ESE's works engine tuner

[husaberg]

Don't do it - any groove on the inside surface of a gudgeon pin is a perfect stress raiser.....

I should rephrase that to a shoulder with a generous radius at the transition.
Starting with a thick walled blank.

[2T Institute]

Even a couple of my 'GP spy pics' ended up in the 'Frirs Files'

[dinamik2t]

You'd have to talk to Spank about that. But in the past it's caused some problems with double posts etc so it's much less irritating not having it.

Aha! Ok then, no prob

[bucketracer]

page 380, other link lists and interesting quotes on the decade pages 370-360-350 .... etc

Thanks, Mental; everything seems to be fine now. So here they are again:

http://www.kiwibiker.co.nz/manual/Aprilia-1.zip (6.8 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-2.zip (8.3 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-3.zip (9.2 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-4.zip (7.2 MB)
http://www.kiwibiker.co.nz/manual/Aprilia-5.zip (5.6 MB)

Kel sent me this link http://www.deraceheldenvanweleer.nl/...opic,51.0.html on the lifes work of Jan Thiel all in Dutch but its worth a look for the pictures alone, lots of mouth watering stuff on Jamathi's and other 50cc racers of the 60's -70's.

. http://www.elsberg-tuning.dk/piovaticci.html

And there is another one on 50cc history: http://www.elsberg-tuning.dk/engineering.html

Heaps of interesting classic bikes here:- http://www.eurospares.com/graphic2.htm#Vintage Japanese motorcycles

This is a overview on how to cast a cylinder the old fashioned way
http://www.youtube.com/watch?v=Lj4h9...eature=related

Great video. But you better start here: it is a series of three videos, and very, very instructive:
http://www.youtube.com/watch?v=I-2rJ...eature=related
By the way, the leading actor, Gabriele Gnani, is one of the founding fathers of the new Continental Championship Race Tech, CCRT.

Interesting engine? An early crankcase reed 1958 http://www.rearenginekarts.com/clark%20engine.htm

The calculator in EngMod was added by Neels after I had done dozens of tests with tripple and T port designs. The calculator simply uses 75% of the total effective port area as a guide. This always works and always makes allot more power and generally I found that the duct exit should be about the area of the main port alone. This usually ends up around 75% of the total ( by taking away the extra area of triple ports) needed for lots of blowdown - thus power.

It was never intended to be used with a single port only as I haven’t tested that at all, apart from years ago on TD3s etc, and we always went bigger back then, not smaller.

Theory says that having a smaller duct volume changes the Helmholtz frequency ( higher ) , and reduces the amount of exhaust residuals able to be stored in that duct ( meaning more clean mixture sits close) , but im not sure this theory will apply to making more power with a single port.

Having said that, a 40mm pipe entry on an engine only making 30 Hp is way too big, so reducing the duct and or header area, or maybe both, will very likely work real well.

… you reduce the port height in the curve; the ratio of inner curve radius to outer curve radius becomes larger, and that is very good for the flow. Look at any air conditioner ceiling-outlet: they are all shaped like that.

I also like the idea of closing off the outer/ upper transfer ducts. It would prevent wrongly-timed exhaust pulses from shoving fresh charge from the cylinder back into the crankcase, and that would yield a very civilized power curve.

The exhaust exit "nozzle" was used first by Helmut Fath ( my hero ) when tuning for Honda where their V twin 250 had one stinger 150 long the other 450 long.

I have tested all manner of variations and the best is around 10mm of parallel nozzle and then 10mm of divergence to a stinger around 1.5mm bigger. This reduces the effect of the waves bouncing up and down the stinger off atmosphere disrupting the rear cone waves.

The length to end of header and length to end of diffuser. so few pipe designs are "correct" and its a pain to calculate all the time. But the header end should be 30 to 32% and the diffuser should be 64 to 68%

The Rotax 24/33 rear cone was dropped in Superkart racing when I discovered that a single 28* made more power on the dyno.

This led to the development of the so called Silverstone pipes that we made when I worked for JL when he was still in England. These won dozens of World and Euro titles.

I have spent days of dyno time testing multi angle rear cones, and have always been able to achieve the same or better power with a single rear of the right angle.
In many cases the sim likes a sharp rear cone, but in reality its no better.

Seems to me that the main reasons you got better power with the modified pipe, was down to a gradual front nozzle, stinger nozzle, and a way shorter tuned length.

There is a relationship between how wide you make a port, and how gradually it should widen in order to keep the ring healthy.
With a good ring, 70% chordal of the bore is the optimum width. If you make it any wider, the widening has to be so gradual that you loose surface area at the top, where it counts most, because that's the area that opens first and stays open the longest.



The drawing shows that with too wide a port you have to sacrifice the yellow areas at the top. But sacrificing those areas costs blowdown angle.area. That red port may have more open area, but not where it counts, at the top; the blue port is better.

