ESE's works engine tuner

[TZ350]

I think Riley was referring to the max flow duration used rather than all revs.

Yes, the window of time is wide enough. Was there any on track drivability comments.

Funny enough the rest sounds like 3 times past the main Jet..........

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[jonny quest]

I've been searching the World Wide Web, but haven't found anything, which I'm surprised.

Looking for some pipe specs for a NSR250 MC21. Stock, or aftermarket.... even both preferably. I don't have bike yet, so I can't do any measuring, trying to get a good start on how I want to dimension out the 2 into 1 I'm going to build for it.

https://youtu.be/hGAR539cmAs

I have never been able to get this lovely sound out of my head, I will gladly lose some HP to have my NSR sound like this.

[breezy]

The problem with that idea is that you will end up with differing A/F ratios within the scavenging streams.
This will then in effect produce almost a stratified charge scenario within the compressing mixture.
Unless you can do a heap of CFD or try an endless combination of air, or fuel, or both in different places, the chances of fluking
the best ( or even a good ) charge distribution is near zero.

Wobbly, what would identify that the engine was having this problem of stratification of the mixture?, erratic running at lower rpm? or all over the rpm range ? poor or erratic emissions? is there any noticeable difference in speed of air passing through the transfers and air fuel mixture passing through transfer ports?

[speedpro]

Mention is made of problems when the small injector is on for smaller times. Why not put a small injector in and have it on for longer to compensate?

The duration and it's possible effect has me thinking that it is more of a timing issue rather than duration. TZ has already calculated the fuel requirement. If that was all that was required the motor should run OK. It doesn't. TZ has probably tried it but what about radically changing the timing of the injection?

I was just thinking of air flow through the engine at the speeds and throttle settings that are a problem and it seems that a fair proportion of the air would simply pass on through. If that portion contained more fuel than it should, say in comparison to a carbureted engine, that might cause the problem. All the air going through a carb picks up fuel and that air then passes through the engine. With the injectors "on" for longer periods at higher revs and loads it would be starting to mimic a carb as far as having the fuel mixed with air and as TZ says, it works fine up there.

[TZ350]

Mention is made of problems when the small injector is on for smaller times. Why not put a small injector in and have it on for longer to compensate?

This is exactly my problem, in fact the only problem preventing this project from being a runner.

I suspect it is a fundamental problem with fuel injecting performance two strokes and was or maybe still is a problem for BRC too. I have seen video clips of them making noise on the dyno, but I can do that too. Has anyone seen a BRC EFI cart engine running successfully and competitively on the track, it would give me some hope.

I have tried smaller slow speed injectors and being on for longer, they work better and like you say, the rest of the answer could be in the timing. I have tried different end timings and found 180 to be a good number for the big injectors. I have about 20 injection end maps setup. Now that I have a better idea of what the issue is I will take some time to carefully try each one in turn again but with different end points for the small injector.



For the slow speed injector I have tried the 128 - 80 - 60 and the 38 g/min units from a UAV, now there is only the 30 g/min unit that is smaller.

[Moooools]

Probably because we are not trying to emulate a carburetor. I particularly want to avoid the fuel laden blow back associated with a carburetor and see if I can take advantage of the possibilities offered by EFI. Its the learning that is rather challenging and very interesting.

Agreed. You are not trying to emulate a carburetor. That doesn't mean that starting with emulation isn't a good option. It is a very kiwi thing (and something that I am often very guilty of) to throw every idea into the air at once and see what happens , as opposed to a more iterative approach. Having the 'Emulate Carburator' box ticked off would be a mighty good step to sorting out many of the problems you have encountered. It is obvious that you have come very far with this. EFI can be a tricky beast, especially in very non standard setups. The further away you get from a 4cyl 4 stroke with a 6000rpm red line, port injection, and a single throttle body, the harder it gets - and you are pretty far off that.

The injector turns on for as long as it needs to to deliver the fuel required. You cant just turn the injector on 10 deg before the inlet opens and off 10 deg after closing. But the timing of the inlet gives a window of opportunity of about 6ms at 6,000 rpm and 3ms at 12,000.

