A thunderheader question : V-Twin Forum: Harley Davidson Forums

JustDave71 · 10-10-2009, 11:49 PM

OK, so I have thunderheader exhaust and...part of me thinks "why the hell did they build this this way?"

one of the main questions is...what's the purpose of the tacked on "cone" at the exhaust output? It almost looks wrong on there. Anyone ever pop one of those off? what was the result?

Also, I've heard about bending the baffles to create more backpressure. On an 89 stroker would there be any point in doing something like that?

any thunderheader mods or the like?

aharp · 10-10-2009, 11:54 PM

Bending the baffles out will help get rid of some of the typical dip on the bottom with that pipe but after doing that don't be surprised if the baffles loosen up and start falling out.

JustDave71 · 10-10-2009, 11:55 PM

well...my bike aint no dyno monster...probably won't ever see a dyno so I don't know about any "dip." Feels plenty solid for the engine size at all throttle ranges so not gonna worry about that

what about the "cone"?

aharp · 10-11-2009, 12:09 AM

My advice as far as the exhaust is to leave it alone, everything on that pipe is there for a reason. The baffle "tuning" is more noticeable on a dyno graph then by the ass-o-meter anyway.

JustDave71 · 10-11-2009, 01:25 AM

heh. ass-o-meter

yeah...I'm new to harleys as far as owning one, but so far everything I've done has been by feel.

but...being a persistent son of a gun...what purpose does that additional cone serve?

gsxrboy96 · 10-11-2009, 01:46 AM

Quote:

Originally Posted by JustDave71

heh. ass-o-meter

yeah...I'm new to harleys as far as owning one, but so far everything I've done has been by feel.

but...being a persistent son of a gun...what purpose does that additional cone serve?

Im not sure this is gonna be the most technical answer, but after looking at my thunderheader, i would say that additional cone promotes some sort of scavaging effect at the end of the pipe, if you notice, its open at the front to let on coming air past the escaping gas. follow me?

JustDave71 · 10-11-2009, 01:50 AM

Quote:

Originally Posted by gsxrboy96

Im not sure this is gonna be the most technical answer, but after looking at my thunderheader, i would say that additional cone promotes some sort of scavaging effect at the end of the pipe, if you notice, its open at the front to let on coming air past the escaping gas. follow me?

yeah, that makes sense if we're speculating. There's clearly an intentional gap there.

Hell...I ain't messin with this thing. I love how it sounds

btw...you slapped a thunderheader pipe on your jixxer?

gsxrboy96 · 10-11-2009, 09:24 AM

Quote:

Originally Posted by JustDave71

yeah, that makes sense if we're speculating. There's clearly an intentional gap there.

Hell...I ain't messin with this thing. I love how it sounds

btw...you slapped a thunderheader pipe on your jixxer?

nah.....

ive almost completely gave up the metric bikes since buying my first harley, i keep one simply to race. the thunderheader was on my flht, it sounded beautiful, then i added compression, and the pipe really cam alive.

Dave63 · 10-11-2009, 09:37 AM

Quote:

Originally Posted by JustDave71

OK, so I have thunderheader exhaust and...part of me thinks "why the hell did they build this this way?"

one of the main questions is...what's the purpose of the tacked on "cone" at the exhaust output? It almost looks wrong on there. Anyone ever pop one of those off? what was the result?

Also, I've heard about bending the baffles to create more backpressure. On an 89 stroker would there be any point in doing something like that?

any thunderheader mods or the like?

The tip "cone" is a diffuser shroud, that's attached to the reverse cone. It's designed to defuse the air rushing in as the pressure inside of the system becomes equal to atmosphere. Like an anti-reversion type device.

The 2-1 exhuast already created more backpressure then a 2-2 system, so bending the baffles isn't necessary. Of all the aftermarket systems, you'll lose less low/mid range torque with this pipe. Most people have gains in that area, with this pipe, due to it's design of equal runners and it's 2-1 design.

The company is allegedly run by 81 and the pipe is American made. I like knowing my money is staying here, and not supporting Japan, China or some 8 year old Malaysian kid, doing 18 hours shifts.

POPS87FXR · 10-11-2009, 10:33 AM

Go to thier website, there is a cutawy drawing of the pipe in action.
I have sold a couple of hundred of TH's and everyone has been real pleased with them.

Like was stated above, a properly made 2 into 1 will scavenge exhaust an actually will create more torque, and TH does the best job of that.
BTW they are not owned by 81, but are tight with them.

Dave63 · 10-11-2009, 10:39 AM

Quote:

Originally Posted by POPS87FXR

BTW they are not owned by 81, but are tight with them.

I wasn't sure. Heard the rumor, which is why I said, "allegedly" and didn't state it as fact. Even if they were, I'da bought it anyway. Excellent product and American made.

Good info.

POPS87FXR · 10-11-2009, 11:22 AM

Yeah it (rumer) has been around for awhile, the actual name of the company is Rich Products and sometimes Rich is the guy answering the phone, I asked a couple of years ago just to satisfy my own couriosity

ReformedHippy · 10-11-2009, 11:49 AM

Quote:

Originally Posted by POPS87FXR

Go to thier website, there is a cutawy drawing of the pipe in action.
.

Can you post a link to this or is that in the dealers only area?...I cant find it...

JustDave71 · 10-11-2009, 03:37 PM

don't care if they're owned by 81.

thanks for the cool answers!

claydbal · 10-11-2009, 04:34 PM

Quote:

Originally Posted by POPS87FXR

Yeah it (rumer) has been around for awhile, the actual name of the company is Rich Products and sometimes Rich is the guy answering the phone, I asked a couple of years ago just to satisfy my own couriosity

if you were 81, would you go telling just anyone that asked? not starting something, just wondering.

gotta love that sound. i wish they would build one to handle the higher output motors.