ESE's works engine tuner

[Grumph]

A stepped transition at the header joint is common on fourstrokes for just the reason Jan Thiel stated.

If I remember correctly it will flow just like a cone section for outward gases. The step has no effect on the return wave activity but does resist returning "solid material".

[wobbly]

The areas of a header transition is whats important - a 39 duct exit is 75% AREA of a 45 header,39 isnt 75% of 45 obviously.
The 75% isnt set in stone - just a guide.
I have noticed that the best ratio seems to be when you use the header area the same as the full Total Effective Area of the Ex Port, along with a duct exit restriction
nozzle about the area of the main port.

Re the smooth transition nozzle Vs a stepped design.I started to experiment with this after getting hold of a genuine A Kit Honda spigot.
I did a series of dyno tests using a late model HRC RS125, when beta testing Luytens cylinders.
The cylinder as first produced had a 40 by 35 duct exit oval.And as a reference any dummy that removes the oval and makes it simply 40 dia round, just lost 2 Hp and all the overev power.
This was first tested with a simple 40 dia round spigot, thus having a step - top and bottom.
Next I bolted on an early model A kit RS250 spigot, this is a cast oval to round transition from the factory.This test immediately gained around 1.2 Hp, and alot more power past peak.
Then I ground the duct out to 41, and welded the duct up inside as far as I could, to enable a 32 high oval shape.
Hondas later model RS250 A Kit has this size spigot but with the oval 35 high, so I welded that and reshaped it as well to 32 high.
A new pipe with the bigger header was built to suit.
This gained another 1.5 Hp, so as a last test I made a simple 41 round spigot - and this lost all the power just gained.
The 41 by 32 oval was right on 76%.

So - I can say definitively with a T port that the transition is better than a step, but all the 3 port engines I have done have made alot more power as well, though not as well tested back to back ( I was paid to do the T port testing ).

I believe that the Aprilias slightly different system can work just as well, maybe even slightly better - as im sure Jan Thiel would have tested it to death, as it promotes the flow from the triple ports right up to the header.
But when you are modifying an existing design, the CNC oval to round setup is quite easy to implement, on a T port or a triple port design, especially as I have tested it to death on 50cc up to 500cc cylinders,and given you the basic numbers to follow.

Edit - re the so called "power port" idea.This was developed as a tuning aid back when engines made no power at all, and running a bigger piston port timing, along with forcing inflow to be pushed thru the boost port, just happened to add a Hp or 2 on top of none to start with.
What we find now is that cylinder reed engines always end up being power limited by the effective STA that can be obtained by cutting holes in pistons, adding big Boyesen ports and even then adding floor ports.
All this is attempting to get the inflow around and or thru the piston that is in the way alot of the time.
That is why case reed is ultimately better when done properly.

[husaberg]

Edit - re the so called "power port" idea.This was developed as a tuning aid back when engines made no power at all, and running a bigger piston port timing, along with forcing inflow to be pushed thru the boost port, just happened to add a Hp or 2 on top of none to start with.
What we find now is that cylinder reed engines always end up being power limited by the effective STA that can be obtained by cutting holes in pistons, adding big Boyesen ports and even then adding floor ports.
All this is attempting to get the inflow around and or thru the piston that is in the way alot of the time.
That is why case reed is ultimately better when done properly.

Case reed sounds interesting i wonder if it will catch on. Put Vanessa down for one of those I guess then.

Although what is a Boyesen port? I know he had quite a few patents. I will see what Mr Google says.

Auxiliary intake ports

Passages leading to the transfer port tunnels which are extended from the intake area without entering the crankcase. Also called Boyesen ports

So they are like the Kawasaki ones that link the reed cavity with the Transfers or these Cagiva ones

ps I can not be blamed for these sharpened Septums it was not I. (I have sharpened the odd one or two in my youth though.)

Thanks Wob

[F5 Dave]

yeah also had the boysen action bar or somesuch which was a wing in the reedblock to try reduce the velocity reduction. Never seemed to catch on so he made teh boysen radvalve. Sort of then got over-taken by Vforce, supposedly. Never been too sure how much of this reedcage titivation alters the real life performance. Usually use lots of hard to quantify anecdotal claims such as throttle response.


Used to be just 'throw the biggest cage you could in there' as it would be an improvement, Husky got a bit silly in that regard.

[wobbly]

The oversized reed cage is one of the multiplicity of reasons a TZ125 is a piece of shit compared to an RS.

[TZ350]

EngMod2T



Found where I can create and save the prescribed combustion data file. and I was able to edit and save this dummy data file.



Found where I can get the real data to enter into the prescribed combustion data file.



Previously I have had trouble saving this file so this time I added the correct data a bit at a time saving it as I went and when I added the 100 deg duration’s it fell over again.



Now I dont mind getting an error message, in fact welcome it if I can go back and edit the data, even better if it tells me which fields are wrong.



But this program kicks me right out and worse deletes my previous work forcing me to start over. now that’s just plain stupid and frustrating as it's a lot of data to have to keep re-entering until I get it right.

Now an experianced person might recognise bad data before they try to save it, but a newbee like me won't. One should be given the chance to edit it and not just have all of the combustion data dumped and then made to start over.

I know the algorithms have been developed over a long period of time and I have every confidence in them and their coding.

But the data input and editing side of this application can make this a frustrating package to use. Hopefully with time these things will get sorted and made more crash proof for dummies, as I believe this package is realy worth it .......

But if it pisses me off too much Bucket will get the job .......

