ESE's works engine tuner

[SS90]

O.k. i havn't read anything yet and despite what i said earlier about not spoutin forth I've a sneaking suspicion SS90 is on about shaping the transfer port inlet to creat a pressure pulse to aid crankcase scavenging rather than shaping them for least restriction. Comments,praise or scorn please.

100% correct mate!

You on to it.

This system is referred to a "THE SCAVENGE PATTERN", and it currently is where huge amounts of research are still (even after all these years) being done, and I have been told (from the industry) that there is still more to come.

I also will point out that the "scavenge pattern" does, not only include the transfer design, but also the area at the bottom of the liner (again surprising amounts of power can be found, with just some basic applications of logic that most of us miss.)

I even think that there is a chance that TeeZee has (inadvertedly compounded this problem with his piston he uses.....which, by the way TeeZee, I did the same thing! (water cooled piston,poor "scavenge pattern" at the cylinder side)

This is what I meant when I was talking about "signature" of a 2 stroke tuner, while some basic rules in these areas remain constant, small changes have profound effects in not only power, but also characteristics of the power delivery, and every tuner has his own design, based in his (or her...there are a few) own experiences.

I was fully aware that someone here would be familure with this, and am trying to make the point that this is where a large amount of work is still being done.

It would be cool for TeeZee to develop his own scavenge pattern (in my opinion, then it would truly be his own "signature" of his tuning!

I believe that his "scavenge pattern" would be quite unique, because he has to run a carb that is too small for the engine.........

Thanks mate, it was all worth it!

[SS90]

And expanded on again to include the "suck from the exhaust pipe and expanded once more to include the push from the inlet resonance and you have the picture that Speedpro was painting.

From what Speedpro says I can see Mass flow comes from an inter-dependent system made up of several parts of which crankcase pumping is one part.

.

O.K, I am going to choose my words carefully, and please be aware that I mean no malice with what I write, and nothing personal.

Speedpro wrote

The crankcase volume has very little to do with getting the mixture from under the piston to on top of the piston. The pressure differential across the transfer ports at the moment they open at operating speeds is mostly due to tuning specs - pipe/ex port. Gas velocity, and therefore inertia, in the ports also contributes and what is trapped/returned to the cylinder after the transfers close is due to the pipe design again and the port. The crankcases are more or less just somewhere to store air/fuel mix until it's sucked up the transfers.

The Crankcase has every thing to do with getting the mixture from under the piston to the top of the piston.

I hope I have established this already.

The pressure differential (the same physics as the pressure differential between the crankcase, and the cylinder) ASSISTS with the "transfer of the gasses" (and as does the chamber, assist with this (among other operations, the chamber really is a busy piece of kit!)

I maintain the the pressure difference (crankcase/combustion chamber) is 70% of the reason the fuel gets into the combustion chamber in the first place (the other 30% is from the exhaust, the scavenge pattern, and intake resonance)

Remember, there was engines before the "schnürle loop" (like the "cross flow"), which obviously had no "scavenge pattern" whatsoever, but would still run.......... The way to make it run (and make at least some power) was to include a "kicker" on top of the piston (which incidently made huge scavenge flow, but had a big piston crown area, which restricted high specific output.

The transfer Shape, size and "spray" pattern, in a "schnürle loop", if properly developed (different for every application) can be developed to assist (quite alot) in the scavenging of the crankcase (as saxet has pointed out).

But, the use of an origonal GP125 "scavenge pattern" is 25-30 years behind the time......and if you have enlarged them....(maybe it is worse!)

I mean no disrespect. I just think it prudent to point that out, as it is relevant.

[SS90]

I hope so, if the GP transfers need reshaping because of the thick cylinder spacer I use I have the room to do it.

As I need to reduce the crankcase volume, building up and reshaping the transfer inlets would be a good way to do it.

.

Yes, but that's only one part of it......(like saxon has mentioned), The "scavenge pattern" also (and predominantly) includes the "spray pattern" of the transfers into the cylinder.

