| Author | Message | ||
     Martin |
I just took my 9 header off to have bosses welded-on for individual cylinder O2 sensors so i can direct-link tune on the dyno and started thinking....What if I got a 12 header instead and did the work to that. I already have twin throttle bodies so intake flow isn't a problem. I have a Hillbilly-Motors race-can if I want to use it. I know that the larger diameter will reduce gas speed and thus bottom end but feel I could tune that out a bit with the DL software. I harbour fantasies of making it a 12 someday but not for a year or so. The top-end is stock. So what do you guys think? | ||
| Diablobrian |
Should be ok if you can tune it via direct link. You may end up with some tuning anomalies. If you are building incrementally, and accept some minor glitches, there should be no reason it wouldn't work. | ||
| Xb9 |
Better than the 12 header, go with the Micron system. Look at the dyno run Terry did over in Al's AmericanSportbike sponsor section. (Message edited by xb9 on March 26, 2006) | ||
| Kowpow225 |
I really don't think it will give that much of a gain even after significant amounts of tuning has taken place. I hope I'm wrong though. (Message edited by kowpow225 on March 26, 2006) | ||
| Martin |
Yes, I would like to fit a Micron system, especially if they make a road-legal version, but I can't afford it at the moment. It is getting increasingly problematic to have a loud exhaust over here, so I compromised and drilled a couple of holes in the outlet as described elsewhere on Badweb. My 'standard' can gets through the MOT (A compulsory annual tech inspection) and is quiet enough for quiet track-days-except poor Donington-it even keeps my neighbours happy. I must be getting old. | ||
| Bigsherm9r |
Martin- what twin intake setup do you have? Pics?? Sherm | ||
| Martin |
Its a homebrewed twin 42mm t/body thing. I have posted pics before but I'll have a go when I get home. I think with Direct link I might just get it running good this year | ||
| Martin |
 This fits with an oval K&N completely within the standard air-box cover so it is 'stealthy'. I used the standard cables and quadrant, TPS etc. I fitted 330cc injectors but that probably wasn't necessary. | ||
| Bigsherm9r |
NICE!!!! Keep us posted on the results! Sherm | ||
| Alex |
Martin, "I already have twin throttle bodies so intake flow isn't a problem. " I told You once before that You might be on the wrong way. First of all a 42mm throttle plate is way small for this engine (and again, the stock engine breathes through the 45 system with only one cylinder at a time, so actually Your system is SMALLER than stock). Second I doubt that Your manifold is of a pretty good design (sorry to sound a little harsh, but Iīm dealing with flow bench science every day). Third the stock throttle body design is capable of feeding enough air for stock heads. If the heads are reworked it is worth to rework the throttle body but not vice versa (I get above 100rwhp with a reworked 45mm throttle body without enlarging it). You may find tuning advantages with Your setup. You may wonīt. But Iīm sure You wonīt find additional flow. If You want to know for sure I would offer to test Your setup on the flow bench. Best regards Alex M-TeK Engineering | ||
| Martin |
You are absolutely right Alex. The manifold 'fits where it touches' and that's about all you can say, although the inside is definitely better than the outside! I would love to visit you if I ever get over to Europe again but wouldn't waste your flow-bench time on what was a hobby-project done more to see if I could do it than set the world alight. My aim with the smaller diameter was to improve what I felt was poor throttle-response but I could probably achieved that with better mapping had that been available at the time. I still have memories of an old Renault I had that had a large motor with a small carburettor and was lovely to drive. Keep keeping us honest! Martin | ||
| Alex |
Martin, I wouldnīt see it as a waste of time to test different things on the bench (otherwise Iīm waisting a tremendous amount of time during the year). Iīm interested in seeing what Your setup would do on the bench, otherwise I wouldnīt offer to test it (for free). Regarding the higher air speed in a smaller induction system: thatīs right but it will only work with carburettors where you can boost the fuel signal by choosing a smaller venturi size. For injection systems the air speed in the throttle body is of minor importance as you donīt need vacuum there to draw fuel into the air. So injection systems often are chosen on the bigger side to not bottleneck the heads. See the RR with 62mm throttle bodies. Martin, doubting the flow design of Your system wasnīt meant to be offensive in any way. Still I know that there is little space between the heads and packing two single runners in between normally results in restricted square area and sometimes sharp turns (for example I remember the MagnetiMarelli single runner injection system of early Twin Cams where there is much more space in between the heads. It didnīt flow well). So again, if You want to know the flow capacity of Your system I would be glad to help. Best regards Alex | ||
| Martin |
There may be a parcel heading your way next winter, Alex, thanks for the offer and no offence taken | ||
| Alex |
Youīre welcome, Martin. Regarding Your 12 header question (which completely dropped out of sight): the XB 9 header is really restrictive on the flow bench (especially the rear one with the Lambda sensor in it). Iīm not sure if it will make too much difference on a stock head, but with a reworked head a 12 header is a good idea. Remember that a XB 9 "produces" about the same exhaust volume at 7500rpm as a 12 does at about 6200rpm (at least theoretically). If You get the chance to try a 12 header and reprogramm the ECM I would give it a try. Tell us what You found. Best regards Alex | ||
| Blake |
172689 http://www.badweatherbikers.com/buell/messages/3842/3598.html | ||
| Martin |
Sorry, Blake, I know that we just make more work for you when we post technical stuff in the General board. |
