The cost of a DISC engine is best estimated from the cost of a diesel engine, since the fuel
injection system complexity rivals that of an indirect injection (IDI) diesels’ fuel injection system
and the higher compression ratio imposes higher pressure loads on the cylinder block and
reciprocating parts. In the Martin Marietta analysis,^58 RPEs for IDI diesels are estimated to be
$400 to $450 for a four-cylinder, $550 to $600 for a six, and $750 to $800 for a V-8 engine.
These incremental RPE effects are likely to be applicable to the DISC engine, but the incremental
effect of a lean-NOx catalyst must be included. If the DISC uses variable valve lift and timing, the
price increments should be approximately additive so that the prices shown in table 3-6 may be
reasonable.
Low-fiction components are relatively low-cost items and were examined in some detail in the
Martin Marietta report. Estimates of supplier costs of low-fiction components were obtained
directly from engine valvetrain and piston component suppliers who provided the following range
of incremental costs:
lll
lRoller earn followers: -$0.50 eachLightweight valves/springs: -$1.00 each (titanium/ceramic)Lightweight pistons: ~1.00 eachPiston coatings: -$0.50 eachThe total investment for each of the four items was provided by auto manufacturers at $4
million for each component type for tooling, engineering and launch costs. The RPE for each item
(for four-valve engines) is shown in table 3-7. Given the values shown in the table, friction
reduction should result in an RPE of $65 to $120 depending on number of cylinders. Note that
many engines already have roller cam followers.
DIESEL ENGINES
Background
Diesel engines differ from SI engines in their method of fuel ignition; instead of igniting the
mixture of fuel and air with a spark, diesels rely on compression alone to ignite a mixture of fuel
and heated air. Diesel engines enjoyed a brief burst of popularity during the early 1980s, following
the second oil price shock of 1980. Since the oil price collapse of 1986, diesels have practically
disappeared from the U.S. market. In Europe, however, diesels have recently enjoyed a rebirth,
and their market penetration is over 30 percent in some countries such as France.
(^58) Ibid.