ESE's works engine tuner

[Pursang]

You getting a lot of Snow atm in Brisbane atm?

Noooo!..... but I bet the KX500 would work for this!



Cheers, Daryl

[katinas]

How many mm offset is that pin looks about 5mm is it just the pic?

Yes , difference is 4.5 mm with 2.25 mm offset.
Piston pin dia 15 mm and circlip just from one side, other side 1.5 mm step ( 12 mm hole ).

Add this because of interesting graphs from C, with different effective petal lengths.

[oldjohnno]

[Norman]

What two stroke is F1 thinking about you think? Opposite piston Achates type?

[Greg85]

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.

hi wobbly
I want to tell you that your R1 exhaust tm is simply a success!! I have seen R1 engines horribly modified the cylinder where the exhaust light was digging like pigs (198.5 exh timing) and the engine was still working well...no loss of low revs and overev to know what to do with it...
I bench tested the C exhaust to see if the loss was significant! the R1exhaust is catching up with a lot of preparation mistakes..good job!!

Translated with www.DeepL.com/Translator (free version)

[karter444]

Happy new year to everyone on this great informative forum
I have a question for Wobbly and anyone else keen to comment
Why is it that the kz10 range of engines seem to be the only engine that I know of that does not have water coolant flow directly over the head insert only through the casting of the head cover . this seems to me to make the engine prone to detonation especially if you are right on the edge of the correct tune .I would imagine that the top divers are only one jet away from deto
I have found 2 things happen when the head and insert are modified to allow water flow directly over the insert , the jet required to bring the egt back to the correct temp was about 4 jet sizes less and the head insert was able to be run with a 8 mm squish with no sign of deto . But due to a lack of testing and no dyno i dont actually know if these changes produce more power .
Cheers Richard

[wobbly]

The design of the R1 pipe was a very tough project to get exactly what Claudio ( the owner ) and Franco of TM wanted.
Making more power was easy , but the problem is that at much over 50Hp the engine becomes very deto prone and hard to tune correctly.
So they wanted more front side power , only a little more peak , and better power in the overev at 14,000 , so that every customer would get the benefit.
But they were adamant that if the pipe didnt suit the " factory " engines they would be happy to change those to suit.
This proved to be extremely hard to achieve - especially the need to keep peak power down , as well as achieving better overall power without getting into deto.
Using Engnod i was able to show them exactly what I was getting , without picking up the tig torch.
In the end I built 4 sample pipes , dyno and track tested those , then combined the best elements to build a sample to send to the factory.
After they dynoed the sample , all I got was a reply " send the laser patterns file please " , then DeConto and Fore track tested it and both wanted to keep it - but Franco smiled and put it back in the truck.
I truly believe that doing such a good job for them would have been impossible without Neels code to work with.

[wobbly]

Richard , yes the TM insert is hard to get your " head " around.
But put simply we want to get as much cold water thru the head as possible - for only one reason , to keep the squish band cool thus preventing overheating and deto
of the trapped end gases.
BUT , cooling the combustion chamber creates a heat sink that is directly in contact with the combustion gases.
This pulls valuable energy , of which there is only a finite amount per stroke , and puts it directly into the water - not into heating the expanding gas above the piston.
This big temp delta simply throws away Hp.
One way of cooling down the squish is to delete the 3.5mm spigot into the cylinder , and one way of keeping the chamber " hot " is to surround it with alloy, to slow down the heat rejection path.
There is another way that I have kept pretty much secret for several years now ( and 6 years of National titles ).
Keep the chamber hot , and only cool the squish area.
You can coat the chamber inner surface with ceramic ( actually illegal , but hey , who's gonna know ) or you can keep the TM system and add water cooling to the squish only.
Today's your birthday son.

[koenich]

Wob, in the 2-Stroke R&D group on Facebook you mentioned using 1 mm steel instead of 0,6 mm or 0,8 mm will loose power (sth like 2 HP for a RS125). Can you explain why?

Thermal inertia is certainly increased with t = 1mm, so it'll react slower?

