The Autobiography of Stuart Hilborn

Chapter Three

"The First Fuel Injector"

Out of the Air Force now and back at work at my old job at the paint company. I have started construction on the fuel/injection system, but a lot of my time is devoted to getting my car ready to run at the dry lakes. The first race of the new season is coming up soon. The work on the fuel injector is progressing quite slowly because it is all hand built. I don't have any machine tools. Fortunately, I am able to use a friends milling machine to make two ,)f the most difficult parts. The rest is all hand filing and fabrication. Also, there is another different type of problem waiting to be solved. How much fuel do I need to run the engine?
All of us racing at the lakes are using carburetors that automatically control the fuel flow by means of the air flow through the venturi tube. But, the fuel injector doesn't have a venturi tube. And, none of us know the actual amount of fuel the engine is using at full throttle with carburetors. Remember, there are no dynamometers or fuel meters available to measure such things. To solve the problem I had to rely on my training as a chemist. I set up the chemical equation for the oxidation of methanol in air. This allowed me to calculate the stoichiometric, or theoretical air fuel ratio for methanol. Engines don't perform well at stoichiometric ratios and have to be richened up. About 2/3 of stoichiometric works good. Next, I needed to know the amount of air the engine used. This is fairly easy to calculate from the engine cubic inches and the rpm Flat head engines don't breathe real well, so I knew if I used 100% volumetric efficiency I would be well on the safe side. I could always lean the system down a little after I started running it. I now could calculate the required fuel flow I needed.

Next, how to measure the fuel flow to be sure I had the right amount. To do this I hooked the fuel pump up to an electric drill motor to drive it. I already had one injector nozzle built, guessing at the size. I connected the nozzle to the pump outlet, turned on the motor, and adjusted the fuel pressure. I then collected the fuel discharged from the nozzle in one minute, in a coffee can. After weighing the contents on a small scale, and some more calculations, I finally had an actual fuel flow number. I hoped it would be 1/8 of my calculated fuel flow number. I was off by a mile. The nozzle was much too small. After several more attempts I was able to make a nozzle that flowed exactly 1/8 of my previously calculated total flow for the engine. So far, so good. But I still needed seven more just like it. They must all flow precisely the same amount. I built seven more nozzles and measured the fuel flow. Disaster! None of them matched the first one. In fact, there weren't any two alike out of the entire seven, even though I had drilled them all with the same drill but that wasn't going to be as easy as I thought.

I still was spending most of my spare time racing my car at the dry lakes and with all the preparation needed before each race. I had now gotten up to 139 m.p.h., which was quite pleasing. Along the way I kept building and testing more nozzles. My success wasn't increasing, but my pile of rejected nozzles sure was.

The racing season finally came to an end and I could now devote all my spare time to finishing, the fuel injector. Besides the nozzle problem, I still had one other major problem left. I had to find some way to mount the aircraft fuel pump I was planning to use, to the engine, in such a way that it could be driven by the engine. It was essential that the pump speed vary directly with the engine speed. The best solution seemed to be to extend the oil pump shaft right through the flywheel housing to outside the engine and then build a mounting pad for the pump right over the extended shaft. Simple enough. However, the execution was far from simple. The old problem of no machine tools was the trouble. This would be easy to do on a large milling machine, but all I had was an electric drill and some hand tools. I took an old oil pump and removed the shaft and gears and installed it in the engine in place of the regular oil pump. Then, using a long drill the same size as the oil pump shaft, I went down through the pump bushing and slowly drilled right through the flywheel housing. The pump bushings kept the drill in alignment so that everything stayed centered. The rest was fairly easy, requiring only a longer oil pump shaft, a housing and bearing to fit the shaft. The pump bolted right on the main fuel injector plate, which was already completed.

Everything is finished now and on the engine, except I still have no injector nozzles. I am reluctant to continue to make them the same way I had been because I had no real control over the flow. Maybe, if I made 100, I might get 8 matched nozzles. Or, maybe I would only get 3 or 4. I decided to try a different approach. I would take the nozzles I had already made and separate all the nozzles that were low on flow and see if I could find a way to alter them to increase the flow. Drilling them out to the next larger drill size didn't work. It was far too big a jump. I tried a few different ideas, but none of them worked. Then I tried. a big chamfer on the inlet side of the fuel orifice. Bingo! The fuel flow jumped up. Too much in fact. I found by adjusting the size and shape of the chamfer, I could trim the fuel flow right into the number I wanted. Within an hour I had 8 perfectly matched nozzles. The first fuel injector was finished.

