Dyno Jet vs. Mustang Dyno

BlackenedSVT · Apr 15, 2005

- What the hell is the difference? What do they do thats so different?

- Do they both operate the same?

- Which is better, and why?

- Are their either one of these in northern New Jersey (07647)? I think La Rocca's near Englishtown is the only one I know of at the moment.

Ever since I've heard the difference, and the Mustang dyno making like 10% less hp rating, i've been wondering why someone would get their car dynoed on a machine that shows a 10% loss of the hp you really have

CanadaStang · Apr 15, 2005

The Dynojet 248C is actually an accelerometer whereby it uses a 3000-3200 pound drum that is used to create an inertia load on the vehicle being tested. The vehicle's horsepower (HP) and torque try to overcome the weight/inertia of the drum to accelerate it. As a result the software and electronics try to measure the horsepower and torque that the vehicle is developing to overcome the drum's weight and inertia. The resulting horsepower and torque will be higher than a true loading dyno because once the drum starts rolling not as much power is needed to keep it going. For example:if your pushing a Chevy on a flat road, once the car starts moving not as much effort is needed to keep it going. The software does not ask for vehicle weight or anything like horsepower needed to maintain 50 MPH (a number that is actually put out by E.P.A. and N.H.T.S.A.).

The Mustang dyno is a true loading dyno, because it uses an inertia weight as well as an eddy current motor that is attached to the rollers. This eddy current motor creates a drag on the shaft by way of electricity that causes a magnetic field to try and overcome the torque going through the roller shafts. This current is controlled by software that is always trying to simulate load as if the car is driving in real world conditions. The real benefit from the loading dyno is the ability to maintain a load that allows a tuner to properly go through a fuel map or ignition map and tune the chip for optimum horsepower and torque.It has the ability to also simulate the IM240 emissions test as required in some states. It can check 1/4 mile times as well as times for 0-60 MPH and 0-100 MPH. It can also be used for road testing and simulation for drivability problems. As a result of the loading capability, the dyno numbers from a mustang dyno will come out lower than the inertia (dynojet) dyno.
I hope that makes sense, someone else may be able to chime in if I left anything out.

Ernad · Apr 15, 2005

CanadaStang said:
The Dynojet 248C is actually an accelerometer whereby it uses a 3000-3200 pound drum that is used to create an inertia load on the vehicle being tested. The vehicle's horsepower (HP) and torque try to overcome the weight/inertia of the drum to accelerate it. As a result the software and electronics try to measure the horsepower and torque that the vehicle is developing to overcome the drum's weight and inertia. The resulting horsepower and torque will be higher than a true loading dyno because once the drum starts rolling not as much power is needed to keep it going. For example:if your pushing a Chevy on a flat road, once the car starts moving not as much effort is needed to keep it going. The software does not ask for vehicle weight or anything like horsepower needed to maintain 50 MPH (a number that is actually put out by E.P.A. and N.H.T.S.A.).

The Mustang dyno is a true loading dyno, because it uses an inertia weight as well as an eddy current motor that is attached to the rollers. This eddy current motor creates a drag on the shaft by way of electricity that causes a magnetic field to try and overcome the torque going through the roller shafts. This current is controlled by software that is always trying to simulate load as if the car is driving in real world conditions. The real benefit from the loading dyno is the ability to maintain a load that allows a tuner to properly go through a fuel map or ignition map and tune the chip for optimum horsepower and torque.It has the ability to also simulate the IM240 emissions test as required in some states. It can check 1/4 mile times as well as times for 0-60 MPH and 0-100 MPH. It can also be used for road testing and simulation for drivability problems. As a result of the loading capability, the dyno numbers from a mustang dyno will come out lower than the inertia (dynojet) dyno.
I hope that makes sense, someone else may be able to chime in if I left anything out.

Thanks

csledd · Apr 15, 2005

good answer

Gearbanger 101 · Apr 15, 2005

CanadaStang said:
The Dynojet 248C is actually an accelerometer whereby it uses a 3000-3200 pound drum that is used to create an inertia load on the vehicle being tested. The vehicle's horsepower (HP) and torque try to overcome the weight/inertia of the drum to accelerate it. As a result the software and electronics try to measure the horsepower and torque that the vehicle is developing to overcome the drum's weight and inertia. The resulting horsepower and torque will be higher than a true loading dyno because once the drum starts rolling not as much power is needed to keep it going. For example:if your pushing a Chevy on a flat road, once the car starts moving not as much effort is needed to keep it going. The software does not ask for vehicle weight or anything like horsepower needed to maintain 50 MPH (a number that is actually put out by E.P.A. and N.H.T.S.A.).

