Hey guys, I've been doing a lot of research into exhaust and I think I've narrowed it down to two different pipes.

Either the Rinehart 2 into 1 in Black
Or the D&D Fat Cat 2 into 1 in Black

Looking at the head pipes it looks like the Rineharts have a larger bend radius on each of the bends, especially for the rear header pipe. My understanding of exhaust flow is that the tighter the bend the more you will kill exhaust gas velocity.
The other difference I was reading about is that the Rineharts are 1 7/8" (1.875") diameter on the head pipes.
Whereas the Fat Cats are 1 3/4" (1.75") at the head pipes, stepping up to 1 7/8" before the collector (how much before I don't know)

Smaller head pipes should keep your exhaust gas velocity high. Up to a point, and that point being where they start becoming a restriction to flow.

No in practical application from reading people experiences it seems like the D&D is more of a low-end pipe. Relative, as it doesn't exactly suffer on the top end.
And that the Rinehart is more of a high end pipe. RPM wise that is.

Sound like I got my facts right so far?

Now a word about my build and riding style:

Currently the bike is dead stock. It's a 2009 Fat Bob, 96 Cubic Inches. Denim Black. Probably pretty lightweight as far as Harleys go.
Plans are to go with an Exhaust, Air Cleaner (haven't researched these yet), and a TTS Mastertune for now.
When the Harley warranty runs out, I'd like to cam it, go with a 107" Big Bore kit, and some headwork. Probably one of the HQ builds, but I have alot of time to decide on those details.

Riding style: I'm coming from a sportbike background, so I've already bounced off of the rev-limiter a few times *oops*.
Looks like I need a tach. Also most of the time I just ride the torque wave through corners, power out a bit, then slow down before I get into too fast illegal speeds.
Mostly I ride solo, and mostly I ride off into the twisty roads of Wisconsin. Though occasionally I ride two-up, and on nice days I'll be using it for commuting to work also. I haven't once yet ridden it into the city or bar-hopping, though it'd be nice if the power band was friendly enough to accommodate that.
Finally. gotta take the wife out for dinner sometimes, and am also planning on a short couple thousand mile tour this summer, so obnoxiously loud pipes are out.


As far as looks go between the two, I think they look almost exactly the same, so visually the decision is out.
Price looks to be essentially the same between the two. As is ground clearance. They both work with mid controls and forward controls.
Seems like build quality is pretty much the same between the two.

What do you experts say for performance? Will the Rinehart feel flat for the next couple of years until I go big bore?
Or will the Fat Cat be great now but be a limiting factor when I get the big bore kit.

Or will the only difference between these two be visible on a Dyno. I don't plan on paying for Dyno time until I go with the Headwork and Big Bore kit.

Thanks

Oh, and more pics of those two in black would be awesome. Haven't found many in black....

 

Fatcat is a better performing pipe. IMHO it looks a lot better too. Of course it is all up to you. I for one love the low end to midrange pull on my fatcat. Much more usable on the streets.

 

+1 on what Rounder said. I love my Fatcat.

Check out Centerline's bike, he's got the black Fatcat but it's on a Fatbob not the Streetbob.

 

D&D Fatcat. I have a 117" and the performance is great. If you want to see a dyno run let me know and I'll post it up.

 

#1...you're reading too much..ride your bike like it was meant to be ridden
#2...you're not on a crotch rocket anymore...it won't handle like one
#3...exhaust gas velocity?????????WTF
#4..."loud pipes are out"...(I'm satisfied to go deaf now 'cause I heard it all)

I would say more but I lost a finger and can't count any higher...

....

 

Love the sound and performance of my bub7's (reinhart makers),but recently spoke to someone at wood's cams who told me supertrapp make the highest performing exhaust!

 

This is such a tired subject. All 2-1's are about the same. Pick whichever you think looks and sounds the best. They are ALL going to be within a horsepower or two.

 

true, but, their torque curves and how they come on through the RPM range will be quite different. we ride 99% of the time through the rpm range and not at peak HP and torque. Heck, my big radius 2-2(BCT baffles) had about the same peak HP and torque on the dyno, yet the curve and the way the D&D feels on the road over the big radius is unbelievably different.

 

You sound like a good candidate for the Fatcat with the Big Bore baffle.You might loose some performance in the beginning with the stock motor,but when you do the cams,headwork & raise comp you get all that & then some!! Fatcat gets my vote.

 

1. That's part of the problem, Winter here in Minnesota, no riding.
It's pretty warm out today, all the way up at 22 degrees...

2. Never said anything about Handling. Just as an example of where I'm used to revving a motor

3. Exhaust gas velocity. Yes. Exhaust theory: You have to keep the exhaust gas velocity high to make power. That's why you loose torque if you go with an exhaust that's too large. The velocity drops and each pulses exhaust gases don't effectively get out of the way of the next one. If the velocity is high you get a scavenging effect.
If you go too small the exhaust velocity stays high, but it becomes a restriction.
So Ideally you want it just large enough to flow at max throttle, so it's not a restriction there, and just small enough to keep velocity high at small throttle openings.
Couple that with large abrupt direction changes tend to slow the exhaust down.

It's part of why Header Wrap works to make more power. Without header wrap you're radiating heat out of the headers. Well that lost heat causes the exhaust gas to shrink. This causes it's velocity to drop, and so on.

Conversely when you wrap the headers the heat stays in the exhaust gases and velocity stays high.

Yes I am an engineer, why do you ask?