TAFB
Expert Class
Posts: 138
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posted May 18, 2004 06:18 PM
Dyno with and w/o cat mod
Thanks to Paul and Kevin at Fast By Gast (Grand Island, NY) for taking good care of me on the dyno and letting me use the shop to remove my cat.
Dynojet 150 with 200 module; temp 83 degrees; barometric pressure 29.45 Hg; vapor pressure 0.43 Hg. (hot and humid for Upstate NY).
Here are my dyno numbers...with the cat, the bike pulled 143.5 SAE hp stock. Just to give you some sense of comparison, I was told that stock Busas generally pull 149 SAE hp on their dyno. I removed the cat (hammer and chisel), and we dynoed the bike again. Top end saw an increase of about 1 hp to 144.4 SAE hp (147.4 STD) and 73.8 ft lbs torque (ran in 4th gear and 5th gear...same result). The largest increase came in the 7-8000 rpm range...up 3 hp without the cat. Bike sounded better too (deeper, throatier exhaust noise). I did not put any holes through the internals of the exhaust...only removed the cat.
  
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Hamilton
Novice Class
Posts: 49
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posted May 18, 2004 08:52 PM
Thanks for the post, I think I'm going to try this.
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dket
Expert Class
Posts: 189
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posted May 18, 2004 11:53 PM
 Edited By: dket on 19 May 2004 02:37
Numbers sound good TAFB . I would really like you to punch 2 holes and dyno again . Just want a second opinion as I already have done this mod . My pics are on this forum . The 2 holes are where the extra exhaust gas flow really comes into play .
Also TAFB did not mention a Power Commander 3 was installed . Not bad for FREE huh TAFB !
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TAFB
Expert Class
Posts: 138
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posted May 19, 2004 04:31 AM
the price is right. no PC3, just removal of the cat. should be enough to hold me over to a new pipe.
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salsa1
Needs a life
Posts: 5971
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posted May 19, 2004 04:44 AM
Mr. Dket should it follow that anything bigger than two holes allow for more flow? I can see the plate from the tail end viewd from an angle so it's apparent it creates a clean break through.
Do ya Think a guy could make openings too big and mess up plate. I am asking myself and whoever can answer how much is too much on opening thru plate? whats the worst that can happen?
Thanks in advance.
good job!
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DKET
Expert Class
Posts: 189
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posted May 19, 2004 07:11 AM
You could never open up the midplate too much . The exhaust gas still exits through the same exit pipe . The more you open up the midplate the more of a deep Ferrari sound you get . 2 ONE INCH HOLES ARE ALL YOU NEED . Exhaust exit tube on the can is only like 1.5 inches in diameter , haven't measured it .
Don't worry about messing anything up . You can remove the entire midplate and will cause no harm . Besides when the full systems are out in a month or two there will be tons of stock cans for sale cheap .
The final 'SOUND" comes from the exhaust exit tube diameter and length . The larger in diameter the total exit is , the deeper the sound will be . It is all about tuning resonances . Take a glass of water and a straw . Place the straw at the bottom of the glass . Now blow across the straw and listen to the tone . Now while blowing raise the straw in the water . The pitch will become lower in frequency . You can do this with a coffee straw and a McDonalds drink straw . That will simulate a larger diameter exhaust outlet pipe . I can see SWFT at McDonalds right now trying this out , haha .
Akrapovic tends to use 50mm outlet pipes . That is roughly 2 inches in diameter . That is why their pipes are so quiet . Smaller pipe kills the sound . Also is why the Akrapovic has a high raspy pitch to it that I dearly hate . The Akra runs like 60mm mid-pipes and finally chokes the muffler to 50mm for sound reduction . They use a conical muffler core .
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salsa1
Needs a life
Posts: 5971
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posted May 19, 2004 07:26 AM
Edited By: salsa1 on 19 May 2004 08:46
I like your explained rational answers DKET ;being an engineer it's the kind I myself appreciate most.
Thanks for your time....