The Mustang dyno is a true loading dyno, because it uses an inertia weight as well as an eddy current motor that is attached to the rollers. This eddy current motor creates a drag on the shaft by way of electricity that causes a magnetic field to try and overcome the torque going through the roller shafts. This current is controlled by software that is always trying to simulate load as if the car is driving in real world conditions. The real benefit from the loading dyno is the ability to maintain a load that allows a tuner to properly go through a fuel map or ignition map and tune the chip for optimum horsepower and torque.It has the ability to also simulate the IM240 emissions test as required in some states. It can check 1/4 mile times as well as times for 0-60 MPH and 0-100 MPH. It can also be used for road testing and simulation for drivability problems. As a result of the loading capability, the dyno numbers from a mustang dyno will come out lower than the inertia (dynojet) dyno.
I hope that makes sense, someone else may be able to chime in if I left anything out.

You sack of $h!t....don't try to make us believe that you just yanked all that from memory out of the vast vault of knowledge you call a brain. You cut and pasted that from somewhere. You and I both know Canadians aren’t that smart!

myponyrocks · Apr 15, 2005

Dyno Jet numbers = Better numbers to calculate your BHP and Bragging rights

Mustang Dyno= Better numbers to tune against the track

He said all the scientific stuff, this is the cliffs notes

BlackenedSVT · Apr 16, 2005

Yeah thanks for the info, I didn't quite understand it though. Scientifically you explained how they work and why some produce lower numbers, but I still don't follow.... Maybe i'll read that post like 6 more times

What is the point in using a dyno jet and whats the point of using a mustang dyno. Like why would u take it to one over the other?

I guess what I dont get is why one would rate your car at say 300rwhp, and the Mustang dyno would rate it at like 285rwhp. Like, why is there a huge difference? How can your car make two different numbers of hp. Like, which one is the REAL one? And whats is the OTHER one then!?

So confused

jstreet0204 · Apr 16, 2005

Gearbanger 101 said:
You sack of $h!t....don't try to make us believe that you just yanked all that from memory out of the vast vault of knowledge you call a brain. You cut and pasted that from somewhere. You and I both know Canadians aren’t that smart!

Who needs a brain when you have google
http://www.activeautowerke.com/dyno/MustangVsDynojet.asp

CanadaStang · Apr 16, 2005

jstreet0204 said:
Who needs a brain when you have google
http://www.activeautowerke.com/dyno/MustangVsDynojet.asp

Actually, that's not where I got it from. I typed it from an article from the "All about Dyno's" manual. It has a lot interesting info on Dyno's and how they work aswell as guides on how to build your own dyno. It appears as though the info from the Active Auto web page came from the same source or vise versa.

CanadaStang · Apr 16, 2005

Gearbanger 101 said:
You sack of $h!t....don't try to make us believe that you just yanked all that from memory out of the vast vault of knowledge you call a brain. You cut and pasted that from somewhere. You and I both know Canadians aren’t that smart!

BlackenedSVT · Apr 16, 2005

jstreet0204 said:
Who needs a brain when you have google
http://www.activeautowerke.com/dyno/MustangVsDynojet.asp

Ok well from that link and the info that you guys already stated, it would seem that the MUSTANG DYNO is the accurate dyno. Am I not right?

So when they dyno a car from the factory to get 260base hp for a 99-2004 GT. Do they use a mustang dyno, or regular dyno (dyno jet)?

EDIT: Is the name of this second type of dyno (the mustang dyno) called a Mustand dyno because it gives a better hp rating for mustangs? Or that just happens to be the name of it? Like when my friend dynos his Lexus IS300 this summer, could he take it to a place that has a mustang dyno?? ...or take it to a dyno jet only?

trinity_gt · Apr 16, 2005

CanadaStang said:
The resulting horsepower and torque will be higher than a true loading dyno because once the drum starts rolling not as much power is needed to keep it going. For example:if your pushing a Chevy on a flat road, once the car starts moving not as much effort is needed to keep it going.

But it's not about keeping it going. The Dynojet is measuring the rate at which the rollers are being accelerated. As the roadwheels' ability to accelerate the drums increase or decrease, the power calculated increases or decreases accordingly. If the drum is niether accelerating nor decelerating then there's no net power put into the drums by the car.

The absolute speed of the drums doesn't matter...it's always all about the rate at which they're being accelerated and that's given by w=T/J where w is the angular acceleration, T is the torque applied and J is the moment of inertia of the drum.

I still think that the Dynojet represents the more realistic ability of a car's wheel-road interface to do work on the car. When a strap my car to a Dynojet and run a 255rwHP run, I know that that is an exact measure of what my engine is able to apply in terms of power - the ability to do work - to the rear wheels through the trans and differential.

I agree that a loading dyno like the MD is a better tool for mapping EFI parameters or doing smog sniffer apps. But if one is purely interested in what power is being applied to the wheels, I don't think it gets much simpler or accurate than an inertia dyno: the parameters are quite deterministic, the math simple and there are no fudges for wind speed and vehicle weight. It's all about what is being delivered to the wheels.

trinity_gt · Apr 16, 2005

UDTBadkarma said:
Ok well from that link and the info that you guys already stated, it would seem that the MUSTANG DYNO is the accurate dyno. Am I not right?

