I sent this a bit ago but did not see it post. Sorry if it is untimely. LEH

 

It's true that our informal process isn't especially
efficient; but no process can work if a piece of work isn't
submitted for review.

My $.002,
Dale R.

 

I have been going to Sun&Fun for a number of years now, and some recurring themes seem to have developed. Maybe in my mind if nowhere else.

 

Fuel pumps, fuel lines, oil lines and control system components too close to heat sources. Or actually touching header pipes.

 

Low burst strength automobile filter cans in everything.

 

Wrong application hose systems, including vinyl garden hose. The green stuff.

 

Hardware store bolts in high stress applications.

 

Welding/welds of such poor quality that would be found only in an instruction manual.

 

Misapplication and misunderstanding of common mechanisms/systems.

 

Disreguard/lack of knowledge of weight and balance.

 

Mostly I just say wow when looking at most of the beautiful home builts and warbirds. But sometimes the hair on the back of my neck stands up.

 

I think I am clever enough to build anything I can imagine. My crew chief delights in finding under torqued fasteners, misrun lines and chafing hoses. He will not stop looking until he finds a few things to fix. This has saved many weekends for us.

 

If you see a good idea, steal it. Have a disinterested party look over your work. Even a person who has little knowledge of aircraft can see things you have been too close to, to notice.

 

When I first built the current race car, we had fuel pressure problems. We wanted 6 PSI and after a long run the pressure would go wild and the engine would run lean. I had 2 pumps feeding through 2 filters to a "T" then to the engine and a Holly regulator the to the carb.

 

I added a third pump to boost the pressure to 14 pounds and the problem went away until a full race and then it came back near the end (45 minutes).

 

The fuel was boiling in the regulator.

 

I moved the regulator to the top of the frame tube opposite the headers. I insulated the regulator. I built a shield around the top of the headers.

 

It works fine. Now back to 2 pumps. No problems in years. 

 

I had a similar problem on an old Lola with a rotary engine. The long fuel cells had 4 outlets and I used 4 pumps with a high mounted sump tank with an overflow back to the right side tank. The overflow from that tank ran into the left tank where the fast fill was located. So there would always be room in the left side tank to dump in fuel during a stop.

 

The thing would run fine until it was very hot OAT then it would loose fuel pressure. The dash 6 90 out of the left rear of the bladder was exposed to the energy from the header (about 8" away). A 3" square piece of stainless shielding over the elbow cured the problem.  

 

Fuel pulled below ambient pressure boils with very little added heat. Always did, always will. Zero suction lift to the pumps is better. A head (positive gravity pressure) on the pumps is ideal. No fuel system pieces exposed to radiant energy (line of sight) ever.

 

Suction side filters should flow enough to support the engine when draining into a bucket. (with no fuel pump at all) Change them often.

 

My fuel pumps are mounted even with the bottom of the fuel cell. As low as I could go without getting them knocked off the car. 

 

 

Lynn E. Hanover