| Author | Message | ||
     Blackbichgsx |
I have a XB9R and I was thinking of putting XB12 exhaust headers into it. I have a XB9 drummer muffler which I plan to still use. I know the XB12 has bigger pipes, but I did not know if they will fit with the XB9 muffler. Also sometimes bigger is not better. I have searched on multiple forums and I can not come up with any answer to this question. Someone had said it does not yield anything, but has anyone swapped headers and tested the results? Any info or links would be great. | ||
| Rocketsprink |
everything matches up. From what I've been told from a very reliable source, going with the 12 header on a 9 with the factory race kit will give you one less horse power at about 5k and three more horses at the top end. Is it worth it for a street bike? I don't know, but that is what I'm running my race bike with this coming season. | ||
| Nuerburgringer |
The XB9 motor in particular is pretty danged finnicky about exhaust mods. I wouldn't swap that header out unless I knew precisely where I was headed with an engine build. The last thing that you want is a big fat midrange hole, whether street or track. Just my $0.02. | ||
| Rocketsprink |
exactly what I stated in my above post is what will happen. Of this I am sure. That's all I can say. | ||
| Old_man |
You know the old expression "six of one, half dozen of another" A larger pipe may give more power at the top end but kill the bottom. The Buell engineers chose that size pipe for a good reason. I would personally leave it as it is. Remember you can't get something for nothing. | ||
| Rocketsprink |
Exactly. You live in the upper RPM range at the track. Street, not so much. The info I speak of comes from someone with first hand knowledge. Of the people you speak of above. | ||
| Blackbichgsx |
I realize that bigger is not always better when it comes to N/A based engines. I also realize that it is mainly going effect the lower end torque and hp, but I did not know if it would be drastic. I also have a K&N open to air and a race ECM that I intend on doing further tuning to. As for engineering, I don't know what the reason is that it has smaller pipes. It could be for noise reasons? Plus they do there design with stock components. Working for H-D currently as an engineer I know we don't make exhaust changes just to increase power. | ||
| Old_man |
Since the 9 was a new engine based on the 12, I supposed that the pipe was engineered for it. Since the larger pipe is on the 12. | ||
| Jos51700 |
The XB9 needs all the torque help it can get. Smaller diameter pipes offer that help. I can vouch for everything Rocketsprink has said. Engineer at Harley, eh? That might be where you need ask such questions. I figured most of their non-disclosure agreements would keep you from admitting such info. | ||
| Blackbichgsx |
Well as most know there are government regulations for everything that get's put on the road, so there are limitations. If you companies wanted to optimize power I think diesel trucks would come with 4"+ exhaust out of the box. I work as a manufacturing engineer at the York plant. I have never spoke with anyone from Buell, but if I wanted to track someone down I prob could. More than likely the person that designed the pipes in 2001 or 2002 is in another department. I do have to agree though. With the 9 torque is essential. | ||
| Kds1 |
I put the 12 header on our racebike (xb9) and it killed the little motor on the bottom, I don't care what the dyno says, it was a freaking turd....the little shortstroke motor needs exhaustgas velocity, has to have it, piston speed is quicker, so the pulses in and out, well have to be fast also, thats my 2 cents, but what do I know...I can't wait till you guys see the header I'm putting on my XB12 streetbike..... Kevin www.kdfab.com | ||
| No_rice |
how bout one for an xb9 streetbike... hint hint! lol |
