When a top fueller flames out it causes a hydraulic lock, 4 injectors per cyl are pumping in fuel and 2 fuel pumps supply them to keep up the pressure. There is a special blanket come restraining strap that goes over the supercharger and around the upper section of the engine in an attempt to keep it all in the vehicle when it goes bang. On a final side by side pass on the old Eastern Creek drag strip, one let go and sent the blower and head into the fence separating the spectators from the track, the force was so great it snapped the Kevlar straps. The whole security blanket idea was revised after that, if it had been the other side head that escaped, it would have hit the driver of the rail that was beside him at the time.
The next top fuel meeting, in the final again, a clutch and flywheel departed from the rear of the engine and went over the heads of the spectators on the hill beside the grandstand and landed out on the road beside the race complex ...... milli seconds later and it would have gone into the grandstand ..... the bellhousing scatter sheilds were revised after that incident.
Further investigation into just what was happening before the explosions uncovered a now banned practice of having a bypass supply that had no fuel restrictors (known as pills) in the fuel lines to the injectors directly over the intake valves ..... The driver had the option of hitting this button at the end of the run if they thought they needed the extra power to win and they believed the engine would stay together for the last second or less.
The over fuel in the first instance blew out the homogeneous flame in the cyls on one side (the spark plugs are melted by the 60 ft mark, under a second from the launch) the clutch and flywheel disintegration was the result of the pressure plate not being able to apply enough clamping force on the clutch plates resulting in massive clutch slip.
That last throw of the dice button is still available (the yanks call it a scramble button) but the amount of added fuel is limited to 10% now .... well that was the rule back when I was still involved in drag racing.
The next big bang was in a Sainty Racing engine, built in sections so the block each side was seperate to the crank case and naturally the heads, all billet machined from aircraft grade aluminium blocks, so no cooling jackets at all. The whole upper section of the engine came away from the crankcase section, very spectacular, they cleaned up the mess from that and a few passes later, a Keith Black engine threw the crankshaft out the bottom of the block and into the race track disintegrating the rear section of the rail leaving the driver and front section still going forward in one direction, the back half that remained went up in the air and across the other lane, fortunately the other rail was far enough in front when it landed to avoid it.
They blamed the atmospheric conditions for those two events, not the fact there was huge prize money offered for the first 4 second pass
T1 Terry
