ESE's works engine tuner

[wobbly]

The RSW Vs the RSA is not even a close apples for apples comparison regarding the physical layout and many other detail changes - I have serious difficulties attributing
the RSA power increase to simply 25cc of CCR = going from 1.238 to 1.227 = only 8/10ths of 1 % change.
That % would be 0.4 Hp in 54, sure, absolutely worth doing, along with at least 5 other changes with far more significance.
But the RSA had its own downsides - the rear valves gear drive, and the front mounted bent pipe that also negatively affected the bikes weight balance and thus its handling.
Jan has said that given the opportunity to do it again, he would far rather have a valve on each side, not one on the back.

[TZ350]

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The Dutch are at 20RWHP with their 50's. This is where we are at now. Not even the best for NZ but we are working on it.



This is someone else's but essentially the same motor as I am building. Hopefully with some direction from EngineMod2T we can do a bit better with our Rotary Valve Suzuki RG50 motors.

[Frits Overmars]

The Dutch are at 20RWHP with their 50's.

In 2025 each FreeTech50 bike in the first start row had about 24 rear wheel HP.

[wobbly]

After wasting near on 5 years of his and our time building completely dumb off the wall shit on UTube, Alex is now running a pretty much conventional 50cc 2T
and is achieving 27HP at the sprocket on petrol for his Bonneville LSR project.
During this time I wasted a bunch of time arguing with him about CCR, as he originally had a reed inlet system and by shear chance had close to a 1.3 CCR ratio but then decided to suddenly change to a rotary valve.
As usual that initially made about as much power as a chainsaw, until he finally listened and changed the case to around 1.2 CCR in part by adding a heap of clearance around the crank.
I havnt commented since about his engine, as Im afraid he will go wildly off on another tangent, and automatically start thinking " bigger is better ".

It will be a very interesting and worthwhile exercise to model your rotary 50cc TeeZee in EngMod, try the CCR in increments, then see what happens with the dyno real world tests.
In that case, I dont think absolute power numbers are the goal at all, but seeing the trend will be very informative.

[pirkka1]

50cc power levels and dynos have been a HOT topic recently here Finland



Do all commercial dynos have "Fudge" factors like dynojet?,and can 20+ Rear Wheel Horsepower be measured straight from the roller without fudge?
??

[wobbly]

Read this, explains it all.

http://www.factorypro.com/dyno/true1.html

[TZ350]

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I have started setting up the engine part of the project in EngMod2T. The first simulation does not match the dyno results of my friends bike. Which has the same engine as the one I am building.
I will need to enter his pipe specs before things properly align. My friend has a 50cc high end Barakit pipe on his bike that we dynoed.
I have tried modeling the pipe without much success.

If anyone has a drawing for the 50cc high end Barakit pipe they could post. I would be very grateful.

I have graphed the EngMod2T output in kW as that sort of represents rwhp after transmission losses. The DynoJet graph is in std RWHP.

[TZ350]

In 2025 each FreeTech50 bike in the first start row had about 24 rear wheel HP.

I expect that at least some of the bikes on the front row have cylinders that the clever tuners have made themselves. Bikes on rows behind are probably sporting special aftermarket cylinders they have purchased.

There is a lot about FreeTech50 that is similar to F5 Buckets. Making your own cylinder is Ok and to be applauded but you need skills like Flettner's. In F5 Buckets you can't just buy your HP. You are expected to make your own from basic non competition engine parts. Excepting, Carb, Ignition, Piston Pipe and anything you can make yourself like a cylinder is unrestricted.



Not possessing Flettners skills I think my best rout is to convert a Suzuki RG50 to rotary valve so I can make use of a basic inexpensive cast iron version of the 50cc AM6 cylinders from China. There is nothing "race" about them other than some over excited advertising.

We have a few RG50 bottom ends but no good cylinders. We have worn them out ages ago and they are like rocking horse poo to replace. The best we ever achieved with them was 14 RWHP.

I am not expecting to break 20 RWHP any time soon. But it will be a lot of fun trying and not to expensive which is what Buckets is mostly about, fun and not being to expensive.

[Betaversio]

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I have started setting up the engine part of the project in EngMod2T. The first simulation does not match the dyno results of my friends bike. Which has the same engine as the one I am building.
I will need to enter his pipe specs before things properly align. My friend has a 50cc high end Barakit pipe on his bike that we dynoed.
I have tried modeling the pipe without much success.

If anyone has a drawing for the 50cc high end Barakit pipe they could post. I would be very grateful.

I have graphed the EngMod2T output in kW as that sort of represents rwhp after transmission losses. The DynoJet graph is in std RWHP.