Thanks also to TAFB for posting results.
Peace.
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runninhorn
Expert Class
Posts: 442
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posted May 19, 2004 07:44 AM
I just did this to my stock can, granted the redneck route, but man, it did make a good difference power wise, and noise wise. I took a saw, cut the end of my can off. I then took a dremel, drill and chisel/hammer and went to work on the honeycomb cat and got 100% of it out (it took a while) I then took some lanscaper spikes, drove 4 small holes on each side of the Center X in the mid plate. I then took a larger spike, and made the holes bigger. I then took a wood post, like you see on all the garage sale signs, shaved the end to a point, and drove it thru all the holes, and at the end, it caved in and collapsed and made one big hole. Now I messed up a little on the can as I had it held in a vice, with cloth all around, but wasnt paying attention and it scuffed the side up a little, but after I got my one big hole punched, I welded it back together and it indeed does sound like a ferrari, and made some power gains, but the key is the hole(s) you punch once past the honeycomb, because at first, I too just took out the honeycomb cat, welded it back together and put it back on with little to no difference..........
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DKET
Expert Class
Posts: 189
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posted May 19, 2004 08:28 AM
runninhorn , did you not read my original post on this can mod ? I am curious as to why you are cutting and welding your can .
A very large screw driver and hammer will and DOES remove the cat . 1 inch rebar steel used to reinforce concrete ground to a point will and does punch a perfect hole in the midplate . I spent around 30 minutes tops on my can mod . Plus my can is still in perfect shape , no vise gouges . I didn't even use or need a vise . You see what I am getting at ? I am not attacking you runninhorn , just trying to understand you is all . No doubt it is your bike and will have a slip-on or full system soon .
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runninhorn
Expert Class
Posts: 442
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posted May 19, 2004 08:43 AM
quote:
runninhorn , did you not read my original post on this can mod ? I am curious as to why you are cutting and welding your can .
A very large screw driver and hammer will and DOES remove the cat . 1 inch rebar steel used to reinforce concrete ground to a point will and does punch a perfect hole in the midplate . I spent around 30 minutes tops on my can mod . Plus my can is still in perfect shape , no vise gouges . I didn't even use or need a vise . You see what I am getting at ? I am not attacking you runninhorn , just trying to understand you is all . No doubt it is your bike and will have a slip-on or full system soon .
Yea I read your original post, why cant I do something the way I WANT TO DO IT? You got most of it out, I wanted ALL of it out. I did it that way as I wanted the absolute most crap out of that can as possible, and I got that. I achieved what I wanted to and am satisified with it, and if i hadnt bought the slipon yesterday, I would have just painted the can black until my other system got here, I have a cool as hell dealer, that doesnt care about mods, so i wasnt worried about what the can looked like or whatever........it sounded good, and made more hp, thats all that matters....... 
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dnwhoop02
Expert Class
Posts: 204
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posted May 19, 2004 11:57 AM
RUNNIN>
didn't you just put a D&D on it anyway? and aren't you going to replace that with an Arata? or Sato? (I don't remember which) What, are you planning on opening a used exhaust store?
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David
'04 ZX-10R
'00 SV650
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salsa1
Needs a life
Posts: 5971
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posted May 19, 2004 12:05 PM
Hi guys... well; I measured 1 7/8 inch on rear exit of stock ZX-10R pipe (almost two inches).
Area of a circle is expressed by : Area = pi (3.14) x r (radius) squared.
a 2 inch hole has about 12.56 square inches of area where two one inch holes have a total of 6.3 square inches of area.
What does this mean? more than two one inch holes could benefit for optimum flow. Hole sizes required depends on how much flow is allowed around internal midplate.
Make any sense to you DKET?
No big deal; if bigger holes does not comprimize the structural integrity of anything inside then no damage done if bigger holes are done on midplate.
Should mention that I talked to dealer about warranty and aftermarket exhaust ;now he agrees that it affects zero on the warranty. Like I said before; I just heard "loose comment" from salesperson which I needed to look into. I paid about $600.00 for 5 year warranty.It's a non-issue as planned.
