Does matter. Getting baffles out and reinstalling matters. Exhaust in this system needs baffles - too loud as is with baffles - as I said, I was surprised.
As to whether inserts help my particular build, it wouldn't have mattered if they would have been easily installable, which I was led to believe, and they are not.
Of course baffles matter... But for the key points/thrust I was trying to make they don't.
Additional thoughts... Your overall approach/solution may not the best way to go. Say you are successful at getting those lollipops installed in your Grand National slip-ons. How will they actually impact performance (in particular where it matters)? Will they be a detriment? You going to do dyno runs before and after to see the effect (the only way to really tell). What if you find that you're unhappy with how they impact performance or sound? You've now drilled holes in them and if you're unhappy with the results, you'll likely have difficulty with offloading them.
Back in the EVO era HotBike did a two issue exhaust pipe shootout where they dyno’d back to back something like 30 different popular performance pipes. They showed all the dyno charts and even a little tuning with each one. Thunder Header and that stupid ls2 pipe were both in the mix.. there were I think only 3 sets of drag pipes. They did each of those with and without a 1/4” bolt across the back…. Not even a lollipop. They also did a chart with highest averages of torque and hp.
Results? All three sets of drag pipes (out of 30 performance pipes) with the 1/4” bolts made the top 5 highest average torque, all 3 made the top 5 highest peak. All three drag pipes pushed out the thunder header from making the top 5 list… Oh, and if memory serves… they only ran the bikes to 5500rpm.
I still have those issues. I’ll look for them. If anyone pays the online fee to see old issues and wants to post, that would be cool.
So for you guys who think light to light or racing your buddy happens at 2000 rpm… no need to bother worrying about it. You just keep making as much power as you can at idle. You keep watching the S&S video and rewind over and over and Indoctrinate the drag pipe dumpster scene in your mind, chug some Amzoil and install your hypercharger air filter on your 1000 lbs bike and keep those cam durations below 230.
Every engine build and set of variables needs what it needs to be at its peak performance. There is no such thing as “this” pipe is the best for all bikes. The Thunder Header has a very good reputation for a reason. If you run the very same engine as what they built it for, it will be impressive. Sometimes it is the right pipe. I’m very touchy about this subject because money was tight when I was sponsored and racing. I spent more money than I had believing, being fooled) that 2 into one pipe was the answer. Not once but twice. I ruined an entire season (with my everyday street ridden street class raced bike) spending all that money sounding like a rototiller.
I believed the industry hype.
All I’m saying is the humble drag pipe if you tune it, is a viable performer for street use. The industry hates it because it’s hard to sell it for big bucks and few understand or bother to tune them. It’s easier to go buy a 2 into 1 and bolt it on concentrating at how much power you make in the driveway..Look way up ahead of you, see those dots up ahead, those are the bikes that passed you. Some of them use drag pipes, some of them were purring like a kitten right next to you with beautiful street manners at the light.
EDIt: Actually upon finding at least article 1 so far, it’s over 45 pipes tested.
Last edited by Rains2much; 03-29-2024 at 09:08 AM.
Ok, found article 1. I’ll keep looking later for article2 where they do a side by side comparison and average the torque and hp. Pretty sure there is another just like this from like 1997ish.. This one is 2001. I was racing from 2000-2003.
Last edited by Rains2much; 03-29-2024 at 07:00 AM.
There is so much miss info here, it would take forever to correct.
Yes, ideally you maximize flow so you don't waste energy but that is only a small part of the equation. You also want to utilize that flow to create scavenging. The exhaust pipe is basically what engineers call a transmission line. The flow/pressure at any one place is continually changing with time, RPM, temp, load on the motor, etc. The task is to optimize the wave so that proper scavenging occurs throughout the planed usable RPM range.
