GIACUser

In Calif. we have 91 at the pump. You can also buy 100 at almost 5.00 a gallon (yikes).My chipped car runs so much better on 100. Would it be feasible to have a small auxillary fuel cell installed that could hold your stash of 100 for those times when you need it so you don't waste it. Anybody ever done anything like this... ??? Too crazy???

Singletrack

before. A big *** van that literally had two tanks and you manually had to change from one to the other. I'm not sure what the pitfalls would be really. Anyone care to comment?

-st

2.7tDallas

prperly mounted. Plus, will the ECU even adapt that fast?

TXurS6

Not to mention twice the fuel sensor problems :-)

j/k

brian 4.2

what you want. I run 100 on track days but I start to run 100 3-4 days in advance.

captainbilly

like the EMCS form APR. THen you could switch to the 100 octane program and switch tanks to 100 octane fuel. It is, unfortunately, a bit complicated due to emmissions equipment and fuel injection. The fuel injection system sends most of the fuel that passes through the fuel pump back to the fuel tank. The fuel gets pumped into the injection manifold and then the pressure is relieved (through a relief valve) back to the tank. This means that your fuel selector would have to have two circuits, one for fuel from the tank and one for a return line. You could do without the return if you didn't mind your 100 octane fuel being returned back to the main tank but even then you would run the risk of overflowing the main tank if it was completly full when you switched to 100 octane.

The next problem is the fuel vent and vapor recovery system. The fuel tank on a new car is not simply vented to the atmosphere but instead it uses a vapor recovery system that collects fuel vapors and returns them to the tank. You would probably need to plumb that system into your 100 octane tank although it might work without it.

A little work and some thought and I think it could be done. If I was going to do it I would probably opt for an exposion proof metal tank and self sealing if possible. The explosion proofing is done with either an open cell foam or metal mesh filling the tank. By keeping the cells small enough the fuel/air vapors in the tank can not ignite in the tank (the required cell size is something on the order of a centimeter or so). Military aircraft, and I think race cars, have been doing this for many years and it is not very expensive. The self sealing deal is something I know little about but if the tank is going in the trunk it would seem like a good idea in an accident.

One last thing, if you don't connect to the the vapor recovery system then at least make sure you vent outside of the trunk so the trunk doesn't fill with exposive gas vapor.

BobT(nolonger)A6

... and has all the plumbing, vapor recovery, electric valves, etc. etc. etc.

Considering how finicky Audi engines are, the pressurized fuel system, etc. adding a second aftermarket fuel tank sounds seriously silly to me.

YMMV

GIACUser

Is it your experience that after 3-4 days the car is actually running stronger than on the first day?