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Fuel, Oil and Materials Consumption As described in the Introduction, fuel economy on uncontrolled C-W rotary engines was within 1 mpg of conventional pre-control engines by as carly as 1965, even when demonstrated in vehicles designed for heavier reciprocating engines. Still, there is widely discussed and confused information based on the characteristics of current production Mazdas. As reported by Toyo Kogyo in their testimony to this Committee, fuel economy comparisons between vehicles are complicated by many design and operating parameters. An important one is car weight-to-power ratio which is fundamental to acceleration performance, a critical safety consideration. Toyo Kogyo's estimate of correction for this factor led to their acknowledgment of a 15 to 17% penalty for their present cars compared to conventional engines in their testimony before EPA in March of this year, This deficiency is based on the design trade-offs incorporated in their current production engine and its exhaust reactor system installed in a vehicle designed to accept a reciprocating engine and not optimized for rotary. Until recently, the RX-2 was available in this country with a four cylinder 81 horsepower reciprocating engine, and fuel economy of this combination was quite close to similar size and power vehicles offered by others. Rather than build a new lighter and shorter vehicle around the same or an iteratively lower power rotary engine, Mazda chose instead to offer the option of a 120 horsepower rotary. Clearly, the traditional forces favoring minimum variations on the production floor appear to have prevailed and no general system optimization around the rotary was involved.
It is generally agreed at present that the .4 grams/mile Nox limit will require
Confusion over current Mazda fuel consumption was evident in these hearings
Perhaps more useful is the Mazda data provided by Table 4 of Ref. 12. Here the American Petroleum Institute reports "consumer cycle" fuel consumption accumulated in some 70,000 miles of Mazda operation by six different major U.S. oil companies as ranging from 17 to 21 mpg. The same source shows oil
(4) consumption averaging about 1 quart per 1,000 miles. Lest the reader conclude that this last figure is what one may expect on all rotaries, we must forecast the likelihood that in the not too distant future rotary engines will be available which, because of particular uniquenesses of this geometry, will not require oil changes but will live out their lives on make-up oil only. At that point, oil consumption of such rotary engines will be substantially superior to reciprocating.
A point should be made regarding the consumption of metals by rotary engine cars. The savings in engine and vehicle weight discussed earlier must be interpreted in a broader way than simply efficient use of materials resources. Though we have not attempted a quantification, there is attributable energy consumed in the movement and configuration change which a pound of metal experiences on its trip from the ore deposit to the showroom floor.
Safety It 18 this objective which is least 11kely to be well served by an undue focus on emissions. Aspects of safety are not as easily dismissed as suggested by this Committee's discussion with Mercedes (Page 166, line 5-11, Ref. 13). Here, the exchange between Senator Muskie and Mr. van Winsen suggests that passing performance would not be important if all automobiles were diesel (low) powered. When one is passing another car which is traveling at, say, 50 MPH on a two or three lane road, it makes little difference how long it took the other car to get to 50 MPH in the first instance. What counts is how long the passing
car will be exposed to oncoming traffic during the passing maneuver. The same argument holds in merging onto a busy throughway or in crossing an avenue from a stop-street. Sluggish response is clearly a threat to safety.
The above point concerns crash avoidance. It is also important to consider vehicle breakup characteristics when a high-speed crash occurs. In this case,
deceleration rate and the integrity of the passenger compartment become most important, and this aspect is the subject of much current investigation, In the case of front-engined cars, two engine characteristics are critical, The first is engine length, since the shorter the engine the more forward space is available for energy-absorbing crushable structure. The second factor is engine weight and general bulk. There is a higher probability of being able to deflect a light, small engine and avoid penetration of the passenger compartment.
The general point to be made regarding safety is that of all the engine types in present contention for automotive use, only the rotary promises adequate power while at the same time affording major reductions in size and weight.
Conclusion: We have attempted to briefly describe and support why rotary engines are, in our opinion, the most promising replacement for conventional automotive engines of any identified to date. As in the case of conventional reciprocating engines, different rotary automotive design teams will come up with somewhat different total systems solutions influenced by considerations beyond, in number, those discussed in this submittal. But we are convinced that the fundamental advantages of the rotary give this type of engine a substantial margin, one which will grow even more dramatically as the engine matures.
We believe that the Clean Air Act has contributed to the acceptance of rotary engines by domestic car manufacturers and that the maintenance of present emissions standards will accelerate the availability of clean, safe, costeffective vehicles built around this new engine type. And, as stated by General Motors in recent testimony before another Senate Subcommittee, "Other than the emission controlled conventional piston engine and the rotary engine, none of the alternate powerplants has a chance for volume production passenger cars in 1975." (p. 635, Ref. 14)
(1) In Ref. 3, General Motors states that the advantages of the
rotary "will not be realized until we are satisfied that the engine is reliable on the basis of volume and the economics normally associated with our industry."
(2) "critical materials" refers to high temperature alloy steels
used for valves and valve seats in conventional engines. The alloying constituents are "critical" in terms of cost and availability of ore deposits.
(3) This result was achieved on a low-mileage vehicle; however,
as also reported in Ref. 11, high mileage tests of an essentially similar system on an RX-3 plus the results underlying Ref. 10 all point to stable 50,000 mile characteristics in Mazda emissions controls.
(4) The Committee has evidenced a belief that Mazda oil consump
tion is 1 qt, per 500 miles. There is one data line in Table 4 of Ref. 12 which gives this value. This line, however, is that of a single NSU RO-80, and not a Mazda.
Jones, Charles, "A Survey of Curtiss-Wright's 1958-1971 Rotating Combustion Engine Technological Developments". Society of Automotive Engineers paper number 720468, May, 1972. (attached)
Letter, A. F. Kossar, C-W, to Mr. George Allen, EPA, April 7, 1972.
Zimmer, Thomas R., "Rotary Combustion Engine". p. 45ff Report on
Templin, Robert J., "Rotary Combustion Engine". P. 39ff Report on
5. Report by the Committee on Motor Vehicle Emissions, National
Academy of Sciences, Feb. 12, 1973.
"Control Techniques for Carbon Monoxide, Nitrogen Oxide and
7. "Control of Vehicle Emissions After 1974", Report to The
California Air Resources Board by the Technical Advisory
Jones, C. and Lamping, H., "Curtiss-Wright's Development Status of the Stratified Charge Rotating Combustion Engine", SAE Report 710582, June 1971, Table 2. (attached)
Jones, C. and Cole, D.E., "Reduction of Emissions from the CurtissWright Rotating Combustion Engine with an Exhaust Reactor". SAE paper number 700074, Jan. 1970. (attached)
Federal Register, Vol. 38, No. 84, Part III, May 2, 1973.
11. Austin, Thomas C., "An Evaluation of Two Toyo Kogyo 1975 Prototypes
with Rotary Engines". EPA Test and Evaluation Branch, Feb. 1973.