ESE's works engine tuner

[husaberg]

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Wayne and Frits how do you work of how much air an engine consumes to say make say 50hp if its 125cc.
Do you work your way backwards from the power output or is there a rule of thumb He asks hopefully.
I realise the was flow measurements done so I am hopeful there is a rule of thumb.

I found this its American diesel but will it still work?

For practice use an air flow of 80 cubic feet per minute and it will equal 115.27 horsepower and use this for your hosepower to air flow calculation.
So 50 hp =34.7cu ft/minute

34.7ft³= 0.98m³/ minute

The next question is, Is it calculable how many hp This takes moving this wet mixture though the case and into the cylinder approx. is cool (He asks hopefully............)

[ken seeber]

Husa,

This is a bit of a rough guide, but I am sure Wob or Frits could come up with something better with EngMod:

"So, using the RSA 125, 54 hp @ 12,000 rpm as an example. Rounding numbers as we go, this equates to 40 kW. Referring to an SAE paper 2004-01-3561, the instrumented dynamometer performance of a Honda RS125 engine was measured and compared to various computer predictions. This showed a best BSFC (brake mean specific fuel consumption or basically fuel mass flow rate per unit of power) of 400 gm/kWhr. Using this figure as a general guide, we can calculate a fuel flow rate of 40 * 0.4 = 16 kg/hr = 0.27 kg/min = 270 gm/min.

At 12,000 rpm, this gives us 0.023 gm/cycle. Using a fuel density of 0.74, this gives us a fuel volume per cycle of 0.031 mm^3.

If this was a cube of fuel, it would be of (0.031)^0.333 = 0.31 mm per side or if a spherical droplet, it would be of (0.031 *3/4 * π)^0.333 = Ø0.4 mm.

Pretty small stuff really, not something like the Ø3 -4 mm as one might imagine a droplet might be.

Taking this one stage further, if the A/F ratio was 12:1, this would mean 0.023 * 12 = 0.28 gm air was entering the engine per cycle. Using an air density of 1.2 kg/met^3 (at sea level & 15 deg C), this would give us a volume of air entering the engine of 0.000233 met^3 = 233 cc. From this the Delivery Ratio can be calculated at 233/125 = 1.87 : 1. This is pretty good, and sort of correlates with the DR indicated in the SAE paper of around 1.4 : 1, this engine under their test conditions was around 30 kW, not the 40 of the RSA."

[husaberg]

Husa,

This is a bit of a rough guide, but I am sure Wob or Frits could come up with something better with EngMod:

"So, using the RSA 125, 54 hp @ 12,000 rpm as an example. Rounding numbers as we go, this equates to 40 kW. Referring to an SAE paper 2004-01-3561, the instrumented dynamometer performance of a Honda RS125 engine was measured and compared to various computer predictions. This showed a best BSFC (brake mean specific fuel consumption or basically fuel mass flow rate per unit of power) of 400 gm/kWhr. Using this figure as a general guide, we can calculate a fuel flow rate of 40 * 0.4 = 16 kg/hr = 0.27 kg/min = 270 gm/min.

At 12,000 rpm, this gives us 0.023 gm/cycle. Using a fuel density of 0.74, this gives us a fuel volume per cycle of 0.031 mm^3.

If this was a cube of fuel, it would be of (0.031)^0.333 = 0.31 mm per side or if a spherical droplet, it would be of (0.031 *3/4 * π)^0.333 = Ø0.4 mm.

Pretty small stuff really, not something like the Ø3 -4 mm as one might imagine a droplet might be.

Taking this one stage further, if the A/F ratio was 12:1, this would mean 0.023 * 12 = 0.28 gm air was entering the engine per cycle. Using an air density of 1.2 kg/met^3 (at sea level & 15 deg C), this would give us a volume of air entering the engine of 0.000233 met^3 = 233 cc. From this the Delivery Ratio can be calculated at 233/125 = 1.87 : 1. This is pretty good, and sort of correlates with the DR indicated in the SAE paper of around 1.4 : 1, this engine under their test conditions was around 30 kW, not the 40 of the RSA."

Cheers Ken

[Frits Overmars]

Husa, here is a rule of thumb: a racing two-stroke consumes about 7 cc fuel per hp per minute (the Ryger engine consumes considerably less).

using the RSA 125, 54 hp @ 12,000 rpm as an example.... the Delivery Ratio can be calculated at 233/125 = 1.87 : 1.
This is pretty good, and sort of correlates with the DR indicated in the SAE paper of around 1.4 : 1, this engine under their test conditions was around 30 kW, not the 40 of the RSA."

