Topic: Sigh..Inside Line Hyping the 2011 Mustang GT Horsepower...ERROR!!

[rrocket]

As many of you know (or don't, or could care less) I've spent ALOT...I mean ALOT of time at the dyno with my Supra.  In a one year span I literally had 50+ pulls alone on my Supra.  Plus I've had Import Queen's car, and pretty much any other car I could dyno, tested.  Beyond that, I used to hang around the dyno with all of my car friends and their cars.  So I know my way around a dyno and what needs to be done.  But apparently, the people at Inside Line (Edmund's) do not.  Their article linked below is hyping the new 2011 Mustang GTs horsepower.  Their tag line says "Ford is lying. The new 5.0 V8 is making more than 412HP".  Apart from the fact the engine is a factory pre-production ringer, the doorknobs dynoed it in FOURTH gear.  According to Ford, 4th gear is a 1.32:1 ratio.  Everyone knows you have to dyno a car at a 1:1 ratio, which in this case is FIFTH gear.  So yea...when you f-up the dyno run and use the wrong gear, the car will show the wrong HP....and in this case HIGHER horsepower.

  I suppose the only "out" for them would be if this isn't a Dynoject dyno.  On a Dynojet, it uses a mathematical equation based on the known weight of the rollers and acceleration of said rollers.  If you use a gear that accelerates faster (in this case 4th gear instead of 5th gear) the rollers will spin up quicker (accelerate) and skew the numbers in a positive way.  The opposite would happen if you used 6th gear (.65:1)...you'd have lower numbers.

IMO there's no excuse for this type of error...unless they were deliberately trying to skew the numbers for a great headline.

http://blogs.insideline.com/straightline/2010/03/inside-line-dyno-tests-the-2011-ford-mustang-gt-50.html

[Nathan@1010tires]

In their defense, I can't even think of another car that doesn't have fourth gear as 1:1. I am not sure but perhaps 6 speed FWD cars do not, but pretty much every 6 speed RWD car has two overdrives.

On the other hand, it's good to see Ford is finally putting a 6 speed in the GT, it's only about 15 years overdue.

[rrocket]

In their defense, I can't even think of another car that doesn't have fourth gear as 1:1. I am not sure but perhaps 6 speed FWD cars do not, but pretty much every 6 speed RWD car has two overdrives.

On the other hand, it's good to see Ford is finally putting a 6 speed in the GT, it's only about 15 years overdue.

No excuse.  It takes 10 seconds to look up the specs...

[Nathan@1010tires]

Meh, I would have made the same mistake, but I may have done some digging if the numbers were way off. I have been around cars a long time and for the life of me I cannot think of another RWD car that does not have 1:1 fourth gear, whether it be a four, five or six speed. Why Ford would change this one seems odd. Must be an entirely new trans.

[Erik]

Or it could be a typo....

[HeliDriver]

Or rrocket could be wrong... 

I know nothing about how dynos work, but it looks like rrocket's post on InsideLine got a response from the author. He does make a good point about the rear-end ratio: even if the transmission is 1:1, how would the dyno know if the car has a 2.78 or 3.73 rear end? Or maybe the rear-end ratio is something that the operator has to factor into the equation before the dyno spits out its number? Inquiring minds want to know... 

From http://blogs.insideline.com/straightline/2010/03/inside-line-dyno-tests-the-2011-ford-mustang-gt-50.html :

"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 puts more heat stress on driven tires. As the dyno operator, I don't like either of those things."

[rrocket]

He's wrong....on a Dynojet it matters.  Period.  Don't take what I say, do your own research.  Google it.  Whatever.  On a Dynojet inertial dyno it absolutely matters.  Here's  a quick blurb from a tuning house:

A chassis dyno is susceptible to gearing bias. Recorded power can be affected on a dyno graph by simply running the test car in too low or too high a gear. Dyno operators should pick the trans gear that is closest to a 1:1 ratio to avoid gearing bias. This ratio is 4th gear in most cars. In a 1:1 ratio, the two gears that make up a gear set are the same size. When one is larger than the other, either in a lower gear than 1:1 or a higher gear than 1:1, there are frictional losses that translates to less power put to the wheels. Also, too high of a gear that causes the test car to go to a top speed far greater than the available fan cooling capacity will produce invalid results.

Seems like the Camaro boys caught it too....  http://www.camaroz28.com/forums/showthread.php?t=727368&page=30

[vdk]

They pulled the same trick for the 2.0T Genesis Coupe. Sometimes I wonder who works at Edmunds...

[rrocket]

They pulled the same trick for the 2.0T Genesis Coupe. Sometimes I wonder who works at Edmunds...

Good point.  In a turbo car, it can matter even more.  If you put it in a taller gear (like 6th for example) this lugging will "load up" the turbo, and you'll usually see a dramatic increase in TQ.  Now combine it with a diesel (turbo diesel) and the results can usually be skewed by a few HUNDRED TQ depending on what gear you're in. 

