There can be no serious doubt that the ideal exhaust system for a given RPM and load is a pipe of the ideal diameter and length. Whether that is practical for your use or works across the largest possible RPM range that could be designed is a separate question.

 

I haven’t found the second issue yet but will..what did all this mean?




It means this entire discussion the best 2 into 1 vs the best drag pipes with just bolts… not even lollipops or DK’s is about 2-3 hp at 3000rpm… oh and average at 4500 rpm… guess what.

I made this page 23 years ago… but if you average 2500 to 3500 the drag pipes are still within 3-4 foot pounds of torq… AND THESE ARENT EVEN TUNED. It only gets better when you tune these numbers.

‘Also consider most of the over the counter 2 into 1 pipes are made or engineered for stock compression and stroke. The big motors today have more of both.. it’s even MORE important they are free flowing. When the TP Engineering dyno tests took place the most streetable power was made from 2” straight drag pipes with no baffles over the RB Racing 2 into1. That was published in I think Iron Horse magazine.

 

Nice pictures... Took a quick gander... Don't think they bolster your case... Seems to me they do just the opposite. Which actual set of "drag pipes" do you think makes your case in that smorgasbord (vast majority are not drag pipes)?

 

As mentioned:
1) There is a follow up article you don’t have yet
2) These are not TUNED difference is only 2-3 dyno’s lie that much
3) best highest average 2 into 1 made less power then best drag with screwdriver mimicking lollipops.
4) This was 80 inches with mild compression and a low duration cam.. it only get better for drags as u increase

Now imagine TUNED with good DK solution.. the gap between is gone.

I’m really NOT saying Drag Pipes are better.. I’m not saying everyone should run them. I am saying people should stop acting like they are not a truly viable option for many good street bikes. Especially today when 117 is a average size. And sound… one of the better 2 into 1 the Hooker was only 3 db quieter than the winning drag pipe that made a higher average of power than any other pipe tested.

 

Really, if anything, it shows that there is entirely too much focus on exhaust theory since they're all so close as to be practically the same. So pick what you like the look and sound of and don't worry about it.

 

That was my assumption way back over 20 years ago when I looked at these articles. But I actually had access to a Dyno back then and I was racing. As long as you’re not doing something crazy like upswept Fish tales, or those goofy 18 inch long LA pipes a standard set of drag pipes on a medium mild built motor with some kind of baffled, toque cones, or lollipops, DK solution, etc. or a viable pipe.

As long as you’re not doing something crazy like upswept Fish tales, or those goofy 18 inch long alley pipes a standard set of drag pipes on a medium mild built motor with some kind of baffle, torque cones or lollipops, decay solution, etc. or a viable pipe.

However we are in an era when people are getting big motors, and even through the factory getting pretty good power. And a lot of us are spending a lot of money to increase that power. And you can kill the potential of a motor putting the wrong pipe on it. The right pipe makes a big difference and allows all those performance modifications to shine. For some builds, that would be a good quality two into one. For other builds, that’s some massive free-flowing big drag pipes. The motors want with the motors want.

 

A 1.75" dual exhaust is more than enough pipe for a 120 cubic inch engine. It's actually probably closer to double the exhaust volume that is needed for an engine at the horsepower levels our motorcycles are at.

If my truck can make 350 horsepower through dual 2.25" exhaust, there can be no serious doubt that a 100 hp engine is not choked by a 1.75" exhaust system.

Like I said, entirely too much focus on these details when it is sound and preference driving all of the marketing of Harley-Davidson exhaust systems and mufflers.

If you like drag pipes, run drag pipes.

if you like mufflers, run mufflers.

3 hp one way or the other is not even worth measuring.

 

If your lawn mower is missing 3 hp you're not going to get through those weeds, pal!