Load-Bearing Dyne (i.e. Mustang) or Traditional (i.e. Dyno-Jet)???

[Locofrancais MR2Guru]

Discuss amongst yourselves!

[gibsanez]

As long as you end up with clean, safe A/F's and a smooth torque curve, I don't care. Don't forget people, a dyno isn't a "horsepower measuring" tool, it's a tuning tool.


Edit - Wow, talk about a slow moving sub-forum. I didn't even realize this thread was almost 5 years old...

[PHOENIX]

This section just got added a few days ago.

[CJMR2T]

Originally Posted by PHOENIX

This section just got added a few days ago.

Yeah, but the actual first post was back on 07/11/2006..

[CJMR2T]

Originally Posted by gibsanez

As long as you end up with clean, safe A/F's and a smooth torque curve, I don't care. Don't forget people, a dyno isn't a "horsepower measuring" tool, it's a tuning tool.


Edit - Wow, talk about a slow moving sub-forum. I didn't even realize this thread was almost 5 years old...

Yes and no... inertia units like dynojets are only good for full power recording and can not be accurately tuned on except for full load condition and even then its hard to get an accurate tune.

Load units or more correctly, brake dynos (like mustang and dyno dynamics) are intended for and should be used for tuning and diagnostics since you can load the engine to sustain a specific point of operation. This allows you to dial in the fuel and ignition for MBT (Maximum Best Torque).


While on this subject, dyno's do not measure horsepower. They mathematically calculate it.
Inertial dyno's measure acceleration then calculate the torque then from that, the horsepower. The computer measures the rate of acceleration of the roller and uses the simple equation F=MA. Since it knows the Mass of the drum (roller) and it measured the Acceleration of it, it can calculate the Force. Since this force is in a rotation of an object, the force is expressed a torque. Then once the torque is calculated, the HP can be calculated (Torque X RPM / 5252).

Brake type dyno's on the other hand apply a brake load to find the point at which the engine is neither accelerating nor decelerating this load is directly proportional to a specific amount of torque and thus the computer knows the torque for that given point of operation and going back to Torque x RPM / 5252, horsepower can be calculated.

As you can see, with. Brake type dyno, an entire map can be tuned since you can load for part throttle situations, something an inertial dyno cant do. On an inertial dyno, you can only do a full throttle run, then make changes and do another run and overlay the two plots to see what the changes did. On a brake dyno, one can sustain a specific point (RPM and Load) and make changes and watch the torque change as you make the changes. This obviously makes for tuning MBT much much easier.

[kbrew8991]

Originally Posted by PHOENIX

This section just got added a few days ago.

technically no, but the Racing Section that contained them did go away and these were merged under the General heading.

FWIW I'd lean towards Dynojet since there are some racing sanctioning bodies that use them for rules compliance checking and also since they're the most widely accepted brand currently.

[CJMR2T]

Originally Posted by kbrew8991

FWIW I'd lean towards Dynojet since there are some racing sanctioning bodies that use them for rules compliance checking and also since they're the most widely accepted brand currently.

That sir is very true.... unfortunately though the common misunderstanding of the two different types is what makes it the most widely excepted brand. If majority of the people knew that you can't accurately tune on a DJ, I doubt people would use shops that use them thus they wouldn't be nearly as accepted as they are.

[AdrianS]

For mapping an injected car, you need a "loading" dyno, so you can hold it at various speeds and loads. You can then get instant feedback as you change the fuel / spark - is the power going up or down, is the AFR getting better or worse, etc.
Inertia dynos are a pretty crude tool when you are trying to find the last couple of percent improvement.

Disclaimer - I may be accused of bias, because I design dynos for a living.

[CJMR2T]

Originally Posted by AdrianS

For mapping an injected car, you need a "loading" dyno, so you can hold it at various speeds and loads. You can then get instant feedback as you change the fuel / spark - is the power going up or down, is the AFR getting better or worse, etc.
Inertia dynos are a pretty crude tool when you are trying to find the last couple of percent improvement.

Disclaimer - I may be accused of bias, because I design dynos for a living.

That sir is 100% correct... I wouldn't call you biased by any means regardless of your job...

About the only thing you can map on Inertial type is WOT and thats it. Even then, its difficult to do correctly and easy to destroy an engine on.

[niterydr]

Originally Posted by CJMR2T

That sir is 100% correct... I wouldn't call you biased by any means regardless of your job...

About the only thing you can map on Inertial type is WOT and thats it. Even then, its difficult to do correctly and easy to destroy an engine on.

In my opinion the only way you will get even WOT tuning on an Inertial style dyno is if the drum weights the exact same as your vehicle. What Inertial style dynos are good for is consistancy. So I do like using a dynojet when simple bolt ons are being done and I just want a quick snapshot of the changes made.

I miss tuning on a Dyno Dynamics dyno.

[ats_scott]

Old thread but I had to post. My experience is with inertial dynos exclusively (dynojet 248c). I have been tuning on them for 10 years.

It is complete BS that you can't get an excellent tune on an inertial dyno. I have done it hundreds of times, all on MR2's. I don't think anyone has tuned as many MR2's as Aaron and I have.

To be honest you dont even need a dyno to get a good tune, but it does make it easier, and then load holding dynos are probably easier to tune on than an inertial. That will make them more popular amongst the amature tuners out there.

[CJMR2T]

Originally Posted by ats_scott

Old thread but I had to post. My experience is with inertial dynos exclusively (dynojet 248c). I have been tuning on them for 10 years.

It is complete BS that you can't get an excellent tune on an inertial dyno. I have done it hundreds of times, all on MR2's. I don't think anyone has tuned as many MR2's as Aaron and I have.

To be honest you dont even need a dyno to get a good tune, but it does make it easier, and then load holding dynos are probably easier to tune on than an inertial. That will make them more popular amongst the amature tuners out there.

For starters, the sense of the word "tuned" can mean multiple things.... yes you can tune on DJ's for WOT, but load can be off a bit to. In the past 15+ years I've seen 100's of engines get tuned on inertia dynos and have what appeared to be a great tune looking at the datalogs and had ZERO evidence of detonation but when when put on the street and or track, they blew up from detonation. Now yes, some of them could have been other factors like bad gas and such but I know all of them weren't.

The problem is inertia dynos can not account for aerodynamic drag / the additional load it causes. So even it the weight of the roller is close to the weight of the car, there is still additional load that can be applied once off the dyno. This becomes problematic when mapping the ignition more then anything unless you go a little more conservative then what you were able to do on the dyno. Load types do not suffer from this problem because its applying the absolute maximum load that could ever be applied since its in effort, trying to prevent the engine from accelerating any further.

So yeah, you can tune on an inertia dyno, but in the truest sense of the word "accurate", is it? No!