ESE's works engine tuner

[Flettner]

Hello Fletner


Will it be possible to adjust the compression ratio with the small upper piston?
I mean get that toothed belt away and and put a handle on the upper crank
The compression needs only to be adjusted as fast as load,fuel supply and temperature varies and this does not sound difficult with modern electronics and a servodrive and a couple of traingauges on cylinderbolts that tell when combustion is to early or correct at TDC.

Good plan. But I want to "ignite" after TDC and this is what my design allows for, if a little complicated.

Well, I could fire it up tonight if it wasn't for my clumsy fingers breaking the piston ring

Apprently there are three sets of rings (at .5 oversize) in Australia, I got my eye on one of those sets. Or I just bore it out to 40mm and there are plenty of pistons

There must be the second set somewhere in my workshop!?

[TZ350]

Page 1510 .... already

first race meet at Kaitoke on the 2 smoker:- https://youtu.be/WVmNVIHHU5E

That is real Bucket racing.

https://www.youtube.com/watch?v=nZ5CzJco5Mw

Lambda O2 sensor can be useful for tuning a two stroke in spite of the short circuited O2 showing up in the readings.

The Ecotrons EFI has barometric and air temperature sensors for automatic fueling compensation so hopefully once I am on the money with the dyno the ECU's auto compensation will give pretty much the same results as changing the jets 3 times a day.

I feel very comfortable with tuning the EFI system for maximum power, above 50% throttle position that is relatively easy.

The problem I am struggling with is at the low end, if this was a carb then the EFI bit that is challenging me now is the area covered by a carb's pilot jet and transition to the slide cutaway.

May I ask why you're not using a wideband O2 to tune this area? It would be relatively straightforward with a wideband and a brake dyno.

I started out trying to get a 12.5:1 A/F everywhere on the map, as you do if you don't know any better. Things weren't going well and I gave it away when it was pointed out to me that it was the short circuiting fooling the O2 sensor into thinking the system was running lean when it was not.

It really confused things and it looked like the O2 sensor was not going to be very useful so I discarded it. But your experience encourages me. And it looks like that with a bit more experience myself. I might be able to get somewhere with it now I have a better idea of what is going on and can see that 12.5 in the peak torque area is good and something like 14 in other areas might be a good number.

Why a brake dyno? Then you would be developing an engine for a set of circumstances that it will never see on a race track. Going through the revs on an inertia dyno and registering revs, torque and lambda simultaneously is an excellent way of establishing an injection map. Besides, running constant revs on a brake dyno with too little fuel or too much ignition advance may kill your engine, whereas it might survive on an inertia dyno.

When i say brake dyno i mean an eddy current or similar that allows both constant rpm tests and normal 'runs'... Im sure that doing only constant rpm tests is not ideal.

Personally I do a combination of both to tune an engine and so far it has worked well for me, especially when tuning the low throttle area that TZ was talking about... in saying that ive only ever had an eddy current dyno, never an inertia-only dyno. And have developed my own methods of tuning without ever seeing first-hand anyone else's process for tuning a two stroke... maybe its a case of ignorance is bliss, however I find my process to be very quick and very reliable for a wide range of engines.

I find that the lambda sensor is a little slow to react at low revs and part throttle. Its fine at higher revs and higher throttle. By holding the engine at a certain rpm point for 3-5sec at each throttle position it gives the readings time to stabilise and gives much better, more repeatable data.

I start by doing a range of fixed rpm tests at different throttle openings, with the revs building higher each test... eg 4000, 6000, 8000, etc at 1/8, 1/4, 1/2, 3/4, full throttle. By doing this you can easily see the areas that need changing (pilot, slide, needle diameter, clip position, needle taper, main jet, etc).

If there is a serious problem with the tune you will always catch it before doing damage as you’ll see AFR's begin to lean out or detonation begin to show before you get too high in rpm. Once I’ve done basic tuning like this then i do full runs and constant load testing and fine tune if necessary, but these are normally only very minor changes.

Whether the AFR reading is showing true AFR or not doesn’t really matter, the numbers can still be used to tune an engine... around full throttle and peak torque it is fairly reliable to use ~12.5:1 and leaner readings below that, down to around 13.5-14:1 at part throttle/low rpm.

