SuzukiSavage.com - Tuning intake and exhaust

marshall13

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Re: Tuning intake and exhaust
Reply #15 - 05/17/09 at 18:57:30

the headpipe is 1 1/2 if it's really double tubed... so Lancer has posted, and as ive never seen him run for office, i have no reason to doubt him... so the pipe is probably dimensioned for the HP peak in the literature, around 5000 to 5500... as Verslagen pointed out, the zig-zag flow of the gas in the muff makes an "overall length" measurement kind of hard without dissection... the varying diameters on the interior of the muff will have an effect too....

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diamond jim

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Re: Tuning intake and exhaust
Reply #16 - 05/17/09 at 19:12:12

Yep, it is actually 1.5". For my exhaust, the first half (header) is 1.5" and the second half (pipe) is 1.75". So for formulas would it be reasonable to split the difference and use 1.625"? There will be a pressure drop when the exhaust passes from header to pipe but how significant do you think the 0.25" increase is?

I also need to correct info I posted somewhere about my quick test pipe from my M50 (800cc v-twin). It is 1" ID. I mentioned somewhere that it was 1.5" ID.

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marshall13

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Re: Tuning intake and exhaust
Reply #17 - 05/17/09 at 19:19:55

so, basically, all we've learned here confirms the assertion that this motor is but 1/8 of a 320 cubic inch v8... the pipe sizes jibe with what they hang as smallblock exhausts.... so, better inhaling, better exhaling, the next stop logically is spark... it's the only performance mod left that doesnt open the motor... then you can do a max stock baseline to compare internal mods too.... after that comes the real gains, but the real expense too...

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diamond jim Serious Thumper Offline Posts: 1425 North Alabama Gender:	Re: Tuning intake and exhaust Reply #18 - 05/17/09 at 19:27:16 What is the opening point of the exhaust valves BBDC with the stock cam?
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marshall13 Senior Member Offline the first step is to admit your ignorance Posts: 301 Fort Lauderdale FL Gender:	Re: Tuning intake and exhaust Reply #19 - 05/17/09 at 19:32:53 diamond jim wrote on 05/17/09 at 19:27:16: What is the opening point of the exhaust valves BBDC with the stock cam? it's a 224 degree at .050 lobe... so figure 20-ish, no more than 25 BBC, just as a guesstimate... the dr650 manual shows the cam profile, but not the savage...lol
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verslagen1

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Re: Tuning intake and exhaust
Reply #20 - 05/17/09 at 19:44:32

diamond jim wrote on 05/17/09 at 19:12:12:

Yep, it is actually 1.5". For my exhaust, the first half (header) is 1.5" and the second half (pipe) is 1.75". So for formulas would it be reasonable to split the difference and use 1.625"? There will be a pressure drop when the exhaust passes from header to pipe but how significant do you think the 0.25" increase is?

I also need to correct info I posted somewhere about my quick test pipe from my M50 (800cc v-twin). It is 1" ID. I mentioned somewhere that it was 1.5" ID.
http://i255.photobucket.com/albums/hh128/russ_diamond_jim/S4022076.jpg

Cremonestly putting on engineers hat... Minors rule Grin

Measure each section for length and diameter.
Calculate each section as if it stood alone.
Then calculate the percentage of each duct to the total length.
Multiply each section by it's percentage and sum together.
Taking off hat and tossing over shoulder, it's the weekend, don't want that on fer very long.

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marshall13

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Re: Tuning intake and exhaust
Reply #21 - 05/17/09 at 19:45:38

diamond jim wrote on 05/17/09 at 19:12:12:

Yep, it is actually 1.5". For my exhaust, the first half (header) is 1.5" and the second half (pipe) is 1.75". So for formulas would it be reasonable to split the difference and use 1.625"? There will be a pressure drop when the exhaust passes from header to pipe but how significant do you think the 0.25" increase is?

I also need to correct info I posted somewhere about my quick test pipe from my M50 (800cc v-twin). It is 1" ID. I mentioned somewhere that it was 1.5" ID.
http://i255.photobucket.com/albums/hh128/russ_diamond_jim/S4022076.jpg

ok, just reread that post... id calc the speed for the 1.625 pipe, and run all further calcs with all 3, and you'd get the answer by which most emulates your real world results...

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marshall13

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Re: Tuning intake and exhaust
Reply #22 - 05/17/09 at 19:48:39

verslagen1 wrote on 05/17/09 at 19:44:32:

diamond jim wrote on 05/17/09 at 19:12:12:

Yep, it is actually 1.5". For my exhaust, the first half (header) is 1.5" and the second half (pipe) is 1.75". So for formulas would it be reasonable to split the difference and use 1.625"? There will be a pressure drop when the exhaust passes from header to pipe but how significant do you think the 0.25" increase is?

