exhaust systems - torque curve variations - Suzuki GSXS1000 Forum
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post #1 of 31 Old 04-05-2018, 06:00 PM Thread Starter
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exhaust systems - torque curve variations

hi fellow gsx-s users, ive had a black widow full exhaust system on the bike for a week or two now, ive been comparing its performance to the extracter i had previously made for the bike, its still running the the same ecu reflash, which i admit wasnt fueling very well in the lower 1-3500rpm range, its apparrently difficult for the brake dyno tuner to get reliable info in that range., im thinking of an inertia dyno run with this b/widow exhaust to get a base run for comparision, we dont have a lot of dyno tuners for m/c's around my location, a couple in two cities a couple hundred km's away
but ive found a few differences with this b/widow ex system, with its decibel killer in the 300mm carbon muffler the lower 3k rpm responds better to under half throttle, 3-7krpm is very muted in its reponse, i.e a hole in torque curve , 7-11500rpm is strangled, power feels down by approx 10hp in this range, without the d/killer its stronger thruout midrange/topend slightly
the pipe i built used the same size header tubes for 165 ft /sec gas speed, but the b/wid has smaller secondary tubes, with fairly basic collecters which are marginally better than standard, i had also die ground the remains of the tig welding internally on the collecters prior to fitting as these have a negative effect on wave reversions. my next stage will be to remove the b/widow secondary pipes, install a proper set of race collecters and lenghtened secondary pioes to remove the hole in the mid-range power as i had with my pipe. ill put up some pic's for you all to see the differences between aftermarket and race built pipes, i.e they are internal not external as looks dont matter to to gas flow, shape does !
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post #2 of 31 Old 04-05-2018, 07:17 PM
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imagine if they made some sort of valve that changes position based on RPM so you could achieve maximal engine response by controlling exhaust gasses depending where you are on the curve.
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post #3 of 31 Old 04-06-2018, 07:17 AM Thread Starter
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imagine if they made some sort of valve that changes position based on RPM so you could achieve maximal engine response by controlling exhaust gasses depending where you are on the curve.
ive previously made mufflers that by their design, help the gas flow maintain a constant flow in and out regardless of rpm - that being a "recycling inertia" type muffler, think of a sock being turned inside out and you'll start to get the idea.
they are fairly involved to make but do work very well, they also weigh abit as they have 2 canisters and alot more internal plumbing than a "regular" muffler, ive developed various types of mufflers over the years, the best power gain i acheived was 22% max increase with a huge increase in torque thruout the rev range on a completely tapered exhaust system with a recycling inertia muffler. just about all the race mufflers you see on aftermarket exhausts are just a reduced outlet, back pressure, single baffle tubed design - as basic as it gets, though they are lightweight.
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post #4 of 31 Old 04-06-2018, 08:12 AM
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Temp...No doubt you know your stuff. My observation is this. There is a long standing belief among bikers that the only way to a achieve a good running bike is to have no restrictions in the exhaust and have it be as open as possible. If that were true, you would see 0 exhaust pipes on at at least some race engines because they would cause some restriction.

The problem is that these beliefs came into existence before active exhaust management existed.

The relationship of ideal exhaust tube diameter for an engine is linear and depends on desired flow rate per a given RPM.......The result being that a higher flow speed is typically favored at lower RPM (more narrow tube) and less flow speed at high RPM(wide tube).

Ferrari, for example, builds some cars with literally 2 sets of exhaust pipes. At lower RPM, the more narrow pipes are in use and then a "valve" shunts the gases to the wider set at higher RPM/throttle.

By the laws of physics, there is not one exhaust pipe setup for an engine that will be optimal for every part of the power curve....Your rpm/power keep going up and down as you ride and give/cut fuel delivery but your exhaust outlet is always the same.....This is why gsx-r1000 comes with 3 set valves. They are the best attempt to replicate a dynamic tube size.

The truly ideal exhaust would not have one diameter but would always be constricting or dilating. It would be made of something like the Terminator in T2.
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post #5 of 31 Old 04-13-2018, 03:06 AM Thread Starter
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Originally Posted by temporarykiwi View Post
hi fellow gsx-s users, ive had a black widow full exhaust system on the bike for a week or two now, ive been comparing its performance to the extracter i had previously made for the bike, its still running the the same ecu reflash, which i admit wasnt fueling very well in the lower 1-3500rpm range, its apparrently difficult for the brake dyno tuner to get reliable info in that range., im thinking of an inertia dyno run with this b/widow exhaust to get a base run for comparision, we dont have a lot of dyno tuners for m/c's around my location, a couple in two cities a couple hundred km's away
but ive found a few differences with this b/widow ex system, with its decibel killer in the 300mm carbon muffler the lower 3k rpm responds better to under half throttle, 3-7krpm is very muted in its reponse, i.e a hole in torque curve , 7-11500rpm is strangled, power feels down by approx 10hp in this range, without the d/killer its stronger thruout midrange/topend slightly
the pipe i built used the same size header tubes for 165 ft /sec gas speed, but the b/wid has smaller secondary tubes, with fairly basic collecters which are marginally better than standard, i had also die ground the remains of the tig welding internally on the collecters prior to fitting as these have a negative effect on wave reversions. my next stage will be to remove the b/widow secondary pipes, install a proper set of race collecters and lenghtened secondary pioes to remove the hole in the mid-range power as i had with my pipe. ill put up some pic's for you all to see the differences between aftermarket and race built pipes, i.e they are internal not external as looks dont matter to to gas flow, shape does !
Heres some reference pics so you can see the different length dimensions
the black widow ex basicly doesnt have secondary pipes, which a 4-2-1 traditionally have, i have repaired the exhaust i built that was damaged, ive reinstalled it for back - back impressions. the biggest performance difference is the midrange torque/power, which is fairly flat on the b/widow pipe, is in effect a bulge with my pipe, this is utilizing the same carbon 300mm b/widow muffler , which is internally mted on my pipe as the tail pipe is 2 sizes larger @53mm id , vs 53mm od on blac widow.
Attached Images
File Type: jpg exhaust 006-s.jpg (329.8 KB, 138 views)
File Type: jpg exhaust 008-s.jpg (91.3 KB, 107 views)
File Type: jpg exhaust 009-s.jpg (71.0 KB, 104 views)
File Type: jpg exhaust 001-s.jpg (118.6 KB, 111 views)
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post #6 of 31 Old 04-13-2018, 06:53 PM Thread Starter
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Originally Posted by dqban View Post
Temp...No doubt you know your stuff. My observation is this. There is a long standing belief among bikers that the only way to a achieve a good running bike is to have no restrictions in the exhaust and have it be as open as possible. If that were true, you would see 0 exhaust pipes on at at least some race engines because they would cause some restriction.