Is that so different to the valve opening times for a high revving 4 cylinder? (Serious question, I don't know the answer)

Attachment 321144

The next move is to try the slow speed injector in a throttle body and as its only on for 60% or so of the inlet event I will try varying its timing. Hopefully there will be a sweat spot .

This looks like a really good step to compliment your high speed setup, which does look like it is behaving well. Having the injector downstream of the throttle will stop all of that fuel dropping out of the air as it comes up against the stagnant sections before the throttle. Plus lots of time for mixing of the fuel. I would expect you to see some success with that setup.

My last thought is that you (as far as I remember) are running a single tooth crank pickup. At low throttle I would hazard a guess that the engine speed varies substantially throughout each revolution. It is possible that the injection timing is not where the ECU thinks it is, especially if it is on the opposite side (180 degrees out) to the crank pickup. I think the sort-of-standard for EFI at the moment is a 60 tooth pickup with 2 missing teeth, so that cank speed can be checked several times during each revolution.

[husaberg]

Yes, the window of time is wide enough. Was there any on track drivability comments.



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Message needs more carrot/actors

Riley Will BRC
http://translate.google.co.nz/transl...on&prev=search
gentlemen,

2 years ago I did an Indirect EFI project was 125cc Disk Valve Kart Racing Engine. I used a Vortex engine qui FC Produced 49HP carbureted. With our EFI, it made 55HP !!! The engine was very easy to start and the tuning Was very simple. Here is how I did it:

Rather than attach sensors to the Figure out everything for me, I Went with information That Was Known to me. I have been tuning Dellorto carbs for years and needle-have used Their charts along with various software That calculate Comparative MainJet Sizes throttle at 10% increments. I used this information to calculate initial year map for the injectors. I did a test on the carbureted version of at Each throttle position to score the EGT That Was Giving the proper performance. Once running with the EFI i tried to tune it to achieve achievement la même EGT numbers as the carburetted versions.

In total I ran for 3 hours on the dyno and ended up with 10% more power everywhere!

The only sensors I used Were Throttle position, engine RPM, Crank Angle, and Water Temp for initial start up enrichment.

How did I get an injector to fire every cycle at 15,000 rpm ?????? I didnt! What I did is used a butterfly Janvey 41mm throttle body with 2 injectors on the engine side of the butterfly. That way When the throttle is closed, fuel still feeds the engine to lubricate it like a Jet Pilot Would do. To get 15,000 RPM, I Had Each injector firing at alternating engine revolutions. Thereby the injectors Were seeing 7500 at 15000rpm pulse of engine speed. I tricked 'em into thinking This was a 2 cylinder 4 cycle engine firing in tandem.

In total I Spent $ 1,600.00 in componentry to validate my "Simple EFI" idea! I will be doing more tests this winter and will be testing track in the spring. We are workind miimum on the battery and packaging requirements.

I used 2.5 bar of pressure and will be more testing. I thing a disk valve engine for the symmetrical inlet timing. I used a valve at the open 137 degrees BTDC and closed at 87 degrees ATDC. I started firing the injector 10 degrees Earlier on the opening and stopped the injector 10 degrees partner after the valve closed.

Upon engine disassembly It was Noted que la lubraction Seemed to be better Dispersed thru-out the engine (only an observation). The engine Would start at less than 800 rpm of speed and crank Would Instantly accept full throttle from 1200 rpm and load up!

The only hurdle I see is to come over the packaging.

I am confidant That my way of Giving the ECU the MAP Rather than calculate the HAVING the ECU map is why I was successful. We-have tuned by EGT for years and continues to see the relevance When using EFI in correlation to EGT. Increase the power cam by better fuel atomization. It stands to reason due to the limited time "tuning" the system That-even more power gains are to be Realized with more work and data collection / analysis.

I am posting this information so more people will try this easy method and post Their results here. I hope you all find the success That I did.

