Larger Capacity Fuel Tank...seems easily achievable

[freds]

Boyd Tank Mounting: Instead of going for extra leg room, the tank can be moved forward

It can be mounted with the forward lower tabs right up against the chassis cross member.

The tabs do not align accurately with the cut-outs in the firewall, so they were trimmed.

The upper securing tabs can be secured to the chassis in the normal place by using stand-offs.

When mounted this way there is good clearance between the firewall and the tank

and 2 1/2 inches + between the tank and the rear upright chassis.

That means the Boyd or any other tank similar, could be at least 2 inches "thicker" with huge capacity

increase.

24973249742497524976

[Bob_n_Cincy]

Boyd Tank Mounting: Instead of going for extra leg room, the tank can be moved forward

It can be mounted with the forward lower tabs right up against the chassis cross member.

The tabs do not align accurately with the cut-outs in the firewall, so they were trimmed.

The upper securing tabs can be secured to the chassis in the normal place by using stand-offs.

When mounted this way there is good clearance between the firewall and the tank

and 2 1/2 inches + between the tank and the rear upright chassis.

That means the Boyd or any other tank similar, could be at least 2 inches "thicker" with huge capacity

increase.

24973249742497524976


Freds,
Boyd makes a very similar 13 gallon tank as you described for the 33 hot rod.
Also the FFR factory steel tank is like this.
Bob
24977

[Xusia]

If you don't need the leg room, I'd say a larger tank is definitely possible. The question on my mind is why? My logic:

According to folks on this forum, the WRX can be made to get near 30mpg with a good tune (software tune, not a "tune up?)
Removing 1400 lbs should allow for >30mpg
But assuming only 30mpg, just a "small" 10 gallon tank delivers 300 miles of range (how far do you need to be able to travel on a tank??)
Gas weighs just over 6 pounds per gallon, so for every 30 miles of range you are adding 6 pounds of weight (assuming a full tank)

[flynntuna]

30mpg is assuming 65mph in 5th gear @2000 rpm what fun is that?

[Xusia]

A lot of those are broad assumptions, but they illustrate the point. I don't know of a lot of places off the track where you can drive like you're implying for several hundred miles with no gas stations. If you have that, then definitely get a larger tank, but that probably doesn't apply to most folks. On most roads you are going to encounter a gas station at an acceptable interval...

[Frank818]

Other thing to remember, you never drive the car until it coughs and there is not one single drop of fuel in the tank. There is often still about 2 gallons left in the tank (assuming you fill her up when you have 20% left on a 10gal tank). That means your 300miles has just dropped to 240. then if you drive the car with fun, 30mpg may be around 25mpg, which means the 240 has dropped to 200. I think that's a closer range.

I am not saying a bigger tank is better, I am just saying the 200miles is probably closer to what you'll get in real life out of a 10gal tank. :)

P.S.: FFR's is 13gal, right?

[Xusia]

True. And perhaps I have a different perspective coming from the motorcycling world where ~120 mile range is just a fact of life (and even with that, I've NEVER run out of gas out on the back roads). To me, a 200-250 mile range seems easily livable.

[freds]

My reason for doing it the way I show in the first post was to add space between the tank and the engine...as I am going to put a firewall on the inside of the vertical chassis/roll bar section and insulate the tank side.

Completely flush...no cutouts only penetration holes where needed.

I had already installed the engine when I decided a firewall would be good there, and didn't want to "mess" with putting bits in place on the engine side. I chose the "easy way!

But thought that others (including Boyd) may want to use that space for fuel capacity as is discussed in the posts above. I too ride a motorcycle (Bandit 1200 S) and am comfortable with a 160-180 mile range.

fred