NZ951

Whoa thats an impressive torque curve! She really runs out of puff though eh? Have you got an exhaust leak?

NZ951

Mustang reads low... by 10-15% dependng on your source, the Dyno Dymanics reads 12% lower than Dynojet.

emwporsche

haha no that was the run that was shut down from overboosting (24 psi on pump gas)

why I don't really count it
https://rennlist.com/forums/showthre...&highlight=355

I could have sworn the mustang was the one that read higher, damn!

NZ951

Only 24psi? I thought you said it was shut down from overboost?

PS can you format your entry, I cant be knackered.

emwporsche

format what?

NZ951

Your entry to go on the list... ie name HP etc... I keep asking as it saves me time, but on one does

emwporsche

I asked for it not to be placed on the list.

it was a fluke, it is unrepeatable.
I was running leaner than ally mcbeal in an episode of survivor.

NZ951

Oh I didnt know you referring to posting it on the list... dude you made the power, one way or another, you deserve to be on the list! let me know if you change your mind

emwporsche

maybe the vitesse stg 3 will get me up there! heh

good to know:
A Mustang Dyno is one of the BEST tuning devices you could ever use. They put a wideband oxygen sensor down by the collector of the header, so you get VERY accurate readings instead of delayed readings and readings when the exhaust has cooled down by the time it hits the tail pipe, which is where some Dynojet operators put it. A Mustang Dyno requires that you enter a weight for the vehicle and then provides a resistance throughout the entire run, simulating wind resistance. For this reason, it is an excellent tuning device but its no good to put down big numbers. Once a car begins moving, there is less resistance at the wheels when you overcome the polar moment of inertia, but the Mustang Dyno keeps applying this force acting against you. If you were on a Dynojet you would only have to overcome the polar moment of inertia and then you'd have nothing but BIG numbers getting put down. The Dynojet will generally put down another 10-15% more whp than a Mustang Dyno.

The Dynojet 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.

Ski

I'll have to try and find the second dyno sheet on the track car - 351/347. The sheet on the link is 337/327, then switched software(vitesse race chips), tweaked the fuel a bit and got 351/347 on the second go round.

daniel951

if you look at scott gomes posts its debatable which one reads higher. Alot of people on this board say mustang reads lower.

Jake951

The Dynojet measures acceleration of the drum and then uses the physics of inertia to compute the force that accelerated the drum. (For those of you who are not familiar with physics, inertia is essentially the resistance of an object, in this case the drum, to changes in its motion. It has nothing to do with friction but depends on object mass and size). The force to accelerate the drum gives torque, which is then converted to horsepower.

If you are at a steady speed (not accelerating) then the only power needed to keep the drum rolling is the power to overcome frictional losses and rolling resistance of the tires. However, in a typical dyno run on the Dynojet, the drum does not run at a steady speed but is constantly being accelerated under WOT and it takes more and more power to get it moving to higher speeds. The power required does NOT decrease.

One reason the Dynojet usually gives higher numbers than the loading dynos like the Mustang is because of the proprietary "correction" factors used to compute torque and horsepower from acceleration (these are not the usual corrections for temperature and altitude). Nobody (except Dynojet) seems to know exactly what those factors are. What's the purpose of these corrections? For one thing, the car is not only accelerating the drum but also its own drivetrain and in particular the wheels, which have their own inertia totally independent of the drum. These external components add to the total inertia that the engine has to overcome to accelerate the drum. The Dynojet computation software allegedly applies a correction factor for drivetrain/wheel inertia, because otherwise the hp/torque numbers would actually be low! However, the Dynojet has no way of knowing what that external inertia is, so there is no way the correction factors can be right for any particular car except by dumb luck. That's why you can get better hp numbers by running lighter wheels on a Dynojet dyno (but not a Mustang). The bottom line seems to be these Dynojet correction factors are overly generous and result in inflated hp/torque numbers.

Andy

When is ST going to run on the dynojet so we can put this dyno debate to bed?

Andy

special tool

I am waiting for a few special parts to level the playing field a little.........

NZ951

Something tells me your are going to blow the playing field apart. And without fitting every part in the shop in it!