ESE's works engine tuner

[andreas]

All right, imagine how the wrong conclusions appear. Thanks Frits and Wobbly.

[RomeuPT]

Depending on which KZ piston you tried, there may be one that has a larger radius to keep the exhaust covered.
Last year Meteor released a TM KZ 10C piston that had the larger radius as shown in the pic. Casting 2630 (117gm) on top/left of original style 2311.
They also have a flat top version the TM factory team was using in 2018 as well with the larger radius.

Mondokart don't reply to emails :/

is this the one with larger radius too (2641)?

https://www.mondokart.com/en/meteor-...sive-news.html

[Brett S]

Mondokart don't reply to emails :/

is this the one with larger radius too (2641)?

https://www.mondokart.com/en/meteor-...sive-news.html

That looks to be an exclusive (2702) to Mondokart with the 0.7mm ring.
I believe the 2641 has the same skirt cutout as the 2630 but cast with alowance for the flat top and is the light weight model to the 2630.
Without seeing one the, 2677 is the light weight, flat top with 0.8mm ring that might either be the same casting as the 2641 or the mondokart 2702 or they are all the same casting, i'm not sure.

[Frits Overmars]

Blairs 500 single was hamstrung by super conservative design elements. A square Exhaust port - parallel header - 120mm skinny pipe etc. This then results in very low dynamic compression, and with the low bmep generated , peak combustion efficiency was only gained with a ton of advance.
Modern race engines generate double the bmep , and all end up needing around 15* advance at peak power.

Yep. The RSA has 16° ignition advance at 12.500 rpm (maximum BMEP and maximum torque) and 15° at 13.000 rpm (maximum power).

[Tim Ey]

Yep. The RSA has 16° ignition advance at 12.500 rpm (maximum BMEP and maximum torque) and 15° at 13.000 rpm (maximum power).

Talkin' RSA Power: Why did I never see a correction factor and air pressure & temperature on the power diagrams?
At which ambient conditions was the RSA investigated/developed?

[Frits Overmars]

Talkin' RSA Power: Why did I never see a correction factor and air pressure & temperature on the power diagrams? At which ambient conditions was the RSA investigated/developed?

There is a whole lot more than just air pressure and temperature that does not show on the power graphs Tim. All it would take is one push at a button on the dyno computer and you would see something like this:

DRVE3452.PC:
2006-10-25; N°curva 3452 moto DRVE n°03/06
Albero Drd 01/05 C004 raf.sp10.1bilan; biella Drd 120mm n°13 C004;
cuscinettiRulli Apr.giocco 0.057 C004; pistone 2544 (961) C04;
testa AC 56-G std TR0.75-0.76 C36; cilindro APE341 54.011;
valvola scarico/condotto sup.C004 Inf.C004 molle C004; tubo 69/03 moto Protti ferro;
Colettore/termin/silenz: 38.7 +0m+1gr.Sil.Dlr Hrc-std; mappatura GP184+0%A0
98B-V020B-P083B; candela Denso 35 usata C036; accensione Poker; Carburatore Vhta 41
Moto n°7 new valvolina; carburazione AU248T1.5P265Max218m48-4f-P120;
benzina ELF olio ELF 909 4%; alimentazione 155°/89.5° as20°r0sc25°r10C004

But that would really clutter up the graphs, wouldn't it?

By the way: the dyno rooms, pictured below, were climatized, so temperature, pressure and even humidity were pretty constant.

[Haufen]

There is a whole lot more than just air pressure and temperature that does not show on the power graphs Tim.

I think he's got a point there. Nowadays, a dyno chart showing power without a reference under which ambient conditions this power was measured and by which formulas the power was corrected (eg. DIN 70020..) and where it was measured (e.g. engin, rear wheel etc.) is totally worthless.

By the way: the dyno rooms, pictured below, were climatized, so temperature, pressure and even humidity were pretty constant.

Of course they were, but I do not see a reference to this in your last post. What was the temperature of the intake air? What was the cabin pressure? By which formulas was the power corrected? What kind of power are we looking at? Has it been corrected at all?

But that would really clutter up the graphs, wouldn't it?

Not at all! A documentation like this (plus ambient conditions and test conditions (e.g. typre pressure, tyre type etc) is pure gold for everyone making dyno runs on a more or less regular basis and trying to get the max our of it. Be it for finding problems on the engine or understanding which direction to head to for more power. One could put it on a second page though.

Was that the data which belonged to the 54hp graph Tim was referring to? Or just a random one? Can you help us 'decipher' it?

