Triumphrat

stevewal · 10-28-2009, 11:47 PM

Had the Bird up on the lifter today while I was designing some new pipes for her.
Dropped off the old ones and started her up ,the note coming from the Cat/converter is what we are all looking for ,very muffled and muted not at all offensive just right,it wont be long before people are just using dump pipes direct from the cat opening and removing the muffler completely.
The cat is a maze of baffles and doo dads that rob all our power.No matter what the Spin Doctors tell you,you will not get any power gains till the cat is removed.
Back to the drawing board to fab some longer ones that bypass the cat..
Will keep you posted
Stevewal

dazco · 10-29-2009, 12:03 AM

Thats what we're all hoping, but till we can tune these bikes we may not really know. My dealer says running sans cat w/o a proper tune for that can be damaging. I have no idea whether thats true but i don't want to be the one to find out. But even if it doesn't hurt anything, are you really going to see an performance gains w/o a tune optimized for running catless? Just questions we all have been pondering bt more so waiting to see what the answers turn out to be. If you do this all i can say is thank you for blazing this trail and i hope it works out w/o problems. Keep us informed.

steveg56 · 10-29-2009, 12:16 AM

Thats weird because D&D Exhaust says they tried a version of their pipes on the dyno with the Cat, and without, and not much change removing the Cat, so they kept it and just made slip ons. Someone will find out how to eek more power out of this beast

stevewal · 10-29-2009, 06:18 AM

I think D & D are playing with their Willies or they have heads full of wet sand.
Why would anyone developing a new exhaust system deliberately put it on the Dyno without any support mapping for running without a cat..The revs needed for dyno runs would have done untold damage to an unmapped engine.
Hope they own their own bike and did not use a customers????????? .
If we can /and we will get rid of the cat we can unleash untold power from the Bird,I am still working on the the longer pipe to bypass the cat ,then I will source out the racing tuning guys to write a map for me,it is not real difficult to map ,but the bird does have some type of sensor on the crank that will take a little time to sort.
Cheers
Stevew

dazco · 10-29-2009, 11:20 AM

Quote:

Why would anyone developing a new exhaust system deliberately put it on the Dyno without any support mapping for running without a cat..The revs needed for dyno runs would have done untold damage to an unmapped engine.

I was asked to lend my bike to BC for pipe development. There are several reasons i didn't, but that was the big one. I don't know about untold damage, but i wasn't about to chance it. Dynos are hard enough on a bike as is w/o doing it with an improper map, especially if overly lean.

mad_angler · 10-29-2009, 01:09 PM

bypassing the can will not do any damage with out the correct map, the bike could run like crap but no damage, the cat will add back pressure to the engine at the exhaust ports thats it,

i have been tuning cars for years,the amount of Myths regarding cats is unbelievable, bike is no different,for more info on back pressure see below

"THE MYTH OF BACKPRESSURE"

…is probably the most widely misunderstood concept in engine tuning. IMO, the reason this concept is so hard to get around lies in the engineering terms surrounding gas flow. Here's the most impotant ones you need to be aware of to understand the things I'm about to say:

BACKPRESSURE: Resistance to air flow; usually stated in inches H2O or PSI.
DELTA PRESSURE (aka delta P): Describes the pressure drop through a component and is the difference in pressure between two points.

One other concept needs to be covered too, and that's the idea of air pressure vs. velocity. When a moving air column picks up speed, one of the weird things that happens is it’s pressure drops. So remember through all this that the higher the air velocity for a given volume of gas, the lower it's internal pressure becomes. And remember throughout all of this that I’m no mechanical engineer, simply an enthusiast who done all the reading he can. I don’t claim that this information is the absolute truth, just that it makes sense in my eyes.

Ok, so as you can see, backpressure is actually defined as the resistance to flow. So how can backpressure help power production at any RPM? IT CAN'T. I think the reason people began to think that pressure was in important thing to have at low RPM is because of the term delta pressure. Delta pressure is what you need to produce good power at any RPM, which means that you need to have a pressure DROP when measuring pressures from the cylinder to the exhaust tract (the term "pressure" is what I think continually confuses things). The larger the delta P measurement is, the higher this pressure drop becomes. And as earlier stated, you can understand that this pressure drop means the exhaust gas velocity is increasing as it travels from the cylinder to the exhaust system. Put simply, the higher the delta P value, the faster the exhaust gasses end up traveling. So what does all this mean? It means that it's important to have gas velocity reach a certain point in order to have good power production at any RPM (traditional engine techs sited 240 ft/sec as the magic number, but this is likely outdated by now).

The effect of having larger exhaust pipe diameters (in the primary, secondary, collector and cat-back exhaust tubes) has a direct effect on gas velocity and therefore delta P (as well as backpressure levels). The larger the exhaust diameter, the slower the exhaust gasses end up going for a given amount of airflow. Now the ***** of all this tech is that one exhaust size will not work over a large RPM range, so we are left with trying to find the best compromise in sizing for good low RPM velocity without hindering higher RPM flow ability. It doesn't take a rocket scientist to understand that an engine flows a whole lot more air at 6000 RPM than at 1000 RPM, and so it also makes sense that one single pipe diameter isn't going to acheive optiaml gas velocity and pressure at both these RPM points, given the need to flow such varying volumes.