Now I can hardly wait to test it. However, it is winter time and the dry lakes are no longer dry. Often they are under water. I'll have to wait for spring, but I want to get a test in before our first race in April. At a meeting of our racing association, The Southern California Timing Association, we were informed that a big auto show, for hot rod cars only, was going to be held in Los Angeles. They wanted everyone to display their cars in the show and to support the show in every way. I didn't have a lot to do to get my car ready. Three days before opening day everything was set.

Then I had a thought. Maybe I should take my new fuel injector along and display it on a table by my car. It might be of interest to some of the spectators. However, the fuel injector was made mostly of just plain steel, and wasn't as pretty as I would like for a show. I decided to have it chrome plated. So, I disassembled the whole thing and took all the steel parts to the plater. I asked for a rush job because the show opened in three days. The day before the show I still had no parts from the plater, only promises, I went ahead and took my car down to the show and got it all set up for the show starting the next morning. Upon returning home, I again called the plater. The parts would be ready that evening. Well it was much later that evening when I finally got them. By the time I got it all reassembled, and all the metal lines and nozzles polished, it was 2:30 in the morning.

The show opened with enormous crowds. I soon found there was more interest in my fuel injector than there was in my car. As the show continued, thousands of people looked at the fuel injector and many discussed it with me. Many were engineers, tech writers, engine experts, teachers and so on. Soon, I could almost predict the conversation. It was always the same. It went like this:

Expert: "How fast. have you gone with the fuel injector?"

S.H.: "I just finished it and haven't run it yet."

Expert: "Tell me how it works."

I explain the system.

Expert: "How do you time the fuel injector to the engine?"

S.H.: "It's not timed. It's a constant-flow system."

Expert: "It won't work."

S.H.: "Why not?"

Expert: "Because you are injecting fuel into the engine when the intake valve is closed. There is no place for the fuel to go."

S.H.: "Yes, but that doesn't matter. My engine runs at 5000 rpm and the time element is so short between openings that the fuel just accumulates in the port for a fraction of a second."

Expert: "Every fuel injection system in the world is timed to the engine. Why do they go to all that trouble and expense if it isn't necessary?"

S.H. : "I don't know, Maybe it's just follow the leader."

Expert: "They must gain something or they wouldn't do it."

S.H.: "What do you gain by interrupting the fuel flow 40 times per second?"

Expert: "I don't know but everyone does it. Your system won't work."

S.H.: " I'm going to find out."

End of conversation

The weather has now improved to where I think I can run my first test at the dry lakes. But first I decided to drive up without my race car to scout around and see how good the lake bed was. Since the test I was planning was just a private test for my car only, there would be no time clocks, and no other people there. Instead of going to our regular lake, EI Mirage, I went to Rosamond because it was much closer. The lake bed was completely dry and looked to be in good shape. Returning home I made plans with a few of my friends to return the next weekend for the test.

Upon arriving at Rosamond the following week, we unloaded the car, fueled it and checked all the innumerable things that needed checking. The next thing was to plan which direction I wanted to run. This was very important because we seldom ran at Rosamond because it was small and the lake surface sometimes wasn't as hard as EI Mirage. We weren't real familiar with the lake. I remembered a test I ran here in my old roadster some years earlier. I was running right at 118 m.p.h. when my engine blew and the car stopped. My crew came out to tow me back to our base camp, and as they did so~, we discovered a ditch about 6 feet deep and maybe 20 feet wide about 100 yards ahead of where my car had stopped and directly across the path I had been headed in. The ditch was completely invisible until you were right on top of it. If my engine hadn't blown up when it did, I would have hit that ditch at full speed. This time I made sure we picked a safe direction and then memorized the distant mountain peak I wanted to aim at. There are no landmarks on the lake bed itself.

