Because Mustang dyno’s have so many more variables, it’s not a simple percentage difference. We’ve had cars that made 422rwhp on our Dyno, two days later make 458rwhp on a DynoJet the next day. We’ve also had cars that made 550rwhp on our dyno, make 650+rwhp on a DynoJet a few days later at another shops Dyno Day. For instance, my 2002 Z28 with a forged internal LS6 Heads/Cam/Intake, makes 460rwhp on our dyno. I thought that was a little low, since I’ve had cam only LS6 Z06 vettes make 450rwhp. So I overlaid the dyno graphs. Guess what, the PAU force for my car was almost 200lbs more than the C5Z06 that made 450rwhp with cam only. So I entered the weight and horsepower at 50 number for a C5Z06 and did another horsepower rip with my car. The only reason I did that was to compare Apples to Apples. This time my car made 490rwhp, no other changes. Now I don’t go around saying my car made 490rwhp, I say what it actually did with the correct information entered into the computer. It made 460rwhp. Now if I ever get a chance to take it on a DynoJet (which I plan to in the spring), I have no doubts it’ll be over 500rwhp. I know this based on airflow and fuel consumption on the data logs.
But since we’re asked this question constantly we're fairly conservative, and hence tell our customers that the difference is closer to 6-7%, but as you make more power, and the more your car weighs, the difference increases as well. You must remember, Dyno's regardless of the type are tuning tools, and are in no means meant to tell people how fast their car is. Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalactic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coefficient, and you race on a planet called Earth, then use a Mustang Dyno.
10-21-2019, 08:12 PM
#145
Race Director
When the eddy current brake is applied to mimic aerodynamic drag of whatever vehicle, it holds those peak numbers more toward reality by increasing the resistance at speed (ever hear the explanation about how much hp a car uses to run 150 vs 200? Here's a hint, double to reach that last 50mph look into it. Quite remarkable the resistance at that speed). Just picture an inertia dyno at 150mph vs an eddy current dyno at same speed... one is spinning a static roller the other is spinning the roller under resistance.
10-21-2019, 08:14 PM
#146
Just wait... they’ll have articles about the “factory ringer” GM sent them instead of admitting their screw up.
10-21-2019, 08:27 PM
#147
Guys,
Just think straight 1 minute. On the cars and driver track test, in the straight the C7 Z51 managed 140. The C8 managed only 142 with a dct transmission. The C8 only has it's 495 HP
Recently I tuned myself my C7 GS on a Mustang dyno. Did 460WHP with the dyno setup as it should.
First pull showed 545 WHP, asked the guy what was this BS and he told me he forgot to put back the dyno in normal "accurate heartbreaker" mode. He set it up like that because people cry when they see their Mustang numbers...If I remember well the weight was entered correctly but there was a ratio at 1.15 instead of 1.00
$1000 this one was badly setup
Just think straight 1 minute. On the cars and driver track test, in the straight the C7 Z51 managed 140. The C8 managed only 142 with a dct transmission. The C8 only has it's 495 HP
Recently I tuned myself my C7 GS on a Mustang dyno. Did 460WHP with the dyno setup as it should.
First pull showed 545 WHP, asked the guy what was this BS and he told me he forgot to put back the dyno in normal "accurate heartbreaker" mode. He set it up like that because people cry when they see their Mustang numbers...If I remember well the weight was entered correctly but there was a ratio at 1.15 instead of 1.00
$1000 this one was badly setup
Last edited by Nabush; 10-21-2019 at 08:33 PM.
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RapidC84B (10-21-2019)
10-21-2019, 08:30 PM
#148
If road and track did their nonsense negative good but not great...motor trend just did its BS dyno test to balance the PR nightmare from R & T...
click click click...read all about it from both auto magazines seems more like whats going on..
disappointing state of affairs when journalistic integrity is out the window on both sides.
nobody is getting560 hp out of a naturally aspirated motor...with out a turbo to dial up and down...its a dyno twist of the dial...or a dramatic change in correction factor....
id love this hp rating to be real but its click bait ..
click click click...read all about it from both auto magazines seems more like whats going on..
disappointing state of affairs when journalistic integrity is out the window on both sides.
nobody is getting560 hp out of a naturally aspirated motor...with out a turbo to dial up and down...its a dyno twist of the dial...or a dramatic change in correction factor....
id love this hp rating to be real but its click bait ..
10-21-2019, 08:37 PM
#149
Burning Brakes
I am 100% convinced these results are bogus for some reason I won’t speculate. It is however possible to make big power out of an NA LS/T motor.
https://www.hotrod.com/articles/4-8l...pm-ls-stroker/
https://www.hotrod.com/articles/4-8l...pm-ls-stroker/
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RapidC84B (10-21-2019)
10-21-2019, 08:41 PM
#150
I am 100% convinced these results are bogus for some reason I won’t speculate. It is however possible to make big power out of an NA LS/T motor.
https://www.hotrod.com/articles/4-8l...pm-ls-stroker/
https://www.hotrod.com/articles/4-8l...pm-ls-stroker/
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10-21-2019, 08:45 PM
#151
Race Director
10-21-2019, 08:50 PM
#152
Burning Brakes
Like most C6 ZR1's 540 HP at the wheels was about average. That's very similar to this C8, and so is the trap speed. The numbers don't lie. GM sent them a cheater and they got caught.
10-21-2019, 09:05 PM
#153
Advanced
Horsepower = Weight/(ET/5.825) = 525.6 HP Rear Wheel
3637 lbs
11.1 seconds
=
525.6 RWHP
Horsepower = Weight/((ET/5.825)*3) = 525.6 HP Rear Wheel
Look at Powertrain Loss @ 15% = 525.6 / 0.85 = x 1.15= 604.44 hp at Crank
or
DCT at @ 8 % loss 525.6 x 1.08= 567.5 HP at Crank
assume Driver weight with some safety equipment and fuel
+200 lbs (3637 + 200)= 3837 lbs with driver
554.5 rwhp
11.1 seconds
=
525.6 RWHP
Horsepower = Weight/((ET/5.825)*3) = 525.6 HP Rear Wheel
Look at Powertrain Loss @ 15% = 525.6 / 0.85 = x 1.15= 604.44 hp at Crank
or
DCT at @ 8 % loss 525.6 x 1.08= 567.5 HP at Crank
assume Driver weight with some safety equipment and fuel
+200 lbs (3637 + 200)= 3837 lbs with driver
554.5 rwhp
Last edited by Ford John; 10-21-2019 at 09:51 PM. Reason: math formula ommission
10-21-2019, 09:08 PM
#154
That ratio doesn’t account for the efficiency of a DCT.
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10-21-2019, 09:13 PM
#155
Racer
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10-21-2019, 09:21 PM
#156
10-21-2019, 09:28 PM
#157
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10-21-2019, 10:21 PM
#158
Race Director
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Of course it's what they should do. It's not what they're going to do, though. They even told us what they're going to do: put another C8 on the same dyno in the coming months. I suspect that by then, the dyno operator will have figured out his error and the resulting numbers will be quite a bit lower. Just imagine the resulting article? "Proof that GM gave us a pre-production ringer!"
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10-21-2019, 10:23 PM
#160
Racer
Without the correction factor and without knowing if the numbers are from the roller drums loaded (or maybe as predicted unloaded which yields dj comparison values), there's no way to know. Im not sure they have the correct gear used and input values even remotely close. Its easy to open the file and share the results and values used i'm thinking.