With more restrictive baffling you gain low end torque. With less baffling you gain top end HP. Either way, YES.
Let me add: The science is that one exhaust pulse creates a vacuum in the other exhaust port thereby increasing each cylinders evacuation. That in turn leads to a fresher, fuller fuel charge on the next cycle. More fresh fuel, more power.
I prefer the look of the stock dual exhaust, but will a 2-in-1 add power? And if so, how? What's the science behind it?
Also, how much of a power boost?
Even though I prefer the dual look, I might consider going to a single if the benefits are there.
If you have the stock dual exhaust then there is a crossover that makes it work just as good if not better than a 2-1 exhaust.
Jerry Branch (Branch Heads) did a study of exhausts back in the day and he came up with the stock setup was the best with 2-1 a close second.
He wrote up his results in a small book that I got to look at once but I haven't found a copy that I could buy.
If you don't have the crossover you don't have stock exhaust and 2-1 will help you.
I don't know that you'd see a noticeable gain if everything else is stock. For a free flowing exhaust to push more air out, you have to take more in....
I built in line 4 motorcycle engines for drag bikes, Suzuki and Kawasaki, the gains from the 4 into 1 was from the continuous flow of the hot exhaust gas, I don't know how much difference it would make on a V2, only a dyno would tell.
I do have a 2 into 1 on my 1996 Ultra Classic, but I changed a lot of things when I changed the exhaust...
If you have the stock dual exhaust then there is a crossover that makes it work just as good if not better than a 2-1 exhaust.
With no other changes than stock exhaust to a 2-1...you will see little to no change...even with upgrades in the motor...the stock headpipe with the cross-over, and some free flowing slip-ons .i would still work very well.
Most people get rid if the stock head pipe with the cross-over because they don't like how it looks..it works very well.
Any exhaust manufacture is going to say yes, 3-5 hp bolt on, solid as a rock advice.
In the real world on a stock engine no, you will also loose the real sound of a Evo, a 2-1 changes it's identity. The scientific weakness of the dual system is the collision of gases that causes a torque dip in the lower rpms but clears out in the uppers. A 2-1 clears out the earley torque dip from the design explained by Stiggy.
Years ago a stock head pipe with a cheap set of Cycle Shack slip on's was money in the bank when all of the Space Shuttle Nuclear Flow expensive systems was showing up. Advertised proven 5-8 hp bolt on, great marketing, the dual systems where made well, sounded well and purdy but the cheap Cycle Shack would kick it's a$$ on a mild to stock application.
You start getting into areas like some of these horsepower nutjobs in the Evo forum, the 2-1 and it's scientific design works, only problem is which 2-1 scientific design works for that application, makes buying a exhaust still a crap shoot knowing a 2-1 is what your want.
I'm running a 80" engine with street porting of the heads, EV27 cam, tuned CV carb, and Dyna 2000 ignition. When I switched from the OEM duals with SuperTrapp slip-on (16 discs) to the Thunderheader (https://www.hdforums.com/forum/evo-c...exhausted.html), I noticed some mild (very subtle) drive-ability gains. Also noticed a slight (ever so slight) increase in MPG. The trade off was increased sound level of the Thunderheader. And losing the visual aesthetics of the dual exhaust system on an E-Glide.
Look at the two Dyno sheets, identical build one with RB Racing 2-1 and the other with older Python III staggered duals (without crossover). Yes there is a difference up to 3000 rpm but after that it's really not a comparison as to how the 2-1 hits harder and faster than the staggered duals from 3k up. Keep in mind this is a well built 80"er... But I imaging a motor is a motor and the characteristics of the pipes will be the same...
01-06-2018, 04:28 PM
Does a 2-in-1 exhaust add power to a stock EVO?
