| Author | Message | |||
     Doughnut |
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| Ft_bstrd |
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| Xl1200r |
On a hot day at a standstill or in parade duty... a) An aftermarket RSS undercools can hinder adequate cooling of the fuel rail, as outlined by the Ask Abe article posted in here twice now Great, so you said the same thing I did. Now what the heck might happen if the ambient air is cold and humid and what if there is plentiful ambient airflow, you know like when cruising down the road? Might that be problematic in combination with the refrigerative cooling action of atomized fuel mixed with ambient air, of high humidity? Ever hear of how a carburetor can ice up? For starters, there is no atomized fuel in the fuel rail, so there is no added regiferative action taking place there. If the equivalent of carb icing were to occur on our fuel-injected bikes, it would take place at the throttle body, where there is no fuel yet, and where a RSS would play little to no role in the condition. I suppose it's possible that some icing could occur, in theory, at the base of the intkae manifold where the injectors are, but I highly doubt this would happen. Did you ever think that this condition may have been tested by the folks at Buell? Is it not possible that an aftermarket RSS, while increasing the cooling capacity to the rear cylinder, would decrease the cooling capacity to the fuel rail in extreme conditions, while the factory RSS does not over-cool the fuel rail in the opposite, but equally extreme conditions? | |||
| Spiderman |
And what is the freezing point of gasoline? | |||
| Xl1200r |
The freezing point of gasoline depends on a lot of factors, but it is somewhere around -97 to -120 degrees F,but that's not what causes icing. Gasoline evaporates very quickly, so it creates a colder condition than would exist without it in the air. This colder condition causes the water vapor in the air to freeze, which then builds up on things like carb throats. (Message edited by xl1200r on August 07, 2008) | |||
| Lost_in_ohio |
Wow it got to 185 posts. Gotta luv these RSS treads. | |||
| Spiderman |
and what is the freezing point of water in a preasureized fuel rail at 32psi? | |||
| Treadmarks |
 Message edited to reflect my true feelings toward the owner and the mother ship. (Message edited by treadmarks on August 07, 2008) | |||
| Xl1200r |
and what is the freezing point of water in a preasureized fuel rail at 32psi? The freezing point of water actually decreases as pressure increases. However, it would remain at essentially 32 degrees under 32 psi. It takes almost 2000psi to lower the freezing point by 1 degree C. (Message edited by xl1200r on August 07, 2008) | |||
| Blake |
Why would there be water inside the fuel lines?  The water is in the air, not the fuel. The fuel when evaporating is an extremely effective refrigerant, behaving exactly as freon does in your air-conditioner's evaporator. Evaporator, going from liquid at high pressure to vapor at low pressure. The throttle body, especially at low throttle openings is a low pressure evaporator. Treadmarks, "I traveled at night for two hours at interstate speeds in SC this past new years when the temps were below 20 degrees with the RSS installed. I did not notice any symptoms of icing." At 20 F, the temperature is too far below freezing for icing to occur, exactly as your quoted material says. That quote however is in error in its explanation of why icing is unlikely when the temperature drops significantly below freezing. "Once ambient temp is below freezing it no longer matters as the moisture in the air is already frozen and simply passes through the carb with no effect. That is incorrect. The subject moisture (water) in the air is in vapor (gaseous) form. When it is cooled sufficiently--this depends upon the ambient air's relative humidity--some of it condenses into liquid. This is because warmer air is able to hold a significantly higher percentage of water vapor than cooler air. It's why clouds, rain, fog, and it's why dew happens, and why water often condenses on the outside of a cold drink container. The problem in an engine's intake tract arises when/if the now condensing liquid water inside the throttle body contacts and then freezes into a solid (ice) when on cooled (refrigerated) surfaces inside the throttle body. When it is much below freezing, the humidity is typically very low, so either condensation doesn't form inside the throttle body or it transforms too quickly from vapor straight to solid (ice) while still airborne before it has a chance to stick to the surfaces inside the throttle body. Once solid/ice, it merely bounced off the also below freezing temperature surfaces inside the throttle body. This is why throttle icing typically occurs when ambient air temperature is above freezing and the relative humidity is high, the nearer the dew point (the temperature at which water in the air begins condensing from vapor to liquid). | |||
| Blake |
SCOOP ENVY The above states nothing about what the effects of a larger right side scoop might be in fan-off, cold ambient conditions. It is simply logically untennable to try to use the above information to refute a claim that a larger RSS can cause problems in cold conditions where a moving bike and RSS are subject to significant ambient airflow. Anony basically confirmed that there is an issue with the larger RSS subjecting the fuel rail to excessive cooling airflow which hinders fuel vaporization. That may well be something different from icing, but possibly related. I've certainly heard of XBike owners who have suffered fouled spark plug(s) in cooler weather. Might a larger RSS exacerbate that problem? I can sure see that it could do so. If you cannot imagine a potential problem, then until it happens to you, it will seem outside the realm of possibility. I'm gratified that the engineers at Buell operate in a much more responsible fashion. Their professional integrity is superb. (Message edited by Blake on August 07, 2008) | |||
