SuzukiSavage.com - Tuned intake and exhaust track?

verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28752 L.A. California Gender:	Re: Tuned intake and exhaust track? Reply #15 - 09/27/10 at 15:50:22 Is there calculations for the optimum diameters as well?
Back to top	Versey's Place Tech Section Index IP Logged

Charon

Serious Thumper

Offline

Posts: 1811
Harvard, NE
Gender: male

Re: Tuned intake and exhaust track?
Reply #16 - 09/27/10 at 20:52:13

Rotary valves for two-strokers are nothing new. My 1966 Bridgestone 175 had them, and they were not really new even then. Their virtue is allowing asymmetrical intake timing(not possible with piston-controlled ports), and allowing the intake to open with less flow restriction than reed valves. Their drawback is that they require the carburetor to be on the end of the engine, which works fine for one or two cylinders but has serious problems with three. They also require some fairly close tolerances to avoid leakage. This is, of course, off-topic for the Savage.

The airbox in a sense substitutes for some of the length of the intake tract. Its volume is also resonant at some engine speed. The engine sucks in a gulp of air from the airbox, and the airbox sucks in air from outside. The outside air acquires momentum as it moves in to fill the airbox. When the air stops, its momentum is converted to pressure, so the pressure in the airbox can rise above atmospheric. At some engine speed, the intake valve will open just as the pressure in the airbox is at maximum, so flow will start more quickly. If this coincides with the pulses in the exhaust tract the engine can develop a lot of "free" power. But it will be very peaky. Manufacturers may try to put the intake resonance at a point where the exhaust is "flat" in an effort to smooth the torque curve.

Back to top

Eschew obfuscation.

IP Logged

ebonysresearch Junior Member Offline SuzukiSavage.com Rocks! Posts: 93	Re: Tuned intake and exhaust track? Reply #17 - 09/28/10 at 06:09:08 I have some carb diameter formulas and some stepped exhaust formulas. The carb diameter formula is usually done when they design the engine though...and a stepped exhaust is some serious fabrication. I'll post them after work.
Back to top	IP Logged

klx650sm2002 Serious Thumper Offline The more I learn the less I know. Posts: 2041 Cumbria,England Gender:	Re: Tuned intake and exhaust track? Reply #18 - 09/28/10 at 09:10:48 This is what happens at the end of a pipe. And this at a transition (diameter change) Clive W
Back to top	IP Logged

ebonysresearch Junior Member Offline SuzukiSavage.com Rocks! Posts: 93	Re: Tuned intake and exhaust track? Reply #19 - 09/28/10 at 15:54:22 Carb size : ( RPM x bore squared x stroke ) / ( 108000 = square root x 24.5 ) = Carb size in mm Carb size by intake valve diameter ( Intake valve diameter x .85 x 25.4 ) = carb size in mm Step exhaust : Step 1 25% of total exhaust length Step 2 32% Step 3 43%
Back to top	IP Logged

Trippah Serious Thumper Offline I ride, therefore I am. Posts: 2517 central Mass Gender:	Re: Tuned intake and exhaust track? Reply #20 - 09/28/10 at 16:21:00 the aside - Charon, do you do a route? I drive a ' big yellow bus' mostly to sporting events, occassionally as a sub, also vans when everyone hides. 40 something chatty little people can sure be noisy.
Back to top	IP Logged

Charon

Serious Thumper

Offline

Posts: 1811
Harvard, NE
Gender: male

Re: Tuned intake and exhaust track?
Reply #21 - 09/28/10 at 19:40:16

Trippah, I usually do field trips and sporting events. I sometimes run routes if one of the other drivers is unable for some reason.

We are a small K-12 school, so I get a little of everything. Perhaps the noisiest is a first or second grade field trip. The teacher will usually bring along a boombox and some children's CD. Then the kids sing along to the music. I have seriously considered earplugs.

Back to top

Eschew obfuscation.

IP Logged

BurnPgh Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1732	Re: Tuned intake and exhaust track? Reply #22 - 09/28/10 at 20:56:12 a boombox? My teachers always just told us to sit down and be quiet. Had one field trip where the rest of the class wouldnt do so. Teacher had the driver turn around and go back to the school. We copied a section of the dictionary for the duration of the planned field trip.
Back to top	IP Logged

verslagen1

YaBB Moderator
ModSquad

Offline

Where there's a
will, I want to be
in it.

Posts: 28752
L.A. California
Gender: male

Re: Tuned intake and exhaust track?
Reply #23 - 09/28/10 at 21:41:50

ebonysresearch wrote on 09/28/10 at 15:54:22:

Carb size :
( RPM x bore squared x stroke ) / ( 108000 = square root x 24.5 ) = Carb size in mm

Carb size by intake valve diameter

( Intake valve diameter x .85 x 25.4 ) = carb size in mm

Step exhaust :
Step 1 25% of total exhaust length
Step 2 32%
Step 3 43%

square root of what?
and what about that equal sign, don't look like it's in the right place.

Back to top

Versey's Place
Tech Section Index

IP Logged

Lupo Senior Member Offline Posts: 356	Re: Tuned intake and exhaust track? Reply #24 - 09/28/10 at 21:52:30 Whoa...this is the third night in a row that this has made me very sleepy...............
Back to top	IP Logged

ebonysresearch

Junior Member

Offline

SuzukiSavage.com
Rocks!

Posts: 93

Re: Tuned intake and exhaust track?
Reply #25 - 09/29/10 at 06:22:58

I'm having some trouble with that one too. Guess I should have taken better notes. it looks like a check mark in my notes...? freakin dumb harley technicians...

I just had my heads apart too when i re did it at work so I could have measured the intake valves. I'll look through my black book at work today and see if I have that equation available with better writing.

Back to top

IP Logged

ebonysresearch Junior Member Offline SuzukiSavage.com Rocks! Posts: 93	Re: Tuned intake and exhaust track? Reply #26 - 09/30/10 at 16:46:35 All right. I found it. Carb size: Square root of ( RPM x Bore X Bore x Stroke / 108000 ) = Carb size in inches. I am not finding the symbol for the Square root on my keyboard...?
Back to top	IP Logged

verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28752 L.A. California Gender:	Re: Tuned intake and exhaust track? Reply #27 - 09/30/10 at 17:31:35 (yada yada yada)^.5
Back to top	Versey's Place Tech Section Index IP Logged

LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10585 Oklahoma Gender:	Re: Tuned intake and exhaust track? Reply #28 - 10/01/10 at 04:13:41 OK SO WHAT ARE THE REAL NUMBERS ?
Back to top	IP Logged