Jump to content

New Larger vs. 2nd Tank


Alvin

Recommended Posts

Hi All, this is my first post, and I'm new to the RV universe. Bought a 1989 Odyssey with good working everything, except that it has a new generator in the generator void, which appears to have been installed about 2 years ago, but had never been hooked up to gasoline or power... it has never run. I am making it my project to get the generator hooked up, but the first thing is generator fuel. The fuel system for my Odyssey works great, there is nothing wrong with it. It is currently a small tank (probably about 17 gallons... I'm guessing... first trip with vehicle is this coming weekend and I'll know more). I think the last owner said I could only go 220 miles before needing a fillup... at 15mpg.

My options are...

1) run a fuel line from my generator to the small fuel tank.

2) Install a 2nd fuel tank, and run fuel lines from the generator to the 2nd tank, and also from the vehicle (using a switched valve) to the 2nd tank.

3) Replace the original fuel tank with a new bigger fuel tank... (I want to have it built, I'm thinking 25 to 50 gallons would be fine), and have the generator fuel line run to this. I know a fuel tank fabricator who could help me with this.

Any experience with this from anyone else? I'm leaning toward option 3, replacing the original fuel tank for something humongous.

A 2nd question, what is the biggest fuel tank anyone has ever put into his Toyota Odyssey? Is 50 gallons unheard of? I looked under the vehicle, and there seems to be lots of extra space.

Thanks in advance.

Alvin

Link to comment
Share on other sites

I believe I have read about larger capacity tanks that were, I think, 29 gallons. I don't really see too much need to go much larger than that. With 400 mile range, I'd be looking to take a break anyway. And what's the point of carrying around the weight of 20 more gallons of fuel. These are overloaded even with the standard tank!

Is the new generator you're trying to hook up a portable generator or one designed for permanent RV use?

Link to comment
Share on other sites

I believe I have read about larger capacity tanks that were, I think, 29 gallons. I don't really see too much need to go much larger than that. With 400 mile range, I'd be looking to take a break anyway. And what's the point of carrying around the weight of 20 more gallons of fuel. These are overloaded even with the standard tank!

Is the new generator you're trying to hook up a portable generator or one designed for permanent RV use?

Good point about the extra fuel. I was thinking about generator usage in the Utah/Nevada desert area (about 1/2-gallon per hour) for the Air Conditioning.

I'm attaching pictures of the generator. It is for permanent RV use. Gererac QP-40G

http://www.generac.com/RV/Gasoline/Products/QuietPact_40G/

post-3988-12795121229922_thumb.jpg

post-3988-12795121404324_thumb.jpg

Link to comment
Share on other sites

I believe I have read about larger capacity tanks that were, I think, 29 gallons. I don't really see too much need to go much larger than that. With 400 mile range, I'd be looking to take a break anyway. And what's the point of carrying around the weight of 20 more gallons of fuel. These are overloaded even with the standard tank!

Is the new generator you're trying to hook up a portable generator or one designed for permanent RV use?

More pictures:

post-3988-12795122262969_thumb.jpg

Link to comment
Share on other sites

  • 5 weeks later...

We put in a 2nd fuel tank just in front of the existing 17 gallon tank. The 2nd fuel tank adds an additional 23 gallons. The total is now 40 gallons. Both fuel tanks are filled through the same existing spout, with a Y-fitting in the fuel line. Each tank has it's own air tube which goes up to the fuel spout for air release while filling. Also the bottom of the 2nd tank is slightly higher than the bottom of the existing 17 gallon tank. It seems to work perfectly, although we're about to give it a real workout on a 6000 mile trip across country and back; the system was pressure checked, then leak checked with fuel.

We also had a 3600-watt Generac installed (actually is was already there when we bought it... unused since the previous owner never hooked it up... it's a new generator); the generator fuel line is connected to the 2nd tank. We believe that because the 2nd tank is higher there is no chance of the generator running us out of fuel at night. Generator consumes up to 1/2 gallon per hour if fully loaded and 1/4 gallon per hour if unloaded.

The whole project took about 4 days and we were only charged $1000 total... plus the $138 to fill the tanks for the first time so it could be checked for fuel leaks.

Very clean. The only thing that had to be slightly moved was the parking break line, but this was accomplished with the help of a pulley welded onto the frame.

------------- Vehicle wise, we have also replaced the spark plugs with iridium hot plugs (to burn at a high temperature) and installed a $44 K&N Air Cleaner. We had the oil changed and put an engine reconditioner product in the oil. We expect better MPG's but don't know how much yet. The old air cleaner was VERY dirty... we could get as much as 25 to 30% high mileage... we were getting about 11-mpg average. I'll let you'all know.