| Blake |
Spidy, The better question might be... What effect does temperature have on the vaporization temperature of gasoline? Liquid gasoline won't burn. It must be in vapor form to do so. Optimum combustion requires virtually all the fuel to be in vapor form prior to ignition. | |||
| Spiderman |
I am just trying to figure out the icey gas is all  I know all about the RSS, from all angles. Just want to stir the pot some more  | |||
| Surveyor |
I'm gratified that the engineers at Buell operate in a much more responsible fashion. Their professional integrity is superb. Me too,...even if their interpersonal skills aint. sorry sorry sorry...I couldn't help myself please disregard this post. (Message edited by surveyor on August 07, 2008) | |||
| Greenlantern |
I know all about the RSS, from all angles. Just want to stir the pot some more How about you stop stirring and start rolling! After reading all this ......um ... info, I could use a tug mon!  | |||
| Court |
>>>Me too,...even if their interpersonal skills aint. My interpersonal skills leave a lot to be desired in some venues and situations. I tend to do things like fire folks who can't perform. Somehow I manage to do the things I do quite well in spite of my lacking skills. How terrible it would be if the folks at Buell were just exceedingly good at designing, engineering and building motorcycles. If someone came on the internet and slung mud as many of the things I do I'd be a bit pissy as well. Court | |||
| Greenlantern |
Contstruction worker, mud, slung, Now that there is funny!  | |||
| Id073897 |
This is why throttle icing typically occurs when ... So when and how does icing occur in FI equipped engines? The conditions differ significantly from carbs. And which role does fuel temperature play in this all, as this is the only variable? Regards, Gunter | |||
| Badlionsfan |
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| Ekass13 |
I know where you could put the fuel rail to warm it up.... ouch, vapor lock!  | |||
| Xl1200r |
Anony basically confirmed that there is an issue with the larger RSS subjecting the fuel rail to excessive cooling airflow which hinders fuel vaporization. Blake, I think you're understanding this backwards. I have read and re-read the article, and everytime I do, I come away understanding that an aftermarket RSS won't cool the fuel rail enough in the described conditions. It sounds like you're saying a larger scoop will cool the rail too much. So when and how does icing occur in FI equipped engines? The conditions differ significantly from carbs. And which role does fuel temperature play in this all, as this is the only variable? I tried to some research on this, but it seems that FI engines where the injectors are not located in th throttle body (i.e., our XB's), this will hardly ever happen. However, in theory, it could. As Blake explained, a throttle body accelerates the air moving through it. That means the pressure drops, and with it temperature. | |||
| Deanbush |
I have the RSS from American Superbike and have applied resettable temperature sensor's on the front & rear heads and I have been logging data for the last 2 weeks and the rear head seems to be averaging around 30 degrees F hotter than the front, oil temp 185, transmission, 170 riding in 95 F air temp. . | |||
| Treadmarks |
Welcome Deanbush. Very impressive documentation pertaining to Buell related problems in your profile. It's just like another Gastonia boy to have his shit together and say it like it is. I raise my glass to you sir, and look forward to your presentation of real world facts.  ps..Try not to draw to much attention to yourself, as this site has been invaded by aliens from the mothership. I think their leader goes by the name of Annony.  | |||
| Damnut |
I guess it was too much huh Blake, sorry man. But did ya think it was just a tad bit funny??? I laugh my ass off when I see that dancing stick man. | |||
| Jaimec |
What is the average air velocity of an unladen swallow? | |||
| Johnnylunchbox |
Deanbush, did you log data prior to putting on the RSS? | |||
| Metalstorm |
IS that an African swallow? | |||
| Id073897 |
. As Blake explained, a throttle body accelerates the air moving through it. That means the pressure drops, and with it temperature. Yes, but the main requirement for icing is that the humid air's dew point needs to be reached. How many iced vacuum cleaners did you see in your life? Do the tubes even feel colder than anything else? No, at least not those I touched in my life. Regards, Gunter | |||
| Blake |
"Blake, I think you're understanding this backwards. I have read and re-read the article, and everytime I do, I come away understanding that an aftermarket RSS won't cool the fuel rail enough in the described conditions. It sounds like you're saying a larger scoop will cool the rail too much. " You no read good. Me have no patience. You maybe try read again what me already say. If you still confuse, then maybe you learn read better, try again. | |||
| Blake |
"So when and how does icing occur in FI equipped engines? The conditions differ significantly from carbs." Not so much actually. Not for throttle body injection. "And which role does fuel temperature play in this all, as this is the only variable? " Colder fuel is more susceptible to freezing? Only variable? Says you. You maybe mistaken? Do you understand the great effect of evaporative/refrigerative cooling? |
