ESE's works engine tuner

[Grumph]

So what class would a 300hp electric bucket run in ??

F5 ??

You've got the knowledge/qualifications to work out an energy equivalence formula, J. Base it on a fixed race length, same energy allowance for electric and fossil fuels. Then put a remit forward for a new "fiddlers formula' class.....may even get accepted as a green initiative.

[WilDun]

Subtle difference, yes. Although if 2 strokes didn't store compressed gas why do they need reed/rotary valves?

I suspect the largest issue with case-charged 4 strokes might be keeping the valve closed, you'd need damned near double the spring pressure.

Back home again, I haven't read the other posts yet, - yes I agree about the spring pressure - but there's always desmo!
Will have to think about the rotary valves bit etc.- however, it worked phenomenally well on the model engines.

[richban]

Now that is Trap (5) of electrical trickery things that could be wrong.

Faulty Reg. Good as gold with new one on.

First outing on track today. Not to bad. Improved the turning as the day went on. Went around in circles a bit with jetting. It never really felt great. No more tack tuning. Time for the dyno. One thing is for sure I need to step up my game. I was slow.

Good fun though.

[WilDun]

You've got the knowledge/qualifications to work out an energy equivalence formula, J. Base it on a fixed race length, same energy allowance for electric and fossil fuels. Then put a remit forward for a new "fiddlers formula' class.....may even get accepted as a green initiative.

"Fiddler's Formula" sounds great! and if you are into electric machines, Bunnings might sponsor it as their sales of power tool battery packs would soar right off the scale!

[jonny quest]

Couple of oddities in the pic of barrel and pistons...those are big cutaways on the skirt sides...

And the cutback rear wall is pretty much exactly what I did on an RS125 at the customer's request...and it lost power.

Are you talking about the B transfer ducts. .. or the Reed cage inlet being very wide entering crankcase?

[Grumph]

Are you talking about the B transfer ducts. .. or the Reed cage inlet being very wide entering crankcase?

The piston side cutaways looked unusually big to me - but what do I know...

The rear cylinder wall is usually much more prominent - to the point where a customer thought there was more flow to be gained by cutting it back like the pic in question...he was wrong as it turned out.

[chrisc]

The piston side cutaways looked unusually big to me - but what do I know...

The rear cylinder wall is usually much more prominent - to the point where a customer thought there was more flow to be gained by cutting it back like the pic in question...he was wrong as it turned out.

Rear cylinder wall in red, as I understand it. Could you offer a potential interpretation as to why this did not offer any gains? It surely would have affected crank case volume to some extent.

I have another question if I may. In yellow, the entry to the transfer ports protrudes into the casings. I have seen these (and admittedly done so myself) cut these down to be flush with the face of the cylinder floor. My initial thoughts are extending these would extend the length of the transfer ports which would need to be considering in the overall tune of the engine. Do you have any thoughts or recommendations in keeping these or cutting them down?

[Grumph]

i don't know enough about these subtleties to advance an opinion worth snot....

People like Frits or Wob with enormous dyno time behind them may have some ideas, I'd only embarass myself.

[husaberg]

pictures.................

http://www.geocities.jp/noda_keni/h/...0/00nsr500.htm

[wobbly]

Answers are easy to "get " when you know the effects of the mods.
Cutting away the rear tang support at the base of the cylinder means that the flow thru the reeds then smashes directly onto a flat surface - the piston.
This may seem counter intuitive, in that most people think ( wrong ) that when the piston rises it creates a depression that opens the reeds and it is this that causes inflow into
the case.
The rising piston may make a piston port lawnmower operate, but the vast majority of bulk flow in a race 2T is caused by the pipes diffuser depression, around BDC - when the piston is very much in the way.
This negative pressure ratio at the Ex port is then communicated to the reeds via the transfer ducts , creating flow when the piston is at BDC - exactly opposite to the theoretical scenario.
Secondly - many , in fact most modern engines have the same sharp edge scenario as is shown in the pic of the Honda transfer entry, at the bore.
But be aware - Mr Thiel is no idiot, and the Aprilia ( and all my engines ) have a LARGE ball nose radius where the duct meets the bore edge.
This is one of the ideas that last weekend won the National Kart title for KZ2 - 125 against the very best World Cup winning engines tuned at enormous expense in Europe by
a French dude called Savard.
We kicked arse - making the pass for the lead by simply having more power down the shute, and better chassis setup to drive away on better tyres.
Transfer duct length is a very tricky area, in that most times when you shorten this, in effect you are reducing the duct volume, AND reducing the area ratio between entry and exit.
This I believe has more effect than the actual "tuned" duct length has.