We always started our car by towing it with a long rope which had a release cord that led back to the tow car. Thus, once the engine started, the tow rope could be disconnected by simply pulling the release cord by someone in the tow car. We hooked up the tow rope and started out.. No one knew what to expect. Maybe it wouldn't even run. Much to my surprise it started up instantly. The tow rope was released and I cautiously increased the throttle as I headed across the lake bed. Running at part throttle I could tell that the mixture was too rich, but not enough to require an immediate stop for adjusting. I ran around at fairly low speed for awhile to warm up the engine then I got on the throttle hard to see if it had good throttle response. It sure did. It snapped my head back and took off like a rocket. I backed off and returned to camp. I wanted to look things over to see if anything was going wrong. Everything seemed to be perfect. No problems were evident. With only one car running on the lake, the exhaust sound could be heard clearly a mile away. My crew said they could hear it when I was on the throttle hard and that the engine never missed a beat.
I then adjusted the fuel metering valve to get rid of the excess richness at part throttle and went out again. This time I got on the throttle early and hard. I could feel the engine was really strong and was pulling hard. I stayed on it. If it was going to blow I wanted it to blow now, not next month at our first race. I kept my eyes on the tachometer. I knew pretty close what the speed was at each rpm. The speed rose, 100 mph, 110, 120. That was good enough for the first test, and I backed off and returned to base camp. At 120 the car was still accelerating so I knew things were pretty close to right. I didn't want to push it higher because we were all alone out on the lake without the usual ambulance standing by. In case of an emergency, I could be in real trouble We loaded up and headed for home. Everyone was delighted with the first test.

The first race of the 1947 season finally arrives. It is to be held at Harper Dry Lake. Not really the best lake. I'm ready and anxious to see what my first time will be. Usually everyone participating in the race arrives at the lake on Friday to set up camp and get ready. We followed the same procedure and unloaded the car. I wanted to make a check-out run on the lake bed at full throttle to be sure I was ready for tomorrow's time trials.

I headed out across the lake and slowly increased my speed to about 125 mph. Everything felt good. Suddenly, I saw flames shooting out from the engine compartment. I was stunned, because the engine was still running good. It had not blown up. By this time I am a couple of miles away from our camp, far from any possible help. I shut the engine off and stopped as quickly as I could. I always carried a fire extinguisher in the cockpit of my car for just such an emergency. It was one of the old "Pyrene" types, consisting of a metal cylinder about 2 1/2" in diameter and about a foot long with a hand pump on the end of it. I got out of the car and grabbed the extinguisher. When I opened the hood of the engine compartment I could see a lot of flames and a puddle of fuel on top of the injector base plate. I went into action with extinguisher, but I couldn't get all the flames out. The trouble was, there was a wind blowing and I had opened the upwind side of the hood which allowed the wind to fan the flames into greater intensity. So, I closed that side down and ran around to the other side of the car on the down-wind side. I opened the hood and began again with the extinguisher.

Things were better now and I soon made good progress toward extinguishing the flames. The flames were almost gone, but so was my supply of fire extinguishing fluid. Methanol burns with an almost invisible flame that is hard to see in bright sunlight. I had to be sure I got all of the flames before I ran out of fluid completely. I could not depend on outside help. I was so far from camp my crew did not even know I was in trouble. Then, suddenly I felt funny. I was getting dizzy, I felt sick at my stomach, and my eyes were watering. I kept pumping the extinguisher but by now I was unsteady on my feet and could barely stand up. What was happening to me? The last flames that I could see, flickered out just as the extinguisher emptied. I hoped there were no invisible ones still burning. If there were, my car was doomed. I dropped the extinguisher and staggered over to the rear of the car so I could lean on it for support. I felt terribly weak and nauseous. I hung on to the car for about 15 minutes before my crew finally found me. By then, with the wind blowing in my face, I began to feel a little better, but not much. It took the rest of the afternoon, about 3 hours, before I recovered fully.

During that period I had time to think about what had happened to me. Suddenly, due to my experience as a chemist, I knew the answer. The fluid in my fire extinguisher was carbon tetrachloride. In the presence of heat it reacts to form phosgene, one of the mostly deadly of the poison gases used in World War 1. When I moved to the down-wind side of my car and leaned over with my head near the engine, the wind blew the phosgene right into my face. Since it is completely colorless and odorless, I simply wasn't aware of it. Now I know why carbon tetrachloride is no longer used in fire extinguishers. If the concentration of phosgene had been higher, I'm not sure I would have recovered. It was the most horrible feeling I have ever experienced.

