ESE's works engine tuner

[husaberg]

Just sent an email to Neels.

The answer is NO, wtf is going on - how hard can this be.

might i suggest as many users as possible on ask the same question (respectfully) in this thread) worth a crack?https://www.kiwibiker.co.nz/forums/s...post1131243035

[Wos]

WOS, 15* BTDC is an optimum advance number that occurs when the static compression plus the dynamic compression created by the Delivery Ratio and the Trapping Efficiency combine
to reduce the pumping losses of compressing that retained charge, and if it all works together the peak cylinder pressure occurs near 15* ATDC.
If you can get away with more advance then one or both of the compression cycles is sub optimum.
Having to retard the ignition, leads to the opposite conclusion.

Thanks for detailed explanation Wobb!

[Jan Van Hamme]

Deleted post

[husaberg]

Just sent an email to Neels.

KB's top dog has replied for Neels to try now.

[Vannik]

might i suggest as many users as possible on ask the same question (respectfully) in this thread) worth a crack?https://www.kiwibiker.co.nz/forums/s...post1131243035

After more than a month I am back! Wow, talk about serious withdrawal symptoms.

[Jan Van Hamme]

After more than a month I am back! Wow, talk about serious withdrawal symptoms.

Welcome back, Neels. I am delighted to be able to read your contribution once again.


@Wobbly, Mach 0.8 and 51% gives less power when I simulate it. What I have also found is that when Engmod generates a fospipe on my engine, it results in a stinger diameter that causes a Mach of 1.
And that Mach 1 does not cause any detonation in the fos exhaust or in my own exhaust.
I think something is wrong and will send a pack file to you and Neels.

[F5 Dave]

Thanks for making the effort. And for Spank for sorting the issue. It must be hard for amateurs to cope with odd issues.

[Peter1962]

After more than a month I am back! Wow, talk about serious withdrawal symptoms.

Great news ! Welcome back, Vannik.

[wobbly]

JVH, having Mach in the stinger nozzle means that tube is sonic choked. ie it is impossible for more flow to happen - talk to GPT about this.
If its not getting into deto, then that simply means the TubMax is very safely low.
IMHO, with a bigger stinger @ 0.8 Mach ( plus with MSV @ 40m/s ) and way more compression to push the TubMax up near the deto limit , it will make alot more power.
The only question to ask is will the new squish configuration cause piston clipping - I doubt it, as for example Jan has said the RSA didnt hit at 0.4mm/14000 rpm.

I did ask sarcastically " how hard can it be " - what was the actual problem with Neels access here?

[Jan Van Hamme]

JVH, having Mach in the stinger nozzle means that tube is sonic choked. ie it is impossible for more flow to happen - talk to GPT about this.
If its not getting into deto, then that simply means the TubMax is very safely low.
IMHO, with a bigger stinger @ 0.8 Mach ( plus with MSV @ 40m/s ) and way more compression to push the TubMax up near the deto limit , it will make alot more power.
The only question to ask is will the new squish configuration cause piston clipping - I doubt it, as for example Jan has said the RSA didnt hit at 0.4mm/14000 rpm.

I did ask sarcastically " how hard can it be " - what was the actual problem with Neels access here?

Wobbly, Msv 40m/s
Squishband 50%
Compression 12.7
Stinger mach1
Squish 0,65mm
Stroke 57mm
Tubmax 960
Deto @ Tubmax 970
Thanks that you will look at it over the weekend.

[Frits Overmars]

having Mach in the stinger nozzle means that tube is sonic choked. ie it is impossible for more flow to happen...

In sonic choked flow, lowering the pressure downstream of the throat will not increase the flow velocity past Mach 1, and neither will raising the pressure upstream of the throat.
But raising the upstream pressure will increase the gas density and thus the mass flow, even if the throat velocity remains Mach 1.
One more pedantic point: Mach 1 flow in the stinger may not be Mach 1 all of the time. The practical limit of Mach 0,8 may be an average value derived from practical experience and your Mach 0,8 flow guideline may contain instants of Mach 1. But we must proceed with caution there; Mach 1 all of the time will be risky.

[wobbly]

Here is a stinger nozzle Mach trace at peak power.
In this and all the other cases I have simulated if 0.8 Mach is exceeded it means ignition or compression has to be reduced to some unexpectedly low value
as the retained pipe pressure is overly excessive.
The peak velocity is occurring as the main wave descends down the rear cone and enters the stinger - this plot is logged 1/2 way along a 25mm long nozzle.
Subsequent peaks and troughs, are reflections and superpositions off atmosphere, the pipe entry and the step up to the main stinger tube, I assume.
I do not know if going sonic creates a shock wave at the nozzle entry - maybe Neels can enlighten me/us.