[husaberg]

But if it pisses me off too much Bucket will get the job .......

All the Best managers delegate Rob.

After-all the CEO of KFC doesn't Kill the chickens.

Team ESE is becoming a large operation now.
What with Project Managers and IT team leaders. development riders. researchers, PR consultants. Overseas development consultants. Merchandiser, R&D, Dyno Operators and Umbrella Girls.

Yes I am Jealous.

[dinamik2t]

The areas of a header transition is whats important - a 39 duct exit is 75% AREA of a 45 header,39 isnt 75% of 45 obviously.
The 75% isnt set in stone - just a guide.
I have noticed that the best ratio seems to be when you use the header area the same as the full Total Effective Area of the Ex Port, along with a duct exit restriction
nozzle about the area of the main port.

Sorry, my mistake. Seems I'm too excited and overlook things, not you too busy!
Reminded me of the fault about squish percentage reference. It is the area, not diameter that is compared.
[Trying to save my a** :P] As area calculation has no other variables than diameter, the relation between those can be expressed by the 85% (86.7% to be accurate). 0.75 square rooted is 0.867

----

About the steps in ExP duct exit. Does is have anything to do with how waves & pressure pulses behave on convergent (while exiting) and divergent (while returning) cones??
I was thinking that since duct diameter is larger at Port than at exit, it behaves like so. Is this the right route to continue thinking?

----

Hey TZ, I think you are being way NOT accurate with the inputs in Vibes. You should choose only one variable at a time to copy the values. Futhermore, you should use the "Supplied" option in X/Y-axis limits (it's on the window for choosing perf. data) to limit the range and get even more accurate values.
A small trick I use is this: say I see the value of delay at 10500 is between 10 and 12. I limit the Y-axis between these two, and set the X-axis to start at 10500. It says the exact value right on the Y-axis scale.

Basically, now that I think about it, while you keep using Prediscribed, there is no need for too great an accuracy, since you are only looking for differences between modifications. I like to keep an accuracy of 1 decimal point in short-ranged variables (i.e. not duration) and 2 for VibeM.

Here's the latest predicribed model I use. Look at the accuracy I am talking about. It gives me about 0.5hp inaccuracy over the turbulent.



If you have problems copying the values, I can help you if you send me your files. It's no big deal.

[TZ350]

Hey TZ, I think you are being way NOT accurate with the inputs in Vibes. You should choose only one variable at a time to copy the values. Futhermore, you should use the "Supplied" option in X/Y-axis limits (it's on the window for choosing perf. data) to limit the range and get even more accurate values.
A small trick I use is this: say I see the value of delay at 10500 is between 10 and 12. I limit the Y-axis between these two, and set the X-axis to start at 10500. It says the exact value right on the Y-axis scale.

Thank you for your suggestions, I will try them. I notice the top (options) on your graph screen looks different to mine.

I think this is a great program, I like what it can do when the data input is right ....

[wobbly]

Just a couple of things to note - the program will crash with an entry greater than 100 for duration - its not a "real" entry.
And your ignition timings are very wierd - never ever seen any 2T that will run 40* at any rpm.
But for example running straight Methanol in a 125, the dyno testing has been done a hundred times, and won dozens of titles.
Run 18.5:1 com ( 17.5 in air cooled ) and a "normal" ignition curve for petrol, ie around 28* in the mid and 15* at peak torque.This sort of setup gives the best power every time.
Its a long drawn out fallacy that you can make big power by taking a petrol based engine, pour in a high latent fuel, and simply wind in timing - it doesn't work.
Its best to run an "average" input for the variables until you are confident with the other inputs, then run turbulent,then transfer the calculated data.
These are 12 for AFR, 9 for delay,50 for Duration,6 for VibA, 1.25 for VibM.
This always works well as a baseline.

[F5 Dave]

. . .
After-all the CEO of KFC doesn't Kill the chickens.
. . .

I doubt he eats them either.

[teriks]

wobbly, now that you mentioned methanol, could you share some numbers on critical temperatures for a methanol engine?
-Or anything else methanol specific to watch out for for that matter.

Now, I don't have the luxury of a programmable ignition, heck, I cant even set a static ignition timing with the glow plug ignition I'm using.
Avoiding getting too much off topic with glow-plug stuff, I might be able to use at least something like Max unburnt from a "normal" engine as a guideline.

[wobbly]

Sorry Teriks, methanol is banned here now so I havnt done any work on it to help you.
I am about to get all the parts for a Rossi hydroplane engine that uses methanol,to design a pipe for it, so I will be working on that soon.
Your pipe trace looks very good, except the peak ratios are low, maybe the pipe needs to be fatter to create more wave action.

[teriks]

Hydroplane, thats funny, my dad just got nostalgic and got a hydroplane again after 30 years or so off.
Had a quick glimpse on his CMB45, seems there are quite some room for improvement.

I'd be happy to discuss and share my models etc. if you are interested, but it might not be right to clutter up this thread with miniature engine stuff.
TZ350, your opinion on the cluttering-up-your-thread part?

EDIT: Thanks for the comment on the pipe, have spent way too much time on the simulator on that one. -Now I just need to have it made, that, and wait for some decent outdoor temperatures.

[Frits Overmars]

...I am about to get all the parts for a Rossi hydroplane engine that uses methanol,to design a pipe for it

From what I've seen you can gain 20 HP right there if you can convince Rossi to shield his pipes from the boat's rooster tale. Talk about water-cooled exhausts....