Pipes for 2012 Street Bob
#21
12-27-2012, 11:07 AM
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#22
12-27-2012, 11:23 AM
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Short Answer:
The Thunder Torque Inserts have a proprietary shape that is much better at increasing exhaust gas velocity, thereby reducing reversion, which reduces engine pumping losses, and increasing inertial scavenging. Net result is a significant increase in power & torque in the low and mid range Without sacrificing any top end.
Long Answer:
Here's a bit of info that is relevant to the Thunder Torques that might be interesting to some.
The type of material, shape, size, thickness, & surface coatings all make a difference in how well the Thunder Torque works at increasing exhaust gas velocity.
The TTI's obviously have their genesis in the simple lollipop concept. But they are quite a bit more, especially the W series.
Technically exhaust systems cannot increase or decrease an engines power. However, and this is a BIG however, exhausts systems can have a profound affect on increasing or decreasing engine pumping loss.
You can loosely compare engine pumping loss with adding an extra 200 lbs weight to the bike. The engine still has the same amount of power, but with the extra weight on the bike it will accelerate slower...it will feel like it has less power than it would if the extra 200 lbs was removed.
Every engine will suffer to some degree from engine pumping loss. The goal of many exhaust systems (including the Thunder Torque Inserts) is reduced engine pumping losses, resulting in more felt power at the rear wheel. If efficiency of the engine increases then fuel mileage may also increase because less throttle is needed to move the bike forward at the same speed.
There are Many design factors that can affect whether an exhaust system increases or decreases engine pumping losses, far more than could be put in a post here (by me anyway lol).
Generally most of us that ride Harley's want the most felt (rear wheel) torque in the low to mid rpm range as possible. Inertial scavenging has a major effect on that felt power.
The nuts & bolts of increasing inertial scavenging is the following-
When the exhaust valve opens two thing happen. A pulse (wave) of energy enters the exhaust pipe, generally at 1300-1700 feet per second. This can be understood as a shock wave from an explosion.
At the same time the spent combustion gases enter the exhaust pipe at 150-300 feet per second. (Generally the faster the exhaust gases travel, the better the inertial scavenging and the less engine pumping loss)
The energy wave that is heading toward the end of the pipe will get to a low pressure area faster (low pressure being a bigger area of the pipe OR the end of the pipe) WHEN that happens some of the wave will reverse direction and collide with the slower moving exhaust gases that are still traveling toward the end of the pipe. This will slow down the speed of the exhaust gases. This will produce the result of less felt torque at the rear wheel.
Exhaust systems that are are successful in increasing exhaust gas velocity (resulting in an increase in inertial scavenging and a decrease in engine pumping loss) will make the bike have more felt torque across the RPM band, especially in the low & mid range.
There is much more to how exhaust systems help or hurt the felt power. But the main goal that is achieved by the unique design and combination of materials in TTI's is to increase felt power in most any exhaust system for a low price
The Thunder Torque Inserts have a proprietary shape that is much better at increasing exhaust gas velocity, thereby reducing reversion, which reduces engine pumping losses, and increasing inertial scavenging. Net result is a significant increase in power & torque in the low and mid range Without sacrificing any top end.
Long Answer:
Here's a bit of info that is relevant to the Thunder Torques that might be interesting to some.
The type of material, shape, size, thickness, & surface coatings all make a difference in how well the Thunder Torque works at increasing exhaust gas velocity.
The TTI's obviously have their genesis in the simple lollipop concept. But they are quite a bit more, especially the W series.
Technically exhaust systems cannot increase or decrease an engines power. However, and this is a BIG however, exhausts systems can have a profound affect on increasing or decreasing engine pumping loss.
You can loosely compare engine pumping loss with adding an extra 200 lbs weight to the bike. The engine still has the same amount of power, but with the extra weight on the bike it will accelerate slower...it will feel like it has less power than it would if the extra 200 lbs was removed.
Every engine will suffer to some degree from engine pumping loss. The goal of many exhaust systems (including the Thunder Torque Inserts) is reduced engine pumping losses, resulting in more felt power at the rear wheel. If efficiency of the engine increases then fuel mileage may also increase because less throttle is needed to move the bike forward at the same speed.
There are Many design factors that can affect whether an exhaust system increases or decreases engine pumping losses, far more than could be put in a post here (by me anyway lol).
Generally most of us that ride Harley's want the most felt (rear wheel) torque in the low to mid rpm range as possible. Inertial scavenging has a major effect on that felt power.
The nuts & bolts of increasing inertial scavenging is the following-
When the exhaust valve opens two thing happen. A pulse (wave) of energy enters the exhaust pipe, generally at 1300-1700 feet per second. This can be understood as a shock wave from an explosion.
