Header Clunk Dual Tank

[Oxyacetylene]

I know some people have added a second tank to help the savage maintain more consistent fuel pressure through the whole tank which results in more consistent engine temps. Would you guys post some pics of where you have put the tank. What size tank did you use? The smallest I can find is a 1oz round tank. I am using the stock tank for the 25 rtr (new tank design with rear pickup and no primer). Anyone tried replacing this tank with a different one that may work better? What about replacing it with a smaller one and a second tank together that would fit in the same place with some creative mounting? What about check valve or pressure regulator of some sort?

 

[bmoc2008]

I believe that only the .21 had the problem of leaning out after half a tank but I think hpi took out the primer because it was a problem but I maybe mistaken.

 

[Oxyacetylene]

I never ran one of the original tanks so I can't speak for them, but I know with mine I can see 15-20 degrees of difference in temp between the start and end of a tank, and by start I mean once it gets warmed up.

 

[mcvickj]

There are a couple of different options for the leaning tank issue. Some have gone with an Ofna fuel tank and did a small mod to make it fit where the normal tank sits. I know there is an aftermarket company that makes the mount to sit in the same spot. I would have to find the link.

The S25 tank still has the leaning issue but not near as bad as the S21 tank. I went with the 2 oz Hayes Header Tank with the aluminum bracket. I bought both from HeliProz.

Here is a few pictures of my header tank.

The bracket design that you see that holds the tank onto the Savage was created by iCow on Savage-Central.

Here is a link to his instructions.

Here is also another link about the Ofna fuel tank and the header tank going head to head.

 

[Oxyacetylene]

that looks pretty cool. Thanks for posting the info!

 

[SkyMaxx]

Almost all RC car/truck fuel tanks have this self-leaning tendancy. It has more to do with the way the fuel system is set up than the engine size or tank design (although some tank designs produce less of this tendancy than others).

So far, the only two methods that I am familiar with are the dual tank method and the fuel pump method (Costly, additional weight, and generally too much for this application).

My recommendation is to tune the engine with the fuel tank at half full. This will give you a little bit of a rich run from full to half tank and a very slightly lean condition as you bottom things out.

 

[Road Rage]

Good article there mcvickj, I like the idea of the header tank and longer run time myself.

 

[mcvickj]

Originally posted by Road Rage
Good article there mcvickj, I like the idea of the header tank and longer run time myself.

I didn't create the article. Savaged did the head to head fuel tank article and iCow did the article on the header tank mount. Just wanted to clear this up and give credit to where credit is due.

 

[Oxyacetylene]

While I was at my LHS a few days ago one of the guys there said he had a customer who hot glued one of the Hayes 2oz tanks to the original tank. When I look at mine I'm not sure how well that would work. For the dual tank setup to work properly does the second tank have to be higher than the carb for a gravity feed effect?