I know it seems unbelievable, but check out the graph that I have attached.....(this was early days in the work, and, as such, there have been much more improvements (exhaust design, ignition etc.....), but I assure you, this was ONLY "scavenge pattern work"

I'm serious.

[F5 Dave]

SS I assume your rambling post a few pages back was done on a Friday night after the effects of some mind altering drugs that bring out a Jekyll & Hyde personality.

I work in the electronics industry & it irks me that some characters talk in ever increasing TLAs (three letter acronyms, it is of course a PT to give it an acronym). Sometimes it simplifies conversation & documentation, but it spirals out of control & the purpose ends up becoming to hinder communication & make those ‘in the know’ of these meanings feel special about themselves. QA & wanky management use TLAs for the same purpose.

So no; I’ve never heard the TLA CVF. So therefore I must be behind the times. Well, - behind the times in scooter design marketing speak. Whoopie.

Since the dawn of time people have been adding more transfer ports, often fed by the piston with holes near the top. This does smack of a compromised transfer arrangement. To put them in the main transfers more so.

I suspect this is borne of your typical scooter having a very compromised crankcase design affecting where you can place & feed transfers. Sometimes you really have to work with a compromise & go in that direction.

For instance my 50 has a dumb arrangement where the intact is primarily a piston port, but has a reedvalve passage to the crankcase. Also due to this the transfers also feed the rear ‘boost ports’ that would otherwise be fed from the reedblock, (often directly). This is a compromise & was popular on RMs (& some very early KTMs I think). But ultimately it has been discarded by mainstream. However it can work acceptably. My 50 still retains this feature, although I do appreciate its compromise. The fact that this engine has spanked Aprilias & Derbis in the past attests to this. . . and the odd aircooled 125, well, all of them at Taupo.

I suspect you are next going to be introducing collide stream porting as the big secret (Kevin Cameron did an article on this using 91 TZ250 as example, but had been used to some extent well before this).

But I am getting a bit tired of the attitude that is coming with all this. Some very condescending tones are super evident. Why come with attitude?

I’d say there is only one person on KB who I’d call a 2 stroke expert. And he frequents the suspension forum & never talks about 2 strokes.

[TZ350]

Yes, but that's only one part of it......(like saxon has mentioned), The "scavenge pattern" also (and predominantly) includes the "spray pattern" of the transfers into the cylinder.

Jante Patterns do you know what they are SS90 if not, you can find examples of them on P182 The High-Performance Two-Stroke Engine. Dr John C. Dixon.

.

[TZ350]

Remember, there was engines before the "schnürle loop" (like the "cross flow"), which obviously had no "scavenge pattern" whatsoever, but would still run.......... The way to make it run (and make at least some power) was to include a "kicker" on top of the piston (which incidently made huge scavenge flow, but had a big piston crown area, which restricted high specific output.

As an apprentice I remember hearing about a two stroke (Diesel?) industrial engine with no crank case pumping at all and was "cross flow" I think. It ran at a constant speed and was charged and governed by the inlet resonance, it had a long inlet from memory. To start it you cranked it up as fast as you could then sent a puff of compressed air down the inlet and it chugged away happily.

.

[TZ350]

Originally Posted by saxet
O.k. i havn't read anything yet and despite what i said earlier about not spoutin forth I've a sneaking suspicion SS90 is on about shaping the transfer port inlet to creat a pressure pulse to aid crankcase scavenging rather than shaping them for least restriction. Comments,praise or scorn please.

Posted by SS90

100% correct mate!

You on to it.

This system is referred to a "THE SCAVENGE PATTERN", and it currently is where huge amounts of research are still (even after all these years) being done, and I have been told (from the industry) that there is still more to come.

I also will point out that the "scavenge pattern" does, not only include the transfer design, but also the area at the bottom of the liner (again surprising amounts of power can be found, with just some basic applications of logic that most of us miss.)

Posted by TZ350

A while back I read up about the work being done on Honda RS125 crankcases and the "Tuners" offering to work magic by reworking the flow inside the case/transfer-ports.

