stock exhaust question

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Apr 7, 2006 | 06:20 PM

TowJam

Thread Starter

Road Warrior

Joined: Jul 2005

Posts: 1,751

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From: USA

stock exhaust question

Apologies in advance if this is a stupid question, but it's been gnawing at me... Since each cylinder on a TC88 has its own exhaust pipe, why is there a crossover? By having this crossover, I'm assuming that the majority of exhaust will come out the right-side pipe. Is this correct? Why oh why?

Apr 7, 2006 | 06:25 PM

bountyhunter

Banned

Joined: Nov 2005

Posts: 3,499

Likes: 2

From: CANADA

RE: stock exhaust question

It don't matter why, stock pipes just SUCK! Cut em' off, toss em' out and put on a rockin' set of duals. You and your bike will both be a lot happier, guaranteed. Nice RG.

Apr 7, 2006 | 06:32 PM

100thRK

Elite HDF Member

Joined: Feb 2006

Posts: 4,519

Likes: 5

From: Slidell, LA

RE: stock exhaust question

Quote"A crossover pipe increases bottom end (read torque) significantly, and it does so without sacrificing horsepower. The stock Harley bagger setup takes advantage of this well known property of the law of physics." Unquote

Saw a post awhile back and this was the response.

I am just the messenger. Though I do run stock pipes with SEII mufflers. Tried Rhinehart slipons, Rhinehart true duels and the SEII's. Best tq/hp curve was with the SEII's. Dynoed bike and Tq/hp cross at 100. Others make more hp but overall the SEII provided the curve my tuner was looking for. Everybody has a opinion on this and each bike is different.

Apr 7, 2006 | 07:40 PM

RBJones

Tourer

Joined: Mar 2006

Posts: 485

Likes: 10

From: East Tennessee

RE: stock exhaust question

Quote:

ORIGINAL: TowJam

Apologies in advance if this is a stupid question, but it's been gnawing at me... Since each cylinder on a TC88 has its own exhaust pipe, why is there a crossover? By having this crossover, I'm assuming that the majority of exhaust will come out the right-side pipe. Is this correct? Why oh why?

I think you're right. Most of the exhaust comes out the right pipe. I was curious, too and found out that exhaust design is based on complex scientific principles. As 100thRK mentions, the crossover indeed has proven to give better torque/h.p. at the lower end of the rpm curve, the region that most baggers like to cruise in. Since a V-twin's rear cylinder is several inches closer to the back of the bike, that cylinder's exhaust pipe is shorter than the front cylinder's, which creates an imbalance in exhaust flow and back pressure. The crossover helps equalize.

I'm in the minority here, but I think the stock system is fine. It doesn't sound all that good but I can assure you Harley engineers have spent a lot of time and money testing and perfecting the stock Harley exhaust systems that it can perform at its best for the type of bike you own (touring) and still meet EPA guidelines. Is stock perfect? No. I'd like to hear a deeper rumble with no increase in volume. But I have smooth power and performance throughout the range, from a rock bottom pull to winding out. I hesitate to mess with something that works. I haven't had to fuss with dynos, EFI mapping, spending more $$ and all that stuff.

Sound seems to be the primary selection criteria for most people, with looks and performance coming in second and third. These three things don't work in perfect harmony so it always ends up being a compromise situation based on individual preferences. Most experts will say that if you're really interested in performance, the two-into-one exhaust is the best. But many baggers don't think their bikes look right with just one pipe.

For a well-written article on exhaust design, go to this one by Donny Peterson, who writes for American Iron and has many years of experience with Harleys: http://www.heavydutycycles.com/exhaust.htm

Apr 7, 2006 | 09:42 PM

wjl24

Road Captain

Joined: Aug 2005

Posts: 743

Likes: 4

From: Ohio

RE: stock exhaust question

The best performance comes from a 2 into 1 exhaust. That's not an arguable point, it's proven. The stock set up is a compromise. It gives the classic bagger look with dual mufflers and good low end torque. Doesn't sound quite as good as true dual but close. But it works off the 2 into 1 principal.

Apr 7, 2006 | 10:00 PM

HD Renegade

Road Warrior

Joined: Jan 2006

Posts: 1,808

Likes: 0

From: Waynesville, NC

RE: stock exhaust question

Quote:

ORIGINAL: 100thRK
I am just the messenger. Though I do run stock pipes with SEII mufflers. Tried Rhinehart slipons, Rhinehart true duels and the SEII's. Best tq/hp curve was with the SEII's. Dynoed bike and Tq/hp cross at 100. Others make more hp but overall the SEII provided the curve my tuner was looking for. Everybody has a opinion on this and each bike is different.

Sorry, but I call BULL$HIT on this one, no way anyone is going to pull 100 HP on a stock motor, with stock front pipes, and slip-ons.

Bob

Apr 7, 2006 | 10:24 PM

blowe

Tourer

Joined: Aug 2005

Posts: 390

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From: Southeast

RE: stock exhaust question

Quote:

ORIGINAL: HD Renegade

Quote:

Sorry, but I call BULL$HIT on this one, no way anyone is going to pull 100 HP on a stock motor, with stock front pipes, and slip-ons.

Bob

It helps to pay attention before screaming BS.

He didn't say anything about running a stock 88.

Look at 100thRK's signature...
100th 2003 FLHRCI SE Hi comp HTCC Big Bore/Six speed ~101 hp/106tq