[Nathan@1010tires]

They pulled the same trick for the 2.0T Genesis Coupe. Sometimes I wonder who works at Edmunds...

What are the actual numbers on that car? Hyundai rates it at 228 crank hp on premium I think? That car does have 1:1 fourth gear though.


I still can't figure out why Ford would make 5th gear the 1:1 gear. The only thing I can figure is they're using shallow gearing in the rearend and steepend the transmission, and then only using one overdrive. Seems like re-inventing the wheel if that is the case, and you have to shift more in the city.

[rrocket]

Here's an e-mail I received from Dynojet this morning:

Yes, gear ratio does matter, and ideally we suggest using the 1:1 ratio or as close as possible.

The simple reason is that in 1:1 your engines crankshaft and the  transmission should be running at the same ratio, thus the  most direct level of power delivery available.

The proof is simple to see, at the end of your run session, simply shift up or down a gear and make another quick pull. You may see a change in power.

There are some cases where this can be very dramatic, others not so much.

But the  1:1 gear ratio as a guideline is still preferred.
 


Keith Royle

Director of Dynamometer Sales

Dynojet Research Inc.

keithr@dynojet.com

1-800-992-3525 xt 1121

[vdk]

Here's an e-mail I received from Dynojet this morning:

Yes, gear ratio does matter, and ideally we suggest using the 1:1 ratio or as close as possible.

The simple reason is that in 1:1 your engines crankshaft and the  transmission should be running at the same ratio, thus the  most direct level of power delivery available.

The proof is simple to see, at the end of your run session, simply shift up or down a gear and make another quick pull. You may see a change in power.

There are some cases where this can be very dramatic, others not so much.

But the  1:1 gear ratio as a guideline is still preferred.
 


Keith Royle

Director of Dynamometer Sales

Dynojet Research Inc.

keithr@dynojet.com

1-800-992-3525 xt 1121

It only makes sense..

[blur911]

Here's an e-mail I received from Dynojet this morning:

Yes, gear ratio does matter, and ideally we suggest using the 1:1 ratio or as close as possible.

The simple reason is that in 1:1 your engines crankshaft and the  transmission should be running at the same ratio, thus the  most direct level of power delivery available.

The proof is simple to see, at the end of your run session, simply shift up or down a gear and make another quick pull. You may see a change in power.

There are some cases where this can be very dramatic, others not so much.

But the  1:1 gear ratio as a guideline is still preferred.
 

To me this implies that you could have more power loss by using a gear other than the 1:1, which AFAIK usually means that the input shaft is locked to the output shaft and not actually running through a gearset, hence the decreased loss.
Shifting up or down a gear means going through a gearset and accumulating more driveline loss, but how does it affect the  calculated power to read more as you are claiming?

[vdk]

They pulled the same trick for the 2.0T Genesis Coupe. Sometimes I wonder who works at Edmunds...

What are the actual numbers on that car? Hyundai rates it at 228 crank hp on premium I think? That car does have 1:1 fourth gear though.

Yeah they got 227hp in 3rd and 4th. 

http://blogs.insideline.com/straightline/2009/03/inside-line-dyno-test-2010-hyundai-genesis-coupe-20t.html?mktcat=enabler&AID=10364102&PID=3671579&kw=N&synpartner=edmunds&mktid=cj260233

[rrocket]

Here's an e-mail I received from Dynojet this morning:

Yes, gear ratio does matter, and ideally we suggest using the 1:1 ratio or as close as possible.

The simple reason is that in 1:1 your engines crankshaft and the  transmission should be running at the same ratio, thus the  most direct level of power delivery available.

The proof is simple to see, at the end of your run session, simply shift up or down a gear and make another quick pull. You may see a change in power.

There are some cases where this can be very dramatic, others not so much.

But the  1:1 gear ratio as a guideline is still preferred.
 

To me this implies that you could have more power loss by using a gear other than the 1:1, which AFAIK usually means that the input shaft is locked to the output shaft and not actually running through a gearset, hence the decreased loss.
Shifting up or down a gear means going through a gearset and accumulating more driveline loss, but how does it affect the  calculated power to read more as you are claiming?

Dynojet measures how much time it takes to spin a roller of a given weight.  When you use something other than 1:1, as you said there is a torque multiplication occurring through the gearset.  This skews the numbers.

[wing]

Jalopnik got 395hp at the wheels did they not?

[safristi]

..Maybe T 'BOB can give it a wee R.I.M jobbie..........AP applied for R...................... ...Dyno Dyno show us a LEG......................

[rrocket]

Jalopnik got 395hp at the wheels did they not?

IIRC that wasn't them directly.  They just posted a vid.

[Zombie]

There are allot of number being thrown around here. What are the actually numbers at the wheels of the 2011 5.0 then?

[rrocket]

There are allot of number being thrown around here. What are the actually numbers at the wheels of the 2011 5.0 then?

Too early to tell IMO since no proddie engines avail yet..  I would guess 360-375 would work.