Mark Donahue who was an engineer and a driver, wrote very frankly about the teething troubles of the 917/10 and 30 in his book the Unfair Advantage. Here are some excerpts:
"After lunch they asked if I would drive the car, to give the photographers some action shots. I didn't expect to have to drive it right then! It had been a hectic few days. We were out drinking late the night before, and we had to get up early for our meetings. I had no desire to drive at all. But it seemed to be such an important thing for them that I got in the car, fired it up, and took it out on the track.
...Just driving around, my initial reaction wasn't too favorable. In the first place, I was hung over, and didn't want to go too fast. But even at that speed the car was terrible. It was "hunting" back and forth on the straightaway is if it had an inch of toe-out. I had to jam my legs against the steering wheel to keep it in a straight line at 150 mph.
...I came in thinking, "Christ! I'm glad that's over with. They have their pictures and we can all go home." I was ready to take the car to the skidpad and start over from scratch. Flegl [Porsche factory engineer] walked over to the car and said, "You went around in 53 seconds. The record for this car is 51.5 seconds. What do you think is wrong?" I looked over and there were five mechanics standing there. Suddenly it hit me that they were expecting a command performance--some new lap records, right there! Then I remembered the huge "record board" they had on a wall at the factory. It had a map of the course, and lists of the lap records set by various cars and drivers. I had never driven the track before. I had never sat in the car before, and they expected me to break the lap record. Germans are very tough people. They expect the maximum from everybody at all times.
...When we were at the track a truck showed up with another 917 It looked like the Spyder we had seen before at Can-AM races--an ugly, dirty, beat-up old thing--except that it was longer. It turned out to have a sixteen-cylinder motor that they wanted me to try. I was told that it was built by special order from the Piechs, and it was quite expensive...
They didn't tell me much about it, but I clearly got the impression that it was a possible alternative to the turbocharged twelve, or that it could even be turbocharged itself--for something like 2000 horsepower. So I drove the thing for them, and it was a real monster. The motor was so long that you could hear one end start up before the other. There were exhaust pipes sticking out everywhere. Although it wasn't set up properly to try for any lap records, it was truly impressive in a straight line.
We realized then that we had to have the turbo-motor, and as soon as possible. I told Flegl that we must have one to test in America, because of the weather problems in Germany in the winter. since we had never even seen the turbocharged version before, they sent their engine guy, Fritz Springler, with it. We went back to Atlanta with the first turbo-motor in February. But it was cold there and the engine wouldn't start. Eventually we towed it around the track a few times before we got it to run at all. Then, once it started, we damn near couldn't keep it running... We sent it back to Germany with a long dissertation on the problem, and possible solutions they could try. Another engine arrived shortly, with Flegl and their head engine guy, Val Schaffer...We had to tow the car to get it started, and it wouldn't run at part throttle. I was getting exasperated. I showed Flegl and the engine expert what was happening, and they said they understood, but neither one knew what to do about it. ...I decided that it was foolish to waste any more time in the States. I told Flegl that I'd have to go to Germany and work with their engine men personally.
...I told Roger that we were going to get smoked by Mclaren if we couldn't get the turbo-motor to run right...
...I was totally exasperated. I said, "We are wasting our time on the track. Now we must take the engine out of the car, put it back on the dynamometer, and i will try to show you what is wrong." While they were doing that, I looked at their dyno output curve. They had all the necessary data--torque, RPM, boost pressure, and so on--except that their curve started at 5000 RPM. I said "Why are there no curves up to that point?" They said, "The motor does not run there." I thought "Christ! That's what I've been trying to tell you for a month!" I couldn't believe it was that simple. I couldn't believe that they had simply calibrated the fuel injection for wide-open throttle with full boost, and had totally ignored any part-throttle operation.
...The first thing I recognized was that we would have to run the motor with no blower. They said "But it is a turbo-motor. It will have no power." Finally I convinced them that there were times when the boost was very low and yet the engine must keep running. When we took the blower off--it wouldn't run at all! When we tried to accelerate above idle, it just died. So we fitted the motor with two control levers--one for the throttle butterflies and one for the fuel-flow meter. The engine guys were a little angry. They were mumbling in German, "He runs in America with the blower and is not happy. Then he runs here with the blower and is not happy. Then he runs on the dyno with the blower and is not happy. Now we run on the dyno without the blower and he is still not happy. We are going backwards."