ESE's works engine tuner

[TZ350]

I notice certain Honda cylinders have different transfer rear angles, why is that?

I would be very interested in that too...

[Yow Ling]

I would be very interested in that too...

Is it just a land for the ring gap to run on ?

[Frits Overmars]

Is it just a land for the ring gap to run on ?

Yes it is. The asymmetric bridges between B- and C-port appeared in Honda cylinders from the previous millennium. Now that the ring gap is center rear, running over the C-port, the need for the asymmetry no longer exists.

[Frits Overmars]

You will need at a minimum 6kg-m^2 to have a reasonable run time with 50hp, but generally the more the better as the longer run lengths help show up weak spots in the motor. I have a small 2.2kg-m^2 dyno that is useful for up to 25hp but the run lengths get short (around 8 seconds)

As I wrote yesterday, you cannot make such a categorical statement. If you gear your small flywheel twice as fast, the acceleration time will quadruple. But you will have to make sure it will be up to the centrifugal forces which will also quadruple.

BTW: 8 seconds is a fine acceleration time, provided you start at the lower rpm of the power band. Starting the measurement much lower won't do any good as the acc. time will then be strongly influenced by erratic engine behaviour.

Attached you will find a little program; play with it; see what happens if you change the gearing or the desired acceleration time.

EDIT: Damn! I cannot even upload a zipfile here.

[dinamik2t]

Frits, you could try changing the extention to .jpg for example. And then we turn it back to .zip or .rar or whatever.

edit: I checked the attachment help and you better use .doc, because .jpg's are limited to 750kB per file. Doc is up to 2MB.

[Sketchy_Racer]

As I wrote yesterday, you cannot make such a categorical statement. If you gear your small flywheel twice as fast, the acceleration time will quadruple. But you will have to make sure it will be up to the centrifugal forces which will also quadruple.

BTW: 8 seconds is a fine acceleration time, provided you start at the lower rpm of the power band. Starting the measurement much lower won't do any good as the acc. time will then be strongly influenced by erratic engine behaviour.

Attached you will find a little program; play with it; see what happens if you change the gearing or the desired acceleration time.

EDIT: Damn! I cannot even upload a zipfile here.

Yes this would be true for an engine dyno where gearing up is simpler. I assumed he was talking of a chassis dyno where generally the "flywheel" is the roller driven by the wheel(s)

[Frits Overmars]

Yes this would be true for an engine dyno where gearing up is simpler. I assumed he was talking of a chassis dyno where generally the "flywheel" is the roller driven by the wheel(s)

You may be surprised to learn that people actually manage to alter the gearing of a motorcycle .

Frits, you could try changing the extention to .jpg for example. And then we turn it back to .zip or .rar or whatever.
edit: I checked the attachment help and you better use .doc, because .jpg's are limited to 750kB per file. Doc is up to 2MB.

If that works, I can send the EXE-file directly, disguised as a DOC-file. So right-click attachment FLYWHEEL.DOC, select 'Save Target As' , rename it to FLYWHEEL.EXE and have fun.

[Forgi]

The real point I was making is that lower and wider is better - assuming you end up with the STAs matched to the required performance.
Case in point is 125cc TM kart race engines, that make 44Hp at the sprocket, on my dyno, with a 30mm carb.
The real factory tuned engines have around 196* Ex duration and as delivered will rev to around 14300.
The engine i built that has just won our National Champs, has 194* but the Aux are hugely deeper and wider, and the transfer stagger is reversed, to get extra room over the A port
This makes 46Hp and easily revs to 15,000, and in the process destroyed a real expensive,super secret, genuine factory World Cup winning engine.

BUT - I dont know that going from 190* down to 185 will be better, as any engine with only 190* in the first place could not make any serious power to begin with.

@Muciek: Thank you for the pics, as I can see in Poland people like simsons as much as here in Hungary.

„Polak, Węgier, dwa bratanki, i do szabli, i do szklanki.”

@Woobly: Ok, I can understand what you are saying, and thank you for sharing your experience.

I plan to make a nozzle in which the aux port's duct helps to get better blowdown (just like on your Fig. 3.), but of course at the end the area will be 75%. It is true that this way the volume of the duct will be bigger as the duct will be wider (now I can't modify the height of it), but I hope that the effect of these changes will be positive on the whole.

Once I get results I will share them.

[RomeuPT]

Yes it is. The asymmetric bridges between B- and C-port appeared in Honda cylinders from the previous millennium. Now that the ring gap is center rear, running over the C-port, the need for the asymmetry no longer exists.