Unless you keep the revs really low, a single exhaust port with a 70% chordal width does not give sufficient blowdown time.area, but because of the reason I explained above, making the port wider will be even worse. You will either have to use a bridge, add auxiliary exhaust ports, or raise the timing of the single port to well above the 190° that is optimal for pipe resonance.

The Aprilia cylinder is extreme in that respect: the middle exhaust port is 38 mm wide (older versions were 40 mm wide) and there are huge auxiliaries but even so the middle port is raised to 196° and then it gets a large radius at the top. The radius makes it difficult to measure the timing but if you shove a piston ring in the bore until you can just see light between the ring and the bore, you will find an exhaust timing of 202°.

Don't try this at home, unless you want your engine to produce its maximum power at a mean piston speed of 23.6 m/s. But then your transfer time.area will probably be insufficient. And you know: if you raise the transfers, that will eat into the blowdown time.area.

Why does Aprilia use an exhaust timing that is too high for optimum resonance? It is a compromise: any lower, and the maximum torque will rise, but the reduced blowdown time.area will cause an early torque collapse and the product of torque times revs (yes, that's power) will be lower.

STA stands for Specific Time.Area. STA depends on rpm: the higher the revs, the shorter the ports are open per revolution. So I can only give you STA numbers if you specify for what rpm you wish to know them.



It's like this: a cylinder has port windows with a certain width and certain distances from the cylinder top plane to port roof and port floor. You can only express the window dimensions in millimeters and square millimeters (or in other funny length and area units that english-speaking folk still use).

Put this cylinder on an engine with a crankshaft with a certain stroke and a certain conrod length. Now you can also express the window dimensions in crankshaft degrees.

Now we can look at the angle.area concept (the point between angle and area indicates a multiplication; I make a point of writing it like this )

Let us assume a port window is 1 mm wide. Turn the crankshaft until the window is on the verge of opening. Its open area is still zero.
Then turn the crankshaft 1° further. Let's say the piston descends 0.5 mm, so the open window area is 0.5 mm height * 1 mm width = 0.5 mm² , and it has been open for 1°; that yields an angle.area of 1° times 0.5 mm² = 0.5 °mm².

Then turn the crankshaft 1° further again. That first 0.5 mm² open area has now been open during 2°; and as the piston has descended some more, there is now some additional open window area that has been open for 1°. Multiply all those pieces of open window area with the number of crankshaft degrees they have been open, all the way from initial port opening till port closing, and you get the total angle.area of the port.
But for gas flow it does not matter during how many crank degrees an area has been open; what matters is the number of seconds it has been open.

That is where engine rpm comes into play: twice the revs means half the time; angle.area divided by rpm is time.area. And if you divide time.area by the cubic capacity of the cylinder that has to be filled (or emptied), you have specific time.area.

You may have noticed that in previous posts I sometimes talked about angle.area, and sometimes about time.area. And hopefully now you understand why. When I talk about an engine, I use angle.area. When I talk about a running engine, I use time.area.

With the angle.area values I posted, you should be able to work out the specific time.areas for 13.000 rpm. And these are universal; if you manage to get the same STA values for an engine with any cubic capacity and any rpm, you're doing fine.

But how did you come by the 'mean area' expression? Been reading Gordon Jennings? That was a very coarse approximation of the time.area concept in an era where Gordon did not yet have a computer at his disposal. He certainly would have approached it differently nowadays.

Yes ... after reading Gennings and his idea of measuring the port area uncovered by 50% of the crank rotation between just opening and fully open that not all port shapes will amount to the same equivalent angle area, tall versus wide for instance. My post might not have been a good use of the word "mean" maybe equivalent effective area might have been better.

EngMod2T … the perfect tool for calculating what the RSA must have to make 55Hp @ 13000.
Assuming that is at the sprocket ,add say 5% and put it into EngMod2T - it will spit out the target values, and I can tell you for sure that the end result will tell you VERY close to what is needed in reality, to make that power.

… the ceramic coating on the piston and the chamber is a secret weapon used for years on KT100 Yamaha engines. Its not actually stated in the rules as being illegal, but the way the rules are worded they say that if it doesn’t say you are allowed, then you are not. The coating doesn’t need to be clear, its only done that way so you cant see it. HPC do all manner of coatings, but I know nothing at all about the clear version do I.

[wobbly]

Why put the plug inside the pin with a "new"" groove,there is already a groove available and also there is a chamfer on the end of the pin that can be used - as it was previously - to force outward, the retainer
into this groove.
Wont say any more as this stuff is Frits intellectual property , but with all the pics flying about its quickly becoming public property.
I made these plastic plugs several years ago using glass reinforced Peek,and tested them with no positive results at all.
But now we have tripple ports reaching around to 1/2 bore, and yes they do work a treat.