[karter444]

Richard , yes the TM insert is hard to get your " head " around.
But put simply we want to get as much cold water thru the head as possible - for only one reason , to keep the squish band cool thus preventing overheating and deto
of the trapped end gases.
BUT , cooling the combustion chamber creates a heat sink that is directly in contact with the combustion gases.
This pulls valuable energy , of which there is only a finite amount per stroke , and puts it directly into the water - not into heating the expanding gas above the piston.
This big temp delta simply throws away Hp.
One way of cooling down the squish is to delete the 3.5mm spigot into the cylinder , and one way of keeping the chamber " hot " is to surround it with alloy, to slow down the heat rejection path.
There is another way that I have kept pretty much secret for several years now ( and 6 years of National titles ).
Keep the chamber hot , and only cool the squish area.
You can coat the chamber inner surface with ceramic ( actually illegal , but hey , who's gonna know ) or you can keep the TM system and add water cooling to the squish only.
Today's your birthday son.

Hi Wobbly thanks for the reply and the info . I slotted the insert cover and machined clearance around the insert so ended up cooling the whole insert . So may coat the combustion chamber as you have suggested as we really only run in open .
do you think 4 jets less to maintain correct egt with a cooled insert is about right and do you think that if you can control deto would a 50% squish area produce more power .
cheers Richard

[wobbly]

Running 4 jets leaner means that you have dramatically reduced the bsfc number , and way less energy is seen at the pipe as its disappearing into the water.
A normal 8mm wide 50% squish will have alot more unburned end gases trapped , once again not contributing to heating the expanding combustion mixture.
The turbulence created by that big squish area , is basically the same as advancing the static spark advance , and that will limit the overev capability.
The best setup I have now is the narrow 5mm squish set real close , absolute min cc with well retarded ignition.
This makes the best power on unleaded pump , and allows easy overev to 14800.
the new design of insert I came up with so as not to have to machine the cover at all.

[wobbly]

Koenich , yes many GP race teams ran 0.6 in the header and tailcone - 0.8 in the rest.
This gave an approximate equal rate of heating/cooling to the whole pipe .Seems counter intuitive but it works.
The 1mm has much bigger thermal inertia , and thus bigger surface temp deltas along the length as its being accelerated or decelerated.

[karter444]

Running 4 jets leaner means that you have dramatically reduced the bsfc number , and way less energy is seen at the pipe as its disappearing into the water.
A normal 8mm wide 50% squish will have alot more unburned end gases trapped , once again not contributing to heating the expanding combustion mixture.
The turbulence created by that big squish area , is basically the same as advancing the static spark advance , and that will limit the overev capability.
The best setup I have now is the narrow 5mm squish set real close , absolute min cc with well retarded ignition.
This makes the best power on unleaded pump , and allows easy overev to 14800.
the new design of insert I came up with so as not to have to machine the cover at all.

thanks
cheers Richard

[katinas]

This makes the best power on unleaded pump , and allows easy overev to 14800.

Its the same with less powerful Honda NS engine.
With std RON 98, after many tests with different heads (add photo, every head was changed 2 or 3 times, shape, squish, squish band width) with 57x50.6mm bore/stroke and 109 mm con rod, I always return to 6 mm squish band width for this particular engine. Strong over rev power, engine spins freely.
With 50%, lost revs and power in upper range, and no matter how piston close to head 0.7 mm or unacceptable 1.2 mm. And retarded ignition didn’t help. Only Avgaz helps.
Maybe, wider squish band needs longer conrod on unleaded 98.

[polcat88]

Richard , yes the TM insert is hard to get your " head " around.
But put simply we want to get as much cold water thru the head as possible - for only one reason , to keep the squish band cool thus preventing overheating and deto
of the trapped end gases.
BUT , cooling the combustion chamber creates a heat sink that is directly in contact with the combustion gases.
This pulls valuable energy , of which there is only a finite amount per stroke , and puts it directly into the water - not into heating the expanding gas above the piston.
This big temp delta simply throws away Hp.
One way of cooling down the squish is to delete the 3.5mm spigot into the cylinder , and one way of keeping the chamber " hot " is to surround it with alloy, to slow down the heat rejection path.
There is another way that I have kept pretty much secret for several years now ( and 6 years of National titles ).
Keep the chamber hot , and only cool the squish area.
You can coat the chamber inner surface with ceramic ( actually illegal , but hey , who's gonna know ) or you can keep the TM system and add water cooling to the squish only.
Today's your birthday son.

Wobbly, a few questions on this setup. Looking at the attached drawing is the only coolant path across the insert through the 4 channels? I assume the blind holes around the circumference are centred on the squish band?