Dyno'd
Shelby GT350 Member
Joined: June 9, 2008
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From: Rochester NY
Im sure we will see many dyno #'s coming in the next couple months. The true test will be the track #'s and how well this car can put the power to the ground. No matter if its 365 or 395. Great if this car is a low 12 performer.
I Have No Life
Joined: January 30, 2004
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From: Canada
From over at Inside Line:
Jason Kavanagh replied to comment from rrocket
10:14 PM, 03/24/10
The Dynojet itself doesn't care what gear the car's in. Remember, there's a final drive gear reduction after the transmission, which further alters the wheelspeed - engine speed relationship beyond what the transmission does, so there's nothing magical about 1:1.
In fact, dynoing in a gear that's 1:1 usually results in a hair less (yes, less) driveline loss as its a more (the most) efficient ratio in the gearbox. That's why a lot of dyno operators like the 1:1 ratio. Plus, when using an inertia dyno like a Dynojet, higher gear ratios have a lower rate of acceleration, so less power is soaked up in accelerating the rotating masses, which further props the numbers up.
Higher gears do tend to result in higher tire losses since the wheelspeed is higher... at this point all you're doing is trading off one loss mechanism for another. Generally, though, what I've seen come out in the wash is that on an inertia dyno, higher gears will result in higher numbers than lower gears.
Furthermore, higher gears also load the engine for a longer duration, requiring more cooldown, plus put more heat stress on driven tires. As the dyno operator, I don't like either of those things.
10:14 PM, 03/24/10
The Dynojet itself doesn't care what gear the car's in. Remember, there's a final drive gear reduction after the transmission, which further alters the wheelspeed - engine speed relationship beyond what the transmission does, so there's nothing magical about 1:1.
In fact, dynoing in a gear that's 1:1 usually results in a hair less (yes, less) driveline loss as its a more (the most) efficient ratio in the gearbox. That's why a lot of dyno operators like the 1:1 ratio. Plus, when using an inertia dyno like a Dynojet, higher gear ratios have a lower rate of acceleration, so less power is soaked up in accelerating the rotating masses, which further props the numbers up.
Higher gears do tend to result in higher tire losses since the wheelspeed is higher... at this point all you're doing is trading off one loss mechanism for another. Generally, though, what I've seen come out in the wash is that on an inertia dyno, higher gears will result in higher numbers than lower gears.
Furthermore, higher gears also load the engine for a longer duration, requiring more cooldown, plus put more heat stress on driven tires. As the dyno operator, I don't like either of those things.
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Boomer, he's wrong.
He's just trying to make light of his major f-up. Ask him why he dyno'd the GT500 in 4th gear, which is 1:1? Why did he just decide to do THIS car in 1.32:1? Answer: he was clueless about the car. You can call the inventor of the Dynojet himself, he'll backup what I say. You can also go run your own car in 3rd and 4th and see. It is easy to prove. The guy has no clue what he's doing. The 511RWHP GT500 he did was a crock too. This guy does whatever it takes to make absolutely BS numbers.
He's just trying to make light of his major f-up. Ask him why he dyno'd the GT500 in 4th gear, which is 1:1? Why did he just decide to do THIS car in 1.32:1? Answer: he was clueless about the car. You can call the inventor of the Dynojet himself, he'll backup what I say. You can also go run your own car in 3rd and 4th and see. It is easy to prove. The guy has no clue what he's doing. The 511RWHP GT500 he did was a crock too. This guy does whatever it takes to make absolutely BS numbers.
Last edited by eci; Mar 25, 2010 at 08:48 AM.
dynos are great and all....LET'S LINE EM' UP!!!!! 
FR500 Member
Joined: July 1, 2008
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From: Oxford, UK
Boomer, he's wrong.
He's just trying to make light of his major f-up. Ask him why he dyno'd the GT500 in 4th gear, which is 1:1? Why did he just decide to do THIS car in 1.32:1? Answer: he was clueless about the car. You can call the inventor of the Dynojet himself, he'll backup what I say. You can also go run your own car in 3rd and 4th and see. It is easy to prove. The guy has no clue what he's doing. The 511RWHP GT500 he did was a crock too. This guy does whatever it takes to make absolutely BS numbers.
He's just trying to make light of his major f-up. Ask him why he dyno'd the GT500 in 4th gear, which is 1:1? Why did he just decide to do THIS car in 1.32:1? Answer: he was clueless about the car. You can call the inventor of the Dynojet himself, he'll backup what I say. You can also go run your own car in 3rd and 4th and see. It is easy to prove. The guy has no clue what he's doing. The 511RWHP GT500 he did was a crock too. This guy does whatever it takes to make absolutely BS numbers.
First, I checked out the DynoJet manuals for the 248 model and for the software, to see if they discussed the need for a particular gear. The manual for the software says to put the car in 4th gear. It doesn't mention the need for a 1:1 gear ratio.
The manuals describe why the SAE hp correction factor is used, but do not talk about the effects of drivetrain inertia on the accuracy of the results.
I then searched the web for articles discussing the accuracy of DynoJets, and I found this reprint of a Hot Rod magazine article. It discusses the problem of accurately determining the error in measured power due to the variations in rotational inertia from one vehicle to the next. It goes on to say that since they had no success in correcting for those errors, a fudge factor was MADE UP.
So I agree with you about the fact that dyno results are generally arbitrary, and thus not comparable from one model of dyno to the next.
