ESE's works engine tuner

[TZ350]

That Sir, is a seriously serious looking bike, I had better get a move on, Team ESE's 2T's are being left behind.

[lodgernz]

Why/were do those 1000/12 come from, I'm curious now.

At R rpm, one rev takes 60000/R ms.
E degrees, the exhaust duration from EO to EC, takes E/360 of a rev.
So, rotating the crank through E degrees takes (60000 * E) / (360 * R) ms. = (1000 * E) / (6 *R).

The distance travelled by a wave at the speed of sound S in this time is
S * (1000 * E) / (6 * R) or 166.666 * S * E / R
At Rmax, we want this to be the time for this wave to reach the end of the baffle cone and return to the cylinder,
hence the distance from cylinder to baffle cone must be half the distance travelled by the wave,
i.e. 83.333 * S * E / R

Pretty sure...

[TZ350]

Frits, your FOS concept for pipes has been around for a long time and has been seen by millions, but I have never seen anyone question your formula for the "tuned length".

Attachment 302400

Your formula is: Lmax = Speed of Sound * exhaust timing * 88 / RPM of max power
By my maths, the "88" should be 1000/12 ie 83.3333....
I assume your formula is allowing for some other factor, perhaps the higher speed of sound in the exhaust pipe, and I'm curious to know your logic.

The distance travelled by a wave at the speed of sound S in this time is

S * (1000 * E) / (6 * R) or 166.666 * S * E / R

I think you are right, the answer is in the "Speed of Sound", because its the speed of sound at what temperature?

And the temperature, it is variable along the pipe, and the wave travels faster in the regions of higher temperature.

What is the average gas temperature you are using for your pipe calculations?

If I am right about this, hopefully we will both get a chocolate fish.

[Drew]

The speed of sound is relative to density, no? The temperature is indicative of that, but not perfect. The material that the waves are bouncing off and reducing at the same time is changeable too with being welded and stressed.

Is it possible to bypass the pipe fuckery and fire a pulse back up the exhaust port of ones own creation? Make it of a register so low it is barely perceptable, and the volume of the bike stays nice and civil.

Just a thought. Might go and mount a subwoofer and amp to the GT and see what happens.

[Bert]

That Sir, is a seriously serious looking bike, I had better get a move on, Team ESE's 2T's are being left behind.

Watch closely how the frame / suspension responds to being loaded up... No squatting in the backend under acceleration. Well done Scott, those frame modifications have made it even better.

[Drew]

Watch closely how the frame / suspension responds to being loaded up... No squatting in the backend under acceleration. Well done Scott, those frame modifications have made it even better.

Some squat is accepted as an absolute must on proper bikes. If it is tuned out with a steep swingarm such as that bike, the drive force is fighting the suspension and you sacrifice traction.

Might be alright with twenty or thirty ponies to ride (but could be better), but pump a hundred and ninty through the tread and things get...interesting on corner exit.

[lodgernz]

I think you are right, the answer is in the "Speed of Sound", because its the speed of sound at what temperature?

And the temperature, it is variable along the pipe, and the wave travels faster in the regions of higher temperature.

What is the average gas temperature you are using for your pipe calculations?

If I am right about this, hopefully we will both get a chocolate fish.

I think the SoS in air is around 331m/s, and at 480* it's around 550m/s.
That's the figure I usually use, but maybe Frits is already factoring that into his formula, and expects us to use the SoS in air.
Can't eat choc fish. Hurts my knackered old teeth.

[husaberg]

I think the SoS in air is around 331m/s, and at 480* it's around 550m/s.
That's the figure I usually use, but maybe Frits is already factoring that into his formula, and expects us to use the SoS in air.
Can't eat choc fish. Hurts my knackered old teeth.

When Frits posted it He said something along the lines of....... it was meant to be a simple formula to put you in the ball park.
He said the more complicated formula he uses is based on complex data and measurements
but no matter how complicated it will still need testing and verification.

[Flettner]

So, if your 150 will rev to 14000 and you have a BMEP of 247.6 (that would have to be an absolute max), you will see 40HP. Probably revs higher and BMEP a little lower in reality.