[chrisc]

Answers are easy to "get " when you know the effects of the mods.
Cutting away the rear tang support at the base of the cylinder means that the flow thru the reeds then smashes directly onto a flat surface - the piston.
This may seem counter intuitive, in that most people think ( wrong ) that when the piston rises it creates a depression that opens the reeds and it is this that causes inflow into the case.

The rising piston may make a piston port lawnmower operate, but the vast majority of bulk flow in a race 2T is caused by the pipes diffuser depression, around BDC - when the piston is very much in the way.
This negative pressure ratio at the Ex port is then communicated to the reeds via the transfer ducts , creating flow when the piston is at BDC - exactly opposite to the theoretical scenario.
Secondly - many , in fact most modern engines have the same sharp edge scenario as is shown in the pic of the Honda transfer entry, at the bore.
But be aware - Mr Thiel is no idiot, and the Aprilia ( and all my engines ) have a LARGE ball nose radius where the duct meets the bore edge.
This is one of the ideas that last weekend won the National Kart title for KZ2 - 125 against the very best World Cup winning engines tuned at enormous expense in Europe by a French dude called Savard.
We kicked arse - making the pass for the lead by simply having more power down the shute, and better chassis setup to drive away on better tyres.
Transfer duct length is a very tricky area, in that most times when you shorten this, in effect you are reducing the duct volume, AND reducing the area ratio between entry and exit.
This I believe has more effect than the actual "tuned" duct length has.

Congrats Wobbly!
I do remember reading about the radius on the bore edge and was going to comment on it not being on this NSR cylinder. I'm glad you did, and I'm glad you emphasised LARGE because I had no idea just how much of a radius it required.
Time to read up on duct volume and ratios. I know I saw some good content in this thread somewhere

[koba]

...last weekend won the National Kart title for KZ2 - 125 against the very best World Cup winning engines tuned at enormous expense in Europe...

[Forgi]

They will probably not all be the same, Forgi. A rotary disc usually opens much quicker (= in fewer crank degrees) than a piston port.

You are right Frits, I just couldn't realize this fact. Of course it would be better than a piston controlled port at the same size. But I'm sure the test would give a good guideline how much the power and the powerband can be affected by the fact that the rotary disc opens earlier with 50-60 degrees and that's why the time area could be duble.

Before I have read a Kreidler test in which the piston controlled valve had been transformed to a rotary disc valve. In that case with the same exhaust the power increased +15% and with a modified exhaust increased +40%.

[wobbly]

The other small point I thought of later was that the drop down rear piston support tang,if shaped well also helps to deflect the reed flow sideways
toward the transfer duct entry area, and not allow most of it to migrate straight forward and hide under the piston.
I should temper my comments about reed flow at BDC somewhat in that when you watch the tip lift and case depression curves in EngMod
you see that the case going negative and the inlet going positive, if tuned correctly opens the reeds very quickly and soon after BDC,thus initiating
flow into the case when the piston is still hanging around " in the way ".
But again I emphasise it isnt the rising piston that creates the inflow in a race engine.

[Forgi]

Hi Forgi, I agree, it would be interesting but its not very relevant to my project and its hard for me to do. The std inlet timing for my Suzuki 125 engine is 145/55 so 88 closing is easy, I would only need to cut the leading edge of the disk and it is what I routinely do to get the inlet duration I want. But 88 opening means adding material to the trailing edge, and that would necessitate making new disks.

Hello Teezee. Of course I understand, no problem