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Do you wish you had a larger fuel capacity?

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Discussion Starter #1
Has anyone ever considered/wanted/looked for a way to increase the fuel capacity on their Slingshot? I use mine as a daily driver for an 80+ mile round trip, so I only get 2.5 days out of a tank. I managed to go a full 3 days once, but I was getting pretty nervous by the time I made it to the gas station by my house. There'd obviously be issues with the fuel range calculations and fuel gauge, but any other thoughts or interest? I haven't been able to find anything specifically built for the Slingshot.
 

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First, Welcome! Glad to have you puttering along with us! While there are times I'd like to go a bit farther on a tank, I'm mostly okay with my Slingshot's range as is. Without extensive reworking, I suspect that increasing your fuel capacity is going to be tricky at best. My best suggestion would be to drive as conservatively as possible. This might mean slower acceleration and shifting closer to 2000 rpm than 3000. That can add 2-3 mpg, maybe more, over more aggressive driving. May not be possible on your commute, of course, but sometimes maybe. Granted, conservative driving for maximum mpg is not exactly what the Slingshot is all about. (Personally, I would not be fond of carrying an extra gas can, either behind the seats or in the passenger compartment. I'd rather stop more often.)
 

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I haven't done this, but I'd guess the easiest way to increase fuel capacity would be to mount an auxiliary tank in one of the storage compartments. I'd think you'd need 2 connecting hoses between the auxiliary and main fuel tanks. One, using a larger hose connection, higher up so that once the main tank is relatively full, the gas can then overflow into the auxiliary tank before subsequently completing the fill of the tank. The other, smaller hose would connect lower down on the main tank so the fuel from the auxiliary tank could automatically flow into the main tank for pickup by the fuel pump. This design should avoid the need for a second fuel pump.
Again, just a guess.
 

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Discussion Starter #4
Thank you for the welcome! Unfortunately 95+% of my commute is Interstate driving at a steady speed, so I don't think there's too much I can do by changing my driving behavior. I know wind resistance increases exponentially with speed etc etc, but there comes a point where I only want to go so slow...

As far as putting a tank in one of the storage compartments, I like the idea, but I don't know if that would work without a second pump. Regardless I know any solution wouldn't be an easy solution. I'm just curious if anyone out there has thought it through more than I have.
 

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I too wish it had. But the reality is, how often are you going to drive 250+ miles in 1 run? Simply speaking, I'ld want to get out and stretch my legs more often than that. I know driving 180 miles to Houston the other day, I was ready to get out and fill up.

That being said, I also use mine as a daily driver, but my commute is much more conservative (10 miles 1 way).

Thinking back to my trucks that had extra tanks, there was just 2 hoses connecting them: 1 top-to-top and 1 bottom-to-bottom. You shouldn't need a fuel pump as the fuel would treat them as one single tank. However, if you wanted the capability to switch tanks, you would need to separate them and add the pump switch. You would probably be able to get 3-4 gallons or so in each behind seat storage area.
 

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Discussion Starter #7
I was able to find these pictures of the stock tank's location:

13187840_10205840338319383_712362130_n.jpg


Polaris_Slingshot_Rear2.jpg


Seeing how the tank is about the same height as where the storage compartments would be, I think you all are right that it would work without a second pump.
 

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Discussion Starter #8
Speaking of trucks, maybe I'm just spoiled from having a 25 gallon tank on the truck I had before this. I could go a whole week on one tank, where as now I'm having to stop almost every other day.
 

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@[email protected], have you ever had a request like this or tackled this type of project?
No, we have never had a request for that actually. There are definitely some things that can clean up the aero on the Slingshot that will help on interstate cruise, but I would guess maybe the best would be a 10% increase in range. Also, we get a lot of feedback that a tune can help with fuel mileage, especially on the earlier models.