Link to comment
Share on other sites

We put in a 2nd fuel tank just in front of the existing 17 gallon tank. The 2nd fuel tank adds an additional 23 gallons. The total is now 40 gallons. Both fuel tanks are filled through the same existing spout, with a Y-fitting in the fuel line. Each tank has it's own air tube which goes up to the fuel spout for air release while filling. Also the bottom of the 2nd tank is slightly higher than the bottom of the existing 17 gallon tank. It seems to work perfectly, although we're about to give it a real workout on a 6000 mile trip across country and back; the system was pressure checked, then leak checked with fuel.

We also had a 3600-watt Generac installed (actually is was already there when we bought it... unused since the previous owner never hooked it up... it's a new generator); the generator fuel line is connected to the 2nd tank. We believe that because the 2nd tank is higher there is no chance of the generator running us out of fuel at night. Generator consumes up to 1/2 gallon per hour if fully loaded and 1/4 gallon per hour if unloaded.

The whole project took about 4 days and we were only charged $1000 total... plus the $138 to fill the tanks for the first time so it could be checked for fuel leaks.

Very clean. The only thing that had to be slightly moved was the parking break line, but this was accomplished with the help of a pulley welded onto the frame.

------------- Vehicle wise, we have also replaced the spark plugs with iridium hot plugs (to burn at a high temperature) and installed a $44 K&N Air Cleaner. We had the oil changed and put an engine reconditioner product in the oil. We expect better MPG's but don't know how much yet. The old air cleaner was VERY dirty... we could get as much as 25 to 30% high mileage... we were getting about 11-mpg average. I'll let you'all know.

Where did you get the second fuel tank? Was it a retrofit from another vehicle or was it custom made to fit the space. I would love to have the ability to have to extra range when I wanted it.

Link to comment
Share on other sites

Where did you get the second fuel tank? Was it a retrofit from another vehicle or was it custom made to fit the space. I would love to have the ability to have to extra range when I wanted it.

My wife's ex is a welder and he custom engineered the tank (he has done many fuel tanks in the past). The tank was built in 2 sections, a 16 gallon lower section with a 7 gallon upper section... includes tank baffles too. The two halves were welded together and pressure tested prior to mounting. No leaks after adding 40 gallons of fuel. We're giving it the initial workout tonight.... leaving on a long trip.

We believe that with the engine horsepower increases (new K&N air filter and new iridium tipped plugs... high temperature) along with oil change, engine reconditioning etc, that our range should be close to 500 miles now. I will definitely report back at some point.

Link to comment
Share on other sites

  • 1 month later...

6102 miles. That is the number of miles we just travelled with the new dual fuel tank system.

We had a 2nd fuel tank 23-gallons custom welded and placed just in front of the original 17 gallon tank. One filling spout for both tanks, using a "Y" connection in the main fuel line to both tanks, and a small air hose return coming from each tank near to the fuel cap. The two tanks were connected using a small fuel hose between the tanks...so no switching required from 1 tank to the other. The 17 gallon tank was tapped using the drain cap at the bottom of the tank and welding on a banjo fitting over the drain plug. The banjo arm went to the other tank. Finally, we had our 3600 watt gas generator fuel connected to the new 23 gallon tank too.

Perfection. That is all I can say. Simply perfect. No issues. None. 6100 miles of utter joy passing gas stations along the way. Not being forced to stop and fillip in every city was AWESOME.

We paid an even $1000 for the new tank including the install. I'd have paid more.

Now if I can just fix that mileage. I'd like to get closer to 14 to 15 mpg like some claim. We get 10 or 11. The generator uses about 4 gallons overnight. I have 40 gallons. Whoa. :)

Link to comment
Share on other sites

  • 3 weeks later...

This is probably the proper place to add my fuel system schematic notes on the 17 to 40-Gallon conversion. I noticed a couple of spelling errors in the document and added a note about the Koplin fuel packs which we added, visible on the attached photo.

odie2b.pdf

post-3988-039901900 1287094259_thumb.jpg

Link to comment
Share on other sites

  • 2 weeks later...

Now if I can just fix that mileage. I'd like to get closer to 14 to 15 mpg like some claim. We get 10 or 11. The generator uses about 4 gallons overnight. I have 40 gallons. Whoa. :)

How much does gas weigh per gallon. That extra weight seems like it would dramatically drop gas mileage. And all the wight on one side? Just curious. Anyhow we had the 26 gallon optional tank in our Sunrader. It was nice to have the extra range.

Don't be afraid to use overdrive at freeway speeds. Get the rig weighed fully loaded for a trip. We would all like to see that number!

