Full systems and low-end
11-17-2006, 03:54 PM
#2
evil man of nothing
MotoGP
Join Date: Jan 2006
Location: Boynton Beach, FL
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Well I can answer your second question anyway...my two bros header comes together like an X-pipe and then splits apart again. Not what I would call a 2-1-2, its dual pipes except for the crossover.
11-17-2006, 03:57 PM
#3
Senior Member
SuperBike
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Posts: 1,011
almost always the trade off with more HP is you lose some torque down low to gain more hp up top. personally I'm happy with my slip ons in terms of power. Tuning was enough of a nightmare for those so I can't imagine doing a full system...
11-17-2006, 04:24 PM
#4
evil man of nothing
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Location: Boynton Beach, FL
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With the fear of ticking a few others off who have been thru the tuning nightmares I've been through a bunch of different slip on systems and now have a two bros header with Leo slip ons and have NEVER had any issues with the way the bike runs. I've never rejetted unless the previous owner did, which he claimed to have not. I had a gsxr 600 with a built supersport motor (was a previously 600ss racebike) and an akrapovic header, and when I switched to a V&H muffler there was a HUGE flat spot @7k rpm but it dissappeared when I slipped the akrapovic muffler back on. Never knew a muffler could make that big a difference but just have never had any issues with the superhawk...maybe I'm not hammering on it enough to notice the difference but I've owned enough old crap to know what flat spots, etc are, and also had a tuned ZX12 too. Anyone else actually have problems with the way the bike runs with exhaust without rejetting?
11-17-2006, 04:29 PM
#5
evil man of nothing
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Join Date: Jan 2006
Location: Boynton Beach, FL
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Having said that once I'm done with the front end swap and get it computracked (chaching...)I do want to put in the ignition advancer I have and get the bike jetted and dynoed (chaching again)...but I'd like to find someone who actually knows what the hell they're doing. Prieto Racing's not far away, the guy who Mike Barnes rides/rode or still rides for. Wonder if they'll do anything with the superhawk? Ever wonder why we don't just leave these things alone and ride the wheels off them?
11-18-2006, 01:30 AM
#6
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SuperSport
Join Date: Dec 2005
Location: Sunshine Coast, Australia
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IMO the standard header is not real good. What you want is a header system with an interference design, rather than tuned length. Interference designs promote torque production, tuned length promote horsepower, as a general rule anyway. Get yourself a street system and it will be of an interference design more than likely. This will be better than a stock system.
11-20-2006, 04:07 AM
#8
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Hmmmmm......maybe the best answer here would be to tell you to look it up on the net, as it might give you a better answer than I can, but I will try and explain it briefly. I am no expert so I shall put it in simple terms, as I remember it.
An interference design is essentially pipes of unequal length, at the collector. What this does is make the gas pulses from each cylinder come at different times, therefore helping scavenging, and the gas flow from one cylinder sort of helps the gas from another. This is most effective at low rpm, it promotes torque, and is good for street engines.
Tuned length systems will have pipes of equal length to the collector. Ever seen a set of pipes on a car that wound around under the bonnet before meeting up? This is to get them the same length before the collector, and at higher rpm provides better gas flow and more power. This is more common on race type engines where lower rpm power is not as important.
I have a Moriwaki street system which has unequal length pipes, and a friend of mine has an M4 race system which looks like there is a snake coiled up under the rear suspension. Totally different in their design.
Hope this sort of answers your question. If anyone sees an error here, please post away!
An interference design is essentially pipes of unequal length, at the collector. What this does is make the gas pulses from each cylinder come at different times, therefore helping scavenging, and the gas flow from one cylinder sort of helps the gas from another. This is most effective at low rpm, it promotes torque, and is good for street engines.
Tuned length systems will have pipes of equal length to the collector. Ever seen a set of pipes on a car that wound around under the bonnet before meeting up? This is to get them the same length before the collector, and at higher rpm provides better gas flow and more power. This is more common on race type engines where lower rpm power is not as important.
I have a Moriwaki street system which has unequal length pipes, and a friend of mine has an M4 race system which looks like there is a snake coiled up under the rear suspension. Totally different in their design.
Hope this sort of answers your question. If anyone sees an error here, please post away!
11-20-2006, 09:23 AM
#10
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Location: South Lake Tahoe, CA, USA
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Good comments, shane.
I didn't notice any lack of torque with my Mori full system. Defiinte improvement in top end. Not sure about how it works on a stock engine, but my cam timing was not hugely different from stock to keep the midrange strong.
I didn't notice any lack of torque with my Mori full system. Defiinte improvement in top end. Not sure about how it works on a stock engine, but my cam timing was not hugely different from stock to keep the midrange strong.
