ESE's works engine tuner

[emess]

Hi everyone!



I just clicked a bit of your pipe programm in an excel-sheet. Whilst increasing the exhaust opening duration, the exhaust diameter at the piston (respective X) is decreasing. When I look at this statement:




This seems not to be right. Is this an error in the programm?

Regards,
Chris

Hi Chris
look at Frits' formula -
The diameters depend on X
X depends on 407 - Exhaust timing ..... etc
So as Exhaust timing increases, X decreases and hence so do the diameters.

so your spreadsheet is going the way Frits intended.

Mick

[TZ350]

The Timing numbers i have are, reading around the chart
0 is at TDC, Inlet closes 60 Deg, Exhaust opens 92 Deg, Transfer opens 120 Deg, Inlet opens 230 Deg, Transfer closes 241 Deg, Exhaust closes 269 Deg, Inlet period 190 Deg, Exhaust period 177 Deg, Transfer period 121 Deg, Were they barking up the right track for the time ? Cheers Fred

Hi Fred, those look to be very pedestrian timings, for comparison, my 56mm bore 50mm stroke rotary valve 1978 air cooled modified Suzuki GP125 Bucket engine.
Exhaust 200 degrees duration opens 80 atdc closes 80 btdc
Inlet 220 degrees duration opens 140 btdc closes 80 atdc
Transfers 132 degrees duration open 114 atdc close 114 btdc



Flat torque curve, repeatable runs.

[varthrix]

Happy New Year to TeeZee, Wobbly, Husa and all other kiwis. Frits, and all the other Europeans will have to wait for a couple more hours, but I wish you all Happy New Year in advance. Thanks to everyone who has contributed on this thread, I've learned a lot and have yet to learn even more.
Cheers everyone,
Kind Regards Jordan

[adegnes]

Happy New Year!

[TZ350]

Hi Fred, I have not worked with a Yamaha RV engine but here are some more 1978 Suzuki GP125/100 parts for comparison, hopefully they are helpful.

50.5mm stroke (56mm bore for the 125, 50 for the 100)
Crank wheels 86mm diameter.
Big end pin 19mm diameter.
Crank width 50mm
Rotary valve diameter 116mm and 1mm thick.
Inlet tract 25mm (24mm carb) for the GP125. Smaller for the 100.

The 56 bore x 50 stroke Kawasaki KE125 has a notably smaller diameter RV than the Suzuki. I think the 1978 Suzuki GP125 commuter bike engine was modeled fairly closely on the Suzuki RV racers of the 60's. By the late 60's and early 70's Suzuki certainly had a lot of experience and accumulated knowledge on how to make fast RV engines.



Rods, from left to right.

GP100/125 100mm C-C, 19mm bigend pin and 14mm little end pin.
RGV250 105mm C-C, 22mm bigend pin and 16mm little end pin.
Yamaha TZ/RD/RZ 110mm C-C, 22mm bigend pin and 16mm little end pin.
Yamaha RD400mm 115mm C-C, 22mm bigend pin and 16mm little end pin.

As the engine developed I have tried each rod. The RD400 rod is currently the rod of choice in my Suzuki GP engine and with the right L/E brg any of the longer rods can run a 15mm piston pin too.

The 50 and 56mm Suzuki GP piston had a 14mm pin but generally 56mm (and 54mm) pistons from the late 70's and 80's tend to have 16mm pins and later pistons from the 90's & 2000's tend to be 54mm and have 15mm pins.

The Timing numbers i have are, reading around the chart
0 is at TDC, Inlet closes 60 Deg, Exhaust opens 92 Deg, Transfer opens 120 Deg, Inlet opens 230 Deg, Transfer closes 241 Deg, Exhaust closes 269 Deg, Inlet period 190 Deg, Exhaust period 177 Deg, Transfer period 121 Deg, Were they barking up the right track for the time ? Cheers Fred

Hi Fred, those look to be very pedestrian timings, for comparison, my 56mm bore 50mm stroke rotary valve 1978 air cooled modified Suzuki GP125 Bucket engine.
Exhaust 200 degrees duration opens 80 atdc closes 80 btdc
Inlet 220 degrees duration opens 140 btdc closes 80 atdc
Transfers 132 degrees duration open 114 atdc close 114 btdc



Flat torque curve, and repeatable runs from my tuned Suzuki GP125 commuter bike engine.

Standard 1978 Suzuki GP125 commuter bike specs.

For what its worth here are our measurements taken from a Standard Suzuki GP125.
Bore 56mm Stroke 50mm 15hp at 8500 Rpm Carb 24mm. MJ 90 to 97.5
Inlet opens 145 BTDC closes 55 ATDC.
Exhaust opens 91 degrees ATDC Duration 178 degrees.
Area of exhaust port is 85mm# and 64% of bore width.
Exhaust port diameter at the flange is 36mm.
Trans1 opens 120 degrees ATDC Duration 120 degrees.
Trans2 opens 120.5 degrees ATDC Duration 119 degrees.
Boost opens 122 degrees ATDC Duration 118 degrees.