You have to try and model all mechanics (port and channel dimensions, compression ratios, timings, reed valves etc.) as precisely as possible. For cylinder ports, buy Vinamold to get flow widths correctly. Measuring pipe by hand is good practise, and you have to learn how to do it. It is part of simulator skill. In simulator, you need VERY precise dimensions for pipe to get it matching. You can measure pipe volume (using water) and check if it does match with calculated volume. I once tried to calibrate with 55 mm error in pipe length. It was not possible at all. After correct pipe calibration was somewhat correct after 5 runs. Use always turbulent model when doing calibration.

Vannik, if you happen to read this, does pipe volume number in EngMod mean only "pipe" volume or including exhaust channel also?

Then you have to set up combustion efficiency, transfer model and motor / pipe temperatures. By combustion efficiency you will scale BMEP value into correct number. By pipe temperature you will scale motor rpm into correct. And transfer model, avoid best models (RSW125) unless you have engine with very good scavenging. I have found that if transfer model is correct, then pipe temperatures are easy to calibrate. With wrong model it can be pain in the ass.

Re dyno graph: You need correct engine power to calibrate with. Without precisely known added value in your dyno I would probably just assume that your Dynojet rwhp equals somewhat real engine hp. I have not used Dynojet, so all info I know is in link that wobbly posted some hours ago.

Re simu graph: While showing simulator graphs, just show simulator graph. It does show engine power and it is ok, no need to try to quess some rwhp at that point.

And then, go and convert this dynojet graph in paper to .pou file using Post2T. Then you can overlap these in Post2T when doing calibration runs and it is easy to compare.

-A

[TZ350]

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Use always turbulent model when doing calibration.

Yes, turbulent mode gives a different result all right.

[Vannik]

Vannik, if you happen to read this, does pipe volume number in EngMod mean only "pipe" volume or including exhaust channel also?

The exhaust port duct volume is included.

[pirkka1]

Read this, explains it all.

http://www.factorypro.com/dyno/true1.html

Thanks, that pretty much confirms our experience.
Our small CC(50-125~) tuning community has now 5 DIY inertia dynos that i know of, mine being the latest, and we have always used/referred to using "True RWHP". I dynoed a 2017 bone stock KTM 300 EXC (with a 17" street tire)at ~37Hp for example.

Some have brake dynos but i dont think they are easily compared due to differing load,losses and temps etc.
Most are running free GSF-dyno software,one Simpledyno and one PEREK Dyno controller. all of them showing pretty much within 1hp in 14 so 7% of eachother tested side by side. but 20-30~% less than commercial dynos.
Would for sure be fun to have a dutch 24whp bike visit one of our dynos, atleast just to see how far behind we are in development

[wobbly]

From having done many racebike sims and then having used a DynoJet to to test the project built directly off the sim result, the average loss from crank power, down to the roller
and thus including the built in fudge factor - is close to 14%.
The only different result was a 125 kart setup, with both rear wheels on the roller.
This would have had less tyre/wheel inertia, giving a higher dyno reading, in that case the loss was closer to 12%.
On my inertia engine dyno, with accurate inertia and the as measured dyno rolling friction, I get an 8% loss as measured at the gearbox sprocket - for the 125/50Hp
kart engines I test all the time.

The readings are accurate, as I tested 4 different engines when a new junior class was being researched for Kartsport NZ.
My results were all but identical to all of the manufacturers eddy current dyno results, run in sweep mode.
All the results are slightly different ( more accurate ) since loading the FOS weather correction factor, now available at my request in the latest Sport Devices software.

[TZ350]

.
I was unsure what the "Turbulent" setting in EngMod2T meant. Here is the answer:-

In the context of EngMod2T (a two-stroke engine simulation software), "turbulent" refers to a modeling setting used to simulate chaotic, high-velocity gas flow, particularly within the cylinder and exhaust ports, rather than smooth (laminar) flow.

Here is what "turbulent" means in EngMod2T:

• Combustion Modeling: EngMod2T allows for "Turbulent entrainment combustion," which uses turbulence modeling to calculate how air and fuel mix and burn within the combustion chamber.
• Flow Modeling: Selecting "Turbulent" (usually the default) instead of "Laminar" tells the software to account for chaotic eddy formations, which is essential for accurate simulation of high-speed engine flows.
• Performance Impact: Turbulent flow significantly impacts engine scavenging (how well exhaust is replaced by fresh charge). Proper turbulence modeling helps the software predict how flow separation occurs in the ports and how effectively the cylinder is purged.
• Default State: Because most real-world engine scenarios involve high speeds, turbulent flow is the default setting for simulation.
  

If a simulation is running too slowly, or if it is unclear whether the flow is laminar or turbulent, users might start with "laminar" to test, but true engine operation is almost always "turbulent".

[pete376403]

NZ company that offers directly coupled (car wheel hub or bike chain drive) dynos to eliminate all the variables of tyre adhesion, slip, etc. Located in Victoria St, Lower Hutt. While working for HP I did a (PC) service call there, security up the wazoo, they bought the PC and bits down to the lunchroom so as not to let me in the main office. They have some good testimonials for car and bike customers https://dynapack.com/