These concepts are why larger exhaust piping works well for high RPM power but hurts low RPM power; becuase is hurts gas velocity and therefore delta P at low RPM. At higher RPM however, the larger piping lets the engine breath well without having the exhuast gasses get bundled up in the system, which would produce high levels of backpressure and therefore hurt flow. Remember, managing airflow in engines is mainly about three things; maintaining laminar flow and good charge velocity, and doing both of those with varying volumes of air. Ok, so now that all this has been explained, let's cover one last concept (sorry this is getting so long, but it takes time to explain things in straight text!).

This last concept is why low velocity gas flow and backpressure hurt power production. Understand that during the exhaust stroke of a 4 stroke engine, it's not only important to get as much of the spent air/fuel mixture out of the chamber (to make room for the unburnt mixture in the intake system), it's also important that these exhaust gasses never turn around and start flowing back into the cylinder. Why would this happen? Because of valve overlap, that's why. At the end of the exhaust stroke, not only does the piston start moving back down the bore to ingest the fresh mixture, but the intake valve also opens to expose the fresh air charge to this event. In modern automotive 4 stroke engines valve overlap occurs at all RPM, so for a short period of time the exhaust system is open to these low pressure influences which can suck things back towards the cylinder. if the exhaust gas velocity is low and pressure is high in the system, this will make everything turn around and go the opposite direction it's supposed to. If these gasses reach the cylinder they will dilute the incoming mixture with unburnable gasses and take up valuable space within the combustion chamber, thus lowering power output (and potentially pushing the intake charge temp beyond the fuel’s knock resistance). So having good velocity and therefore low pressure in the system is absolutely imperative to good power production at any RPM, you just have to remember that these concepts are also dependent on total flow volume. The overall volume of flow is important because it is entirely possible to have both high velocity and high pressure in the system, if there is simply not enough exhaust piping to handle the needed airflow.

It’s all about finding a compromise to work at both high and low RPM on most cars, but that’s a bit beyond the scope of this post. All I am trying to show here is how the term backpressure is in reference to a bad exhaust system, not one that creates good low RPM torque. You can just as easily have backpressure at low RPM too, which would also hurt low RPM cylinder scavenging and increase the potential for gas reversion. And understand that these tuning concepts will also affect cam timing, though that is again probably beyond the scope of this post. At any rate, hope this helps, peace.

steveg56 · 10-29-2009, 01:21 PM

WHAT HE SAID...

Quote:

Originally Posted by mad_angler

bypassing the can will not do any damage with out the correct map, the bike could run like crap but no damage, the cat will add back pressure to the engine at the exhaust ports thats it,

i have been tuning cars for years,the amount of Myths regarding cats is unbelievable, bike is no different,for more info on back pressure see below

"THE MYTH OF BACKPRESSURE"

…is probably the most widely misunderstood concept in engine tuning. IMO, the reason this concept is so hard to get around lies in the engineering terms surrounding gas flow. Here's the most impotant ones you need to be aware of to understand the things I'm about to say:

BACKPRESSURE: Resistance to air flow; usually stated in inches H2O or PSI.
DELTA PRESSURE (aka delta P): Describes the pressure drop through a component and is the difference in pressure between two points.

One other concept needs to be covered too, and that's the idea of air pressure vs. velocity. When a moving air column picks up speed, one of the weird things that happens is it’s pressure drops. So remember through all this that the higher the air velocity for a given volume of gas, the lower it's internal pressure becomes. And remember throughout all of this that I’m no mechanical engineer, simply an enthusiast who done all the reading he can. I don’t claim that this information is the absolute truth, just that it makes sense in my eyes.

Ok, so as you can see, backpressure is actually defined as the resistance to flow. So how can backpressure help power production at any RPM? IT CAN'T. I think the reason people began to think that pressure was in important thing to have at low RPM is because of the term delta pressure. Delta pressure is what you need to produce good power at any RPM, which means that you need to have a pressure DROP when measuring pressures from the cylinder to the exhaust tract (the term "pressure" is what I think continually confuses things). The larger the delta P measurement is, the higher this pressure drop becomes. And as earlier stated, you can understand that this pressure drop means the exhaust gas velocity is increasing as it travels from the cylinder to the exhaust system. Put simply, the higher the delta P value, the faster the exhaust gasses end up traveling. So what does all this mean? It means that it's important to have gas velocity reach a certain point in order to have good power production at any RPM (traditional engine techs sited 240 ft/sec as the magic number, but this is likely outdated by now).

The effect of having larger exhaust pipe diameters (in the primary, secondary, collector and cat-back exhaust tubes) has a direct effect on gas velocity and therefore delta P (as well as backpressure levels). The larger the exhaust diameter, the slower the exhaust gasses end up going for a given amount of airflow. Now the ***** of all this tech is that one exhaust size will not work over a large RPM range, so we are left with trying to find the best compromise in sizing for good low RPM velocity without hindering higher RPM flow ability. It doesn't take a rocket scientist to understand that an engine flows a whole lot more air at 6000 RPM than at 1000 RPM, and so it also makes sense that one single pipe diameter isn't going to acheive optiaml gas velocity and pressure at both these RPM points, given the need to flow such varying volumes.