If you want to go with an extra fuel tank, I would highly recommend using a fuel cell if installing it in one of the storage compartments, since a hit to the Slingshot from the side will get into that compartment. A fuel cell can also be made in custom sizes to fit in that area. It would be pretty simple to make a fuel cell that fit in that area, then have a lower hose out of the fuel cell that hooked into the stock tank at a low point. Then the fuel cell would not need any pump and would just be filled up at the same time as the stock tank. There would need to be a vent in the top of the fuel cell to make it work correctly, but overall it would not be that difficult. I am guessing you could easily add 5 gallons and probably a little more. A race shop could do this pretty easily, it is something we could handle here also, but we are booked out until September for installs here at this point.

Hope that helps,
Dave
 

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Well, we purchased our SlingShot as it was marketed, a motorcycle alternative, where having limited fuel is a common situation when considering the purchase of a motorcycle? May I suggest looking at an automobile if such things as minimum fuel is an issue?

Bill
 

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Discussion Starter #11
Well, we purchased our SlingShot as it was marketed, a motorcycle alternative, where having limited fuel is a common situation when considering the purchase of a motorcycle? May I suggest looking at an automobile if such things as minimum fuel is an issue?

Bill
It's certainly not an issue, just a matter of convenience and curiosity.

A more fuel efficient car was considered, but the SS is free on the I-95 Express Lanes outside of Washington, D.C. precisely because it's marketed as a motorcycle. That was personally my main reason for getting one. I gave up my Harley for my wife's peace of mind, so it was a good compromise for us of safety ("safer" than a traditional motorcycle) and convenience (free on the Express Lanes, which saves me over an hour and $25+ a day). I had to stop every 3 days on my Harley as well, so that's nothing new for me. There also wasn't much choice or possibility for extending the fuel tank on the Harley though. The SS has much more potential when it comes to customization and add ons, so I'd like to explore the possibilities and take advantage of that.
 

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I know they sell premix for 2 cycle stuff, but I've never seen them sell something like this. Know what brand, etc?
 

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Yeah, i would assume it had no oil, they just don't list it on their website, that's why I was curious.

Thanks!
 

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Remember that the fuel pump/fuel level sensor rely upon fuel in the tank to keep the pump cooled, so it's never a good idea on any fuel pump-equipped vehicle to let it run down below 1/4 tank or so. I try to keep mine above 1/2 tank, just for peace-of-mind.
 

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My .02 cents,
I watched a buddy design a custom aux fuel tank for a C14 years ago. First mocked it up with foam and cardboard seat mounting plates. Had a local competent metal shop build it then.
1). Make sure its gravity fed. Skip the pumps.
2). Make sure its truly aux. Removable and installs without any perminent vehicle modifications.
3). To accomplish this. Id make a small low profile fashionable (5 or less gallons) aux tank that could temporarily mount (say to the back of the drivers side roll bar) resting/inserted in the oem fuel inlet. It would have its own fuel cap, and vent. It would self feed the oem gas tank from above. Biggest challenge might be to retro fit some kind of "fuel tight" connection between the two.
Just saying,
Webby
 

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I give the engineers a little more credit on the robustness of the fuel pump. It's only moving about 4-6 ounces a minute. Just the fuel going thru it will cool it. I've never had a fuel pump go out and I'm pretty abusive.
20190518_075342.jpg
 

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There is a guy that has a fuel cell on the back of his Sling. It's an additional 10-12 gallons I think. Gravity fed. There are regulations on fuel cells/tanks as far as safety and stuff. Look into it so it's not a safety hazard - not worth getting hurt/burned up. o_O
 

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Discussion Starter #20
There is a guy that has a fuel cell on the back of his Sling. It's an additional 10-12 gallons I think. Gravity fed. There are regulations on fuel cells/tanks as far as safety and stuff. Look into it so it's not a safety hazard - not worth getting hurt/burned up. o_O
Do you know if he's on the forum? I'd be interested to hear what he did.
 
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