[F5 Dave]

yeah that 3rd pic Hus posted of the complex pin. can't work it out.

[Yow Ling]

Would it be to stop the pin flexing and maintain a better contact area with the SE bearing?

[husaberg]

Why put the plug inside the pin with a "new"" groove,there is already a groove available and also there is a chamfer on the end of the pin that can be used - as it was previously - to force outward, the retainer
into this groove.

Oh I get it. Some times I guess the obvious solution is well..... just too bloody obvious for me really.

Any news on Vanessa. Is she still in the delivery room. I can't wait to meet her.

[wobbly]

The baby girl is lost in customs somewhere - not a good feeling as this usually means the feckers are assessing for gst charges before release.
Anything the deemed valued over 500 including freight, is chargeable, but depends if the NZC agent had a good rogering the night before..

[husaberg]

The baby girl is lost in customs somewhere - not a good feeling as this usually means the feckers are assessing for gst charges before release.
Anything the deemed valued over 500 including freight, is chargeable, but depends if the NZC agent had a good rogering the night before..

Rogering ......er...the Handler or the Beagle?

Or if they know who Mick Doohan is.

When they said under 500 they could have meant cc's. So it should just scape in.

Those Nsr$500 common as muck. Honda must have made a couple of hundred thousand of them. The grids used to be full of them after-all. So they would hardly a collectors item and are second hand to boot

Did Benson ever get around to replying about the Rad?

[dinamik2t]

Hey, Wobbly, I have an EngMod question. It's more about performance boundaries actually.
You mentioned that one should try and increase the TuBmax, which is a performance "indicator". EngMod warns for Deto at around 950.
Say someone reaches this value, then that's it? Is there another way of getting more performance out of that engine combo, without changing the RPM of max power?

What I have in mind, is perhaps a way of decreasing TuBmax without losing performance, thus gaining some room to increase it again, in another way, that gives performance. Is that even possible?
I guess one way would certainly be cooling, but let's assume that is left aside.


Also, have you ever encountered this error?

[k14]

The baby girl is lost in customs somewhere - not a good feeling as this usually means the feckers are assessing for gst charges before release.
Anything the deemed valued over 500 including freight, is chargeable, but depends if the NZC agent had a good rogering the night before..

Just FYI, it's actually $400 (if there is no duty, which there isn't on motorbike parts). From here

When duty and GST are not payable:

Customs does not collect duty and GST where the total revenue payable on any one importation is less than $60.​

Also if you get stung then they will charge you another $38 on top of the GST, so if you goods are $400 you will end up paying another $100. Makes buying something under $400NZD a lot higher value when it is arrived. I have however bought bike parts/gear that has been over $1000 and not been charged, but have been charged on stuff in the $500-800 range, it's just pot luck!

[jasonu]

I've sent all sorts of mc stuff to NZ. I labeled it as used and vintage and so far have avoided any import charges.

[NordieBoy]

I've sent all sorts of mc stuff to NZ. I labeled it as used and vintage and so far have avoided any import charges.

Motorcycle stuff is generally duty exempt.
Not GST however...

[wobbly]

Re TuBMax, this is the temp of the unburnt end gases in the squish.
It is affected only by a few factors.The main ones being ignition advance and effective compression.
Effective com is composed of the static com as set by the cc in the head.Then you add dynamic com to this.
The dynamic com increases with charging efficiency ie more air/fuel in the cylinder per stroke - better trapping efficiency ie more air fuel kept in the cylinder per stroke, and lastly scavenging efficiency - less exhaust residuals left behind per stroke.
As you increase the last three mentioned, then the effective compression within the cylinder, as the piston approaches TDC, becomes greater, and more fuel is burnt - creating more pressure and heat, thus power.
Then you will reach a stage where the end gasses detonate, due to radicals forming,from excess heat and or uncontrolled pressure rise.
The only way to reduce this , is to drop the static com or reduce the ignition lead.
As you approach the theoretical limits of charging,trapping and scavenging efficiency,then you have to balance this with a static com and or ignition advance that will keep the piston alive.
This is exactly what happens on the dyno during development - its a juggling act to balance the com and advance to get the highest cylinder pressure you can, to release as much heat into the gas as is possible ,at the right time to suit the engine characteristics needed.
Com and advance put more of the finite fuel "energy" into the piston and cylinder and then eventually into the water - thus this energy is lost, and cannot be used in the external sense ie to heat up the pipe and generate
more overev .
But pushing the limits of all the factors ,in some form of synergy, is the black art we are only just beginning to be able to reliably juggle with in a good sim - without locking up a piston and a rod coming at you thru the screen.

Hope I never see that error on my screen - looks bad.