I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
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have been determined. In general, addition of the halocarbons lengthens engine combustion time, increases the total energy liberated, and alters the temporal energy release pat’tern. As a result of these changes, the ignition timing required for maximum power development’ is increased, and the maximum power output of the engine is increased, but the power output at’ ignition timings less than that for maximum power may be increased or decreased. Addition of the halocarbons decreases the knocking tendency of the engine under conditions of constant power output or ignition t,iming, but increases the knocking tendency a t the ignition timing for maximum power. On the other hand, the halocarbons greatly lowered the octane number rating of fuels containing tetraethyllead but had little effect upon the octane rat,ing of lionleaded fuels. These observations indicate t’hat the addition of the halocarbons may be 8. useful tool for investigating the auliknock mechanism of tet’raethylleatl. The effectiveness of the various halocarbons in altering engitic performance varied markedly wit,h the type and number of halogen atoms present but showed no direct correlation with the stability of the compound. The addition of the halocarbons to the intake charge of an engine for power increases of short duration ~ o u l have d some value in racing applicat,ions if it were not)for the attendant heavy carbon formation which fouls the spark plugs and the production of corrosive exhaust products.
Vol. 46, No. 8
R. E. Schwind for his assistance ill conducting the c~poinicntal n-ork, and to the members of t,he Fuels and Lubricants IIel):ti,tment of the General Motors Research Laboratories for thpir awistance in preparing thii: manuscript. LITERATURE CITED
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ACKNOWLEDGMENT
1497 (1953).
The authors wish to express their appreciation to L. L. Wit’hrow f o i . his advice and encouragement, during the investigation, to
Tttnford, C.. and Pease, R. N., J . CAem. Phys., 15, 861 (19471. RECEIVED for reviev March 2 5 , 1954.
ACCEPTEDM a ) 10, I!):