[Frits Overmars]

Tyre pressure? Tyre type? Haufen, you do not seriously think that you can develop an engine to the required level by measuring rear wheel power, do you?
Tyre rolling losses are dependent on tyre deformation which is dependent on tyre pressure; those rolling losses heat up the tyre, which changes its pressure and the rolling resistance during the dyno run. Need I go on?

The RSA power was measured at the gearbox exit shaft, as has been mentioned repeatedly. The data-example I posted above is not from a 54 hp dyno run but from a different run, which by the way was not far short of 54 hp either.
I do not intend to start a language course of Italian technical abbreviations here, but anyone with a bit of two-stroke background should be able to deduce by the numbers what they are referring to.

The ambient factors were 27°C and 1013 mbar. Initially the ambient temperature was kept at the standardized 20°C, but in order to bring the circumstances more in line with the average circuit conditions it was later raised to 27°C. And because of the constant ambient factors there was no further correction required.
Anyway, most correcting algorithms are useless if not downright misleading when high-performance two-strokes are involved.

[TZ350]

Aprilia's climate controlled dyno rooms are pretty impressive. And the sort of thing you need for professional engine development.

It is pretty obvious that they applied good scientific method in the development of the Race bikes, you would have to have a few screws lose to think or suggest otherwise.

50cc 2T

Team ESE's dyno is just an old Dynojet plonked in the corner of the work shop but we do Ok with it.

Our environmental control amounts to an exhaust fume extractor so we don't choke ourselves on smog.

Sure, we are not so scientific and measure at the back wheel but still make good progress.

The old Dynojet pretty quickly lets you know if your latest idea was a success or complete dud.

The ratio of success's to duds is about 55/45 so far. We make progress slowly but get there in the end.

The Dynojet is a great comparative tool.



Mike was pretty happy recording a 30hp run from his EFI Turbo 4T 100.

Was it 30,34hp SAE or 30,5hp DIN who cares. Just eliminate the variables like tire pressure the best you can and test it the same way each time and let the comparative results guide you.

[Frits Overmars]

I'm sure you Team ESE guys have more fun and less stress than the Aprilia racing department staff

[Haufen]

Tyre pressure? Tyre type? Haufen, you do not seriously think that you can develop an engine to the required level by measuring rear wheel power, do you?
Tyre rolling losses are dependent on tyre deformation which is dependent on tyre pressure; those rolling losses heat up the tyre, which changes its pressure. Need I go on?

I am well aware. I wrote that passage regarding the tyres for the community to benefit from, as I figured the most common dyno type people reading here have acces to is an acceleration dyno just as Team ESE's dynojet.

What do you mean with required level?

Btw (this is again for anyone who is interested), there are good and worse tyres for dynoing. A good tyre for dynoing does not change circumference (by much) during high speed pulls and gives constant and repeatable readings once you start with a high enough pressure (higher than on the road in most cases). There may be differences in hp readings between tyres, even if both tyres can be categorized as 'good' by the definition above.

The RSA power was measured at the gearbox exit shaft, as has been mentioned repeatedly. The data-example I posted above is not from the 54 hp dyno run but from a different run, which by the way was not far short of 54 hp either.

I do not intend to start a language course of Italian technical abbreviations here, but anyone with a bit of two-stroke background should be able to deduce by the numbers what they are referring to.

The ambient factors were 27° and 1013 mbar. Initially the ambient temperature was kept at the standardized 20° C, but in order to bring the circumstances more in line with the average circuit conditions it was later raised to 27°. And because of the constant ambient factors there was no further correction required.
Anyway, most correcting algorithms are useless if not downright misleading when high-performance two-strokes are involved.

Come on Frits, you of all people should be well aware of the sensitivity of the high-performance two-stroke engine to air temperature, air pressure, humidity and when we're at it: water temperature (and EGT). Yet you draw a graph with your name on it containing none of the information just mentioned and when legitimately asked for the missing pieces, you post other information. That info was nice, thank you. But when we ask for temperatures and pressures, we don't care if the rod's name was Giovanna or if the head was the third from the right in the batch from april.

By the way, I am quite sure that - in contrast to the temperature - cabin pressure was not held constant at 1013mbar by the test cell for all the tests. The facilities capable of such a thing are quite expensive and as Jan mentioned elsewhere that he was rejetting on the dyno (there would be no need if everything was held constant), not given an acceleration dyno which he desired and that he did not use indication or a fuel metering device or exhaust gas analysis, (all valuable tools much cheaper than such a test cell) this would be highly unlikely. Also, using such a test cell - let alone several of these - just to keep the pressure at 1013mbar would be a waste of resources, as you could develop dedicated setups for e.g. higher altitude race tracks etc.