So when they dyno a car from the factory to get 260base hp for a 99-2004 GT. Do they use a mustang dyno, or regular dyno (dyno jet)?

They go even further. They use an engine dyno - no trans, no differential...just an engine strapped to the dyno but dressed otherwise as it would be under the hood, including an alternator, power steering pump, A/C compressor, factory intake tract and factory exhaust. This gives the flywheel HP rating in "SAE net" numbers. That 260 is not wheel HP but flywheel. The frictional, fluid and other losses associated with transmissions and differentials and their fluids as wheel as even at the wheel/drum interface (tire deformation == heat and this saps power) causes the wheel HP to be 15-20% on average lower than the crank rating. A 260HP 4.6L Mustang will typically put about 225-230HP to the wheels (as measured by a Dynojet...)

BlackenedSVT · Apr 16, 2005

trinity_gt said:
A 260HP 4.6L Mustang will typically put about 225-230HP to the wheels (as measured by a Dynojet...)

And what would it measure on a Mustang dyno???

I guess im still not seeing the point to using a mustang dyno then.....

The dyno jet gives more accurate numbers (i guess) and gives high hp numbers. So wtf is the deal with the Mustang Dyno then?!

trinity_gt · Apr 16, 2005

UDTBadkarma said:
And what would it measure on a Mustang dyno???

Lower... Typically 10-15% lower.

I guess im still not seeing the point to using a mustang dyno then.....

FWIW, I don't particularly like the MD for just measuring power to the wheels because I don't believe it actually returns that number. If it did then the skew between the dead-simple Dynojet and the MD wouldn't be nearly as pronounced.

However, loading dynos like the MD are invaluable for tuning. The ability to hold an engine at a particular RPM and manifold pressure and to adjust fuel delivery and spark to maximize torque output and to repeat this over a range is about the best way to tune. A Dynojet's run is far too transient to do at-the-moment tuning. You always need to collect data, tune post-hoc and then re-reun the rollers to see what the effect of the new tune is.

The dyno jet gives more accurate numbers (i guess)...

Well for simple, true power-at-the-wheels with few fudges and artificial corrections and compensations and the like, I think it does. I'm sure others will disagree...

BlackenedSVT · Apr 17, 2005

Are there any other types of dynos other than a Mustang and Dyno Jet Dyno?

And back to my previous question about my friend's Lexus IS300. Could he take it to a place with a Mustang Dyno to get tuned? Or does he have to take it to a Dyno Jet only.

topgunz_1 · Apr 17, 2005

UDTBadkarma said:
Are there any other types of dynos other than a Mustang and Dyno Jet Dyno?

And back to my previous question about my friend's Lexus IS300. Could he take it to a place with a Mustang Dyno to get tuned? Or does he have to take it to a Dyno Jet only.

It is just called a Mustang Dyno for some reason, it isnt called that because only Mustangs can use it. any car can use any kind of dyno they want

trinity_gt · Apr 17, 2005

UDTBadkarma said:
Are there any other types of dynos other than a Mustang and Dyno Jet Dyno?

There are a couple of others but MD and DJ are the bigs. Check out this one:

You actually remove the wheels and bolt on these hub devices on this AWD dyno...

And back to my previous question about my friend's Lexus IS300. Could he take it to a place with a Mustang Dyno to get tuned? Or does he have to take it to a Dyno Jet only.

IIMHO, if you're looking only for a curve that shows power actually delivered to the wheels, a DJ is fine and probably better. If you want to tune and varying speeds and loads, if you want to do other testing etc, find an MD.

VividDreams · Apr 18, 2005

i believe ther are also regular in ground AWD dynos

the brake dyno shwon above will give you bigger numbers but wont be as accurate because it cant account for those 28" spinners you have on your geo metro

300bhp/ton · Apr 18, 2005

VividDreams said:
i believe ther are also regular in ground AWD dynos

the brake dyno shwon above will give you bigger numbers but wont be as accurate because it cant account for those 28" spinners you have on your geo metro

yeah but it isn't giving rwhp in the same manor, what it is doing is illiminating the error factor caused by the wheels.

The bigger the wheels the more power is required to to rotate them, but like the dyno jet they also have a greater amount of initeria, which can distort the numbers. On this sort of setup they probably don't care about the peak numbers it to make sure the engine performs correctly all the way thru the rpms.

Even tyre pressure can have a major effect on rwhp if measured on mustang or dyno jet as it can create different amounts of drag and friction. Also atmoshperic conditions will also affect results.

Basically any duno numbers should only ever be used as a guide and taken with a pinch of salt. Other causes of errors include which rating system is being used:

SAE figures
BHP
PS
KW
Metric
Imerpial

They will all show slightly different numbers. A dyno is good for a general idea 'bragging' right, else you want a full tune on a dyno that can measure the engine all the way through the rev range with varying loads, this will illiminate flat spots and have your car producing the most power all of the time rather than just peak numbers.

Dyno Jet vs. Mustang Dyno

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