One thing most may no realize is that when a pressure pulse hits the end of an open pipe, it creates a negative pressure wave back up the pipe. When placing anything in the way to restrict flow, the pressure way becomes positive. A good book for understanding this is Phillip Smith's Scientific Design of Intake and Exhaust Systems. The book was written in the 60s and measurements were all made with mechanical devices. The book still covers all the basics of flow, waves in exhaust pipes.
One thing that missed over on the DK website is that the thunder torque insert actually creates a positive pressure wave back up the pipe.
Back in the EVO era HotBike did a two issue exhaust pipe shootout where they dyno’d back to back something like 30 different popular performance pipes. They showed all the dyno charts and even a little tuning with each one. Thunder Header and that stupid ls2 pipe were both in the mix.. there were I think only 3 sets of drag pipes. They did each of those with and without a 1/4” bolt across the back…. Not even a lollipop. They also did a chart with highest averages of torque and hp.
Results? All three sets of drag pipes (out of 30 performance pipes) with the 1/4” bolts made the top 5 highest average torque, all 3 made the top 5 highest peak. All three drag pipes pushed out the thunder header from making the top 5 list… Oh, and if memory serves… they only ran the bikes to 5500rpm.
I still have those issues. I’ll look for them. If anyone pays the online fee to see old issues and wants to post, that would be cool.
So for you guys who think light to light or racing your buddy happens at 2000 rpm… no need to bother worrying about it. You just keep making as much power as you can at idle. You keep watching the S&S video and rewind over and over and Indoctrinate the drag pipe dumpster scene in your mind, chug some Amzoil and install your hypercharger air filter on your 1000 lbs bike and keep those cam durations below 230.
Every engine build and set of variables needs what it needs to be at its peak performance. There is no such thing as “this” pipe is the best for all bikes. The Thunder Header has a very good reputation for a reason. If you run the very same engine as what they built it for, it will be impressive. Sometimes it is the right pipe. I’m very touchy about this subject because money was tight when I was sponsored and racing. I spent more money than I had believing, being fooled) that 2 into one pipe was the answer. Not once but twice. I ruined an entire season (with my everyday street ridden street class raced bike) spending all that money sounding like a rototiller.
I believed the industry hype.
All I’m saying is the humble drag pipe if you tune it, is a viable performer for street use. The industry hates it because it’s hard to sell it for big bucks and few understand or bother to tune them. It’s easier to go buy a 2 into 1 and bolt it on concentrating at how much power you make in the driveway..Look way up ahead of you, see those dots up ahead, those are the bikes that passed you. Some of them use drag pipes, some of them were purring like a kitten right next to you with beautiful street manners at the light.
EDIt: Actually upon finding at least article 1 so far, it’s over 45 pipes tested.
So your argument is that the poor old drag pipes have just been poorly understood over the decades by countless pros? Only a few have been able to properly understand and tune them? Okey Dokey then.
Just hazarding some speculation.... If the application is solely WOT - i.e. as experienced in let's say... "drag" racing - then "drag" pipes might have a place. Every drag pipe dyno run I've ever seen has shown similar results. Max power and torque in a very narrow part of the power band (usually near max rpm) and total **** (re. reversion etc.) everywhere else. I would hazard a guess that most would not desire these characteristics for everyday street riding. Generally, I'm guessing here, most would rather have a nice wide/flat torque curve across the power band and a nice linear power curve. Maybe something that looks more like this...
Above is a comparison (and unsurprising - likely typical result) in that S&S video between S&S Slip-ons and a set of drag pipes. Guess which setup shows the nasty reversion/trashed power and torque curves in the middle of rpm/performance band. I've never seen anybody claim that this result could be corrected if only the poor old drag pipes were properly understood and tuned. I suspect that the correct answer here is somewhere closer to - some marginal improvement might be made, but, by in large, this problem will largely persist. Guessing that the insurmountable problem here might have something to do what that pesky physics thing. But what do I know?
Then there's the fact that drag pipe are just too F'ing obnoxiously/objectionably loud.
03-28-2024, 12:06 PM
