“saddle-shaped” fuel tank

[ft86Fan]

The car will come with a “saddle-shaped” fuel tank. Do you guys think it will also have a positive side effect and act as "baffles" to prevent fuel starvation under high g-load?

[chulooz]

I highly doubt this car is going to have any fuel starvation issues. Yes, I think the saddle will help, however; I thought its designed in such a way as to be centered under the chassis as much as possible.

[RRnold]

Saddle shaped fuel tanks have been in production for a while now. It should be ok as long as it has an ejector pump.

http://www.patentgenius.com/patent/5133324.html

[ft86Fan]

Originally Posted by Driftster

lol my 80's cadillac had a saddle tank..

I'm guessing your 80's Cadillac does not have fuel starvation issue so I guess it does work

Originally Posted by Driftster

you guys dig too much into this car for possible "performance adds"

I know I know....

[ft86Fan]

Originally Posted by RRnold

Saddle shaped fuel tanks have been in production for a while now. It should be ok as long as it has an ejector pump.

http://www.patentgenius.com/patent/5133324.html

Thanks for the link. Does all saddled shaped tanks use an ejector pump?

[spin9k]

Originally Posted by chulooz

I highly doubt this car is going to have any fuel starvation issues. Yes, I think the saddle will help, however; I thought its designed in such a way as to be centered under the chassis as much as possible.

Let's hope. In the RX-8 the similar type tank it is the cause of fuel starvation when below 1/3 to 1/4 full. Not fun, but not killer either, just very consistant and so one needs to keep above that level to avoid an embarrassing fuel cutout sputtering after high G turns. Of course, this ONLY happens on a racetrack circuit.

Also the tank is direclty under the back seat cushions, just pull them up and you can remove the cover and fuel pump and peer into the tank (#3).

.

[chulooz]

Thanks for the info! Did the rx8 guys or mazda never develope a solution to the issue?

[spin9k]

Originally Posted by chulooz

Thanks for the info! Did the rx8 guys or mazda never develope a solution to the issue?

I haven't really been paying attention as I treat it only a nusiance, keep filling the tank. But on rx8club it's always been a popular topic, Mazda has upgraded the pump in '09 but that's all I know. Many race teams have a fix, but they don't talk much, and it's $$/work I'm sure.

[ft86Fan]

Originally Posted by spin9k

In the RX-8 the similar type tank it is the cause of fuel starvation when below 1/3 to 1/4 full.

I don't think its the "saddle-shape" that is causing fuel starvation. If anything, it is better than a flat bottom fuel tank with no baffles.

[ryude]

My mustang gt had saddle shaped fuel tank as well, its a pretty common setup.

[spin9k]

Originally Posted by ft86Fan

I don't think its the "saddle-shape" that is causing fuel starvation. If anything, it is better than a flat bottom fuel tank with no baffles.

My bad, didn't mean to infer the "saddle shape" was or was not the problem as I have no idea. I meant the gas tank .. something in there .. is the problem! Wish I knew

[Element Tuning]

Saddle tanks are a problem in the newer STis because there is only one fuel pump and then a siphon system on the other side. Now even without the saddle tanks the older STis have fuel starvation issues below half tank (if you're fast on the track).

The FRS has been really good for me while racing but I did pick up some fuel starvation around half a tank in a hard left turn followed by a long right sweeper (on racing slicks). We fix the STis by using two fuel pumps but I need to look more into the FRS system to see if it's similar to the STi where the surge tank on the passenger side is feed by the siphon on the driver's side.

[subaruferrucci]

I know some autoX use an RC airplane/car fuel tank. They would put it over the fuel pump and make sure it captures the return. The RC tank had a few holes cut into it so that it could rejoin the main fuel system and levels could balance out. but if you hit a hard turn where fuel starvation is an issue the RC fuel tank will hold fuel level slightly higher for the moments when it is needed and prevent the starvation.

keep in mind this was on an old subby 2.2 impreza and an AUTOX car so the amount of time needed to keep fuel in one spot might not need to be as much

[Jonny Rochester]

The 86 only has one fuel pump (fuel filter and pump is in the one assembly, and in the tank on the left side). It uses the venturi effect to suck fuel from the other side.