Ken, you might want to review your correlation as the RSA produces its 54 hp @ 13,000 not 12,000 rpm.

[ken seeber]

[QUOTE
Ken, you might want to review your correlation as the RSA produces its 54 hp @ 13,000 not 12,000 rpm.[/QUOTE]

Frits, as #13 is supposedly an unlucky number, I went for the 12k. Could have gone for 14k, but either way, both within a tolerance range of +/- 10% which is probably more accurate than all the assumptions.

[seattle smitty]

. . . rule of thumb: a racing two-stroke consumes about 7 cc fuel per hp per minute . . .

"Fuel"???!! He means gasoline, what you poor bikers have to run.

"Nitromethane can detonate and cause serious harm to people and property.1 A single 5-gallon can of nitromethane
has a fatality range of 42 feet and can cause significant injury or damage at a range of 316 feet. A full 55-gallon
drum of nitromethane has a blast radius of 92 feet and can cause significant injury or damage up to 700 feet away
from the center of the blast."

Now THAT's fuel !!!

[Frits Overmars]

A full 55-gallon drum of nitromethane has a blast radius of 92 feet and can cause significant injury or damage up to 700 feet away from the center of the blast. Now THAT's fuel !!!

Smitty, are you talking real gallons or US gallons?

Nitromethane, wasn't that the baby brother of nitroglycerin, the stuff that I made at home when I was twelve?
Yes, the shed has a new roof now, thanks for asking. And the new neighbours are really nice people.

[Lef16]

Hey guys,
I have a question,I yesterday measure the base advance of my engine,and it is 8*.I was discussing this with a friend and he advised me to modify it for 15*,but when I asked him why should I do this,he couldnt answer.
So I was thinking what excactly is the base advance doing?I have an Ignitech,not standar CDI,so changing the base adv won't change the whole curve in degrees.
Also,whats happens when the lobe passes through the CPS..why some flywheels have wide lobe and some others short?
Cheers!

[adegnes]

This is as accurate as I can get it:

Iame m50 cylinder
Attachment 312254

Stroke = 39.4mm
Bore = 40mm
Stud pattern = 57x57mm


"Cylinder rubbing":
(to show radius of port corners)



Port heights:
Main Exhaust open = 22.4mm atdc Height = 17mm
Aux Exhaust open = 24.1mm atdc Height = 7.6mm
A-port open = 31.2mm atdc Height = 8.2mm
B-port open = 31.7mm atdc Height = 7.7mm
C-port open = 31.7mm atdc Height = 7.7mm


Axial transfer angles:
A = 25°
B = 7°
C = 55°

Radial transfer angles:
Attachment 312351


Exhaust port widths and shape of aux exhaust outer wall:
millimeter graph paper.



Transfer port widths:
millimeter graph paper



Exhaust duct is 27x20mm at the flange.


Hope this can benefit others in search for a 50cc cylinder to, not just me.

[wobbly]

In reply to the question about the base timing.
This number is irrelevant to anything except that under 300rpm when the flywheel first starts moving, the spark fires, by default at the base timing.
7* or 27* makes no difference, except a big single would probably break your ankle if kicking it over at 27* firing.
This simply tells the ECU where TDC is in relation to the mechanical triggering point on the flywheel.
Changing the base advance ( without moving the trigger ) DOES change ALL the timing points.
As you increase the base advance you are retarding ALL the actual programmed spark events.

The lobe length is also pretty much irrelevant, as an Ignitech fires off the trailing edge point - its less susceptible to RF noise being a dropping trigger signal..
A very long lobe causes problems in that the waveform created by the bump upwards being closer to the trigger pole, decays to zero
and you can get random misfiring, but this can be accounted for in software.

And here is the STA analysis with the better data, now we see the guys doing this were pretty close to the money.

[chrisc]

Thanks Wobbly and Frits. It's very worthwhile reviewing the numbers on an engine like this and talking through these numbers.

[ken seeber]

The Ryger engine. Looking at the patents and drawing, if they are the actual patents that apply to what everyone is talking about and what Frits drove (see http://worldwide.espacenet.com/publi...C&locale=en_EP ), I can see lots of complexities. However it may turn out to be a real gun, a lot simpler and be the answer to the next advancement of 2 strokes. Time will tell.
To me, one of the attractions of the 2 stroke is its basic simplicity, the major cyclic moving parts being the piston, rod and crank. OK, we can also have the rotary valve, reed valve and even injectors, but the primary basics are those three items. So sticking with that theme, I reckon a step forward might be to provide an inlet that bypasses the crankcase. The inlet drawing directly from atmosphere and discharging into the cylinder, in place of a regular transfer port.

