ESE's works engine tuner

[Flettner]

So to get STA in 'balance' we need EngMod?

[JanBros]

or you can use my excell :
https://www.kiwibiker.co.nz/forums/s...eads-and-pipes

since I can't change the first post , the most recent downloads are at the back op the topic on page 4

[wobbly]

I was just about to suggest JanBros spreadsheet - it works perfectly , and easily.
There are copies of it also in the Files section of 2 Stroke Research and Development on FB.
Dont go there for any other reason - its a shitfight mess of egoes and complete crap , showing birdshit Mig welded pipes and the age old " what does my sparkplug say ".

[Flettner]

I give up, tried to post pictures again but ..... computer says no.

[Flettner]

or you can use my excell :
https://www.kiwibiker.co.nz/forums/s...eads-and-pipes

since I can't change the first post , the most recent downloads are at the back op the topic on page 4

Some shit going on, all I see is a blank page?
But thankyou anyway.

[husaberg]

Some shit going on, all I see is a blank page?
But thankyou anyway.

https://www.kiwibiker.co.nz/forums/s...eads-and-pipes

[rgvbaz]

The 100cc conversions for rm and cr and ktm are 14mm 52mm
strike does 52mm 14mm pin pistons for kt100's
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

Cool, cheers for that 👍

I've been having a look and the ktm piston looks like a good possibility.

https://www.juddracing.com/products/...c-bigbore.html

Cheers

Dave

[F5 Dave]

Engineering first. Tuning second.

[JanBros]

Some shit going on, all I see is a blank page?
But thankyou anyway.

as I sid above : latest downloads are at the back op the topic on page 4 as I can't change the openning post


https://www.kiwibiker.co.nz/forums/s...nd-pipes/page4

[ApolloMotoMoto]

latest downloads

Heya JanBros!

I wanted to thank you for putting this excel together and for keeping it maintained.

It is a 'must have' tool for designing a portmap.

I have used it for the race-teams cylinders for the past 2 years and the whole team is routinely amazed how accurate the "predictions" are.

We have a basic Performance Trends Inertial Dyno that Performance Trends helped us spec out for our engines that will be used in the future to start validating the power targets, but the "peak torque RPM" from the spreadsheet has been DEAD NUTS on everytime.

We use 80/85cc dirtbike pipes for our engines (I am not really interested in a "custom" pipe until I can start designing them in EngMod) and we will take the OEM dyno sheet for a given pipe and use the peak torque RPM from that dyno sheet as the peak torque RPM "target" in the JanBros spreadsheet in order to create a "good portmap" for that pipe.

It has been working amazingly well in combination with tunable taipipe restrictors to tune the stinger nozzle diameter in for a given setup, essentially using the stinger nozzle size to "adjust" for the BMEP difference between the engine that particular dirtbike pipe was designed for VS the BMEP our engine is actually pumping into the pipe.

I dont think the results we are achieving would be even close to possible without the uderstanding of port "STA" and the philosophy around "balancing" the Blowdown STA to the Transfer STA.


Cheers to all involved, you know who you are!

[ApolloMotoMoto]

The calculator simply uses 75% of the total effective port area as a guide.
This always works and always makes alot 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 tripple ports) needed for lots of blowdown - thus power.

It was never intended to be used with a single port only as I havnt 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.

Did you model the nozzle as a short tapered section ( 30mm say) from the duct exit up to the header dia ( as the first section of the pipe) and this is made as an oval to round transition in the flange on T port and tripple port designs.

Be real interesting to see if the sim reflects reality on a dyno, in your single port scenario TeeZee.


---------------------------------------------------------------------------------------------------------------------


From doing hundreds of simulations and building more engines than I care to count, the best power is made by matching the header inlet area to the total Ex effective area, but reducing
the duct to around the 75% as mentioned.

But when you have a single Ex port, out at 72% or whatever, and lift it to the max at around 200+ duration, the power is ALWAYs limited by the blowdown STA available.
A simple trapezoid will never be able to match a T port for ultimate blowdown STA capability.
Thus having a limited power capability, we already have a matching small port and duct.
I have found in many cases that power will go up if the duct exit is made around 90% for things like a TZ350, that has a big port, but the bmep ,thus power, is fairly low.

As Frits has alluded to we should be matching the duct to the blowdown available, and this would give a much better approximation to the ideal duct exit needed.


---------------------------------------------------------------------------------------------------------------------


Determine the chordal area of the port at the bore face x Cosine of the roof down angle x 0.75/2 = area of each of the two duct exits.
This assumes a T or 3 port setup with shit tons of Blowdown STA.