Lots of details about developing my Suzuki Bucket engine here:- https://www.kiwibiker.co.nz/forums/s...post1130055762

[Frits Overmars]

I just clicked a bit of your pipe programm in an excel-sheet. Whilst increasing the exhaust opening duration, the exhaust diameter at the piston (respective X) is decreasing. When I look at this statement:

Regarding your suggestion to base exhaust duct cross flow areas on blowdown time.area, that is what I keep preaching.

This seems not to be right. Is this an error in the programm?

Why should it not be right Chris? No error in your program either. You don't even need any maths or physics knowledge to figure this out; a bit of logic will do.
Time.area is time * area.
Increasing the exhaust opening duration means more time available for blowdown, so you'll need less port area for the same amount of blowndown time.area.

EDIT: I see that Emess beat me to it. Thanks Mick

Hi Chris, look at Frits' formula - The diameters depend on X X depends on 407 - Exhaust timing ..... etc
So as Exhaust timing increases, X decreases and hence so do the diameters. so your spreadsheet is going the way Frits intended.

[Twopints]

Thanks hasaberg, Grumph and TZ350 , prior to getting in contact with Kevin Drage and found out the Yamaha i was looking at one of these Suzuki specification

I as i said i don't know much about 2 strokes but comparing photos on the web of other engines ,the porting in the mouth of the crankcase of the Clisby the porting is very small, the inlet port that the disk valve opens is 19mm by 19mm and square

Then general arrangement drawing of the 24cyl motor the exhausts are packed in tight ,no expansion chambers and a difficult installation in a car that ends up with 6 of the carbs pointing down and 24 sets of points to adjust and 24 cylinders to be timed

In 1967 when it first came out the Cosworth DFV made 400Hp at 9000 Rpm using the standard Suzuki power figures (15Hp) the Clisby would have been 360 Hp and if an big if ,it could have been developed to point of your racer power it would be 686 Hp discounting for other losses in the bevel drives etc

But i think they had a lot of development ahead of them from were they started

TZ350 i will look through your bucket build

[Grumph]

Drivability would have been a big thing with the Clisby. Probably only a 4 speed box...So very conservative tuning to get it running.
Kevin Drage should be able to tell you how little the Repco made first up...But it was very drivable.

[Muhr]

I am not sure that this is everything SS90 has been talking about but it is good information.

I had to draw pictures and high light stuff to get my head around this.

Pic 1. As more power is developed, a hole/dip (Point B) appears in the the power curve just before max output (Point A).

The drivability of the bike is affected by this dip just before max power.

There is a trade off between power and drivability. (as we all know)

The main things that make more power, are, and in order of priority (1) the primary transfer tangental angle, (2) the inner transfer port radius, (3) the main transfer port axial inclination, (4) and main transfer port open size and shape. All high lighted in pic 2.

Pic 3 data from tests that show the trade off between power and drivability for the different variables.

Pic 4 configuration of the better test cylinders.

Get a copy of the paper from here:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

.

I was fiddling around with port arrangements and came to think about the inner radius of the ports(Pink in picture below). Searched a little on this thread and of course this topic has been touched. Found YZ350 posts, but unfortunately the link did not work. Has anyone done any tests on the subject?
I have felt that cylinders have gone against a bigger bulge over the last 10 years without having put any major thought on it

Best Regards Muhr

[SwePatrick]

Muhr, My experiance with porting both twostroke and foulstrokes is that one should beware of too tapered design in runners.
Flow might 'choke' and just halt the flow.

I would try to get more volume more upwards in the transferrunners.
And maybe a slight less big opening down to crankcase.
But still transferport as the smallest area to get airpseed to fill the cylinder properly.

Rgds.
Patrick

[TZ350]

Pic 4 configuration of the better test cylinders.

I was fiddling around with port arrangements and came to think about the inner radius of the ports. .... Has anyone done any tests on the subject?

The Yamaha paper in the post you quoted studied port arrangement extensively and their conclusion (picture 4) was that for a 125 an inner radius of 15mm and an outer of 55 gave the best transfer ratio on their test bench.

There will be pictures and drawings of the 50hp 125cc Aprilia race cylinder on here some place and you can bet those dimensions will have been the result of a great deal of experimental work.

There is a link on this page all about transfer port theory:- https://www.kiwibiker.co.nz/forums/s...tuner/page1000

[Muhr]

The Yamaha paper in the post you quoted studied port arrangement extensively and their conclusion (picture 4) was that for a 125 an inner radius of 15mm and an outer of 55 gave the best transfer ratio on their test bench.

Thanks! =)

I will dive into the archive and se if I can find something.

[TZ350]

Thanks! =)

Also there is a link on this page all about transfer port theory:- https://www.kiwibiker.co.nz/forums/s...tuner/page1000

[Muhr]

Also there is a link on this page all about transfer port theory:- https://www.kiwibiker.co.nz/forums/s...tuner/page1000

Super

[philou]

New piston wiseco

"the piston to self-adjust to the cylinder. The Racer Elite 2-Stroke Series pistons have enough clearance for the smallest cylinder, adequate clearance for the largest cylinder, and everything in between."

http://blog.wiseco.com/one-size-fits...stroke-pistons