Then I read counter arguments about its worth and decided it was one of those small gain areas. I got the impresion that again it was driven more by the marketing people than anyone with a clue and I put it on the list of things to look at again when the motor was next apart.

Heat is my current problem, not making more power.

.

[F5 Dave]

As an apprentice I remember hearing about a two stroke (Diesel?) industrial engine with no crank case pumping at all and was "cross flow" I think. It ran at a constant speed and was charged and governed by the inlet resonance, it had a long inlet from memory. To start it you cranked it up as fast as you could then sent a puff of compressed air down the inlet and it chugged away happily.

.

Or supercharge it,

[TZ350]

I know it seems unbelievable, but check out the graph that I have attached.....(this was early days in the work, and, as such, there have been much more improvements (exhaust design, ignition etc.....), but I assure you, this was ONLY "scavenge pattern work"

I'm serious.

Its not so great! my bike already does that.

The trick is to quickly do 14 consecutive hard runs (to stress the engine like it was in a real race at Taupo) then see if it can still produce that graph. Or hold it on full load for 30's, the length of a straight (not that you can do that with an inertia dyno) then tell me what the power curve looks like. I expect it will have droped off like my bike currently does.

Inerta Dynos have their limitations, give me a good Dynamic Dyno Brake where you can vary/hold the applied load any day.

.

[TZ350]

Or supercharge it,

Yep, Cummings Diesel, overhalled a few of those. No heads and cranks were all roller mains and rockers connected the conrods to the cranks. Clever. The smart boys got the Roots Blowers of them for supercharging their cars.

.

[TZ350]

My 50 still retains this feature, although I do appreciate its compromise. The fact that this engine has spanked Aprilias & Derbis in the past attests to this. . . and the odd aircooled 125, well, all of them at Taupo.

Yep, rub it in, rub it in. I did try but you beat me fair and square.

.

[speedpro]

You have to agree though that there is very little going on in this part of the world 2-stroke wise anyway. One little project I've noticed but not sure if it counts - http://www.twostrokeshop.com/Aprilia_RS500_2008.htm . Those engine enhancements were designed by a kiwi in Welcome Bay who just happens to have also done a bit of work on my current bike and LOTS on the next one. He did Nigel's motor design as well and anyone who has seen that will attest to the effectiveness. Designed for 31hp at the crank I've seen it make 27.5rwhp on a dynojet.

That transfer system looks to be a real compromise. I can see why they did it. With the big intake ports the bottom of the barrels could easily snap off. It isn't too dissimilar to certain highly modified MB100s I know. The answer is to do what they've done - make the base of the barrel full circle for support. The problem is that the transfer ports are then masked so you need to come up with an alternative transfer method. Piston port TS100s can get close to having the same problem if you are running 200deg intake timing.

I always dummy up the barrel to each case seperately and match the barrel to the transfers and make sure that the bottom of the barrel isn't masking the feed in to the transfers. Typically there is a major problem in standard form. By the time I finishing unmasking the transfers there isn't much metal to support the very bottom of the barrel below the intake port. There's ways around it and so far I haven't had a problem.

My current transfer flow pattern is due to the opposite port roof angles to my past engines but evidently is more modern thinking. It works. HP is unknown at the moment.

Regarding small carbs causing hot engines - fit a big carb and measure the temp. Just the sort of experiment that TZ would be into for sure.

[TZ350]

Regarding small carbs causing hot engines - fit a big carb and measure the temp. Just the sort of experiment that TZ would be into for sure.

Nope. easier for you to put a smaller carb on your bike! But I am happy to take measurements with the Lazer heat gun.

PS great link

.

[SS90]

You have to agree though that there is very little going on in this part of the world 2-stroke wise anyway. One little project I've noticed but not sure if it counts - http://www.twostrokeshop.com/Aprilia_RS500_2008.htm . Those engine enhancements were designed by a kiwi in Welcome Bay who just happens to have also done a bit of work on my current bike and LOTS on the next one. He did Nigel's motor design as well and anyone who has seen that will attest to the effectiveness. Designed for 31hp at the crank I've seen it make 27.5rwhp on a dynojet.