Meantime, my crew was checking the fire damage, and looking for the cause of the fire. The only real damage turned out to be all 8 spark plug wires were burned. They replaced those in short order. The cause of the fire was located and it had nothing to do with the fuel injector. The fuel supply line from the pump was loose at the pump fitting. We try to check all these little things, but once in a while one gets passed by.

The time trials always start at dawn on Saturday and the same on Sunday because we are in the middle of the Mojave desert, and by noon the temperature may be 110° or more. In spite of this, the night time temperature in the desert can be really cold. We all slept in sleeping bags around a campfire and were quite comfortable. Everyone was up early the next morning and it was really cold. All of the cars run on methanol for fuel, and methanol is extremely difficult to start a car with in cold weather. I always had a can of benzol with me when I ran the carburetors. When it was cold, a little benzol poured down the carburetor throats could help a lot in getting the engine started. So I thought, lets try the same trick with the fuel injector. I got the can of benzol out and opened it up and received a shock. It was so cold the benzol had frozen solid! What to do? I wanted to get the engine warmed up and put in line early for my first run. As car after car runs through, the course becomes chewed up and you can't get good traction. The early times were always faster because of this and also because of the heat later on in the day. I noticed that our campfire of the night before was now down to hot coals, no flame. That gave me an idea. I removed the belly pan from the car which exposed the oil pan on the engine. My crew then pushed the car right over the campfire until the oil pan was directly above the hot coals. I let it sit there for about a 1/2 hour while the sun was still coming up. The cold oil in the pan soaked up the heat and soon even the metal engine parts became warm to the touch. We rolled the car off to the side and replaced the belly pan and went out to start the engine. It fired up quickly without much effort, and after running around a bit to warm up everything, I put it in line for my run. The line was a lot longer than I would have liked, but it couldn't be helped.

Finally, I reached the head of the line and it was my turn. Needless to say, there was quite a crowd around the car to see what would happen. I took off on my run and the engine was performing beautifully. About 2/3 of the way down the coarse I began to feel the rear end of the car fishtailing from side to side, not a lot but definitely noticeable. I knew right away what caused that. The lake surface was already chewed up from the earlier cars and I was losing traction. Sometimes the lake surface is better and harder than others. This was not one of the better ones. I kept going, being careful not to over-correct on the steering wheel. By the 3/4 mark I could feel the engine was not pulling real hard, and the tachometer was not climbing. It was definitely too rich at this rpm, as I had predicted in the very beginning. No problem to correct it. My time was 134 m.p.h. Not the best, but respectable for the first run with a radically new system. My best time ever, with carburetors, was 139 m.p.h.

After the run, we checked everything over and found no problems. I dropped the fuel pressure down a little to lean down the mixture and got back in line. The line was really long. The first race of the year always had long lines, and this was no exception. I didn't get my second run until almost noon. The temperature is up and so is the wind. My time was close to the same as the first run. However, the course was even slipperier and the engine still seemed too rich and not pulling good. I decided not to run anymore but to wait for tomorrow morning when conditions would be better. Also, when the course gets real bad, sometimes the official would move it over to the side a hundred feet or so for the next day. Maybe that would happen. Sunday morning, and I have a good position in line for an early run. Unfortunately, the course was not moved. I started my run and right away I could feel the course was in really bad shape, It was hard to keep the car on line. As it ended up, my time wasn't as good as on Saturday.

For the next race the following month, I decided I would like a direct comparison between the fuel injector and a conventional 2carburetor manifold like most of the fellows were using. I would make my first run with the carburetor set up, then switch to the fuel injector. I had been running my special 4-carburetor manifold the previous year and ran well, reaching 139 m.p.h. I had never run a 2carburetor manifold in this car. I started off on my first run, and right away I was surprised at how soft and loose the lake bed was. As my speed climbed, it became more and more difficult to keep the car in line. I kept on going, but before the Lalfway marker, the car hit an extra soft portion of the lake bed and snapped around into a spin before I could even react. I spun around several times when suddenly the left rear wheel collapsed, the axle dug into the ground and I was now airborne end over end.