Link to comment
Share on other sites

Found the weight of gas

(Depends on the API gravity of the gasoline, which varies by grade and refinery. Usually, regular unleaded gasoline has a gravity of around 58 and a weight per gallon of 6.216 pounds per gallon. Premium gasoline may have a gravity of 54, or 6.350 pounds per gallon.)

23 gals x 6.216 = 142.968 About the weight of an extra body. Guess thats not too bad.

Weight from what I read is affected by heat also. Fill up on a hot day and you actually get less gas than on a cold day.

Link to comment
Share on other sites

Found the weight of gas

(Depends on the API gravity of the gasoline, which varies by grade and refinery. Usually, regular unleaded gasoline has a gravity of around 58 and a weight per gallon of 6.216 pounds per gallon. Premium gasoline may have a gravity of 54, or 6.350 pounds per gallon.)

23 gals x 6.216 = 142.968 About the weight of an extra body. Guess thats not too bad.

Weight from what I read is affected by heat also. Fill up on a hot day and you actually get less gas than on a cold day.

Looks like you answered your own question before I had a chance to respond... but you came to the same conclusion that I did; about the weight of an extra person.

Another thought I had regarding the extra gas tank... it really comes down to the weight of the tank only... because if I want I don't have to fill the additional gallons. The additional tank and fuel lines weighs about 100-lbs... but I have to say, I would ALWAYS fill the vehicle unless it's going to be sitting for a long time... remember that the prime reason for this upgrade was because I had about a 160 to 180 mile range... maybe 200 if I drove very slowly. Now I can go at least 350-miles, even if I choose to push it to 70-mph and eat the 10-mpg rate of fuel consumption. For my location in SLC Utah, this is great. Here is the reason... before my range was about 160 miles... the problem is that in almost any direction, the gas stations are few and far between and spaced at about 100-miles. This means that I was stopping in literally every city... especially traveling through Wyoming... cities every 100 miles, since if I had tried to go 200miles I would not have made it. The 2nd reason for the extra tank was that I wanted to run my generator which was not connected to a fuel tank before that.

Next you brought up the issue of balance. The additional fuel tanks is built in 2 sections, a top section and a bottom section, which were baffled and welded together. The top section actually extends over the drive shaft and is centered in the vehicle. The bottom section is on the right side of the drive shaft only, just forward of the original fuel tank. I noticed no difference in vehicle handling.

Even with the tanks full, the entire extra weight is only about 250-lbs... including the weight of the tanks... and it is almost dead-center in the vehicle between all 4 tires.

Link to comment
Share on other sites

I have created a very rough cross-section of the vehicle from the floor down through the gas tank, cutting across where the new tank sits in the vehicle (see the attached pdf a few posts above. The purpose of this diagram is to show how the upper and lower tanks sections sit in relationship to the drive-shaft and the frame, and also to show that some of the weight of the new tanks is actually distributed on both the right and left sides of the vehicle.

post-3988-015380200 1287971478_thumb.jpg

Link to comment
Share on other sites

For gas mileage you should be getting 13 + per gal. There is allot of controversy about running with Over Drive on. Its really only a problem with the 4 cyl's because they do not have a locking torque converter and continually slip as where the V6 torque converter is locked in OD. I was getting 10 to 11 mpg on our last trip until I started using OD then it jumped to 13 +. I might also note though I was running the mid grade gas and not regular and as I now know the mid and premium grades will cause you to get worse gas mileage. The problem with running OD is that it tends to hold in OD sometimes a little to long decreasing your speed more than you would like on a hill. After awhile it becomes second nature and a third sense to hit the button and turn it off before to much speed gets scrubbed off.

The gas tank you have created is very cool. You might think about building and marketing them. Probably some legal issues involved but there has been a demand for them in the past. The company that built the Sunrader optional tank is still in business. Here is a thread on those tanks back when we had the Sunrader http://toyotamotorho...hp?showtopic=17 . With your tank you opted to use a Y instead of adding a second fill spout. Does the second tank just gravity flow into the first as the fuel is pumped out of the first?

Link to comment
Share on other sites

For gas mileage you should be getting 13 + per gal. There is allot of controversy about running with Over Drive on. Its really only a problem with the 4 cyl's because they do not have a locking torque converter and continually slip as where the V6 torque converter is locked in OD. I was getting 10 to 11 mpg on our last trip until I started using OD then it jumped to 13 +. I might also note though I was running the mid grade gas and not regular and as I now know the mid and premium grades will cause you to get worse gas mileage. The problem with running OD is that it tends to hold in OD sometimes a little to long decreasing your speed more than you would like on a hill. After awhile it becomes second nature and a third sense to hit the button and turn it off before to much speed gets scrubbed off.

