| Author | Message | ||
     Martin |
A while ago I asked if anyone knew the flow rate of the standard XB9 injectors. Either nobody knew or they weren't telling so I sent them away to be measured and here are the results: @3 bar fuel pressure flow is 295cc/minute (28lbs/hour) I think that the Buell system works at 56lbs fuel pressure which changes the figures to: 335cc/min (31.9 lbs/hour) It is the convention, I understand, to not exceed 80% duty cycle which equates to: 268cc/min (25.5lbs/hour) That amount of fuel will support 92.7bhp at the crank. For those of you trying to get your TFI to work and suffering rich spots, you might want to consider lowering fuel pressure to lean-out the whole curve before adding some back in.It would appear that the injectors might not actually end up being 'big' enough to do that, though. Dropping fuel pressure to 50Lbs for example, lets through enough fuel at 80% cycle to support 87bhp. I hope that this helps all you fiddlers! | ||
| Wyckedflesh |
I don't think anyone who could say knew what the flow rates were. You could always swap for XB12 injectors since a XB12 is rated at 104hp at the crank. Now I need to find out the flow rate of a 12...who did you send your injectors to? I was thinking of sending mine to RCengineering and have them cleaned and balanced. | ||
| Racerx1 |
Martin, your BSFC assumption is too high on your horsepower estimate and the 80% duty cycle is a general rule...max pulse width is time based and a function of engine RPM and stabilized injector reset time. An 80% duty cycle estimate is on the low side for the relatively low rpm an XB will see. | ||
| Opto |
Thanks for posting the info Martin, not even the service dept manager could answer that for a 12. Weston, (Racerx1) what does BSFC mean? I think you're saying that the stock 9 injectors will handle a lot more than 93HP and I've found from running a non-Buell FI system on a 12 (with stock injectors, basically stock street bike) that it looks like they will handle a lot more than stock HP. | ||
| Wyckedflesh |
Brake Specific Fuel Consumption | ||
| Martin |
Great, I knew that someone would help correct my assumptions, which were based mostly on carcentric books like Cookie Bells turbo book. I had to send my injectors away to Norfolk (England, not Virginia) since I could find no-one local to me who knew what I was talking about. Incidentally the injectors are 4-hole so there may be some advantage to using a Bosch type with a better pattern (More is better, right?) | ||
| Racerx1 |
Opto, Yes, you should be able to support a fairly heavily modified engine with stock injectors without concern! As far as injector hole size/number, thats a bit of a compromise. The smaller the holes/droplet size, the faster the charge atomizes, but you tend to lose inertia and penetration of the fuel plume. It tough to say one option is better than the other, depends on the engine application and what you are trying to accomplish. | ||
| Rotor |
i think i've read somewhere that XB9 and X1 injectors are the same. Starting from this we can think that XB 9 and XB12 injector can supply about the same fuel amount i'm wrong ? |
