Effect of fuel composition, engine operating variables, and spark-plug type and condition on preignition-limited performance of an R-2800 cylinder

Pfender, John. F.
naca-rm-e6j08
1946


The preignition characteristics of the R-2800 cylinder, as affected by fuel composition, engine operating variables, and spark-plug type and condition, were evaluated. The effects on preignition-limited performance of various percentages of aromatics (benzene, toluene, cumene, and xylene) in a base fuel of triptane were investigated. Two paraffins (triptane and S + 6.0 ml TEL/gal) and two refinery blends (28-R and 33-R) were preignition-rated. The effect of changes in the following engine operating variables on preignition limit were determined: inlet-air temperature, rear-spark-plug-gasket temperature, engine speed, spark advance, tappet clearance, and oil consumption. Preignition limits of the R-2800 cylinder using Champion C34S and C35S and AC-LS86, LS87, and LS88 spark plugs were established and the effect of spark-plug deterioration was investigated.

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