For a race single port the multiplier is around 0.9 but for those low bmep engines the bulk gas flow is slow compared to a " hot " engine so in this instance I have been down to around 0.8x to get the exit up near 0.8 Mach.

While we are talking about the "Wobbly Duct" exhaust duct nozzle concept, especially in the context of "non-tripple/T port" designs; like Flettners example of the twin port/ twin duct...

I am in the process of assisting in the design of a cylinder, and I am currently working on applying this "Wobbly Duct" concepy to a LOW BMEP single exhaust port engine.

By LOW BMEP I am talking an 85-90cc engine with a transfer port layout matching the single speed/ direct dirve KA100 Kart cylinders, but with a single exhaust port at 70% width.

Low timing for broad single speed/ direct drive power curve.

Low BMEP target because we only "need" to make ~15hp @10,500 rpm peak power to be pretty dominant compared to what currently shows up to the paddock.

This translates to 8.5 - 9 BMEP at a peak torque RPM of 9,500 rpm in the JanBros spreadsheet.

Yep, thats LOW.

In the linked images (I cant seem to upload any images directly):

I have a picture of the CHORDAL dimensions of the exhaust port window with its resulting area. (axial and radial exit angles are both 0deg currently, so there is no cosine reduction to perform) Along with a circle that yields 80% of that area, and a circle that represents 100% of that area.

Also included is a 'rough draft' of the proposed exhaust duct as cast in the cylinder with bolt on exhaust flange/ spigot and the first section of the pipe that will mate to this spigot.
-"restriction point" is 1.5x the bore diameter from the exhaust port face/ cylinder edge. The "back to 100%" point is 2x the bore diameter from the exhaust port face.

Dimensions: https://ibb.co/qJwLrXP

Exhaust Duct Draft: https://ibb.co/n37JXsB


Questions:

-Am I doing this right?

-Is 80% at the restriction point a fair place to start given the BMEP target of the engine?

-Given this is a single exhaust port at 70% port width (shape matching the "FOS Ideal 70% Port Shape" document), should the port shape at the 80% restriction point still be an ovoid to "pull" better on the outside edges of the single port? I have it as a circle in the image below, but I have a feeling this "should" be an ovoid, perhaps not with the "ears" of an Aprilia RSA, but closer to the older Honda shapes?

[JanBros]

tnx for the nice words, but I just put the knowledge of other people who shared it for free here and on pitlane ( ) together into one spreadsheet. Nothing of it is mine , and since it is not mine I simply couldn't ask money for it.

[husaberg]

Cool, cheers for that ��

I've been having a look and the ktm piston looks like a good possibility.

https://www.juddracing.com/products/...c-bigbore.html

Cheers

Dave

Strike are made for iron liners most KTM are made for coated.
Strike which is a family business based in AUS will make pistons with custom pined rings in any oversize not .25 of a mm if you use KTM you are stuck with 3 fitting pistons abc . Strike do hone to size pistons.
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

piston dimenions KT100s
https://cdn.revolutionise.com.au/sit...avzy51kppz.pdf

or custom applications for AIDKA and Speedway racing applications Custom options include: High Ring Rotated Anti Rotation Pin for reeds and rotaries Dykes rings Sizes are made to order Rings to suit are dependant on application

PSS001 - Piston KT100S Smooth Finish Smooth piston skirt finish To suit Yamaha KT100S and ARC SPEC100 for AKA racing applications Size increments 0.05mm between Æ52.0 and Æ52.75 then 0.01 increments above Æ52.75mm Ring to suit is p/n PRS001 These are aus pasos S001 Piston KT100S Std $83.00 PS002 Piston KT100S >Ø53.00* $83.00 PS003 Piston KT100S >Ø53.75* $83.00 PS004 Piston KT100S Special** POA PSS001 Piston KT100S Std Smooth $91.50 *Not legal for AKA sanctioned events **Custom options: Indexed A/R Pin Location to any angle PRS001 P/Ring KT100S Std $21.50 PRS002 P/Ring KT100S Big Bore 53.5, 55.25, 55.5 $36.00 C001 Circlips Ø14*Ø1.0 x 50 off $45.00 PB001 Pin Bearing Thompson $18.00 PP001 Piston Pin Ø14*Ø8.9*40.4 $7.50 PP002 Piston Pin Ø14*Ø10*40.5 (Light) 7.50

[wobbly]

Yep , an oval @ 80% sounds on the money to me.

[yatasaki]

Cool, cheers for that ��

I've been having a look and the ktm piston looks like a good possibility.

https://www.juddracing.com/products/...c-bigbore.html

Cheers

Dave

Bad experience with mitaka lately on my kr1s, piston pin on both cylinders made one millimeter play in 1500km. Pin wasn't worn out and it was smooth but aluminum ...