Competition The differences of a load/inertia dyno?

[16919]

What are the main differences? Why do you get diffferent numbers? Could you guesstimate what you would get on the other type if you ran on one? Mainly b/c I ran on a load dyno and was curious if I could get an idea what I would throw down on an inertia.

 

[ALehman]

I ran my truck on a Taylor water load dyno at Antrim. They put the same load on as a big rig. Bad idea for my truck. Dynoed at 386 hp then seized three pistons. It smoked like a train when they threw the load, but then I had a gut pile under my truck that reminded me of smoker tractor. Guys think they have bad trucks with big numbers when they run on car dynos but that ain't nothing till your on load dyno.

 

[16919]

Does anyone know the difference?????????

 

[BILLVO]

Does anyone know the difference?????????

An inertia dyno is a drum filled with a thick or heavy fluid and measures how fast you can spin the drum to a certain speed and depending on how much info is entered into the program can give somewhat acurate readings or extremely inflated fun #'s which is what I would say a majority of the #'s here on TDR are. I say that because most dyno in overdrive which inflates the #'s rather than the true reading that would be obtained in a direct drive gear. This again dependant on info entered.



A load dyno has a break in it either an electromagnet or water brake which can actually put a load on the engine. this gets the most accurate number also dependent on the info programed in. and what you want to see or do. There are way more uses for a load dyno, these are the best for tuning accurately.



If you want to compete with #'s here, run on an inertia and run in OD. They are just fun #'s and may be in ballpark of load dyno but not as accurate.



This will probably get a rise from many here but it is the truth.

 

[16919]

Thanks for the info Billvo. Now I understand.

 

[Dockboy]

An inertia dyno is a drum filled with a thick or heavy fluid and measures how fast you can spin the drum to a certain speed and depending on how much info is entered into the program can give somewhat acurate readings or extremely inflated fun #'s which is what I would say a majority of the #'s here on TDR are. I say that because most dyno in overdrive which inflates the #'s rather than the true reading that would be obtained in a direct drive gear. This again dependant on info entered.



A load dyno has a break in it either an electromagnet or water brake which can actually put a load on the engine. this gets the most accurate number also dependent on the info programed in. and what you want to see or do. There are way more uses for a load dyno, these are the best for tuning accurately.



If you want to compete with #'s here, run on an inertia and run in OD. They are just fun #'s and may be in ballpark of load dyno but not as accurate.



This will probably get a rise from many here but it is the truth.

LOL!!!!



You have no idea what you are talking about



An inertia dyno has NO parameters to input other than what the weather station inputs. It calculates the HP it takes to accellerate a known weight (the drum) over a given time. Dynoing in OD only helps load a forced induction engine better and will only show a slight increase in torque only compared to dynoing in 1:1. The HP will be nearly identical.



Load dynos results are totally dependent on what info is inputted into the system, when and how the load is applied and can give you numbers all over the place.



The only statement you made that is even anywhere close to fact is that dynos should be used for tuning :-laf

 

[BILLVO]

The winpep program I have seen on dynojet dynos ask for a lot of info.

 

[Dockboy]

The winpep program I have seen on dynojet dynos ask for a lot of info.

Then tell me what info it asks for that has any effect on the results besides weather info?



And by the way, I do know just a little about winpep and Dynojets

 

[BILLVO]

It took year, make,6 or 8 cyl,auto or manual,gear ratio. I think it may have asked tire size. Also Rpm range to be tested. I do not claim to be an expert on the inertia dyno but fromk being around water brake load dynos for about 15 years now. There is no comparison between the 2 IMO the load dyno is the best way to truely get accurat readings.

 

[DavidTD]

An Inertia Dyno uses drums that are a fixed weight. The DJ248 drums are not filled with fluid. The Dyno Jet software is written for the specific drum weight. Since each set of drums will vary a small percentage in weight, software for one machine is not accurate for anothers drums.



The principle for measuring HP on an ineria style unit is the acceleration rate of that fixed weight. That is basically the definition of HP. It is very repeatable from one machine to the next.



The Dyno Jet software does not care about what is turning the rollers. It doesn't care about tires, weight, gearing etc. You cannot mulitply HP with gearing, only torque and since the Dyno Jet measures HP, gearing has no effect on the calculations.



For turbo diesels, it is recommended you run in top gear. This makes the truck work harder, build more boost etc. In most cases, my Dyno Jet compares with properly run load cell units. There are always exceptions.



Tq on a dyno jet is calculated using the TQ= hpx5252/rpm formula.

 

[Dockboy]

^^^^^^^^^^^^^^^



What David said!! :-laf

 

[DavidTD]

I wil also add that I have not played with the WinPep software for the 224LC dyno jet which is a load unit. It vary well could require some of those inputs like the other load cell units. Don't really know.