Mustang Dyno

**JwMonE99** · 07-19-2008, 10:31 PM

How accurate are they and what about their 1/4 drag racing with the weather climate thing. I heard it can be pretty acuarte in times I just wanted to hear what you guys think of it?
AWD Mustang Dyno

**Mr. Luos** · 07-20-2008, 01:26 AM

Real 1/4 mile is the only answer.

**Sarge** · 07-20-2008, 04:26 AM

+/- 3%

**570SX** · 07-20-2008, 07:19 AM

they're plenty accurate. i think what most people don't like is that they show numbers lower than, say, the DynoJets. must be different algorithms or something. use whichever is available. oh, and the climate adjustments are BS. what they do is account for the different amount of oxygen in the air, the density, the vapor pressure, etc. just the static differences. but inside the engine is a VERY complex reaction, which is *nearly* impossible to mimic with decent accuracy. Ricardo does a good job, but unless you're on Ferrari's Formula One team, or maybe one of the fortunate few Formula SAE college teams, you won't see that program. anyways, the static changes to the air's physical properties are very different to the way that those properties affect the dynamics inside the engine, like suction, combustion, flamefront propegation, etc. if it makes you feel better having a bigger number, use it, but you're just hurting yourself when it comes to measuring the effectiveness of your mods.

in any case, dynos are for measuring the effectiveness of modifications, not for racing. the algorithms for estimating traction of the tires are too complex even for modern engineering and computing to get totally right. that's why auto makers still rely on test drivers to give final tuning to their tires and suspension setups before putting a car on the market. moral of the story: want to say you beat your buddy's car? beat his car.

**Blk99RamAir** · 07-20-2008, 08:06 AM

The only true test is to take it out to the track. The dyno can't take into account wheel spin and such. The mustang dyno shows lower #'s than the dynojet because it is preloaded so it is more realistic in terms of the weight your motor has to push on the street. It has resistance... The dynojet is not loaded, it is more free spinning, thus higher #'s.

**570SX** · 07-20-2008, 09:33 AM

because of the way a dyno works, the rotational inertia of the rollers does not correlate to a higher or lower number produced. all inertial dynamometers take into account the rotational inertia of the roller(s) and calculate power production from there. torque is then calculated from the power production and the tachometer signal.

both dynamometers are measuring wheel horsepower. one seems to spin up faster because it has less rotational inertia, but again, that does not affect the reading. there is something different in the algorithms that different companies use to compute the power of the driven wheels from the angular acceleration of the roller(s).

**JwMonE99** · 07-21-2008, 12:14 AM

Reason why I ask is because a friend of mine runs consistent 13.9s on both a mustang dyno and a real track. I wouldnt think that the dyno would be that acurate but it was consistant numbers at different times.
The other day I put mine on and dyno and so did he, I ran 13.4 and he was 13.9 I still need to take it to the track to find out.

**Sarge** · 07-21-2008, 05:03 AM

Originally Posted by 570SX

they're plenty accurate. i think what most people don't like is that they show numbers lower than, say, the DynoJets. must be different algorithms or something. use whichever is available. oh, and the climate adjustments are BS. what they do is account for the different amount of oxygen in the air, the density, the vapor pressure, etc. just the static differences. but inside the engine is a VERY complex reaction, which is *nearly* impossible to mimic with decent accuracy. Ricardo does a good job, but unless you're on Ferrari's Formula One team, or maybe one of the fortunate few Formula SAE college teams, you won't see that program. anyways, the static changes to the air's physical properties are very different to the way that those properties affect the dynamics inside the engine, like suction, combustion, flamefront propegation, etc. if it makes you feel better having a bigger number, use it, but you're just hurting yourself when it comes to measuring the effectiveness of your mods.

in any case, dynos are for measuring the effectiveness of modifications, not for racing. the algorithms for estimating traction of the tires are too complex even for modern engineering and computing to get totally right. that's why auto makers still rely on test drivers to give final tuning to their tires and suspension setups before putting a car on the market. moral of the story: want to say you beat your buddy's car? beat his car.

Dyno Jets just spin the rollers...Mustang Dyno's put equal to the weight of the car resistance to simulate real world road conditions.....that is the reason Mustang Dyno's read lower numbers.

**570SX** · 07-21-2008, 05:59 PM

Originally Posted by Sarge

Dyno Jets just spin the rollers...Mustang Dyno's put equal to the weight of the car resistance to simulate real world road conditions.....that is the reason Mustang Dyno's read lower numbers.

and how exactly do they place a "weight of car resistance" on a dyno? there's nowhere to put weight. load control dynos can place a resistance to rotation of the roller(s), but that also has no effect on the reading, as long as its calibrated correctly. i've seen more mustang dynos with load control that i have dynojets with load control by a lot, but it still comes down to algorithms and/or calibration.

the algorithms for load control dynos can be especially tricky, since most load control dynos use eddy current retarder units, and a true calculation to convert the current drawn by the unit into a power figure has still not been discovered. 3 different experimental equations exist, and you can use each only for certain ranges of certain input variables where each equation is relatively accurate.

that or they use a torque arm, and then they'll have very complex algorithms for ignoring noise in the signal due to the vibration of the vehicle and the dyno, small spikes in the power supply to the building, spikes in the building's power circuits as other electrical devices turn on and off, small ripples in the power supply due to other electrical devices as they get hit with the spikes, etc. lots of noise makes the torque arm difficult in terms of programming as well.

so like i said, lots of room for variation between different makes just based on the calculations that they have to program into their software, the layout of their hardware, and the calibration of each unit.