The problem is that these beliefs came into existence before active exhaust management existed.

The relationship of ideal exhaust tube diameter for an engine is linear and depends on desired flow rate per a given RPM.......The result being that a higher flow speed is typically favored at lower RPM (more narrow tube) and less flow speed at high RPM(wide tube).

Ferrari, for example, builds some cars with literally 2 sets of exhaust pipes. At lower RPM, the more narrow pipes are in use and then a "valve" shunts the gases to the wider set at higher RPM/throttle.

By the laws of physics, there is not one exhaust pipe setup for an engine that will be optimal for every part of the power curve....Your rpm/power keep going up and down as you ride and give/cut fuel delivery but your exhaust outlet is always the same.....This is why gsx-r1000 comes with 3 set valves. They are the best attempt to replicate a dynamic tube size.

The truly ideal exhaust would not have one diameter but would always be constricting or dilating. It would be made of something like the Terminator in T2.
yes you are correct , ideally the pipe size and length would vary thruout the revrange, but i havent found a practical way to do this on a m/cycle due to contrictions for space/ weight., what i have previously made that does a very simular effect is convergent tapered exhaust pipes, the problem is the tapering needs to match the engines flow rates, the sizing is determined by the amount of heat/ flow produced, so largest by port, smaller the further away from port, and the entire ehaust system requires to be tapered , it does amazing things to the powerband and most of all to the torque curve when you get it right though,.
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post #7 of 31 Old 05-31-2018, 12:55 AM Thread Starter
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heres some pics of the modded black widow pipe, which has transformed it into a torque monster, previously the power curve was fairly good at the bottom with the decibel killer in place, seemed abit less with it out, in the midrange though it was decidedly lacking, had a defined stage where the topend power took over and seemed strangled tne nearer to the redline you got., but without the deci killer the midrange was slightly more responsive and the top end power was seemingly better than the stock exhaust.
now with the secondary pipes lengthened to where i have calculated is the correct volume , the bottom end is even better than b4 with the modded deci killer in place, the midrange is really bulging with torque, which leads into a much improved topend over stock.
it bewilders me why black widow dont take advantage of the extra power and torque available with this style of pipe arrangement....

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Attached Images
File Type: jpg black widow 003.jpg (233.6 KB, 108 views)
File Type: jpg black widow 004.jpg (224.1 KB, 101 views)
File Type: jpg black widow 002.jpg (165.4 KB, 92 views)
File Type: jpg black widow 005.jpg (97.7 KB, 94 views)
File Type: jpg black widow 001.jpg (143.9 KB, 97 views)
File Type: jpg black widow 010.jpg (142.5 KB, 86 views)
File Type: jpg black widow 011.jpg (166.5 KB, 82 views)
File Type: jpg black widow 007.jpg (144.7 KB, 79 views)
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post #8 of 31 Old 05-31-2018, 07:13 AM
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Originally Posted by temporarykiwi View Post
now with the secondary pipes lengthened to where i have calculated is the correct volume , the bottom end is even better than b4 with the modded deci killer in place, the midrange is really bulging with torque, which leads into a much improved topend over stock.
it bewilders me why black widow dont take advantage of the extra power and torque available with this style of pipe arrangement....

-
Brilliant piece of work!

Would this work with the stock manifold. I'd have to pay loads of import tax to import a new manifold but could get my current manifold modified cheaply and easily. Would you need to delete the crossover pipes or leave them in place?
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post #9 of 31 Old 05-31-2018, 06:29 PM Thread Starter
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Brilliant piece of work!

Would this work with the stock manifold. I'd have to pay loads of import tax to import a new manifold but could get my current manifold modified cheaply and easily. Would you need to delete the crossover pipes or leave them in place?
i have noted that the stock header pipe is smaller than the port, those in between pipes have horrible internal obstacles to the ex flow, but yes i think you can gain a much improved midrange by giving this type of mod to the stock pipe, however the std manifold is a mass produced item with many descrepencies to the continuios flow of the ex gases
the std type collecters are very basic folded sheet vs formed bend type on the b/w and fully formed type on my ex, all these deficiencies do degrade the extra you can get, but i still think it would be worth it.
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post #10 of 31 Old 05-31-2018, 11:39 PM
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Originally Posted by temporarykiwi View Post
i have noted that the stock header pipe is smaller than the port, those in between pipes have horrible internal obstacles to the ex flow, but yes i think you can gain a much improved midrange by giving this type of mod to the stock pipe, however the std manifold is a mass produced item with many descrepencies to the continuios flow of the ex gases
the std type collecters are very basic folded sheet vs formed bend type on the b/w and fully formed type on my ex, all these deficiencies do degrade the extra you can get, but i still think it would be worth it.
Thanks, I will try it
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