ESE's works engine tuner

[SwePatrick]

Yes, there are videos that shows it.
And no, not between the webs.

[ken seeber]

Well, the DCI (Direct Cylinder Induction) thing is still happening. See earlier posts #35387 & 35479 for a bit of background.

[Muhr]

Has anyone thought about the engine's internal inertia in connection with gear compensation when running the dyno. This is a shortcoming when one is interested in getting an idea of how an engine performs against an engine with a different gear ratio from the crankshaft. As far as I have seen, a dyno only compensates for the gear ratio but not for the increased power consumption to accelerate the engine's own inertia at a higher gear ratio. This is usually visible when running a all gear pull. Wondering if there would be a good way to generalize this?

[ken seeber]

Took a little vid of the engine running at lower speeds and no load. Does show a depression in DCI passages.

https://studio.youtube.com/video/D6EX3x8yptU/edit

[SwePatrick]

Has anyone thought about the engine's internal inertia in connection with gear compensation when running the dyno. This is a shortcoming when one is interested in getting an idea of how an engine performs against an engine with a different gear ratio from the crankshaft. As far as I have seen, a dyno only compensates for the gear ratio but not for the increased power consumption to accelerate the engine's own inertia at a higher gear ratio. This is usually visible when running a all gear pull. Wondering if there would be a good way to generalize this?

Sportdevices can do both, but.. generally just uninterestiing and you might have got it backwards?
The faster the engine accelerates the more inertialosses, and by this it means that in higher gears it doesn´t need to compensate as much as in lower gears.
Just dyno it for torque and power in the gear closest to 1:1 ratio, and use sweep through gears just to verify the setup works.

Just to clarify: in static dynopulls there are alomost no compensation at all, as it takes very little power to keep engine rotating at the same speed.
And sweeping pulls in dyno(opposite to static) takes more power the faster you accelerate the engine, so the biggest compensation is in LOWER gears.
Dyno program adds power in lower gears to make power equal as in higher gears if setup correct.

[Muhr]

Sportdevices can do both, but.. generally just uninterestiing and you might have got it backwards?
The faster the engine accelerates the more inertialosses, and by this it means that in higher gears it doesn´t need to compensate as much as in lower gears.
Just dyno it for torque and power in the gear closest to 1:1 ratio, and use sweep through gears just to verify the setup works.

Just to clarify: in static dynopulls there are alomost no compensation at all, as it takes very little power to keep engine rotating at the same speed.
And sweeping pulls in dyno(opposite to static) takes more power the faster you accelerate the engine, so the biggest compensation is in LOWER gears.
Dyno program adds power in lower gears to make power equal as in higher gears if setup correct.

To clarify I see 8: 1 higher ratio than 1: 1 if you misunderstood / wanted to misunderstand. What do you usually do when you run 1: 1? Sometimes, it is not possible to get close to previous references and then you start to think about these question.

[Frits Overmars]

Has anyone thought about the engine's internal inertia in connection with gear compensation when running the dyno. This is a shortcoming when one is interested in getting an idea of how an engine performs against an engine with a different gear ratio from the crankshaft.

In static power measurements the engine's internal inertia does not play a role as there is no rpm variation during the measuring phases.
In dynamic measurements the power absorbed by the internal inertia will not show up at the measured power graph which is usually a good thing because most of the time you will want to see the nett power delivered by the engine.
If you really want to know the internal inertia, you can deduce it by calculating and adding the inertias of all rotating engine parts, taking their rpm ratios in relation the crankshaft rpm into account.

Some say a coast-down run will reveal the internal engine losses but this won't tell you much about the inertial losses because there are also pumping losses, oil churning losses and friction losses, most of the latter being a percentage of the engine power sent through the transmission.
However, during a coast-down the amount of power sent through the transmission is much lower than the power delivered by a firing engine, so it is not realistic to add the measured coast-down power to the measured power of the firing engine and present the sum total as crankshaft power, as is often done.

Comparing engine measurements that were done with different transmission ratios from engine to dyno made me develop the Power Range concept that I introduced in this forum some time ago (in 2013 if memory serves). Today the Power Range option is also incorporated in Vanniks EngMod2T software.

[Muhr]

In static power measurements the engine's internal inertia does not play a role as there is no rpm variation during the measuring phases.
In dynamic measurements the power absorbed by the internal inertia will not show up at the measured power graph which is usually a good thing because most of the time you will want to see the nett power delivered by the engine.
If you really want to know the internal inertia, you can deduce it by calculating and adding the inertias of all rotating engine parts, taking their rpm ratios in relation the crankshaft rpm into account.

Some say a coast-down run will reveal the internal engine losses but this won't tell you much about the inertial losses because there are also pumping losses, oil churning losses and friction losses, most of the latter being a percentage of the engine power sent through the transmission.
However, during a coast-down the amount of power sent through the transmission is much lower than the power delivered by a firing engine, so it is not realistic to add the measured coast-down power to the measured power of the firing engine and present the sum total as crankshaft power, as is often done.