100cc, if it was up to the Aprilia 125 BMEP ( 211.85 ) would produce 44HP at 13500 RPM.
These calculations are just out of Graham Bells book, so just a good guide.
My Aprilia BMEP figure might be a little high as I calculated it at 55 HP, 13500 RPM.

If the 100cc twostroke was a twin, say, and reved to 15500, you might see 50 / 51 ish HP
The truth is trying to get these BMEP's would be very difficult.

So lets supercharge our 100cc fourstroke say 365.5 BMEP? at say ( it's a twin ) 16000 rpm,
45HP.

Just some random figures I know but never the less interesting.

[TZ350]

Interesting numbers all right, yes once 20hp was considered good and divided the pretty good from the average, now it seems that the benchmark is going to become 30hp.

[husaberg]

Interesting numbers all right, yes once 20hp was considered good and divided the pretty good from the average, now it seems that the benchmark is going to become 30hp.

Honda did 150hp out of a 250 turbo twin at the first try.......scary just as well all the stuff to do this is unavailable unless custom.
Just as well 50hp would be useless on a kart track as well, look at the f4 vs f5 times

[cotswold]

Frits, your FOS concept for pipes has been around for a long time and has been seen by millions, but I have never seen anyone question your formula for the "tuned length".

Attachment 302400

Your formula is: Lmax = Speed of Sound * exhaust timing * 88 / RPM of max power

By my maths, the "88" should be 1000/12 ie 83.3333....

I assume your formula is allowing for some other factor, perhaps the higher speed of sound in the exhaust pipe, and I'm curious to know your logic.

I had the same issue and was told sounds travel faster in hot air

http://www.thenakedscientists.com/fo...?topic=11505.0

http://www.sengpielaudio.com/calculator-speedsound.htm

I do have the number used somewhere but can't find it. I was told to reverse calculate it

[Frits Overmars]

When Frits posted it He said something along the lines of....... it was meant to be a simple formula to put you in the ball park. He said the more complicated formula he uses is based on complex data and measurements but no matter how complicated it will still need testing and verification.

Husa, your memory serves you well.

The 'FOS exhaust concept' is only meant to help beginning tuners on their way.A lot of important factors, like compression ratio, ignition timing, type of fuel, carburetter diameter, crankcase volume and angle.areas, are not taken into account.
Instead of all those factors that I left out, I included one variable, the speed of sound. Starting with 550 m/s will get you in the right ballpark, after which you can vary this value according to your findings.
You should not use this simple exhaust concept to improve on the highly developed RSA engine, where all of the above-mentioned factors were taken into account.
Final remark: the calculation of the tailpipe restrictor diameter is critical: you can only apply it to engines that are thermally sound. Air-cooled engines are not.

TZ, would you settle for a chocolate teapot?

[wobbly]

Lets quote real figures for what can be achieved with a genius called Thiel in charge of over 100 people in a race dept R&D facility.
The best an RSA made was 58 crank Hp ( assume +5% over sprocket dyno power ) at 13000 rpm.
This is 16 Bar ( 232 psi ) bmep at the crank - here is the sim graph.
Take that bmep and apply it to a 100cc water cooled with 50 by 50 bore stroke.
Assume peak power at 14,000 ( easy ) and we have 49 crank - less 12% to read on a Dynojet and thats 43 RWHP.
No trick shit technology,no weird ideas, just great attention to every detail.
Can it be done, for sure, just not when you start with a 30 year old crankcase and an iron sleeve in a road bike 125 cylinder.

[richban]

Lets quote real figures for what can be achieved with a genius called Thiel in charge of over 100 people in a race dept R&D facility.
The best an RSA made was 58 crank Hp ( assume +5% over sprocket dyno power ) at 13000 rpm.
This is 16 Bar ( 232 psi ) bmep at the crank - here is the sim graph.
Take that bmep and apply it to a 100cc water cooled with 50 by 50 bore stroke.
Assume peak power at 14,000 ( easy ) and we have 49 crank - less 12% to read on a Dynojet and thats 43 RWHP.
No trick shit technology,no weird ideas, just great attention to every detail.
Can it be done, for sure, just not when you start with a 30 year old crankcase and an iron sleeve in a road bike 125 cylinder.

And this is why I am now building a 2 stroke bucket. We are nearly at 300hp pre litre with the heavy piston over square 300. The power to weight just can't be beat. I am converted.