The gas tank you have created is very cool. You might think about building and marketing them. Probably some legal issues involved but there has been a demand for them in the past. The company that built the Sunrader optional tank is still in business. Here is a thread on those tanks back when we had the Sunrader http://toyotamotorho...hp?showtopic=17 . With your tank you opted to use a Y instead of adding a second fill spout. Does the second tank just gravity flow into the first as the fuel is pumped out of the first?

Yes, I've been puzzled about the 10 or 11 per gallon, except that I do tend to push it to 70 as much as possible. I agree it should be 12 to 14. I used 85 octane out here in Utah but like lots of places they now pollute (dilute) the gas with ethanol. My 2004 Sienna now gets about 5 to 10% fewer mpgs than before. I never did drive the Odyssey before ethanol so I have no basis to compare.

I gave he fuel tank quite a bit of thought, but I can't take full credit. The finer details were added by the welder who has been building gas tanks for quite some time for other trucks out in the oil fields of WY and UT... on site. For example the banjo fitting was his... I simply gave him some options and he ran with it. Originally we were shooting for 50 gallons. That could have been accomplished, but only by putting the gas tank behind the rear axle where the tire ought to go (not mine though... not yet). His location of the tank just forward of the existing 17 gallon tank, along with the shape to put it in was his design. The Y fuel adapter was so that it would be no different to fill... costs less to build as well... a 2nd fuel spout was simply not needed. And with the bottom of the 23 gallon tank just about 1" higher than the bottom of the 17 gallon tank... and that very small fuel line connecting the two, fuel flows very well from the bigger to the smaller tank.

The behavior of the fuel gauge is exactly what you'd expect: You fill up the vehicle. You drive for about 120 miles before the needle starts to move off of full. You drive for another 240 miles while the needle goes slowly from Full to about 1/4. The last 1/4 tank starts to go quicker... since by that time most of the gas is now in the bottom of the 17 gallon tank only. You have about 50 or 70 miles to find a filling station at about 1/4 tank.

Very very nice to be able to drive 400 miles without stopping for fuel. Very very nice to have the generator working. The new tanks has made life on the road bearable. Like I mentioned before, I was often having to put in gas every 100 miles due to the way the cities fall along I-15.

And yes, everything is simple gravity flow.

I'm not sure how much of a deal I got. Actually for $1000 I tend to think that the welder of my custom tank gave me a great deal... but if he were to mass produce these he might actually make a bit more. I have to agree with you about the liability issues. I had to agree to take on liability myself... but I'm an Engineer and my Dad is an old Physics/Car-guy... and since even he thought it was a good design, it gave me lots of confidence to run with it. I have to admit that it has worked out flawlessly beyond my expectations... I thought I'd have a problem or two, and no issues... at all. I'm planning on publishing some pictures to go with my pdf and drawings above, but thats about as far as I'll go. Some ideas are best left in the public domain.

Link to comment
Share on other sites

  • 4 weeks later...

The additional tank is almost identical to the optional 26 gal tank on the Sunrader. The guage works the same, stays on Full until the overhead leg is empty. Attached is pic of the 26 gal Sunrader tank notice the overhead portion that goes over the driveshaft.

Allen

post-481-070337200 1290194882_thumb.jpg

Link to comment
Share on other sites

The additional tank is almost identical to the optional 26 gal tank on the Sunrader. The guage works the same, stays on Full until the overhead leg is empty. Attached is pic of the 26 gal Sunrader tank notice the overhead portion that goes over the driveshaft.

Allen

post-481-070337200 1290194882_thumb.jpg

Darn amazing looking at that picture... it almost looks identical to the one I had custom engineered and welded up under my vehicle. Looking at your picture it's almost a picture of mine... except that mine has been painted black. Thanks for the verification that others have done something similar. The one major difference is that I left my original 17 gallon tank in place where this one sits... and the larger 23 gallon tank which goes over the top of the drive shaft is forward of that tank... about 5 feet up from the rear drive axle. To accomplish this we did have to re-route the brake cable slightly.

The rest of the system is the common fuel input spout... Y'ed to both tanks, a small tube connecting both tanks... to the existing tank with a banjo fitting welded to the 17 gallon drain plug to allow easy connection without actually welding on the 17 gallon tank. And of course there are air hoses which rise from both tanks separately to allow the air to escape connected at the top of the inverted "Y" nearer the gas cap. (see drawing pdf odie2b.pdf which I attached earlier for a better schematic representation...a few posts above.)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...