Expansion chamber software design numbers
- Thread starter scott83
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2nd H2 slant head came in today...degree wheel in hand...clutch cover off...intake too..... guess ill have to get my own numbers....I'll update with my numbers...see if theyre are different ones out there ....Must be a REAL SECRET....LMAO..Thanks Micro nice link
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Had a little time this morning and got my timing numbers for the expansion chamber design software. the first picture is the gear puller with the bolt out attached with masking tape to the gear.
Works really good, the puller has a lip that fits almost perfectly inside the CD degree wheel I made up 2nd pic. Here is a link for a wonderful explanation on getting the numbers for both exhaust and transfer RC FAQ: How do I measure the port timing on my engine? , and a link for the right sized degree wheel picture to stick on that junk CD. How to determine the timing of your engine
I repetitively came up with 142 Exhaust and 114 intake 116 transfer had to pop off the head to get acurate measurement on the transfer. Now im off to measure an exhaust port area.
Works really good, the puller has a lip that fits almost perfectly inside the CD degree wheel I made up 2nd pic. Here is a link for a wonderful explanation on getting the numbers for both exhaust and transfer RC FAQ: How do I measure the port timing on my engine? , and a link for the right sized degree wheel picture to stick on that junk CD. How to determine the timing of your engine
I repetitively came up with 142 Exhaust and 114 intake 116 transfer had to pop off the head to get acurate measurement on the transfer. Now im off to measure an exhaust port area.
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Ricardo Wave is the only software that I know of that is truly accurate for the design of exhaust systems.
Jim
Jim
i think your numbers may be a little off, i got somewhere between 172 and 178 on the exh before i did any port work. thats why i don't raise the port very much. but then again, these motors are completely different than the next one on the assembly line. did you line up zero with bdc and not tdc, then note where the port is closed and double it?
as far as design is concerned, check out
Gordon Jenning's Archivek you can download it free. there is a formula on page 33 for figuring tuned length based on exh timing, and rpm for max power. the diameter of the port at the exh flange is another important measurement. other than those few things the rest sort of depends on what type of power curve youre after. i highly reccommend leaning towards the enduro side of things since you have a fixed gear. anyways, read the chapter on expansion chambers before, during, and after you build your pipe. i would stay away from the design software because you won't understand why you are using the angles youre using, therefore wont be able to modify or fine tune anything. but, here is an immensely helpful program that you cant do without and is free Cone Layout - Product
as far as design is concerned, check out
Gordon Jenning's Archivek you can download it free. there is a formula on page 33 for figuring tuned length based on exh timing, and rpm for max power. the diameter of the port at the exh flange is another important measurement. other than those few things the rest sort of depends on what type of power curve youre after. i highly reccommend leaning towards the enduro side of things since you have a fixed gear. anyways, read the chapter on expansion chambers before, during, and after you build your pipe. i would stay away from the design software because you won't understand why you are using the angles youre using, therefore wont be able to modify or fine tune anything. but, here is an immensely helpful program that you cant do without and is free Cone Layout - Product
You need a degree wheel to measure the event timing.
What I found was the best method for event timing is to remove the head and use a piece of paper in the port.
Rotate the crank with the degree wheel on until the paper is only just trapped by the piston and the roof of the port.
Set that point on the degree wheel as zero.
Then rotate the opposite direction until the paper is again trapped and read the degrees.
Write down that number as the port duration - no fancy maths needed...
Foureasy is right about the jennings book on making expansion chambers - the math is a bit difficult at first but it is very do-able. I have built a number of successful pipes and it is very simple to do. You really do not need the fancy pattern program though - just make a cardboard mock up of the pipe so you can get the fitment to your bike how you like and then use the mock up as a pattern to cut the metal to mig together.
Do not start with flat sheet - takes too long unless you are hydroforming a pipe - start with the closest diameter exhause pipe from a parts store, exhause shop or the dumpster behind the muffler place - that way most of the forming is already done for you.
What I found was the best method for event timing is to remove the head and use a piece of paper in the port.
Rotate the crank with the degree wheel on until the paper is only just trapped by the piston and the roof of the port.
Set that point on the degree wheel as zero.
Then rotate the opposite direction until the paper is again trapped and read the degrees.
Write down that number as the port duration - no fancy maths needed...
Foureasy is right about the jennings book on making expansion chambers - the math is a bit difficult at first but it is very do-able. I have built a number of successful pipes and it is very simple to do. You really do not need the fancy pattern program though - just make a cardboard mock up of the pipe so you can get the fitment to your bike how you like and then use the mock up as a pattern to cut the metal to mig together.
Do not start with flat sheet - takes too long unless you are hydroforming a pipe - start with the closest diameter exhause pipe from a parts store, exhause shop or the dumpster behind the muffler place - that way most of the forming is already done for you.
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