I hunched down into the cockpit as far as I could but the car was very narrow and there wasn't enough room to get down really low In those days there were no roll bars and no safety helmets, only seat belts. I curled my head down on my chest which left only my back at the top of the cockpit. Every time the car flipped, it landed upside down with my back on the ground. The next flip it would land upright on its wheels, then upside down again on my back. I don't know how long this went on. I was aware of a blur of light as the ground, then the sky, then the ground again, flashed by. The noise was also very loud. Not engine noise but the clashing of metal body parts at each impact. The noise suddenly ceased and I found the car had finally stopped in an upright position resting on three wheels and a hub. The fourth wheel was completely gone. I was conscious but could barely breathe because the wind had been knocked out of me by the repeated blows to my back.

Instinctively, I reached out and shut off the ignition switch, even though the engine wasn't running. I unbuckled my seatbelt and managed to crawl out of the car to a standing position on the ground. I still could barely breathe, so I lay down on my back on the ground hoping to ease that problem. I remember wondering why nobody had come to help me. I later found out the reason was that I had crashed at the halfway point and the ambulance was stationed at the finish line where most o~' the trouble usually occurred. That was three miles away from me. And, of course the starting line was just as far in the other direction. Finally, the ambulance arrived and loaded me in. They asked how I was and I told them I felt okay except for the difficulty in breathing. Nothing seemed to be broken. They decided I should stay in the ambulance until the meet was over and they would drop me off at the hospital in Victorville on their way home. I thought that was fine because all I wanted to do was lie still and try to get my breathing back to normal. Also, if I insisted on going to the hospital right then, the time trials would have to shut down for lack of an ambulance, and many of my friends were still waiting to run. My crew came by to assure me they would take care of my car and get it home for me. That was a relief.

Just arrived at Victorville hospital. My breathing has finally become normal. The doctors looked me over and asked if I could move my toes. I could. They were checking for paralysis. The only thing they could see was a huge bruise the size of a dinner plate on my back where I repeatedly hit the ground with the car on top of me. Also, my leather jacket was completely ground through and my back extensively skinned up. They decided to x-ray my back. The results were not good. I had a compression fracture of the eight and ninth thoracic vertebrae. Since there was no paralysis, they felt with time, it would heal. They treated my skinned up back and asked where I wanted to go. I told them the Sawtelle Veterans Hospital in West Los Angeles. The doctors there agreed with the other doctors. They kept me there about 3 weeks until my back abrasions healed. Then they put me in a full body cast from neck to waist with holes for my arms. I looked like a turtle. They sent me home with instructions to return in 3 months. The only cure for me was time.

It took several months to rebuild my car and go through the engine. Every cylinder was packed with dirt that somehow had entered the engine during the crash. As a break in the work, some of my friends talked me into going dove hunting in El Centro with them. I never cared much for hunting but a change did seem appealing. So I went. We were only out hunting a short time when I realized what a dumb decision this was. Here I am in El Centro in July when the average temperature is around 1150 and I'm wearing a body cast lined with 1/2" thick felt. I felt like a boiled lobster. Also, I was hesitant to fire a shotgun for fear the recoil might crack my cast. All in all, a miserable trip. I must have been out of my mind.

It's late in the year now and the racing season has ended. My car is all finished and ready to run. My body cast is gone and except for a lingering soreness in my back, I am pretty much healed. Nothing more to do until the new season starts next year.

The 1948 season finally arrives and the first race is to be held at El Mirage lake, my favorite, instead of Harper. I arrive at the lake on Friday as usual, fire up the engine and run around the area a bit at low speed. Everything seems great. Although I am pretty well recovered from my crash, my mother was still upset about it. To relieve her anxiety I finally promised her not to drive the car anymore. So, I asked one of our club members, Howard Wilson, to drive. Saturday morning we get a good place in line and made the first run. The time was 141 m.p.h., two miles per hour faster than the best time with the carburetors, and a new record. We now got ready for our second run which would be later in the day. The air temperature was warming up, so I made some adjustments to the injector. The second run started. The engine sounded sharper than the first run, or maybe it was my imagination. :Speed for the second run was 150.50. The first car to break the 150 m.p.h. barrier! I had proven the critics at the auto show were wrong. The system worked. Even Ford Motor Company showed their approval by publishing an article about the event in their in-house magazine, Ford Times. They described it as equivalent to breaking the sound barrier in aircraft.

Continue to Chapter Four

Return To The Hilborn Story

Return To HOME PAGE