The pics tell the story. What you see is a set of rubberies from a TM KZ10B cylinder, fairly accurately located onto a steel mandrel, its surface representing the actual bore.
In this case the standard B passage is screwed around a bit, presumably to clear the cylinder base studs and nuts and necessary material around there. From memory the RSA passages are seemingly a bit more direct.
Also shown is the suggested inlet passage, in place of the regular B passage. A bit arbitrary in its design, but the principle is clear. It is shown as being throttled. The concept being that the throttle would be closed until the engine speed and load are up there such that the exhaust is working and has the capacity to draw air or air/fuel directly in, bypassing the crankcase. Up to that point, the engine would be running only on the A and C ports. Alternative versions could use a diversion valve in the passage, switching from the regular B passage to the direct inlet.
Would it be better? Who knows, the main advantage I see it that it won’t see any pressure drop and volume constraints associated with coming thru the crankcase and also nice cool air direct from the world.
Issues? Tons. If it was drawing in air only, would that air have sufficient time to mix with the compensated over-rich mixture coming in from the A & C ports. Managing the transition might be interesting, but less so if they were carburetted or injected. Dunno if it would get by the CIK homologation stuff, even if it still had the single Ø30 mm obligatory carb.
Power, how about 75 hp and 17500 rpm? Dream on baby!

[adegnes]

And here is the STA analysis with the better data, now we see the guys doing this were pretty close to the money.

Thanks again!

[Flettner]

The Ryger engine. Looking at the patents and drawing, if they are the actual patents that apply to what everyone is talking about and what Frits drove (see http://worldwide.espacenet.com/publi...C&locale=en_EP ), I can see lots of complexities. However it may turn out to be a real gun, a lot simpler and be the answer to the next advancement of 2 strokes. Time will tell.
To me, one of the attractions of the 2 stroke is its basic simplicity, the major cyclic moving parts being the piston, rod and crank. OK, we can also have the rotary valve, reed valve and even injectors, but the primary basics are those three items. So sticking with that theme, I reckon a step forward might be to provide an inlet that bypasses the crankcase. The inlet drawing directly from atmosphere and discharging into the cylinder, in place of a regular transfer port.

The pics tell the story. What you see is a set of rubberies from a TM KZ10B cylinder, fairly accurately located onto a steel mandrel, its surface representing the actual bore.
In this case the standard B passage is screwed around a bit, presumably to clear the cylinder base studs and nuts and necessary material around there. From memory the RSA passages are seemingly a bit more direct.
Also shown is the suggested inlet passage, in place of the regular B passage. A bit arbitrary in its design, but the principle is clear. It is shown as being throttled. The concept being that the throttle would be closed until the engine speed and load are up there such that the exhaust is working and has the capacity to draw air or air/fuel directly in, bypassing the crankcase. Up to that point, the engine would be running only on the A and C ports. Alternative versions could use a diversion valve in the passage, switching from the regular B passage to the direct inlet.
Would it be better? Who knows, the main advantage I see it that it won’t see any pressure drop and volume constraints associated with coming thru the crankcase and also nice cool air direct from the world.
Issues? Tons. If it was drawing in air only, would that air have sufficient time to mix with the compensated over-rich mixture coming in from the A & C ports. Managing the transition might be interesting, but less so if they were carburetted or injected. Dunno if it would get by the CIK homologation stuff, even if it still had the single Ø30 mm obligatory carb.
Power, how about 75 hp and 17500 rpm? Dream on baby!

I like the way you think, there you have the basics, now cast a cylinder and try it, just put an injector ( or two ) on that.

[Frits Overmars]

The Ryger engine. Looking at the patents and drawing, if they are the actual patents that apply to what everyone is talking about and what Frits drove (see http://worldwide.espacenet.com/publi...C&locale=en_EP ), I can see lots of complexities.

I'm happy to say that patent http://worldwide.espacenet.com/publicationDetails/mosaics? is not the Ryger patent. And I agree: it's far too complicated.
Must hurry now, couldn't even find the time to read your whole post, Ken. I'll get back to you if there is anyting that I am allowed to comment on.