I thought it was something else, because some newer cylinder I posted on pit-lane have that too.

[RomeuPT]

You may be surprised to learn that people actually manage to alter the gearing of a motorcycle .


If that works, I can send the EXE-file directly, disguised as a DOC-file. So right-click attachment FLYWHEEL.DOC, select 'Save Target As' , rename it to FLYWHEEL.EXE and have fun.

Very nice tools you have Frits. Many Thanks
I will test it later with more time, If all went whell the dyno will be a summer project

Another thing that was newer to me was that in a picture Wobby posted showed a T port with the highest part of the exhaust port not at the brigde but at the sides....
Was that just to get BlowDown area and maybe leave the bridge a litle more cool?

Thanks

[wobbly]

Cant hide anything on the internet - that drawing was from many,many years ago.
The idea was that as the outer edges of a T port form the longest part of the duct, they should be opened first, to get a more coherent,bigger amplitude wave
front exiting down the header.
It was used for quite a while in many GP winning engines - but I tested it more rigorously later on, and made more power by simply raising the whole port,back to flat again - bugger.

[TZ350]

Injector Sizing and Locater page

http://www.nitrostreet.com/injectors.htm

A place to go to, to calculate the size of injectors needed.

Because it is a 4-Stroke site and assumes a full 100% duty cycle of 720 degrees as apposed to a 2-Strokes 360 degrees I had to halve my required duty cycle to get a 2-Stroke result.

Ie., my designed maximum duty cycle is 120 degrees or 33% then instead of 0.33 I had to enter 0.16 in the Duty Cycle field.



It was pleasing to see the numbers came out to be the same size as I had previously calculated from the simulated EngMod2T fuel demand curves.

DIY EFI ... might be worth a look. http://www.diy-efi.org/

EFI links list here. http://www.nitrostreet.com/efi.html#...20for%20PC%27s

[TZ350]

Things I am learning about EFI ..... edited scrapes below.

Speed Density

There are several different ways to control the air/fuel ratio. Speed density requires just two main inputs to establish a base fuel map: engine rpm and load. Speed density assumes that a certain amount of air will enter the engine at any particular combination of rpm and load.

This works as long as the engine remains unchanged. Modifications to the engine to increase airflow (and therefore power) at any point would tend to make the engine run lean, since the engine would inhale more air at that rpm and load point than it did when it was stock.

If you take in more air, a proportional amount of additional fuel must also be delivered to maintain the same air/fuel ratio. Speed-density systems cannot perform this function without reprogramming.

Mass Airflow

Systems outfitted with a mass airflow (MAF) sensors. This sensor measures the amount of air entering the engine, giving more precise control over the air/fuel ratio. MAF systems are more accurate.

Alpha-N

There is one other EFI control system that is generally used only in racing called an Alpha-N system.

This control system’s major inputs are throttle position and rpm. This system was developed because race engines often operate at idle and part-throttle with very little manifold vacuum.

This makes using a MAP sensor difficult. This system is less precise than speed density or MAF and is therefore generally only found in racing or on heavily modified street engines with big camshafts. A MAP sensor can still be used with Alpha-N, but it is generally employed as a barometric pressure sensor to detect altitude changes.

[TZ350]

16 x 12 Input Tables or Maps for my EFI unit.

All the variables RPM, MAP, TPS, Load, VE and Lambda values can be adjusted.



Speed Density Map



Alpha-N Map



Desired Lambda Map

I am trying to get my head around these and figure out how much info from the EngMod2T graphs I can use here.

[RomeuPT]

Cant hide anything on the internet - that drawing was from many,many years ago.
The idea was that as the outer edges of a T port form the longest part of the duct, they should be opened first, to get a more coherent,bigger amplitude wave
front exiting down the header.
It was used for quite a while in many GP winning engines - but I tested it more rigorously later on, and made more power by simply raising the whole port,back to flat again - bugger.

Thanks for this info. Really avoid confusions and wasting time for me in the future

Recent Honda cylinder's seem to have the outer edges lower than the old 96/95 cylinders.

Honda Nx users go with 108/109 and 110 rods, the pistons have 21,5 height from top of the pin to the top edge. You said that around 1.3 primary Comp. works best for reed induction engines.

So, why not use 115 rods, with a piston pin about 1,5mm near the top and filing the case a bit where it least affects thus keeping primary compression?

Regards