ESE's works engine tuner

[SwePatrick]

It was just an example.

A fullradius velocity stack seldom gives max power is what i try to say.

Always this black and whiteness........
never nobody tries to understand.
One always need to write a novel to leave out all misunderstandings.

[wobbly]

What I was saying was that the full radius " velocity stack " , in a simple back to back dyno test , gave a big increase over a shorter , smaller diameter bellmouth.
In this case , with a very short intake length already , a big increase in top end power was the result , although a small amount of length had been added.
So the added pressure recovery created by the extended bell , overcame any percieved downside of increased length.
Black is less power - white is more , the dyno does not lie or guess - as we do most of the time.

[Muhr]

The KZ Dellorto kart carb is nothing special at all , its just what was homologated many years ago and no mods are allowed.
But one airbox manufacturer was clever and achieved what im sure all good tuners would have eventually come up with.
They made the rubber clamp on manifold effectively a continuation of the bell , with minimal extra length.
This is worth several Hp past peak over others that simply have an extension to the flat clamp surface.

Here is a sim of 0mm radius 8mm and one ellipse.

It was just an example.
A fullradius velocity stack seldom gives max power is what i try to say.

Always this black and whiteness........
never nobody tries to understand.
One always need to write a novel to leave out all misunderstandings.

It's just a little confusing, if you look at the picture I posted last time. Then you can see on the left a couple of rubbers from 2 engine manufacturers on the intake you refer to, if you then look in the middle of the same picture, there are 2 carburetors that are identical to what you are referring to.
Here is also a link to the air box Wob refers to:
https://www.tkart.it/en/magazine/tec...hetti-ridolfi/

[TZ350]

.

My bike having disgraced itself on the dyno by locking up at full song in top gear was put in the naughty corner to think about its behavior.

It is quite something to have the back wheel stop and the dyno drum still spinning at 100mph.



Pulled the engine out today to see what went wrong.

I had all ways been a bit nervous about the old RD400 rod letting go at 14,000 rpm.



But the mystery depend when I found no real engine damage but a lot of black fine soft almost rubbery stuff coating the cylinder head and crankcase walls. It was everywhere.



The culprit was reveled. The rotary valve blade had broken and rubbed its way through the rotary valve covers outer "O" ring and eventually jammed the engine.

For such a dramatic moment on the dyno there is not much damage thankfully.

[porttiming124]

Happy New Year everyone

[wobbly]

Portiming - same to you .Your question about the numbers on the STA sheet.
Those look just fine , the devil is in the detail .
Post your .pack and we can tell you what isnt going to work - if anything.

[ken seeber]

The recent talk on short carbs coincided with me fossicking around and finding this short carby I made around 50 years ago. Obviously a slide unit, but the fuel metering was done using the same principle as the Wal Phillips carb. I fitted it to my first ever raced bike, a Suzuki A100. It sort of worked, running on methanol, but no magical power boost. Was a pig in many areas and, when running, had a standing fog outside of the carb that left everything smothered in fuel. Trying to get the thing running at night in neighbouring suburban streets was a touch anti-social….they thought. Sold the bike shortly after. Bloody 2 strokes.

[nitro2tfx]

To me it is clear that predictive software and/or taking real time measurements are just some of the tools to assist in the design of one important functional component of the final product, in this case a high performance 2 stroke engine.

The real test is ultimately to use these tools in addition to skills, knowledge, imagination, experience, instinct and dedication to come up with an improved product each time.

Both real time pressure analyzers products and simulation software products are very good and useful tools, but like anything else a lot depends on the end user too. Typically both technologies save a good deal of time and money in the long run, as well as improve performance, some people really run with the ball and some don't, but the opportunity is there.

[nitro2tfx]

One thing I have not noticed in this thread, nor anywhere else, is a discussion of how positive pressure return waves are generated in ways other than just a positive pressure reflection off of a converging cone or flat end surface, in a typical 2 stroke pipe. Has this been discussed at all ?

[TZ350]

One thing I have not noticed in this thread, nor anywhere else, is a discussion of how positive pressure return waves are generated in ways other than just a positive pressure reflection off of a converging cone or flat end surface, in a typical 2 stroke pipe. Has this been discussed at all ?

No. But start it off and tell me more about these magic waves energy source.

[Vannik]

One thing I have not noticed in this thread, nor anywhere else, is a discussion of how positive pressure return waves are generated in ways other than just a positive pressure reflection off of a converging cone or flat end surface, in a typical 2 stroke pipe. Has this been discussed at all ?

1. From a wave going through a contact discontinuity - where the composition and or temperature changes
2. Reflection from a shock wave forming
3. A suction wave traveling down a diffuser will reflect a positive wave back
4. ?

[nitro2tfx]

1. From a wave going through a contact discontinuity - where the composition and or temperature changes
2. Reflection from a shock wave forming
3. A suction wave traveling down a diffuser will reflect a positive wave back
4. ?

Since it seems like 1,2,3 and possibly 4 have not been discussed much, or at all, maybe it would be useful to explain 1,2,3 in some detail to ALL. Then from that I can see if your 1,2,3 includes my "4" or not.

As a side note I think we are going to have to measure the T6 Banshee pipe as there don't seem to be any dimensions for it on the internet. Hoping to get another few tests in before taking anything apart so there will be a bit of a delay in getting those numbers to you.

[wobbly]

Nitro , as I am really keen on using any tool I can in the quest for increased speed of analysis in producing new or better designs , can you explain one thing to me
about the way you implement the data analysis of the real time observations.
To me the process is only one step ahead of the old " suck it and see " approach.
As it seems you have to do a test run , analyse the data , then the only way forward is to modify or rebuild the pipe/ports etc , then do another test - still slow and laboreous , but more informed obviously.

Again I come back to the last big project I did for TM.
They wanted more front side power , so it took me about a week of constant small iterations in the sim, and analysis , to discover categorically that the last part of the diffuser , had the biggest effect on this.
I started out with a short , shallow section , just like an Aprillia pipe , and 30 sims later ,ended up with a cone way longer , and steeper , than I could ever have imagined.
Then to supress the tendency to produce more peak ( not wanted , as it creates too much tuning drama trying to supress deto ) this needed a completely differing approach ( from " normal " )
to the header and 1st diffuser % / length.

I built one pipe to dyno prove the diffuser concept , one to prove the header , and one to prove the rear cone matched the sim effects.

Is the real time data analysis able to match or short circuit this process without spending hours rebuilding pipe after pipe iterations - just to see if a theory matched reality.

[41juergen]

I'm in the need for the KTM SX250 cylinder data for EngMod (ExPort and Transfers) as I don't have the cylinder yet in my hands. Can anyone help me with that? If one would have the whole EngMod project file for the SX250 would be also very appriciated...
cheers
Juergen

Got it, thank you so much Neels!!!!

[136kg136ps]

What say ye? Snake oil or engineering breakthrough?
I was immediately skeptical when it mentioned the high octane requirement and need for high pressure oil in the transmission but always willing to listen.

https://www.sticsupertorque.com/productinfo.html