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Making a tuned pipe...SERIOUS POWER!

A

andyinchville1

Guest
HI All,

I am in the process of trying to make a tuned pipe for out 70CC engines.
I am using a program that I downloaded that is supposed to give you all the
crucial dimensions for the pipe itself BUT It asks for some measurements and information that I do not have or can get easily.
I am hoping that the collective power of our brains can come up with all the info needed by the program so I can make a proper tuned pipe and report how well it works.

Some of the information I will need is:

1) The effective exhaust port diameter (mm).
2) Diameter at the Barrel Flange ( I am not sure what this is actually) (mm)
3) Length from the piston face to the flange
4) The exhaust port opening angle (degree ATDC)
5) Engine speed at max power (RPM)
5A) Mid section Mean exhaust temp at Max Power (degrees C....need an
infrared non-contact thermometer for this I guess)

Other info that may be helpful is: (this is used in another program but I think the program I am using can make do with the items 1-5A above)

6) Bore (mm)
7) Stroke (mm)
8) Connecting Rod Length
9) H.P.
10) exhaust port start opening angle (degree)
11) Exhaust port full open angle (degree)

If I can get all the needed info above I and a friend will begin the build ASAP and report our findings.

Thanks in advance for any and all help....Looking forward to making
some serious power (Hmmm we may soon be needing some sprockets in the 20T range before long!...HA)

Andrew
 


D

dave1490

Guest
HI All,

I am in the process of trying to make a tuned pipe for out 70CC engines.
I am using a program that I downloaded that is supposed to give you all the
crucial dimensions for the pipe itself BUT It asks for some measurements and information that I do not have or can get easily.
I am hoping that the collective power of our brains can come up with all the info needed by the program so I can make a proper tuned pipe and report how well it works.

Some of the information I will need is:

1) The effective exhaust port diameter (mm).
2) Diameter at the Barrel Flange ( I am not sure what this is actually) (mm)
3) Length from the piston face to the flange
4) The exhaust port opening angle (degree ATDC)
5) Engine speed at max power (RPM)
5A) Mid section Mean exhaust temp at Max Power (degrees C....need an
infrared non-contact thermometer for this I guess)

Other info that may be helpful is: (this is used in another program but I think the program I am using can make do with the items 1-5A above)

6) Bore (mm)
7) Stroke (mm)
8) Connecting Rod Length
9) H.P.
10) exhaust port start opening angle (degree)
11) Exhaust port full open angle (degree)

If I can get all the needed info above I and a friend will begin the build ASAP and report our findings.

Thanks in advance for any and all help....Looking forward to making
some serious power (Hmmm we may soon be needing some sprockets in the 20T range before long!...HA)

Andrew

if it,s the expansion chamber design utility prog.youll see 2 design,s 1 for wide band and 1 for narrow band.enter the prameters as listed{use 1 design only}wide or narrow power band.id pick wide band being{diffuser type 2.0,exhaust temp 500,diameter coefficients 2.125,tail pipe dia 0.7}for the barrel exhaust duct go to tools,then profiled exhaust port equ diameter.in-put your numbers,lenth of piston face is the lenth of the piston skirt,exhaust port opening angel is between 70 and 105{i didnt know this because it has to do with port mapping so i used 87}max rpm 6000.it came up with a 4ft pipe 2in in diameter for a 2 stage and 3in dia for a 3 stage with all the locations of the shapes and sizes needed.
 
Last edited by a moderator:
A

andyinchville1

Guest
HI,

Yes, it is the program that was mentioned on another thread on this site....I would prefer to use this program instead of the design on the Traxxis (I think) site since this utility will do all the figuring for you...it would be interesting
to see if the two cone up with similar pipe designs tho...

Just curious but how would one measure the connecting rod length?...is it the distance from the lower end of the piston wrist pin (on the rod itself) to the bottom of the connecting rod to where it meets the crankshaft?

Thanks
Andrew
 
D

dave1490

Guest
HI,

Yes, it is the program that was mentioned on another thread on this site....I would prefer to use this program instead of the design on the Traxxis (I think) site since this utility will do all the figuring for you...it would be interesting
to see if the two cone up with similar pipe designs tho...

Just curious but how would one measure the connecting rod length?...is it the distance from the lower end of the piston wrist pin (on the rod itself) to the bottom of the connecting rod to where it meets the crankshaft?

Thanks
Andrew

no, it,s from the center of the wrist pin to the center of the big end.you realy need the right tools to do this kind of job,for example to find the port angel you need dial indicator to find tdc{top dead center}then you zero the degree wheel and turn the crank to just when the port open,s the number on the wheel will give you the degrees angel.not eveyone has thies tools.
 
A

andyinchville1

Guest
HI,

Yes, I see what you mean...the proper tools in that case would be important...I mean to get the perfect distances of everything...Any idea how accurate the numbers need to be..I mean will a 3 or 4 mm one way or the other be too inaccurate?....I could probably measure better than that tho....A friend has a digital caliper accurate to the thousandth of an inch....I think the degree part would be the tough one for me ( I think I know what the tool looks like but don't know anybody that has one)....Are these specs available from somebody?...Who is the main importer of the 70 CC engines?...You think Duane at Dax would have these specs?...I may try him anyways.

Thanks again.

Andrew
 
A

andyinchville1

Guest
HI,

Just a FYI, I spoke with Duane at Dax earlier today and he does not have the
info we need.....so if any body else has an additional piece of the puzzle I'd love to hear from you!

Andrew
 
G

gone_fishin

Guest
as a planned project, i will be tearing one (dax 70) down to the sinew very soon to have a closer look.

when i do, i'll let you know & you can run me thru the measurements you need. i'm sure i can be accurate enough for the task 8)
 
A

andyinchville1

Guest
Great!....I am looking forward to the measurements!....I may also try tearing my helpers old engine apart just to see what the insides are like (he wrecked his bike awhile back and has not ridden it since even tho he is pretty much fully recovered by now....I almost hate to take it apart for fear of not getting it back together properly...Oh well the things we do for performance! ;-O

Andrew
 
O

OldPete

Guest
augi,

Google images of degree wheel, print out a couple and bond them to stiff cardboard. I like using 10" or 12" dia. because the spacing between degrees fits a coat hanger wire pointer.
Use a long reach spark plug as a positive stop to locate TDC. You know the drill, rotate the engine both ways till it stops then split the difference at the degree wheel.. Then DON'T bump the wheel or pointer once all is set.
 
J

just for kicks

Guest
I hope this project takes shape and there is a real tuned pipe for these in the future.


andyinchville1, If all goes as planned I may be in your area this weekend.
 
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