Of course you still need to use experience and 'feel' to do the fine tuning but the AFR numbers will get you close. Even if the engine is not actually seeing 14:1 at part throttle/low revs, its still a repeatable data point that can be used to tune an engine. Its certainly a lot better than guessing, especially when tuning the part throttle areas.

+1 the above.Adding that putting the Lambda in the stinger, seems to be way more stable and repeatable when logging the A/F data.

Using data this way is something that you really don’t appreciate how good it is until actually doing it.
Hence TeeZees surprise when I related that every time you change a small item in the engines tune - the dyno result for sure is not telling you really what you want to know, unless you reject every time to hit a predetermined baseline.

As Jan Thiel said, most all of the pipe testing at Aprilia was a complete waste of time, when he finally realised allot of the power differences were down to how the egt reacted to that pipe.

Not that the pipe was "better " for some aspect of scavenging, or trapping efficiency in making more or less power.

STA or Specific Time Area, (Port Time Area) is at the heart of 2-Stroke port timing design.

For what its worth and as I understand it. How to determine the STA numbers you have.

Mean open Port Area is the effective port aperture seen when the piston is positioned half way in terms of crank angle between the port starting to open and fully open.

For an Exhaust port that starts to open at 80 deg ATDC and is fully open at 180 deg ATDC. Then the mean port area will be the area of the port uncovered by the piston with the crank angle set half way between 80 and 180 ie, at 130 deg ATDC.

The rough rule of thumb is that this exposes about 70% of the port window, rod length and the bore/stroke ratio influence the actual amount.

The units for STA numbers are Time Area per Unit Displacement or “sec-cm2/cm3”

Derived by dividing the Mean-Port-Area in “cm2” by the cylinder volume in “cm3” and then multiplying it all by the time in seconds “sec” that the port is open (time of total duration).

The number of revolutions in one second = RPM/60

The total number of degrees the crank has turned in one second = (RPM/60)*360 or RPM*6

Finding the Time in seconds of the Total Port Duration. = Total Port Duration / (RPM*6)

Your STA = (Mean Port Area / Cylinder Volume) * Time of Total Port Duration

After measuring Yamaha’s TR3 GP racer and as many other good racing engines as he could using only graph paper, compass and a ruler. And doing the “(Mean Port Area / Cylinder Volume) * Time of Total Port Duration” math, Jennings came up with these numbers and called them Port-Time-Area.

Exhaust 0.00014 to 0.00015 sec-cm2/cm3
Transfer 0.00008 to 0.00010 sec-cm2/cm3
Piston Port Inlet 0.00014 to 0.00016 sec-cm2/cm3
Rotary Valve Inlet 0.00018 to 0.00019 sec-cm2/cm3

In his ground breaking reveal all book that showed the budding tuner how to modify their own cylinders to get GP like porting.

Attachment 243287

Jennings didn’t give a number for Blow Down. And for that reason, I think the importance of the “Blow-Down-Time-Area” and its affect on power output was largely over looked by the old style home tuners.

Bells book with its useful list of port timings for various engine capacities and RPM was also a blessing and a curse as it also didn’t emphasis the importance of blow down. It was great to see what the ballpark timings were, but too many tuners just used the numbers blindly.

With the result cylinders were packed up with spacer plates to get the transfer timing numbers right and the inlet and
exhaust was then ported to match their own set of essential numbers found in Bells book without much regard for blow down area.

Whether you used Jennings Port-Time-Areas or Bells numbers for the inlet, transfer and exhaust the end result was that the essential Blow Down Time Area was often overlooked and a lot of the old engines were less successful than they could have been.

Attachment 243284 Port timing by itself does not mean much, its the STA numbers that are important.

Attachment 243285 Attachment 243286 Early Honda RS125

Low and wide for the transfers is the trick to getting good Blow-Down STA numbers.

Gordon Blair after studying many 2-stroke engines and their behaviour developed a number of formulae that covered the various ports. The beauty of these formulas is that they allowed the designer to start from a target RPM and BMEP or Power-Output and use a computer to crunch the numbers.

Blair called the results of a port time area calculated by his formula based on a specific rpm and target power output, a STA or Specific Time Area for that design criteria.

