Shanes impreza fuel slosh mod
The Storm Tank - (named after the RS25.com user whom I got the idea from)
In stock form, the 00RS has no issues with fueling when under hard cornering. But, my car isn't not stock any more. The handling mods I've added to my ride have resulted in fuel cut on hard right hand corners with anything less than 3/4s of a tank of fuel while on the AutoX track. I pretty much have to show up with a full tank now. Granted, I'm not competing at the national level, but a full tank of fuel is quite a bit of added weight over the rear tires. Combined with the great big sub-woofer box in the trunk (yeah I know), It would be nice if I could run with at least less than 1/2 a tank. 1/4 would be ideal. Hence the need for something, anything, to prevent my car from cutting out on those long right hand corners.
Thanks to Storm and his info from this fuel cut thread on RS25.com. It shows a great method of reducing the fuel cut problem in the GC model Impreza. I've taken what he did, and tweaked it just a little.
- Used 2006 STi 145lph fuel pump (not needed, but I was already upgrading anyway)
- Dubro 26oz Model Airplane Fuel Tank (couldn't find a 32oz Sullivan or Dubro)
- Size: 26oz
- Height: 3"
- Width: 3-1/16"
- Length: 7-1/2"
- 6" of clear pvc hose
The surge tank
- It's just as simple as it looks. I cut the Dubro fuel tank just enough to fit the pump sock and the end of the pump inside the tank. I also drilled 4 very small holes in the end, and 3 larger holes on one side. I put the larger holes on just the one side to keep fuel in the tank while in the hard right hand corner. Remember, the problem is only with right hand corners. With the holes in the side of the tank pictured, the fuel will be up against the other side of the surge tank while turning right. With no holes on the other side, the fuel will want to stay in.
- In order to keep the tank in place, I drilled and screwed it onto the end of the metal support brace. I used a 1/4" stack of plastic washers inside the tank to space the tank away from the end of the pump just a little.
- Then I simply ran a piece of clear pvc hoze from the end of the fuel return directly into the surge tank. The funny looking plastic thingamajig that the hose is connected to is the factory "Jet Pump". It's a little doohickie that is supposed to draw fuel from the drivers side of the tank, into the pump side of the tank as fuel returns from the engine bay. How well this works is debatable.
- The black marker lines on the end of the tank were my design ideas for a one-way flapper door. I abandoned the idea for simple holes instead.
After 4 AutoX events that were all left-hand courses, Jay finally surprised us with a Right-Hand course! I say surprised, because he told me ahead of time it was going to be another Lefty. So, I show up to the track with a hair over 1/4 tank. More than enough for a Left-Hand course. Woo! Guess what! They made a last minute change... we're going right now. This should be a good test of this mod. Note, there is no second fuel pump installed as suggested above. How'd it work? Fantastic!! Not a single hint of fuel cut on either of the right-hand sweepers. By the end of the day, I was under 1/4 of a tank, and still no fuel cut.
Update 6-21-2009' - It's been quite a few AutoX races now, and a good number of long sweeping, and short hard right-hand turns. I've run my tank down to less than 1/8, and even just touching the "E" now. No fuel cut! Jay's iPhone measured over 1G of lateral force in my car, so there is no question the fuel is getting forced to the other side. But, just a little plastic fuel tank has so far prevented all cornering related fuel cut issues!!