This leaves us with two options:
a) power was corrected and it is not known how as it came out already corrected (on the dyno computer screen there may have been two different hp values or at least the values during the measurement were not exactly the same as after post-processing). Or

b)there was indeed no power correction used, in which the repeatability from e.g. Friday to Monday (on a weekend nobody worked, if such a thing exists in motorsports) may be well off by a couple of percent. Let's say +10mbar from 1013mbar on Friday and -10mbar on Monday and we have found or gained a whole horse in 54. That is not really the precision one would prefer to have in one's tools, is it?

If I had to guess I'd vote for option a), and as we do not know by which factors or norm this was corrected, 54hp (measured) @ 1013mbar and 27°C, disregarding humidity, can be anything between 52,7 (SAE) and 54,6hp (Din). Or if it was PS (CV, metric hp) and not hp in Frits' chart, then between 52,1 and 53,9 hp.

The other way round, 54ps corrected by SAE would mean between 55,6ps (DIN) and 54ps corrected by DIN would mean 51,8ps (SAE) (=54,8 and 51 in hp).

So, depending on the method of measuring, the peak power of the Aprilia RSA is somewhere between 55,6 and 51,8 ps (or 54,8 and 51hp). I had hoped we would be able to get a much clearer picture after Tim's question.

[Frits Overmars]

What do you mean with required level?

The level to be the best world-wide. What else?

I am quite sure that - in contrast to the temperature - cabin pressure was not held constant at 1013mbar

Controlling the cabin pressure is about the simplest thing in a test cell, much easier and less energy-consuming than controlling the temperature, let alone the humidity. There are blowers pushing air in and ventilators sucking it out again. A simple set of louvres is all you need to balance in- and outflow and control the pressure.

you of all people should be well aware of the sensitivity of the high-performance two-stroke engine to air temperature, air pressure, humidity and when we're at it: water temperature (and EGT). Yet you draw a graph with your name on it containing none of the information just mentioned and when legitimately asked for the missing pieces, you post other information. That info was nice, thank you. But when we ask for temperatures and pressures....

Which part of '27°C and 1013 mbar' didn't you understand?
Besides, I didn't realize that I was under an obligation to answer questions. In fact I didn't even know I was obliged to post anything.

[TZ350]

Come on Frits, you of all people should be well aware of the sensitivity of the high-performance two-stroke engine to air temperature, air pressure, humidity and when we're at it: water temperature (and EGT).

It is pretty obvious from their success that Aprilia were knowledgeable and careful operators, so your point is exactly? ....

[wobbly]

Quote " By the way, I am quite sure that - in contrast to the temperature - cabin pressure was not held constant at 1013mbar by the test cell for all the tests. The facilities capable of such a thing are quite expensive and as Jan mentioned elsewhere that he was rejetting on the dyno (there would be no need if everything was held constant). " End quote.
OK - two statements couched as facts that are completely erroneous.

Firstly - ambient temp and pressure in a cell are easy and cheap to control.
At BSL we controlled the pressure by simply louvering the inlet and outlet fans by hand just before a test.
The temp was heated if needed by an inline burner , thermo controlled from within the cell.
My standard temp was 25*C and the incoming air was very rarely above this in mid summer , so cooling wasnt needed.
Humidity was deemed "too hard " to control without huge expenditure .But after checking the various correction standards we discovered that the Superflow dyno software predicted very accurately the needed
correction factor when the humidity changed.
The " real " corrected power was all but identical within the normal range of 25 to 75% here in NZ.

Second - yes Jan re-jetted on the dyno.
This had nothing to do with the ambient conditions , although that IS of course needed if the cell isnt controlled like it was at Aprilia.
The re-jetting regime was instituted to standardize testing , initially of pipes.
But since then I have found that virtually every small change made to a very high bmep race engine will result in a change in the final egt at peak power - skewing the results
to show power changes created by differing pipe temp, not the change created by the new setup.
Thus ever since Jan told me about this I religiously ensure every test run ends at 620*C , if not I rejet and rerun.
Same for water temp - every run starts at 40*C and my cooling setup is good enough to hold temp below 45* for the 3 pulls needed to achieve accurate averaging.

[husaberg]

Maybe you always need to look over your shoulder.
To see who is following behind.

I think this pic is from the Garelli period?
We are lucky for the input we get here from some very knowledgeable and respected 2 stroke experts, Like the bloke above and others.
So if you take the time to ask a question of the people who contribute their knowledge so freely on here on the thread.
Respect their time taken to answer it, by reading their answers properly.
Also consider it's not a interrogation, no ones obliged to answer.