Blairs STA numbers for a GP racer turning 11,500rpm and producing 26.5kW at 11 Bar

Exhaust 0.000162 sec-cm2/cm3
Blowdown 0.00113 sec-cm2/cm3
Transfer 0.0086 to 0.0185 sec-cm2/cm3
Piston Port Inlet 0.0162 sec-cm2/cm3

Blairs calculated STA results and Jennings Port-Time-Areas are both physically measured in the same way. = (Mean Port Area / Cylinder Volume) * Time of Total Port Duration. The difference is that Jennings very cleverly figured out what the Factory was up to and Blair developed a method of predicting what is required.

Even the basic CAD type programs that use STA as a basis for getting the ports in the right place for the rpm,power needed and swept vol are hugely better than the old references.

A handy (and cheep $16 USD) Porting Calculator from:- http://www.porting-programs.com/ it is based on Blairs and Jennings work. Use the Blair data for STA and blowdown required for a selected power output.

Kel gave me this link to Blairs very interesting book. www.prme.nl/download/engine-1.pdf

The decade pages from p80 have link collections, links to Jenning and Bells books can be found there somewhere.

[Grumph]

I'm wondering if there's a performance advantage of having bearings and seals "reversed". Better lubrication being the advantage

Doubt it...the optimum for rolling element bearings is an oil mist. I'd pick that the opposite is a bearing full of oil, churning....

[Grumph]

Yamaha TX500 had a Omi phase something
Well I am not totally so sure looking at it that it is two shafts but its pretty unique.
Attachment 320813

And right there is the problem...both the 500 and the TX750 broke in service. Is it surprising ?

Actually, what usually put the 500 off the road permanently was the heads cracking...

[husaberg]

And right there is the problem...both the 500 and the TX750 broke in service. Is it surprising ?

Actually, what usually put the 500 off the road permanently was the heads cracking...

Not looking at the pic of the drive, no.

I finally found a pic TX750

I must admit I have never seen one.
I have had the misfortune of riding a CB250N though, which would have to rate as the most gutless fugly overweigh POS ever.
The 400 was okay though for what it was. But the far older K4 Hondas would piss all over them both,likey the CB72/77 would have as well.

[F5 Dave]

Using the belt to drive the clutch and primary also saves a lot of friction in the general lack of seals needed to make the clutch dry. As well as it supposedly being a few % more efficient than gears.

The only issue is an engine would still need some gears mounted to run a contra rotating balance shaft.
Unless its mounted inboard of the primary or uses special PTFE gears.
The open belts also make a cool noise like Mad Max's Gilmer drive super charger and the dry clutch's make a nice racket as well, shame the noise meter will not like either.
his silly go on off super charger button is actually a hi low selector of a Road ranger truck, chuck on one of those too Neil.

As unlikely as it is for me to fantisise about foulstrokes, i went on a trip in the van this weelend with a couple of dirtbikes and gear, gas etc. Regularly on these trips the madmax pursuit car comes into my mind as i approach a hill, back off to get a run up, try to time it so i can pass the fecker just as the passing lane comes available with enough momentum that i can stay ahead.
If only i could double- de-clutch and switch that supercharger on.
Sometimes for the benifit of a passenger i press the hazard light button and fein being pressed back in the seat by the force of the nitrous. . . also the same movie. Oh the fun we have on long journeys in underpowered vehicles.

[husaberg]

As unlikely as it is for me to fantisise about foulstrokes, i went on a trip in the van this weelend with a couple of dirtbikes and gear, gas etc. Regularly on these trips the madmax pursuit car comes into my mind as i approach a hill, back off to get a run up, try to time it so i can pass the fecker just as the passing lane comes available with enough momentum that i can stay ahead.
If only i could double- de-clutch and switch that supercharger on.
Sometimes for the benifit of a passenger i press the hazard light button and fein being pressed back in the seat by the force of the nitrous. . . also the same movie. Oh the fun we have on long journeys in underpowered vehicles.

Only thing I wonder about is how the well did the MAD MAX pursuit special engine actually run, when trying to breath through a non running supercharger and running with a low comp ratio.
But seriously though, what the van needs Dave, is nitros oxide or if its a turbo Diesel, LPG injection. Or both.
http://www.nitrous.info/
His old site was better. He was the fat guy who had the Dyno burger Van PB used to use in the 1990's.
I used to have a 280HP Hilux SR5 now that was fun passing stuff. Had a gay auto though

[Muciek]

No thinning, no lathes. We will have Laser cut new ones. They are the same as Honda RS250, 2mm steels. Ali is an option as well.

