Direct Fuel Injection - la Bosche

[Robert Harris]

Automotive Fuel Injection Systems - a Technical Guide.
Jan P. Norbye ISBN 0-87938-130-8

Page 55 
M-196 - a mid fifties straight eight na racing engine. DOHC desmodronic,
10,000 rpm Hemi head 2.5 liter Grand Prix engine

" The Mercedes Benz M-196 was an in-line eight cylinder engine with dual
overhead camshafts.  It was used in 2.5 liter form in the W-196 Grand Prix car
of 1954-55, and in three-liter in three liter form in the 300SLR sports
prototype of 1955.  The M-196 engine layout permitted the use of long and
straight induction pipes, giving considerable ram effect.

The injection pump was made by Bosch. It was an eight-plunger design, gear
driven from a central power take off on the engine

The M-196 nozzles were of the pintle-valve type with a single delivery hole.
Fuel pressure unseated a spring-loaded one way valve at the right moment and
no return line for leakage was needed.

The injector nozzles were carried in holes drilled in the cylinder barrels.
Extensive experiments were necessary to determine the optimum position of the
jet itself and the shape of the spray.  Finally the nozzles were placed on the
inlet side of the block at an upward angle, aiming the spray DIRECTLY AGAINST
THE EXHAUST VALVES".


Later

"There was little freedom with regard to injection timing since the pistons
shrouded the nozzles at top-dead-center position.  This left no more than 120
degrees of crankshaft rotation available for effective injection, which
corresponds to only .002 seconds at 10,000 rpm"  Subtle hint?

The production 300 SL Naturally Aspirated MFI used 1100 PSI spraying directly
across the cylinder from an in block injector aimed again at the valves on the
other side of the head ( from several useable drawings) .  Of course you need
to understand that the block deck was milled at a large angle similar to the
Lincoln 462 which caused the entire combustion chamber to be contained in the
block and piston with the head being virtually flat.

So much for high pressure supercharged aircraft engines only.  Again -
atomization is not a problem when you shoot the fuel in at 1100 PSI against
the exhaust valves - common to the automotive setups. 



1963 Ford C-600 Prison Bus Conversion "Home"
1971 Lincoln Continental 460 "Christine"
1972 "Whale" Mustang awaiting transplant
1978 Dodge Long Bed Peeek Up "Bundymobile"

Habaneros - not just for breakfast anymore