Equalizing exhaust pressure
Thread Starter
|
Advanced
Joined: Apr 2012
Posts: 57
Likes: 0
From: south carolina
Equalizing exhaust pressure
After installing Rinehart slip-ons on my Electra Glide, I notice that the exhaust pressure was greater from the front cylinder than the rear. Is there anything short of installing true duels to cure this?
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
Nope.
The left side outlet is longer, there's a vicious crimp in the crossover, and there's two 90-degree bends in the pipe. The exhaust follows simple physics which means it takes the path of least resistance.
I went with a Jackpot header and full-sized crossover. That helps a bit, but that won't overcome those two turns and the length.
The left side outlet is longer, there's a vicious crimp in the crossover, and there's two 90-degree bends in the pipe. The exhaust follows simple physics which means it takes the path of least resistance.
I went with a Jackpot header and full-sized crossover. That helps a bit, but that won't overcome those two turns and the length.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
the line from header to rt exhaust is a straight line
the lft exhaust takes a couple of 90ş turns.
think of the left side as an "overflow" when the flow exceeds the ability of the rt side, the left side will flow more.
on my exhaust system I swap the lft and rt side tips to equalize "wear" so they look more similar.
some systems are set up so that the 2 pipes are different- the left side may be smaller internally so as to keep velocity high
the key with exhaust is not just "flow" but also the velocity of the gasses.
high velocity is good
ike
the lft exhaust takes a couple of 90ş turns.
think of the left side as an "overflow" when the flow exceeds the ability of the rt side, the left side will flow more.
on my exhaust system I swap the lft and rt side tips to equalize "wear" so they look more similar.
some systems are set up so that the 2 pipes are different- the left side may be smaller internally so as to keep velocity high
the key with exhaust is not just "flow" but also the velocity of the gasses.
high velocity is good
ike
Last edited by mkguitar; Jan 17, 2014 at 11:53 AM.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,897
From: Bedford UK
Even true duals are not guaranteed to give truly equal pressure in each pipe, for the same reasons mentioned - they are not the same shape or length. There are one or two exhausts which use equal length pipes, but they are also 2-into-1s and ain't the prettiest things around! They should however give improved performance, in the same way that the Buell equal length pipe systems do.
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
Pretty much. The difference in flow is a non-issue unless you're building a hyper-horsepower race motor.
Outstanding HDF Member
Joined: Nov 2013
Posts: 2,618
Likes: 2
From: Indiana
What about putting a smaller baffle in the right side muffler and adding a full size crossover pipe the equal it out? Just by feel and sound. I've been wanting to try this but I'm sure others already have.
Last edited by WILDWOOD_1124; Jan 17, 2014 at 12:06 PM.
Trending Topics
Outstanding HDF Member
Joined: Nov 2013
Posts: 2,618
Likes: 2
From: Indiana
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
Elite HDF Member
Joined: Nov 2013
Posts: 4,377
Likes: 647
From: Santa Clarita
I have read in this forum that there are some systems that have different baffling in the right versus left pipe...might want to go back and start checking some of those out. I hear ya re: annoying, it was something I noticed at first, but if you're seriously annoyed about it, just go get a two into one system, Thunderheader and V&H Pro Pipe come to mind, and be done with it once and for all, and you'll probably pick up some horsepower along the way. Yes, you'll have to re-map and tweak things a bit, but this particular issue won't annoy you any more.
Personally, it's something I've gotten used to. Just part of the personality of the scooter.
Personally, it's something I've gotten used to. Just part of the personality of the scooter.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
topic related for the Geeks:
An Old Guy was telling me about the Panhead he campaigned in the early 50's.
he was a roaming traveler/racer and his transportation was his racer.
swapping heads and a reverse ground cam, gave him the exhaust ports on the inside of the motor, and the intakes on the outside of the motor (amal carbs w/ remote float bowls).
this gave him exact equal length exhaust headers which came around behind the rear cylinder into a 2/1 on the right side.
as he was racing he needed left side clearance which included a 1" block under the tranny to raise it up.
funny story and outside the box thinking in a day with no catalogs
Mike
An Old Guy was telling me about the Panhead he campaigned in the early 50's.
he was a roaming traveler/racer and his transportation was his racer.
swapping heads and a reverse ground cam, gave him the exhaust ports on the inside of the motor, and the intakes on the outside of the motor (amal carbs w/ remote float bowls).
this gave him exact equal length exhaust headers which came around behind the rear cylinder into a 2/1 on the right side.
as he was racing he needed left side clearance which included a 1" block under the tranny to raise it up.
funny story and outside the box thinking in a day with no catalogs
Mike
Last edited by mkguitar; Jan 17, 2014 at 04:23 PM.