Do you remember what kind of steel You used for those friction plates? And how they worked in bike?

[richban]

Do you remember what kind of steel You used for those friction plates? And how they worked in bike?

Steel was just cold roll standard stuff. They ave been working great in all 3 bikes. They have had plenty of hard race starts and still looking good. Still working great. I had to go back to the normal springs to get some better clutch feel.

[TZ350]

Well.

The good news is that after months of work I have finally given Mr.Bigglesworth a thrashing on the dyno.

The bad news is that there is still a reluctance to come back on the throttle.



Fortunately the Ecotrons EFI software has a data capture function. Max power was at 12250 rpm and max over rev rpm was 12888.



Looking at the left hand courser the yellow line is Inj0 (the small injector) and the blue line Inj1 (the big injector) and the brown line is maximum injection time available. It can be seen that both injectors are topped out at 10,325 rpm. This suggests that Inj1 (the big injector) is to small.



With high rpm and the TPS at 0% Inj0's pulse width is 1.140ms (right hand courser) which is less than the allowable minimum opening time of 1.8ms so on over run Inj0 is still to big.

So the big injector is a touch to small and the small injector is still to big for good tun-ability when throttling off and opening the throttle again like you would negotiating a corner at speed.

Ok, so off to Ecotrons to buy some more injectors.

[wobbly]

But I still dont get how you can deduce what the injector performance is, if you have no idea what the A/F ratio is or what the egt value is.
Sure the small injector may be maxed out, but that simply may be because the fuel volume it was being asked to supply was far too much - who knows.
Same for the big injector - was the pulse width it was programmed into delivering over the recommended max, but was that just because the resultant mixture was way rich.
Data info ,gives you a knowledge base to make informed decisions in the right direction, for the right reasons.

[F5 Dave]

And in absence presumably one leans off the mixture and see if the power rises or falls.

[TZ350]

But I still dont get how you can deduce what the injector performance is, if you have no idea what the A/F ratio is or what the egt value is.

Plenty of people have managed to select the right sized main jet without being able to measure the A/F ratio or the EGT. But I agree, the more info the better.

The small injector is expected to max out and that means max out time wise. Time and injector size determines the tuning range and the outer limits both minimum and maximum amount of fuel that can be delivered.

When the small injector max's out then the system swaps to the big injector and as that max's out the small injector is brought in again to help out. But if they both max out together time wise without over fueling the engine then combined they are not big enough.

Sure the small injector may be maxed out, but that simply may be because the fuel volume it was being asked to supply was far too much - who knows.

In this case the small injector is not small enough to deliver the minimum fuel required, even at the minimum possible injector on time allowed for an injector it is delivering to much fuel.

Same for the big injector - was the pulse width it was programmed into delivering over the recommended max, but was that just because the resultant mixture was way rich.

Did try bigger and lessor numbers like you would and the graph was the best achievable and is similar to the best dyno results for this motor achieved with a carb.

And in absence presumably one leans off the mixture and see if the power rises or falls.

Did try richer settings for the small injector and the symptoms were worse. Suggesting its to rich.

Looking at the graph, the small injector has simply hit the floor and can not be turned down any further to match the engines minimal fueling needs on over run. Its tuning range can not go low enough so a smaller injector is required.

[TZ350]

A fuel injector has a tuning range just like this jet kit has. And just like when you get down to the smallest jet in the kit and still need to go leaner you need a smaller jet kit or injector to move to the next lower tuning range.

That is my problem with the current small injector, it is just not small enough to give me the tuning range required to handle the minimum fueling requirements on high rpm over run on a closed throttle. I need the next smaller injector (kit).

[breezy]

A fuel injector has a tuning range just like this jet kit has. And just like when you get down to the smallest jet in the kit and still need to go leaner you need a smaller jet kit or injector to move to the next lower tuning range.

That is my problem with the current small injector, it is just not small enough to give me the tuning range required to handle the minimum fueling requirements on high rpm over run on a closed throttle. I need the next smaller injector.

maybe you'll need to have three injectors.. one for low rpm ... one for mid rpm.. one for balls out rpm..