These concepts are why larger exhaust piping works well for high RPM power but hurts low RPM power; becuase is hurts gas velocity and therefore delta P at low RPM. At higher RPM however, the larger piping lets the engine breath well without having the exhuast gasses get bundled up in the system, which would produce high levels of backpressure and therefore hurt flow. Remember, managing airflow in engines is mainly about three things; maintaining laminar flow and good charge velocity, and doing both of those with varying volumes of air. Ok, so now that all this has been explained, let's cover one last concept (sorry this is getting so long, but it takes time to explain things in straight text!).

This last concept is why low velocity gas flow and backpressure hurt power production. Understand that during the exhaust stroke of a 4 stroke engine, it's not only important to get as much of the spent air/fuel mixture out of the chamber (to make room for the unburnt mixture in the intake system), it's also important that these exhaust gasses never turn around and start flowing back into the cylinder. Why would this happen? Because of valve overlap, that's why. At the end of the exhaust stroke, not only does the piston start moving back down the bore to ingest the fresh mixture, but the intake valve also opens to expose the fresh air charge to this event. In modern automotive 4 stroke engines valve overlap occurs at all RPM, so for a short period of time the exhaust system is open to these low pressure influences which can suck things back towards the cylinder. if the exhaust gas velocity is low and pressure is high in the system, this will make everything turn around and go the opposite direction it's supposed to. If these gasses reach the cylinder they will dilute the incoming mixture with unburnable gasses and take up valuable space within the combustion chamber, thus lowering power output (and potentially pushing the intake charge temp beyond the fuel’s knock resistance). So having good velocity and therefore low pressure in the system is absolutely imperative to good power production at any RPM, you just have to remember that these concepts are also dependent on total flow volume. The overall volume of flow is important because it is entirely possible to have both high velocity and high pressure in the system, if there is simply not enough exhaust piping to handle the needed airflow.

It’s all about finding a compromise to work at both high and low RPM on most cars, but that’s a bit beyond the scope of this post. All I am trying to show here is how the term backpressure is in reference to a bad exhaust system, not one that creates good low RPM torque. You can just as easily have backpressure at low RPM too, which would also hurt low RPM cylinder scavenging and increase the potential for gas reversion. And understand that these tuning concepts will also affect cam timing, though that is again probably beyond the scope of this post. At any rate, hope this helps, peace.

mad_angler · 10-29-2009, 04:43 PM

first of all i may coming a cross as i am preaching to you guys on here at times but it really REALLY bugs me when dealers spout **** to you, i have been a mechanical/Electrical engineer in the motor industry for years and know when some on is giving BS, however most people don't and rely on their dealer telling them what they can and cant do, the sad truth is you cant believe 80% of what they or there Mechanic tell you, i have been around so many dealers and all but a very few lie, most don't do it on purpose they do it when they don't know the answer, rather than tell you they don't know they just lie.

very very few mechanics understand the new technologies (i say new i mean new to bikes) like the fuel injection systems, they only know what the manufactures what them to know and thats as little as possible, most are so far from understanding how it works its frightening, the fact is a mechanics job is not to understand how it works, all they need to know is how to identify faults and change the parts, if they cant find the fault they refer to the manufacture.

anyway after they rant, i have decided to give my self a challenge, this weekend i am going to bypass the cat, tonight i have removed it, only took 10 minutes, damn this thing is heavy, after a bit of a clean i did a blow test(yes i stuck my mouth over it, all in the name of science) and there is not to much restriction, however my mouth can not produce the puff the engine can so its still going to have to go, i am first of all going to have to make a mockup of the inlet and outlets so i can produce a bypass the same shape, the inlet/outlets are 38mm so i will use 40mm plastic pipe to make a mockup of there positions, then once complete i can cut and weld 38mm pipe in the mockup to replicate the can, i don't see the need to mount the bypass to the bike like the cat is,the header pipes are solid and the muffles are mounted at the rear, once a pipe is between the two it will be solid, just like it it on the speedmaster.

see below pic of the cat removed

[IMG]

[/IMG]

Thatch · 10-29-2009, 05:08 PM

Wooohooo..... way to go mad!

Can't wait to see what you find out. Not sure if you've read the posts I made over at the t1600 board but there is info on the tuneboy and the BC pipes that you might find interesting. BC stated that the cat and stock pipes weigh 33 lbs all told. Their replacement pipes come in at 12 so a nice weight savings there.

What are your tune plans? (though you say damage won't be done, you'll not have optimal tune with the changes)

mad_angler · 10-29-2009, 05:42 PM

as for the tune going to see what stock does to start, i have been looking over all the Rocket 3 De cat tunes and there is very little difference if any to stock tunes, just some minor adjustments to ignition timing, i initially looking to see if the bike breath's better with out it, you should feel a difference with out any tune changes, after then its time to wait for the tuneboy and dyno.