Duals vs. crossover
Seasoned HDF Member
Joined: Jan 2005
Posts: 21,949
Likes: 6
From: My house
RE: Duals vs. crossover
I will stick to the true duals they look and perform good, I have a friend that is rather wealthy, and can play with different parts to see what works best, he has tried them all 2-1, stock with slip-ons and so forth. What is he running, on all three of his HD's? Rineharts after dyno runs and different exhausts the Rineharts did the best on all around performance, did I mention they look good too. There is a former post from TN Heritage about Gerald Rinehart and his exhaust performance if you want to do a search.
Cruiser
Joined: Jul 2005
Posts: 231
Likes: 1
RE: Duals vs. crossover
Gotta go with TC on this one. I have several friends that have switched over and they are not happy with the loss of power. Yes, they will allow the engine to breath a little better, but your sacrificing power. The dyno results don't lie and both of these guys had a significant drop. For the record one of the motors is really built and the other minor mods (cams, breather, etc... nothing major). I do like the looks of the Rineharts, but spend a little time in the twisty mountain stuff and prefer every bit of grunt, I really hate shifting, lol...
Seasoned HDF Member
Joined: Dec 2004
Posts: 11,068
Likes: 1,473
From: Texas! Ya mean there's someplace else?
RE: Duals vs. crossover
Don't compare the various "true duals" to the stock system, but compare them to another high performance system. And forget about the HP stuff; look at the torque figures, especially in the 2000 - 3500 or 4000 rpm range where you spend most of your time.
A well designed 2 into 1 collector system will outperform an equally well designed true dual system. Period. The 2 into 1 has an inherent advantage over the true dual system because it can scavenge exhaust gases from the pipe with the closing/closed exhaust valve. If your cams have overlap (exhaust & intake open at the same time) this scavenging almost completely prevents reversion (spent exhaust gases getting back into the cylinder & mixing with the incoming fuel-air charge).
The true dual is essentially a drag pipe system, and must have some way of preventing exhaust reversion. The Rineharts, and other brands, do this by stepping the pipe from a small diameter, to a larger diameter, and to an even larger diameter. At each step up in pipe diameter the exhaust gases slow in velocity and decrease in pressure. As reversion attempts to happen the lower pressure exhaust gases try to flow back up the pipe toward the cylinder. When they hit the step in the reverse direction they meet a column of gas that is at a higher pressure and are basically stopped. However, the true duals are not as efficient in stopping reversion as is a well designed 2 into 1 system.
I've often wondered why someone doesn't make a 2 into 1 system with a "fake" left side pipe. You bagger-boys would get the looks you want, and also the increased performance of a 2 into 1 system. Or maybe someone has come up with this, but since I ain't a hard core barge pilot I haven't noticed!
A well designed 2 into 1 collector system will outperform an equally well designed true dual system. Period. The 2 into 1 has an inherent advantage over the true dual system because it can scavenge exhaust gases from the pipe with the closing/closed exhaust valve. If your cams have overlap (exhaust & intake open at the same time) this scavenging almost completely prevents reversion (spent exhaust gases getting back into the cylinder & mixing with the incoming fuel-air charge).
The true dual is essentially a drag pipe system, and must have some way of preventing exhaust reversion. The Rineharts, and other brands, do this by stepping the pipe from a small diameter, to a larger diameter, and to an even larger diameter. At each step up in pipe diameter the exhaust gases slow in velocity and decrease in pressure. As reversion attempts to happen the lower pressure exhaust gases try to flow back up the pipe toward the cylinder. When they hit the step in the reverse direction they meet a column of gas that is at a higher pressure and are basically stopped. However, the true duals are not as efficient in stopping reversion as is a well designed 2 into 1 system.
I've often wondered why someone doesn't make a 2 into 1 system with a "fake" left side pipe. You bagger-boys would get the looks you want, and also the increased performance of a 2 into 1 system. Or maybe someone has come up with this, but since I ain't a hard core barge pilot I haven't noticed!
Intermediate
Joined: Aug 2005
Posts: 25
Likes: 0
From: Toronto Ont
RE: Duals vs. crossover
Excelant post Skip Keep it up. Thank you for the True Duals tech tips.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
Thread Starter
|
Ultimate HDF Member
Joined: Jan 2005
Posts: 7,950
Likes: 4
RE: Duals vs. crossover
Over the past few weeks, I have seen some baggers in town with two into one systems. Today, while waiting to pickup my RG, I saw at least 3 EGs with 2-1 systems parked in the bike shop/cafe lot. They don't really look that bad to me.