BRC (make Rotax 256 copy kart engines) Riley Will (who contributed to the pitlane.biz RSA thread) spoke the most sense there

The 2002 500cc bikes used 35-36mm carbs with electronic solenoid type power jets.

KTM used a hybrid system where they used an injector to augment the fueling requirements. It was used in their 250cc program, but I'm not 100% sure if they used it in the 125cc bike as well. Probably, but I cannot be certain.

Aprilia was guilty of throwing out what they perfected (carburation)and introducing a totally new concept loaded with technology EFI system. It was an intelligent system that made all the theoretical calculations at light speed..... It was a perfect system....... Too perfect! For years 2 stroke engine development was being done using less than perfect carburetor. This includes rider knowledge, tire construction, and suspension..... The end result was that the riders and machinery (tires) couldn't cope with the instantaneous increase in torque when the throttle was opened while at maximum lean angles.

When I discussed how I was going to do my EFI, their main electronics engineer started clapping..... What I wanted to do (and later did) was to upload a fuel distribution curve similar to a Del'Lorto needle/tube (needle jet) combination and did not let the computer adjust it. I used a TPS, H2O sensor, Air temp sensor, and Hall Sensor for crank angle/rpm. This way I was using what I knew, but getting the benefit of 3 bar of fuel pressure and injector atomization. I had total control and could add fuel to make the fuel curve "imperfect" if need be. I used 2 injectors mounted on the engine side of the throttle valve and I alternated their firing so that I could rev upto 15000 rpm. That way each injector was mislead into thinking it was feeding a 7500 rpm max 4 stroke cylinder. In total I invested $1600 into the total system and had it running pulling load on the dyno in 3 hours.

Riley later says he timed the injector to squirt 10deg before inlet open and finish 10deg after inlet close

[wobbly]

Lots of interesting ideas coming out of this.
And yes doing a sort of simulation of a carb ( that we know can be tuned even with the flow reversing 3 times ) might help along the way.
What about a pair of injectors situated in the transfer case cutouts ( facing each other at right angles to the transfer flow ).
This way the injected streams might collide and help breakup of the mist, but also simulated a full case of fuel as a carb does.
And secondly i really agree with the 60 tooth idea, this is exactly the reason it is used.
But you will need to find out if the ecu is capable of continuous speed detection during a cycle.
Just programming in the number of teeth ( if thats possible ) may make no odds.
I know Ignitech say that their injection ECUs need at least 20-1 teeth to function correctly.

[TZ350]

The injector turns on for as long as it needs to to deliver the fuel required. You cant just turn the injector on 10 deg before the inlet opens and off 10 deg after closing. But the timing of the inlet gives a window of opportunity of about 6ms at 6,000 rpm and 3ms at 12,000.

Is that so different to the valve opening times for a high revving 4 cylinder? (Serious question, I don't know the answer)

Yes I think so, in several ways. Probably the most obvious is that a 4T does not rely on a significant pressure wall in the exhaust port to stop fresh mixture escaping on the compression stroke.

A 4T's exhaust valve is very effective at blocking the exhaust port whereas a 2T has all sorts of problems stopping fresh mixture escaping. I suspect that in my case the escaping mixture carries some, none or all of the injected fuel with it.

[Moooools]

But you will need to find out if the ecu is capable of continuous speed detection during a cycle.
.

Very good point!
I heard a story of some guys who were having trouble with a single cylinder engine, and spent some serious time putting more and more trigger teeth on the flywheel, and changing the settings in the (quite high end) autronic ECU. Problem was, although the ECU could take many teeth, it still only used one tooth per cycle to calculate engine speed! The setting was just there to tell it to ignore the other 19 teeth.

[TZ350]

The four stroke version of Ecotrons software has multi tooth capability but I think that like some other features this is turned of in the two stroke version, or my version at least. This may have been an option selected at time of purchase, I guess it could be changed.



Flettner has his injectors in the rear transfer boost port cutaway.



