ESE's works engine tuner

[jbiplane]

JB the central sleeve idea is for sure the KISS solution

Thank, Wobbly I experiencing now with a bit modified central sleeve.
Katinas seems as well have answers for all possible variants.

This word should be removed from anyone who works with machinery
its caused grief every time it’s used.

90% of stuff ariving from China should be carefully reworked and in wrong case dropped in garbidge immediatelly.
But it cheap and fast way save some money at ground experiments or use this parts as blanks for further machining.

Muciek, this is interesting idea which kept size and weight of coupling and allow easy detaching.

https://www.jordan-anwar.com/product...king-assembly/ maybe look for something like this and cut lab rings on the outside (or press a liner with them)...

[Frits Overmars]

if you were adding air in wouldn't that oxidise the unburnt fuel and burn it in the exhaust. my initial thoughts would be i think for off throttle emissions it would be good, but not while on the pipe.

Any unburnt fuel in the exhaust pipe had already been mixed with air before it got there. Adding cold air would reduce rather than enhance the risk of burning this fuel.

okay but why does it burn when you do this with the 4ts and the rotaries? Is it because the exhaust temps are hotter?

If there is unburned fuel-air mixture in the pipe, it may ignite if the pipe wall temperature is high enough. Adding cold air won't help.
If there is unburned fuel without oxygen in the pipe, adding air wil make it combustible and depending on the pipe wall temperature it can indeed ignite.
I do not think pipes of naturally-aspirated four-strokes are hotter than two-stroke pipes. Wankel pipes definitely are.

How does unburned fuel without oxygen get into the pipe? Not from short-circuiting, scavenging losses or misfiring, because in all those cases the fuel was already mixed with air.
The only cause I can imagine is an overly rich mixture, whereby all of the oxygen but not all of the fuel was consumed during combustion.
In this case letting air into the pipe would be good for emissions, but getting the mixture correct would be even better.

What you say is what happens in 99.99% of 2S engines, there is a 2S engine that the fuel can reach liquid ( spray) and not gaseous (steam) in the exhaust, which is it?

I'm not sure that I understand what you are saying Ceci.

[ceci]

How does unburned fuel without oxygen get into the pipe? Not from short-circuiting, scavenging losses or misfiring, because in all those cases the fuel was already mixed with air.
The only cause I can imagine is an overly rich mixture, whereby all of the oxygen but not all of the fuel was consumed during combustion.
In this case letting air into the pipe would be good for emissions, but getting the mixture correct would be even better.

I'm not sure that I understand what you are saying Ceci.

This is the only way for this to happen.
The Ski-Doo Rotax 2-TEC engine, its injection system can lead to this loss of liquid fuel.
The simulations were carried out in 2005 to demonstrate the losses of the 2-TEC system.

[ceci]

In addition to the Rotax 2-TEC (indirect injection) engine.
In direct injection engines it is also possible, a study by the UPV showed that the Derbi "TSI" injection prototype has loss of spray to the exhaust.

[Flettner]

In addition to the Rotax 2-TEC (indirect injection) engine.
In direct injection engines it is also possible, a study by the UPV showed that the Derbi "TSI" injection prototype has loss of spray to the exhaust.

TPI seems to work ok.
But you are right, we need to put the exhaust out of halms way, sling it down the other end of the cylinder, aye.

[Frits Overmars]

Afraid that your transfer ducts will catch cold, Neil?

[ceci]

TPI seems to work ok.
.

Its TPI injection system has the advantage of injecting into the crankcase and not into the cylinder as is the 2-TEC, which prevents loss of spray in the exhaust.
Of all the indirect injections, the TPI is the most efficient for 2 reasons: 1st the spray cannot come out directly through the exhaust.
2nd when the spray is against the current, the fuel evaporates before

[WilDun]

Afraid that your transfer ducts will catch cold, Neil?

Yes Frits, and they would normally sneeze straight into the exhaust which then would cough most of it back in and fart the remainder out at the other end - disgusting! (and we all thought that it was ok!! - surely not now?) ..... so as he said, he moved them well out of harm's way!
(Herr Schneurle?) would turn in his grave if he saw that we were still using his system today - he would have moved on!

[Flettner]

Afraid that your transfer ducts will catch cold, Neil?

Frits, I LOLed, it is mid winter here after all.

[jbiplane]

Its TPI injection system ...

Our company www.flame-power.com made new REAL TIME engine management units with ARM processor based on Open Sourse RUSEFI.
It so fast that can calculate ammount of fuel and ignition advance angle each RPM for 1...4 cylinder engines

CAPABILITIES

Primary VR or Hall input (configurable with few resistor changes)
Secondary Hall input
x4 analog thermistor (temperature) inputs
x10 analog voltage inputs (0-5v)
x4 high-Z injector outputs
x2 high-current low side outputs for IAC/VVT/other solenoids
Dedicated main relay control output
x4 low-current low side outputs for relays or warning lights
x4 5v logic-level ignition outputs
x2 5v/12v configurable logic level outputs (requires resistor changes)
Electronic throttle body (drive by wire)
CAN connectivity on the plug
USB connectivity on the plug

[Condyn]

Our company www.flame-power.com made new REAL TIME engine management units with ARM processor based on Open Sourse RUSEFI.
It so fast that can calculate ammount of fuel and ignition advance angle each RPM for 1...4 cylinder engines