That transfer system looks to be a real compromise. I can see why they did it. With the big intake ports the bottom of the barrels could easily snap off. It isn't too dissimilar to certain highly modified MB100s I know. The answer is to do what they've done - make the base of the barrel full circle for support. The problem is that the transfer ports are then masked so you need to come up with an alternative transfer method. Piston port TS100s can get close to having the same problem if you are running 200deg intake timing.

I always dummy up the barrel to each case seperately and match the barrel to the transfers and make sure that the bottom of the barrel isn't masking the feed in to the transfers. Typically there is a major problem in standard form. By the time I finishing unmasking the transfers there isn't much metal to support the very bottom of the barrel below the intake port. There's ways around it and so far I haven't had a problem.

My current transfer flow pattern is due to the opposite port roof angles to my past engines but evidently is more modern thinking. It works. HP is unknown at the moment.

Regarding small carbs causing hot engines - fit a big carb and measure the temp. Just the sort of experiment that TZ would be into for sure.

Because of the fact that it is very rare to be limited by the size of your carb (and water cooling) only there is very little experience in tuning of the type that TeeZee has undertaken, and therefore little published.

If, in the near future, I can either find the time, or, a customer is willing to pay for the work, I will do just that.

Experience (and research) tells me what I will find already (smaller carb, hotter engine), but, I will attempt to obtain the data in a timely fashion.

What I have tried to point out is that his current set up is, by default, highly inneficient, and in particular in the area of crankcase pumping efficiency.....(and, therein began the "I know more that you" nonsense that a few of us all got involved in)

Human nature I expect.



TeeZee has problems with his engine running too hot (as has been the case since people starting trying to extract more power, which is why they went to liquid cooling in the first place)

Now, I have plenty of ideas (backed up by experience) that would enable him to make more power (as I am sure some people on here do as well), and ideas (backed up by experience) that would enable him to make possibly the same power (with a wider power band), for alot longer during the race.

TeeZee still has not shown us any Dyno graphs.

In my opinion (and as was my intention) I have concentrated peoples attention (and their subsequent research) on "things that matter", rather than "coated cumbustion chambers, bronze cylinder heads", and such unfruitful endeavours.

I have never seen a realistic alternative to the venerable alloy head personally.
Just look where everyone (still doing two stroke air cooled work) has been, and are now.....

Also, can I direct you to "the unmasking of the transfer area", I have learned (and proved, conclusively that unmasking is of large benefit (naturally), but more gains can be made in the shapes you use to unmask.......

[SS90]

Its not so great! my bike already does that.

The trick is to quickly do 14 consecutive hard runs (to stress the engine like it was in a real race at Taupo) then see if it can still produce that graph. Or hold it on full load for 30's, the length of a straight (not that you can do that with an inertia dyno) then tell me what the power curve looks like. I expect it will have droped off like my bike currently does.

Inerta Dynos have their limitations, give me a good Dynamic Dyno Brake where you can vary/hold the applied load any day.

.

Now, pleae, please don't be offended, tis really is not my intention.

Please forget all about this 14 consecutive runs nonsense.

Have you any dyno graphs to post?

The last one I posted was not for maxumum power ( you have already seen that one), it was to show the effect of careful attention to ONLY scavenge pattern.

I think that it is a very good graph. An excellent example.

Particularly if you take it in context.

Anyone here is aware that when you pass a temperature ideal, your engine will loose power.

The skill is to get it to run more efficiently (thereby making more power for longer)

Please, if you have not already done, get it on a dyno, do several runs, pay no attention to the numbers (for they are just that.....numbers), and look at the curve, where it starts making it's tourque, at what R.P.M.

That's what you should be concentrating on in my opinion.

More torque, in lower R.P.M's for a longer time is what to aim for!