It is not possible for me to put my small injector in the boost port cutaway like Flettner has but I might be able to bring it through the side on an angle. The mixing should be better than in the back of the cylinder where it is now.

[TZ350]

"" I did a test on the carbureted version of at each throttle position to record the EGT that was giving the proper performance. Once running with the EFI I tried to tune it to achieve the same EGT numbers as the carburetted versions.

In total I ran for 3 hours on the dyno and ended up with 10% more power everywhere!

The only sensors I used Were Throttle position, engine RPM, Crank Angle, and Water Temp for initial start up enrichment.

How did I get an injector to fire every cycle at 15,000 rpm ?????? I didnt! What I did is used a butterfly Janvey 41mm throttle body with 2 injectors on the engine side of the butterfly. That way When the throttle is closed, fuel still feeds the engine to lubricate it like a Jet Pilot Would do. To get 15,000 RPM, I Had Each injector firing at alternating engine revolutions. Thereby the injectors Were seeing 7500 at 15000rpm pulse of engine speed. I tricked 'em into thinking This was a 2 cylinder 4 cycle engine firing in tandem.""

I like the idea of recording EGT numbers from carburettor runs at different throttle positions. (Wob has suggested the EGT thing too).

I too found it relatively easy to make power and to get it to start and idle easily, my problem is getting it drivable on the track, I would love to know if Riley ever took his to the track and how it went.

Clever idea halving the apparent rpm that each injector sees. The actual fuel delivery window time is still only 15,000rpm wide but the apparent 7,500rpm gives each injector time to wind up and close down either side of the 15,000 rpm window.

That way you can use a smaller injector to deliver the same amount of fuel in the 15,000rpm wide window as a much bigger one. Because a bigger one running full speed uses up much of the 15,000rpm window time getting itself open before it can deliver any fuel and there still has to be time left for closing and resting.

At 15,000 rpm the injector has to be big enough to deliver a large dolop of fuel in a very short space of full flow time, the half speed injector gets a much longer space of full flow time.

If we can open and close plus rest an injector either side of the fuel injection window by halving the apparent rpm to 7,500rpm. It may allow one to use an injector that is only a third the size of a suitable injector for full time 15,000rpm fuel injection. And that 7,500 rpm injector could be small enough to give the full tunable range from closed throttle to full throttle at maximum torque rpm.

I guess Riley just lucked in with using a 4T EFI unit, probably the only thing available at the time. Lucky Bugger, I made the mistake of going for a 2T specific unit.

Now that I know a bit more about 2T EFI, Riley's method of a 4 cylinder 4T firing 2 cylinders in tandem looks like a very good idea.

But because the squirt time will be much smaller than the window time we will still have the fuel homogenization issue at high rpm low throttle problem, I wonder how Riley got on.

4 cylinder 4T firing 2 cylinders in tandem, Ecotrons software could do it but without a cam sensor the software looks at the MAP sensor to tell which cylinder is on the injection stroke. And a MAP sensor is pretty useless on a single cylinder two stroke.

[ken seeber]

If the issue is one of cyclic speed variation (due to random/spurious fuel quantities in successive combustion events as per Mooooools point), one way to ascertain the need for a greater crank position resolution (ie more actual functioning teeth) would be to add a decent size external flywheel. If this makes any difference at all, then this would tell you, yay or nay, that you do need greater resolution for the ECU.
Of course, this would affect the performance on an inertia dyno, but at this time the issue is one of fundamental operation.

[TZ350]

If the issue is one of cyclic speed variation (due to random/spurious fuel quantities in successive combustion events as per Mooooools point), one way to ascertain the need for a greater crank position resolution (ie more actual functioning teeth) would be to add a decent size external flywheel. If this makes any difference at all, then this would tell you, yay or nay, that you do need greater resolution for the ECU. Of course, this would affect the performance on an inertia dyno, but at this time the issue is one of fundamental operation.

Thanks for the tip, yes at the moment it is about fundamental operation, been there, done that with maximising the EFI's performance.

[TZ350]

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Plenty to do now, thanks everyone for the helpfull suggestions.