Comparing engine measurements that were done with different transmission ratios from engine to dyno made me develop the Power Range concept that I introduced in this forum some time ago (in 2013 if memory serves). Today the Power Range option is also incorporated in Vanniks EngMod2T software.

Thanks Frits!
As always, you have thought about most things! I'll take a look at your concept and see what I can learn.

[wobbly]

You have a couple of competing variables at play with " inertia " type testing, but some also affect a steady state power test as well.
Thus you need to have a total reduction ratio such that the time taken for the test , will generate realsitic pipe temps.
The other side of that coin is that the higher the inertia ( or lower ratio ) the in cycle speed variation of the crank is reduced , and the engine makes more power.
This was discovered by Dr Fleck at QUB , when using correctly calibrated dyno's the heavyer inertial loaded one would make more power on the same engine.

There is a real Catch 22 with crank or other inertial loads.
More crank inertia reduces the in cycle speed variation , but of course a greater inertia crank is harder to accelerate.

But a test I did on a 500GP bike at Sepang involved two identical bikes side by side.
One had a normal Ti clutch with alloy and the usual fibre clutch plates , the other had a 10.000 GBP AP carbon carbon clutch pack.
Out of the final corner onto the straight past the pits , the carbon clutch bike pulled near on one bike length advantage per gearchange , and ended 8Km/Hr faster into turn 1
The only issue was none of the riders could get the starts to work reliably and it was shelved , as did all the other teams.

[SwePatrick]

To clarify I see 8: 1 higher ratio than 1: 1 if you misunderstood / wanted to misunderstand. What do you usually do when you run 1: 1? Sometimes, it is not possible to get close to previous references and then you start to think about these question.

I just meant the gearbox ratio, always dyno in gear closest to 1:1, this gives you the least impact on the result as there are the least losses inside the engine.
I cannot for obvious reason run 1:1 (crank/dynoroller)
In my opinion there are never any reasons for sweeping through the gears when adjusting the engine.
It only becomes a reason when tracing problems or setting up functions, shifting point´s(to maximize acceleration), shiftcut, etc etc.

And if dyno´s inertia don´t match your vehicles mass, there are even less reasons to sweep through the gears.

No, i don´t start to think about those questions as i see usage of dyno a more openeyed way of what´s what and know how software and physics works.
It just becomes that way when owning a dyno, build one and study

So in short: No the impact of engines own inertia is higher in lower gears, or should i say the impact is bigger when engine runs through the rpm band faster?

If having this(ineria correction) correctly setup in software and pipe and engine is warm, plus got the traction on the roller.(very hard in lower gears)
The powergraph should vary very little in numbers between the gears.

Frits!
i have dynoed my yamaha 84.3hp to the wheel(e85 fuel) and my dyno report it to about 93.7 at the crank when doing a coastdown with holding the clutch, is this about what would disappear in losses through drivetrain?

[Muhr]

If having this(ineria correction) correctly setup in software and pipe and engine is warm, plus got the traction on the roller.(very hard in lower gears)
The powergraph should vary very little in numbers between the gears.

My question is about exactly what you say your program can handle, so I wonder how the program did this guesstimation?

[Frits Overmars]

i have dynoed my yamaha 84.3hp to the wheel(e85 fuel) and my dyno report it to about 93.7 at the crank when doing a coastdown with holding the clutch, is this about what would disappear in losses through drivetrain?

More or less, but as I tried to explain above, it cannot be exact. Transmission losses are mainly a percentage of the transmitted power but this transmitted power is absent during a coast-down run and you cannot measure something that is not there. Furthermore, a pulled clutch never opens 100%; there will always be some drag, and there's no telling how much it will be.

[SwePatrick]

My question is about exactly what you say your program can handle, so I wonder how the program did this guesstimation?

You configure the engines inertia, almost impossible to calculate, you need to calculate each gear(that spins), clutch, crank.
Make it easy for yourself and just measure the inertia of the crank and clutch separated from the engine.
Use falling weight method.

And then,, you got friction, oil churging etc etc.

[Muhr]

You configure the engines inertia, almost impossible to calculate, you need to calculate each gear(that spins), clutch, crank.
Make it easy for yourself and just measure the inertia of the crank and clutch separated from the engine.
Use falling weight method.

And then,, you got friction, oil churging etc etc.

I think most people here have an idea how they could do this the hard way. The question was about a simplified estimation, similar to crank power.
It sounds incredible that your program wants you to specify this for each engine you run.

[SwePatrick]

I think most people here have an idea how they could do this the hard way. The question was about a simplified estimation, similar to crank power.
It sounds incredible that your program wants you to specify this for each engine you run.

As every engine differs, so ofcourse you need to edit this to suit the engine.
But, i don´t use it, it´s not interesting because what i wrote earlier.

Don´t let let it block your mind, forget it and go on with more useful stuff to do, like starting up your project

The simplified way, i hinted of that earlier, but again:

'If value is setup correct the enginepower should differ very little between the gears in a pull through the gears...'

And by that, just put in a random number and look at the difference, adjust until you´re happy.
(and still be asking yourself if it´s really correct)