11-20-2006, 01:52 PM
#11
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An interference design is essentially pipes of unequal length, at the collector. What this does is make the gas pulses from each cylinder come at different times, therefore helping scavenging, and the gas flow from one cylinder sort of helps the gas from another. This is most effective at low rpm, it promotes torque, and is good for street engines.
11-20-2006, 02:59 PM
#12
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Superstock
Join Date: Sep 2006
Posts: 308
Shayne
You have the basic theory right, but some of the details are not correct.
Any exhaust system is 'tuned'. It will have a set RPM "range" where it will work it's best. That "range" may be low end, mid range or high end. Even a straight pipe has a tuned 'range' where it will work best, dependant on, pipe diameter, pipe length and cylinder displacement(Exhaust valve timing and duration which = exhaust gas velocity).
Some highly developed systems (F1, and other true race exhaust systems) work at MULTIPLE RPM ranges. They have a "primary" tuning point where the engineers/designers wanted the max benefit, and as an ancilary benifit, there might be one or more "secondary" rpm points where performance is increased.
Any pipe junction (2 into 1, 3 into 1, or 4 into 1) [or organ pipe resonating chamber/pipe] will introduce a reflected wave back to the exhaust port (ports). Due to pipe size(diameter) and pipe length, cylinder displacement(Exhaust valve timing and duration which = exhaust gas velocity) determines WHEN that reflected wave reaches the other exhaust port(ports)s.
Also, any pipe termination (your muffler tip or tips) will introduce a reflected wave back to the exhaust port (ports). Again, depending on pipe size(diameter) and pipe length, plus cylinder displacement(Exhaust valve timing and duration which = exhaust gas velocity), determines WHEN that reflected wave reach the other exhaust port (ports).
The "strength" of the reflected wave depends on the above parameters, plus atsmopheric conditions.
If you really want to go uber geek on the topic, this is your bible.
http://www.themotorbookstore.com/scdeofexinsy.html
However, unless you're going to start dyno testing your own exhaust confgurations, I highly reccomend you simply buy what's out there and save your hard earned dollars.
You have the basic theory right, but some of the details are not correct.
Any exhaust system is 'tuned'. It will have a set RPM "range" where it will work it's best. That "range" may be low end, mid range or high end. Even a straight pipe has a tuned 'range' where it will work best, dependant on, pipe diameter, pipe length and cylinder displacement(Exhaust valve timing and duration which = exhaust gas velocity).
Some highly developed systems (F1, and other true race exhaust systems) work at MULTIPLE RPM ranges. They have a "primary" tuning point where the engineers/designers wanted the max benefit, and as an ancilary benifit, there might be one or more "secondary" rpm points where performance is increased.
Any pipe junction (2 into 1, 3 into 1, or 4 into 1) [or organ pipe resonating chamber/pipe] will introduce a reflected wave back to the exhaust port (ports). Due to pipe size(diameter) and pipe length, cylinder displacement(Exhaust valve timing and duration which = exhaust gas velocity) determines WHEN that reflected wave reaches the other exhaust port(ports)s.
Also, any pipe termination (your muffler tip or tips) will introduce a reflected wave back to the exhaust port (ports). Again, depending on pipe size(diameter) and pipe length, plus cylinder displacement(Exhaust valve timing and duration which = exhaust gas velocity), determines WHEN that reflected wave reach the other exhaust port (ports).
The "strength" of the reflected wave depends on the above parameters, plus atsmopheric conditions.
If you really want to go uber geek on the topic, this is your bible.
http://www.themotorbookstore.com/scdeofexinsy.html
However, unless you're going to start dyno testing your own exhaust confgurations, I highly reccomend you simply buy what's out there and save your hard earned dollars.
11-23-2006, 02:03 AM
#13
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SuperSport
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As RPV Hawk has shown, like most areas of engine development, there can be a lot to it sometimes. Easy when you can buy a system someone else has done the hard work on already though!
Off the shelf is the way to go I reckon, unless you are really keen.
11-25-2006, 07:05 AM
#14
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I think you guys are all missing one important point. Because the engines are a V configuration the whole 'equal length' thing goes right out the window. The 90° phase shift makes 'equal length' impossible. No matter what you will have unequal length because the system must be tuned for a particular rpm range (just one point actually, but the losses get slowly worse as you move away from this point so the effective power is a range).
There is a lot of fluid flow theory behind all of this. I will not bore you with all of that, just trust that if you wanted to design your own system that it would require a lot of trial and error to tune properly.
There is a lot of fluid flow theory behind all of this. I will not bore you with all of that, just trust that if you wanted to design your own system that it would require a lot of trial and error to tune properly.
11-27-2006, 09:28 AM
#16
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Join Date: Mar 2006
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I love my Slip on Scorpions and I didnt notice a power loss and they sound great. And they are inexpensive, PM me if you want the info on how I got them discounted.
12-01-2006, 11:46 PM
#17
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