At the same time the spent combustion gases enter the exhaust pipe at 150-300 feet per second. (Generally the faster the exhaust gases travel, the better the inertial scavenging and the less engine pumping loss)
The energy wave that is heading toward the end of the pipe will get to a low pressure area faster (low pressure being a bigger area of the pipe OR the end of the pipe) WHEN that happens some of the wave will reverse direction and collide with the slower moving exhaust gases that are still traveling toward the end of the pipe. This will slow down the speed of the exhaust gases. This will produce the result of less felt torque at the rear wheel.
Exhaust systems that are are successful in increasing exhaust gas velocity (resulting in an increase in inertial scavenging and a decrease in engine pumping loss) will make the bike have more felt torque across the RPM band, especially in the low & mid range.
There is much more to how exhaust systems help or hurt the felt power. But the main goal that is achieved by the unique design and combination of materials in TTI's is to increase felt power in most any exhaust system for a low price
#23
12-27-2012, 03:51 PM
There are a lot of choices and even more opinions. I think you'll need to decide on the look you are going for to narrow down choices.
Basically, 2-1 pipes perform better than duals. Duals have the more traditional sound.
The V&H short shots look great, have a decent price, and are loud. Optional quiet baffles help, but they are still on the loud side.
Thunder headers are a very popular choice. I love my V&H Pro Pipe. It fits the look I'm going for and is tame at low RPM and loud at higher revs.
Basically, 2-1 pipes perform better than duals. Duals have the more traditional sound.
The V&H short shots look great, have a decent price, and are loud. Optional quiet baffles help, but they are still on the loud side.
Thunder headers are a very popular choice. I love my V&H Pro Pipe. It fits the look I'm going for and is tame at low RPM and loud at higher revs.
#25
12-27-2012, 04:47 PM
#27
12-27-2012, 10:57 PM
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Yes, you can see them HERE.
We have 3 different Youtube vids on them also. Here is one-
You might want to give them a try with your Pro Pipe.
I never would have thought that it could be beneficial on a high end 2-1, but then had a guy use one with his RB Racing LSR and he got "a noticable amount of low to midrange torque with out hurting the top end pull."
You can see more details at the following link-
https://www.hdforums.com/forum/engin...sapointed.html
We have 3 different Youtube vids on them also. Here is one-
Good stuff Kevin! This can help people understand the dynamic effects of a 2-1 vs 2-2 system. Different methods to achieve similar results. Clearing the way for gases to escape faster.
The problem is now, I paid a bunch for the Pro Pipe but want to try some SS with your cool product.
The problem is now, I paid a bunch for the Pro Pipe but want to try some SS with your cool product.
I never would have thought that it could be beneficial on a high end 2-1, but then had a guy use one with his RB Racing LSR and he got "a noticable amount of low to midrange torque with out hurting the top end pull."
You can see more details at the following link-
https://www.hdforums.com/forum/engin...sapointed.html
#28
12-28-2012, 01:42 AM
IMO Vance and Hines are the least optimum choice. Anyone ever notice that they practically twist your arm to put them on at the Stealership? Look who Harley has a racing team with Just Saying. IMO all 2-1 look like Shyt especially Thunderheaders they look like someone took the chimney off they're house and just threw it on a bike. The best look in most peoples opinions is a 2-2 a lot of companies make some really good pipes just try to find one that not everyone has IMO. +1 on the Samson's -1on the Basannis I had a set of pro streets that literally ruptured and they tried to blame it on the wrap rather than cheap metals used that could not take the heat at the first bend. I suggest going on Youtube and look up your model and see what other people have put videos up of you can get some good soundbytes
#30
12-28-2012, 07:26 AM
IMO Vance and Hines are the least optimum choice. Anyone ever notice that they practically twist your arm to put them on at the Stealership? Look who Harley has a racing team with Just Saying. IMO all 2-1 look like Shyt especially Thunderheaders they look like someone took the chimney off they're house and just threw it on a bike. The best look in most peoples opinions is a 2-2 a lot of companies make some really good pipes just try to find one that not everyone has IMO. +1 on the Samson's -1on the Basannis I had a set of pro streets that literally ruptured and they tried to blame it on the wrap rather than cheap metals used that could not take the heat at the first bend. I suggest going on Youtube and look up your model and see what other people have put videos up of you can get some good soundbytes
I have a lot of experience with V&H on the other hand. I've used them on race and street bikes. Good performance, well built, and usually a good sound to top it off. I think people push V&H because they make good stuff. Reinhardt is another company with this kinda of reputation.