However, when looking at the effects of the losses due to rotational kinetic energy due to running in 4th gear, I have to disagree with you. When you compare a pull in 4th gear vs 5th gear, both the engine's and the input side of the transmission's rotating components will accelerate faster relative to the rear wheels in 4th. This means they are 'absorbing' more power than they would in 5th. Thus the same dyno will give a lower indicated power in 4th than it would in 5th.
So if the Inside Line guys had done the pull in 5th, the number would have been even higher than they were. Not necessarily accurate mind you, but higher.
Last edited by PTRocks; Mar 25, 2010 at 09:37 AM.
GT Member
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From: huntley, il
Nice discussion guys. Much better than another Mustang forum..."they must have secretly installed a CAI and then hid it from view! Edmunds is in cahoots with Ford!" Tinfoil hat type stuff. Keep it going. I'm actually learning on the interwebz!
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PTRocks the reason the manual says 4th gear is because nearly every manual 4th is 1:1. The 5.0 is the first to break away from this.
I have personally had my vehicles incorrectly dyno'ed in a lower gear ( 3rd versus 4th, 1.36:1 versus 1:1 in that case ) by mistake and the 3rd numbers were always 10% higher.
I have personally had my vehicles incorrectly dyno'ed in a lower gear ( 3rd versus 4th, 1.36:1 versus 1:1 in that case ) by mistake and the 3rd numbers were always 10% higher.
Last edited by eci; Mar 25, 2010 at 10:21 AM.
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BTW is any of this over on C5? I can't find anything.
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From: Oxford, UK
PTRocks the reason the manual says 4th gear is because nearly every manual 4th is 1:1. The 5.0 is the first to break away from this.
I have personally had my vehicles incorrectly dyno'ed in a lower gear ( 3rd versus 4th ) by mistake and the 3rd numbers were always 10% higher.
I have personally had my vehicles incorrectly dyno'ed in a lower gear ( 3rd versus 4th ) by mistake and the 3rd numbers were always 10% higher.
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I Have No Life
Joined: January 30, 2004
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From: Canada
ECI: I just posted what the guy on the site said, not sayin its right or wrong. Just so people don't have to flip/flop between pages.
Regardless, I can't help but wonder then.
If the numbers are truly higher than what Ford is advertising, 2 things to think about.
And I'm just thinkin out loud.
1) Freak/Ringer - I HIGHLY doubt this. Ford isn't stupid to put something in the hands of the press that would cause a backlash.
2) The rating changed...before launch. If the engine is capable of more than 412 (which you can pretty much bet) If a new tune has been blessed for production.
They did mention in the article about multiple runs and they kept getting higher.
I'm very curious to start seeing the times on a real track and 'in the customers hands' dyno tests.
I have a hard time believing they are that high...
but if so...
cool
Regardless, I can't help but wonder then.
If the numbers are truly higher than what Ford is advertising, 2 things to think about.
And I'm just thinkin out loud.
1) Freak/Ringer - I HIGHLY doubt this. Ford isn't stupid to put something in the hands of the press that would cause a backlash.
2) The rating changed...before launch. If the engine is capable of more than 412 (which you can pretty much bet) If a new tune has been blessed for production.
They did mention in the article about multiple runs and they kept getting higher.
I'm very curious to start seeing the times on a real track and 'in the customers hands' dyno tests.
I have a hard time believing they are that high...
but if so...
cool
Last edited by Boomer; Mar 25, 2010 at 10:30 AM.
Mach 1 Member
Joined: November 3, 2007
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From: South Florida
But like I said 360+ should be the magic #
Going back to work..laterz
Last edited by TTS197; Mar 25, 2010 at 09:08 PM.
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ECI: I just posted what the guy on the site said, not sayin its right or wrong. Just so people don't have to flip/flop between pages.
Regardless, I can't help but wonder then.
If the numbers are truly higher than what Ford is advertising, 2 things to think about.
And I'm just thinkin out loud.
1) Freak/Ringer - I HIGHLY doubt this. Ford isn't stupid to put something in the hands of the press that would cause a backlash.
2) The rating changed...before launch. If the engine is capable of more than 412 (which you can pretty much bet) If a new tune has been blessed for production.
They did mention in the article about multiple runs and they kept getting higher.
I'm very curious to start seeing the times on a real track and 'in the customers hands' dyno tests.
I have a hard time believing they are that high...
but if so...
cool
Regardless, I can't help but wonder then.
If the numbers are truly higher than what Ford is advertising, 2 things to think about.
And I'm just thinkin out loud.
1) Freak/Ringer - I HIGHLY doubt this. Ford isn't stupid to put something in the hands of the press that would cause a backlash.
2) The rating changed...before launch. If the engine is capable of more than 412 (which you can pretty much bet) If a new tune has been blessed for production.
They did mention in the article about multiple runs and they kept getting higher.
I'm very curious to start seeing the times on a real track and 'in the customers hands' dyno tests.
I have a hard time believing they are that high...
but if so...
cool
However, this guy doesn't know how to operate his dyno. Reasons why I believe this:
1. Incorrect gear selection for pull
2. Previous BS numbers such as 511RW on a 2010 GT500:
http://www.youtube.com/watch?v=yxDS6PLubgY
GTR Member
Joined: February 18, 2010
Posts: 4,990
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From: S.E. Texas
Ford may well have gone conservative on the power ratings so that they can put up new numbers against whatever new numbers the bowtie boys put out in response.
Also, remember that most of the 03-04 terminator cars dyno'd stronger than what their official power ratings would have suggested they would.
Also, remember that most of the 03-04 terminator cars dyno'd stronger than what their official power ratings would have suggested they would.