CAPABILITIES

Primary VR or Hall input (configurable with few resistor changes)
Secondary Hall input
x4 analog thermistor (temperature) inputs
x10 analog voltage inputs (0-5v)
x4 high-Z injector outputs
x2 high-current low side outputs for IAC/VVT/other solenoids
Dedicated main relay control output
x4 low-current low side outputs for relays or warning lights
x4 5v logic-level ignition outputs
x2 5v/12v configurable logic level outputs (requires resistor changes)
Electronic throttle body (drive by wire)
CAN connectivity on the plug
USB connectivity on the plug

Sounds similar to a megasquirt. What control strategies are supported? I’ve been dipping my toes in the world of 2t efi. Currently have mine set up as alpha-n but adding a mass air flow sensor when time permits.

[polcat88]

I have my 3D printer up and running and am continuing on with my snowmobile drag racing cylinder development project. My hope is to design and build a cylinder using the best design features of proven high output engines, notably the Aprilia RSA and Wobbly's further development from there. There are some design parameters that have to be taken into account. My plan right now is to build a 508cc twin with a bore and stroke of 68 X 70mm. If this produces good results an inline four cylinder of 1016cc would follow. I have tentatively chosen a Honda CR250R flat top piston and would move the ring locating pin to the centre of the c port. The 70 mm stroke was chosen because it is stock in a couple of manufacturer variations and allows close to a square engine at the displacements I am interested in. This setup would target max HP at 9500 RPM and due to the use of a CVT belt drive system which will hold the engine at peak power RPM throughout the run requires no overrev power. Snowmobile engines are conventionally inline twin or triple cylinder designs with the intake on the back side of the engine and the exhaust exiting forward. I will be using stock crankcases and crankshafts and this limits the width of the cylinder. In my case the base of the cylinder is approximately 137.5mm wide. I have scaled up and printed an RSA cylinder at a 68 mm bore and unless I have screwed up, which is entirely possible, the base of this cylinder is approximately 173mm wide. Obviously, I do not have the room to include the large sweeping radii of the transfer passages of the Aprilia cylinder. I have attached a couple of pics to hopefully clarify the situation. I can design the exhaust port and ducting and transfer ports themselves inline with Frits' FOS calculations but am concerned that the transfer passages will be a limiting factor. What is the minimum radius that I can get away with? Or am I fighting a losing battle?

[monkeyfumi]

https://www.mahle-powertrain.com/en/...-jet-ignition/

Frits, or Wobbly, to your knowledge, has this (or competitors similar systems) ever been trialed in a two-stroke engine? Seems it would bring similar benefits as in a four stroke.

[wobbly]

Polecat - FYI , have a look at the work already done by CPI making cylinders for the TRX250R ( based on CR250 ). http://www.cpindinc.com/pub/view_pro...6101-6872-1303
The smallest version has a 72 stroke with 68 bore - this would translate to a 1046cc 4 cylinder.
What they call a long rod is 130mm , but thats bullshit. If you use a CR500 rod at 144 that puts a very different light on things , with a 72mm stroke.

It is alot more beneficial to add stroke than it is to add bore in this case as it is much easyer to construct better duct geometry , plus getting sufficient Blowdown STA ( in a full house tune situation ) with undersquare , is much
easyer than going away from the idealogically correct square bore/stroke - with a bigger overbore.
The only downside is piston speed , but at this time all the MX engines at 250cc use 72 stroke and have proven to be race reliable at 10,000 rpm all day , in kart roadrace scenarios.

The other thing that is a bit of a hobby horse of mine at the moment is to optimize the cooling circuit , especially if it can be done at the design stage..
All the cold water should ( after cooling the case ) enter the cylinder each side of the boost port - travel across the transfers , cool the Ex duct area , then go up into the head.
If this isnt possible , then a single entry above the boost port , directly into the water jacket has the same effect.

[polcat88]

Polecat - FYI , have a look at the work already done by CPI making cylinders for the TRX250R ( based on CR250 ). http://www.cpindinc.com/pub/view_pro...6101-6872-1303
The smallest version has a 72 stroke with 68 bore - this would translate to a 1046cc 4 cylinder.
What they call a long rod is 130mm , but thats bullshit. If you use a CR500 rod at 144 that puts a very different light on things , with a 72mm stroke.

It is alot more beneficial to add stroke than it is to add bore in this case as it is much easyer to construct better duct geometry , plus getting sufficient Blowdown STA ( in a full house tune situation ) with undersquare , is much
easyer than going away from the idealogically correct square bore/stroke - with a bigger overbore.
The only downside is piston speed , but at this time all the MX engines at 250cc use 72 stroke and have proven to be race reliable at 10,000 rpm all day , in kart roadrace scenarios.

The other thing that is a bit of a hobby horse of mine at the moment is to optimize the cooling circuit , especially if it can be done at the design stage..
All the cold water should ( after cooling the case ) enter the cylinder each side of the boost port - travel across the transfers , cool the Ex duct area , then go up into the head.
If this isnt possible , then a single entry above the boost port , directly into the water jacket has the same effect.

Thanks for the link Wobbly.I suspect even that cylinder may be too wide. Do you have any idea of verified full race HP numbers for this setup? What size carbs do they use?