1998 Sportster 1800: full or partial enclosure and Fuel Burn at Cruising RPM

[mattbraafhart]

Anybody know of or have a partial or full enclosure for a 98 sportster like for crusing the river in the rain? while I'm thinking of it, also a lighting rod or something for lighting strike protection...

Also, anybody khow what fuel burn at cruising speeds would be or what cruising RPM is? or is there a fuel flow meter I can install easily to tell me real time fuel burn, or the computer? And speaking of the computer, somebody said they could see how many hours are on the boat from the computer, how?

Thanks!

 

[howie099]

You need the OEM seadoo tool that the dealer has to read the computer or the aftermarket one. I have the Aftermarket one, it runs about $400.

 

[IDoSeaDoo]

To read fuel burn, you would have to get an aftermarket flow meter. I have a single engine challenger, hence don't know: do you have two fuel baffles or just one? I'd be quite curious to know what your cruising fuel burn is. Also, what IS your cruising RPMs and what speed does that equal?

 

[swneely]

I have a 1998 sportster, It depends on your engines and tuning. If I'm running WOT, that's around 7000 RPM on both engines, I will burn a tank of fuel in less than 2 hours. I did this ONCE, I ran up river full throttle with 4 people, I averaged around 42 MPH on my GPS. That was tuff on me and the passengers. An average day on the lake, I will use around 40 gallons of fuel. I pull tubes most of the time, I have a few friends who will ski behind the boat. I have learned that you have to pay to play...

 

[mattbraafhart]

I am generally cruising at between 5000 and 6000 RPM depending on water conditions, at this RPM I'm typicaly about 25-30mph. This is a comfortable cruise speed for the boat and passengers in general.

Although I'm not doing extensive monitoring I am guessing based on past usage that I'm burning around 5 gallons per hour at this speed but I really want to know for sure.

I'll have to look at the fuel lines to see if there are two baffles, I'm not sure on that, I think there is just one coming out of the tank though so I could put a flow meter there.

Thanks for you reply!

 

[IDoSeaDoo]

IMO, it would be a very expensive and time consuming effort to get an accurate fuel-burn number. First off, you would need two fuel meters, one on the inlet hose, one on the return. These babies aren't cheap! Depending on the type of data they put out (instantaneous, or totalized), you would have do the correct math to see how much fuel is NOT going back to the tank. Then you have the variables of how many people you have in the boat, how many RPMs you're turning, etc. And at the end of the day, it would only tell you what YOUR boat is using, at that temperature/pressure/humidity etc. and would not consider factors like cavitation, prop pitch or tuning. I would say the most practical way of measuring fuel burn is to fill the boat up, ride it at some particular rpm/speed and measure either the time, or the distance that you cover. Then put the boat up, and refill the tank to the same exact point as when you started. The amount of fuel it takes to refill will tell you what you expended over that duration (of time or distance). Again, this would only be an estimate for one particular boat. Has anyone out there done anything of the sort on any boat/ski?

 

[mattbraafhart]

Thanks for the reply, definitely good things to think about, I'm curious about your statment of tracking the flow on the return?

I've seen flow meters on the web in the $200 ballpark, they only have one line connection, not one for a return as far as I can tell anyway.

Wouldn't putting one of these meters on the line and running it at different RPM's then taking note of instantaneous flow be sufficient? Of course I realize it's going to be different under heavier loads and rougher water, but just looking for some reference point or a benchmark.

of course running a tank empty then filling it back up again will work as well, I typically don't run it long enough in a weekend to empty a tank of gas, however, I could mark the tank as you say, then go do a 1 hour run at fixed RPM, then refill to the mark and do the calculation.

 

[IDoSeaDoo]

Correct, typical flow meters measure only one line of moving fluid. You would have to get another meter to measure the return line to see what it's spitting back into the tank. $200/pop sounds about right, making this an expensive endeavor. To measure the fuel consumption using the fill-up method doesn't require one to completely use the full tank, although the more you consume, the more accurate your result. To measure MPG in a car, you would simply fill up till the nozzle "clicks", reset your trip meter, drive some distance, and again refill to the "click". The amount of fuel from the second fill up is the amount it takes to cover the distance on the trip odometer. You can then divide the miles by the gallos and get your fuel mileage estimate. I do this regularly to keep track of my car's "well-being".
Since our boats have fuel vents, the fuel will start to exit the vent when you fill up all the way. I don't get that "click" from the nozzle, but rather douse my feet in gasoline (my vent is kind-of broken). I'm not sure if all boats overflow like mine, but the overflowing could serve as the marking point though. Try not to spill too much fuel everywhere . The idea is to fill up to some exact point, all the way being the easiest one to determine. If you're gauging from the fuel level in the tank, 1/8" error spread over the surface area of the tank can make a rather large difference and throw off the calculation. Also, we don't have the advantage of a trip odometer. Hence, we need to use either speed or RPM vs time to get a gallons per hour consumption. I've also used google earth and was able to get a rough estimate of MPGs for my seadoo GTS (roughly 6mpg w/ me and one other ) Sorry for the long rant guys. Let me know if anyone tries and what your consumption rates are!