Plumbing a Fuel Safe Cell

[moneymanager]

Car is a 74 with PMO's. Considering a 17 gallon Fuel Safe cell. I'm confused. The outlet on the Fuel Safe is -8. Holley fuel pumps, used by many, have -6 input and output. How do people plumb these things? Is it best to use all AN hardware until you get to the fuel pressure adjuster? Or should I try to stay metric? I'd appreciate knowing how you did it, and whether you'd change anything if you did it again.

[Grady Clay]

Originally Posted by moneymanager

Car is a 74 with PMO's. Considering a 17 gallon Fuel Safe cell. I'm confused. The outlet on the Fuel Safe is -8. Holley fuel pumps, used by many, have -6 input and output. How do people plumb these things? Is it best to use all AN hardware until you get to the fuel pressure adjuster? Or should I try to stay metric? I'd appreciate knowing how you did it, and whether you'd change anything if you did it again.

There are two aspects of this:

First (and most important) is mounting and plumbing the cell, pump, filter and related plumbing so it functions the best possible in a crash.
Here is a link:
100 liter center fill tank - Early 911S Registry Bulletin Board
Ignore the ‘center fill’, that reduces safety.

The other is to install a circulating fuel circuit where cool fuel passes the carb inlets and the unused fuel is returned to the fuel cell. Part of this is to have few fuel system components in the engine compartment and all the fuel hoses insulated from the rear bulkhead to the carb inlets, including the return.

Keep serviceability in mind. You need to be able to easily remove the engine and transmission with only two (supply & return) fuel disconnects. You also will need to service the fuel system so keep everything removable with minimum effort.

For a race car, I prefer to use hose for the entire system. Run the hose through thin aluminum pipes through the cockpit. Never have a fuel connection inside the cockpit.

When sourcing a fuel cell, it is desirable to include an internal ‘surge cell’ and a second fuel pump. This allows you to use all the fuel you carry and know when you are close to the end.

Use all the same type hose and AN fittings. There is no need for any metric fittings or adapters. It is desirable to use different size for the supply and return. Put all the components (pump(s), filter, pressure regulator) low in the front – gas heater compartment.

Keep in mind the cardinal rule for hose systems: no stress (tension or twist) on anything. Have everything where it can flex in a crash as the sheet metal around it crushes. Firmly mount all components. If you use vibration isolators, make sure they are fail-safe in a crash. Tie everything down with zip-ties except clamps near fittings.

Think ahead.
Post your plans for critique.
You are not the first to do this.

Best,
Grady

[JP911]

Swap the inlet fitting on the Holley pump to a -8 (-8 and 3/8 pipe thread fitting). Then run -6 from the pump outlet to the regulator.

[moneymanager]

JP you've answered my question. Thanks much.
Grady, much useful lore. I've been thru some of your earlier posts as well; very helpful. Thanks.