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Message started by Rohko on 06/20/12 at 19:14:03

Title: Mathmatic ideals for header/tail pipe dimensions
Post by Rohko on 06/20/12 at 19:14:03

Found this awhile back and thought it might be interesting.
Got the information in the attached picture from the online preview of this book:
http://books.google.com/books?id=aSKzZIqCk54C&printsec=frontcover&dq=how+to+build+a+harley+torque+monster&hl=en&src=bmrr&sa=X&ei=LX7iT8ywL-yr2AWjq4zLDg&ved=0CDkQ6AEwAA#v=onepage&q=how%20to%20build%20a%20harley%20torque%20monster&f=false
I think I managed to get all the really useful information from the preview and compact it into that image, but there is probably something good from the part that I can't see in the preview.

Title: Re: Mathmatic ideals for header/tail pipe dimensio
Post by verslagen1 on 06/20/12 at 19:53:57

gas velocity = piston speed x bore ^2 / pipe ID ^2
96.08 = piston speed x 3.7008 ^2 / 0.125 ^2, rpm = 2000
144.11 = piston speed x 3.7008 ^2 / 0.125 ^2, rpm = 3000
192.15 = piston speed x 3.7008 ^2 / 0.125 ^2, rpm = 4000
240.19 = piston speed x 3.7008 ^2 / 0.125 ^2, rpm = 5000
288.23 = piston speed x 3.7008 ^2 / 0.125 ^2, rpm = 6000

and a cool pic

5255410F0C094A540B09090B390 wrote:

This is what happens at the end of a pipe.
And this at a transition (diameter change)
Clive W :)

http://i119.photobucket.com/albums/o147/klx650sm2002/Wavereflection.jpg
http://i119.photobucket.com/albums/o147/klx650sm2002/Transition.jpg

Title: Re: Mathmatic ideals for header/tail pipe dimensio
Post by verslagen1 on 06/20/12 at 20:05:54

And let's not forget these...

4E49444552584C474A58582B0 wrote:

I found some of my old engine building formulas. I was taught the same concept but different. we go over this at work with customers wanting shorty drag pipes...they dont realize that it pushes their power band over their red line and they will never see the power. Even on the dyno with the EGA readings it is such a pain to get it right but with open pipes there is always a dead spot in the lower RPMS

Exhaust Header Length *L = Pipe Length
Thermal 1st wave: L=(1380 x (180 Degrees + Exhaust Valve Opening)) / RPM Desired.

Sonic 2nd wave:L=950 x (180 degrees + Exhaust Valve Opening)) / RPM Desired

Intake Track tuning with known pipe length:
2nd pulse: (1100x 1/2 Intake cam duration x .96) /RPM =Length

3rd pulse: (1100 x 1/2 Intake cam duration x .705) / RPM = Length

4th pulse: (1100 x 1/2 Intake cam duration x .538) / RPM = Length

So now I am looking up the cam specs and will get back. Of course I am lazy and a dumb ol Harley technician and would love for someone to check my math. I am thinking about cherry bombing my exhaust which will pass inspection in WV as an open baffle(must have baffles to pass in WV) but I am thinking about making a custom intake. In school the dyno teacher turns off the lights and we started a carberated bike and shined a flashlight a few inches out of the carb to watch the air fuel mixture...reversion is what it is called. then we changed all sorts of exhaust and intakes to watch the changes. Dynos dont lie...people do.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1285523233/8#8

Title: Re: Mathmatic ideals for header/tail pipe dimensio
Post by verslagen1 on 06/20/12 at 20:06:40

3D2E3938272A2C2E257A4B0 wrote:

From lancer's ebay page...

Stock Cam Lift: 0.254" In / 0.244" Ex

Stock Cam Duration: 224 deg @ 0.050" lift

Title: Re: Mathmatic ideals for header/tail pipe dimensio
Post by verslagen1 on 06/20/12 at 20:08:02

And while we're at it...

2B0E020A04320017000604610 wrote:

How far from the engine can you place the carb?

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1317050414

Title: Re: Mathmatic ideals for header/tail pipe dimensio
Post by Paraquat on 07/02/12 at 09:29:33

The math for the carb that I was able to come up, based off the math from my exhaust size thread, was 3" valve including the runner.

--Steve

Title: Re: Mathmatic ideals for header/tail pipe dimensio
Post by Paraquat on 07/02/12 at 11:35:34

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1336587954
It's been requested that I provide a link so here's the math for the exhaust diameter and length.

Following the same text that cat provided for exhaust size I was able to solve for intake.
http://www.bgideas.demon.co.uk/tmanual/Tm_Ch2.pdf

I'd post the math but my break is over.

--Steve