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runninhorn
Expert Class
Posts: 442
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posted May 19, 2004 12:07 PM
quote:
RUNNIN>
didn't you just put a D&D on it anyway? and aren't you going to replace that with an Arata? or Sato? (I don't remember which) What, are you planning on opening a used exhaust store?
LOL,yea, as you can tell i have no patience, and cant stand a quiet exhaust LOL........
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DKET
Expert Class
Posts: 189
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posted May 19, 2004 12:20 PM
quote:
Hi guys... well; I measured 1 7/8 inch on rear exit of stock ZX-10R pipe (almost two inches).
Area of a circle is expressed by : Area = pi (3.14) x r (radius) squared.
a 2 inch hole has about 12.56 square inches of area where two one inch holes have a total of 6.3 square inches of area.
What does this mean? more than two one inch holes could benefit for optimum flow. Hole sizes required depends on how much flow is allowed around internal midplate.
Make any sense to you DKET?
No big deal; if bigger holes does not comprimize the structural integrity of anything inside then no damage done if bigger holes are done on midplate.
Should mention that I talked to dealer about warranty and aftermarket exhaust ;now he agrees that it affects zero on the warranty. Like I said before; I just heard "loose comment" from salesperson which I needed to look into. I paid about $600.00 for 5 year warranty.It's a non-issue as planned.
Salsa1 ,
You might want to check you math out a bit .
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dnwhoop02
Expert Class
Posts: 204
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posted May 19, 2004 12:28 PM
I think he's just mixing up diameter with radius, using 2 for the radius of a "2 inch" hole... (I'm assuming that 2 inches is the diameter, not the radius) I don't think 2 1 inch radius holes would even fit in there... so the area figures should be 3.14sq in for the big hole, and .785 sq in for each of two smaller holes, totalling 1.57 sq in between them both.
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David
'04 ZX-10R
'00 SV650
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salsa1
Needs a life
Posts: 5971
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posted May 19, 2004 01:31 PM
Yeah I see what I did ;had trouble making sense out of squaring fractions so I rounded off and projected with larger numbers to verify to myself that one large hole ;say with 2 inch radius has more area than two small holes with 1 inch radius each.
Exit of pipe area versus sum of area of two 1/2 size holes inside plus flow around midplate should be equal or close for optimum flow correct?.
Math yields larger single hole has much more area as relationship has a squared factor and is not a simple summation of two smaller holes.
Now that makes sense....hehehe.
Did I unravel this deal yet?
Not purposely trying to confuse the issue with the facts.
Time to go home.Later gator.
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TAFB
Expert Class
Posts: 138
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posted May 19, 2004 04:16 PM
oh yeah, 1400 miles at the time of the dyno.
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salsa1
Needs a life
Posts: 5971
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posted May 20, 2004 04:19 AM
Edited By: salsa1 on 20 May 2004 05:23
Hi runninghorn;I like your tenacity; ha ha. just read how you progressed to make holes larger and larger until plate finally collapsed.... I will aim at making holes slightly larger than one inch diameter just in case myself;does not seem matter a whole lot as far as damaging anything. I do not want to leave something loose rattling inside when I am done.
I am figuring hole size assist for less total backpressure unless I am missing understanding something.
Will give it more thought when I do the work with exhaust can off the bike.
Have fun;stay alive.
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RichTJ99
Expert Class
Newbie
Posts: 153
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posted June 01, 2004 09:12 PM
umm. Where was the link with all the pictures for the stock can hack? I searched & found this thread, but I cant find the other.
Any help would be appreciated.
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Admin of http://www.zx-10r.net
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DB
Pro
Posts: 1932
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posted June 01, 2004 09:39 PM
Sometimes I think Runninhorn and dket are related (lol - just kidding guys, relax)
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Dan
04 ZX10r (Track only)
08 Concours14
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