ESE's works engine tuner

[wobbly]

There is already the technology to run a square top edge at 100% bore with no bridge.
This involves an inverted L dykes ring that is trapped within a groove.
The piston " lid " screws on to contain the ring from bulging out into any port.
This can also be combined with removing the small end pin hole from the outer skirt - and is being worked on now by Makr and Mr Two Stroke Stuffing ( I have the T shirt )
But deleting the transfer bridges will , I believe , completely ruin the exiting streams coherency , that has been worked on for decades to create Frits Leaning Tower up the back wall.
Thus destroying the scavenging and trapping efficiency in one foul swoop.
Transfer STA has rarely been the limiting issue , Blowdown certainly has been.

[Emily Strange]

'Frits Leaning Tower up the back wall'

I'm sure he will thank you for that! Gave me a good laugh. Yamaha had the YPVS (known to some in the UK as the Young Persons Vigorous Sausage!), Kawasaki had KIPS (you'll have to make your own interpretation up for that one) and Aprilia have the FLTUTBW... Yikes.!

[MotleyCrue]

There is already the technology to run a square top edge at 100% bore with no bridge.
This involves an inverted L dykes ring that is trapped within a groove.
The piston " lid " screws on to contain the ring from bulging out into any port.
This can also be combined with removing the small end pin hole from the outer skirt - and is being worked on now by Makr and Mr Two Stroke Stuffing ( I have the T shirt )
But deleting the transfer bridges will , I believe , completely ruin the exiting streams coherency , that has been worked on for decades to create Frits Leaning Tower up the back wall.
Thus destroying the scavenging and trapping efficiency in one foul swoop.
Transfer STA has rarely been the limiting issue , Blowdown certainly has been.

Is this developed enough that it is known to stay together (screws don't come loose, top doesn't overheat, screws don't overheat) and would work on any engine (retrofit) or is it in the guinea pig stage?

[JanBros]

any theory/explanation behind the slghtly conical belly ?
benefits/downsides ?

[wobbly]

There is a finite amount of energy available from the Ex port generated wave front within the pipe.
In Aprilias case the diffuser action must have been more efficient than the trapping efficiency numbers.
Thus the angles needed in the rear cone gave better power the steeper they were.
Tapering the mid section allows a bias to be generated toward scavenging ( bigger front mid section ) or toward trapping ( bigger mid section end ).
I have done several designs where scavenging needed additional help , so the diffuser needed to be steeper.
The new TM KZ engine is an example - in this case I needed to make the last diffuser way steep to generate better front side power , and the rear cone could not be as steep as it limited overev ability
thus the mid taper is reversed.

[wobbly]

The screw together piston dome has a patent issued for it , and has been tested to death .
Makr is using his idea of a two piece piston to allow a full length outer skirt with no pin holes and is combining the two together for an even better design.
Not sure about how he is ensuring reliability - search his SpewTube posts.

[andreas]

There is a finite amount of energy available from the Ex port generated wave front within the pipe.
In Aprilias case the diffuser action must have been more efficient than the trapping efficiency numbers.
Thus the angles needed in the rear cone gave better power the steeper they were.
Tapering the mid section allows a bias to be generated toward scavenging ( bigger front mid section ) or toward trapping ( bigger mid section end ).
I have done several designs where scavenging needed additional help , so the diffuser needed to be steeper.
The new TM KZ engine is an example - in this case I needed to make the last diffuser way steep to generate better front side power , and the rear cone could not be as steep as it limited overev ability
thus the mid taper is reversed.

Wobbly are you sure this is correct, the best way to acheive balance between negative and positive wave must be mid- sec diameter, having the belly tapering out just for the baffle to have steeper cones wouldn't increase ramming efficiency, that is as in higher amplitude-they are still the same length? in fact some energy has been lost. I'm not aquainted with the Helmholtz factor of things, maybe this is the reason.

[andreas]

duplicate.

[wobbly]

The convergent cones wave amplitude is directly proportional to the reflecting angle - steeper = higher amplitude.
Wave duration is directly proportional to cone length - longer cones = longer duration.
In the case of a larger belly diameter for the reflecting cone we get the best of both worlds , identical duration ( same length ) with higher amplitude ( steeper cone angle ).
Normally to get steeper angles you would need to shorten the cone length , thereby automatically reducing the duration , and to some extent this relates to powerband width as well.
Having a parallel mid section means that you have no bias in the use of the finite wave energy available - going bigger means the diffuser is affected ,thus reducing the available energy for the reflection intensity.
Sure the reflecting cones then by definition become steeper - but that may not be what the engines dynamic system needs, and as less energy is available the steeper rear cones will not in fact have any greater amplitude.
Swings and roundabouts - and zero free lunch as always.

[jfn2]

wobbly:
when dynoing an engine and monitoring pipe info how important is monitoring pipe average pressure (in the center of the pipe) and what +/- psi would that be? I am assuming that the psi is taken when the avg temp is +/- 425*F. I am told that this pressure is +/- 4 psi. Is that true or just bs?

[andreas]

Wobbly I humbly dissagree, free lunch is available at the diffuser, where bigger pipes offer steeper angles with the same length, but the remaining wave that enters the baffle contains less energy than it would have in a smaller pipe, it is also more expanded with means a steeper angle is needed to give it the same reflection profile, but it has still lost some of its energy to the more efficient diffuser. This is theory, I have no proof.

[peewee]

hey guys i have some wossner pistons of 64mm and 225gram with no pin. i guess the machinist is lazy and doesnt give a shit. the same wiseco is just 185g. what do you think the extra strain on the conrod will be at 4000fpm piston speed?

[wobbly]

Your circular argument to me is self defeating in that you say bigger ( parallel ) pipes offer steeper angles with the same length - correct.
But then you say the bigger dia reflecting cone needs steeper angles to generate the same amplitude profile - correct.
And you then agree that the bigger diffuser has " stolen " some of the energy from the reflecting cone so this will by default reduce the rear cones efficiency.
So , the only way to fix that issue - if that is what is needed to make more power - is to increase the rear cones efficiency again by making its entry diameter bigger.
Thus we are back to biasing the efficiency as needed by using a tapering mid section.
Oh - and by the way EngMod agrees , that fact may be moot to some , but also the dyno doesn't lie , and that we can all agree on implicitly.

[andreas]

Having the baffle cone's entry diameter larger than the diffuser cone's outlet makes the belly itself a shallow diffuser- stealing more energy, and yet this baffle cone returns more energy- where does the extra energy come from?

[F5 Dave]

I shouldn't be drinking while reading this (Epic Hop Zombie double IPA 8.5%) as this is melting my brain. I'm going to have to draw some pictures. Must go spend some time with Mal down the road and get my head around pipe dynamics in Engmod.