I also need to correct info I posted somewhere about my quick test pipe from my M50 (800cc v-twin). It is 1" ID. I mentioned somewhere that it was 1.5" ID.
http://i255.photobucket.com/albums/hh128/russ_diamond_jim/S4022076.jpg

Cremonestly putting on engineers hat... Minors rule Grin

Measure each section for length and diameter.
Calculate each section as if it stood alone.
Then calculate the percentage of each duct to the total length.
Multiply each section by it's percentage and sum together.
Taking off hat and tossing over shoulder, it's the weekend, don't want that on fer very long.

you am de man, sir!! thanks for the tip, Verslagen

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diamond jim

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Re: Tuning intake and exhaust
Reply #23 - 05/17/09 at 22:01:31

So, running the diameter numbers, the stock header is tuned for max torque around 4250 rpms (using 3750 which is 500 below peak rpm).

For length at peak at 4250 rpms I get 101.54".

1700/3750 x 224 (degrees) = 101.54

This is about double the length of the stock exhaust which is approx 51".

101.54/2 = 50.7"

So is the stock exhaust tuned for exactly half pressure waves at 4250 rpm? Or is my math all hosed up?

If it's true, then extending or shortening the exhaust by 1" increments moves the peak up or down by about 62.5 rpm with each 1" change. And my 9" longer than stock exhaust has moved the peak up about 562.5 rpm, or just under 5000 rpm, compared to stock.

Then there's the transition from 1.5" to 1.75" pipe. On V8 motor headers, a reduction in pipe diameter of 1/8" will move the torque peak down about 650-800 rpms and the converse is true if pipe diameter is increased every 1/8" the peak torque is raised about 650-800 rpms. How much would the peak of our singles move with each 1/8" change in diameter?

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marshall13 Senior Member Offline the first step is to admit your ignorance Posts: 301 Fort Lauderdale FL Gender:	Re: Tuning intake and exhaust Reply #24 - 05/18/09 at 00:29:34 verslagen1 wrote on 05/17/09 at 10:16:05: oops I forgot to take the square root. d^.5=rpm x .000469009259 inches 1.19 @ 3k 1.37 @ 4k 1.53 @ 5k 1.68 @ 6k 1.75 @ 6500 So we are tuned for peak HP close to a match, id say....
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diamond jim Serious Thumper Offline Posts: 1425 North Alabama Gender:	Re: Tuning intake and exhaust Reply #25 - 05/18/09 at 06:34:51 Listed specs show stock as: HP: 30.00 @ 5400 RPM Torque: 33.6 ft.lbs @ 3400 RPM Compression: 8.5:1 Bore x stroke: 94.0 x 94.0 mm (3.7 x 3.7 inches) What is the diameter of the internal pipe of the stock muffler and the overall length of the stock exhaust? I sold my stock muffler a while back.
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Duane Senior Member Offline Creatively Maladjusted Posts: 335 Terra Plane Gender:	Re: Tuning intake and exhaust Reply #26 - 05/18/09 at 08:42:35 After all this info, mabye I'll ride my stock muffler till it falls off or rusts out.
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bill67 Serious Thumper Offline old tired Posts: 8517 genoa city wisconsin Gender:	Re: Tuning intake and exhaust Reply #27 - 05/18/09 at 08:46:54 Stock s40 comes with a tuned intake and exhaust,Suzuki does as good as the other motorcycle companies in doing that.
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marshall13

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Re: Tuning intake and exhaust
Reply #28 - 05/18/09 at 08:59:34

diamond jim wrote on 05/18/09 at 06:34:51:

Listed specs show stock as:

HP: 30.00 @ 5400 RPM
Torque: 33.6 ft.lbs @ 3400 RPM
Compression: 8.5:1
Bore x stroke: 94.0 x 94.0 mm (3.7 x 3.7 inches)

What is the diameter of the internal pipe of the stock muffler and the overall length of the stock exhaust? I sold my stock muffler a while back.

id of the muff and length of stock exhaust are problematic measurements... as resident mad scientist Verslagen pointed out, the path the exhaust follows through the muff is far from a straightline, and 1 would have to calculate free volumes to get effective "pipe ids" for the various legs of its trip through..... i think one would have to section a complete muff lengthwise with say a bandsaw, and bust out the dividers... id suspect one would find an initial "expansion chamber", and a few choke points followed by smaller expansion chambers.... muffs are at odds with max performance... the ideal pipe is sized to retain as much energy in the exhaust stream as possible, while the muff absorbs that energy to slow the gases exit, and decrease the pressure diff at the muff outlet... the evidence of the energy absorbtion is the bluing that inevitably shows on the muff inlet...

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28891 L.A. California Gender:	Re: Tuning intake and exhaust Reply #29 - 05/18/09 at 09:11:38 the Hartman muf mod is worth a read. So D'Jim, when you going to the Dyno?
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