The most important factors affecting comfort and performance in motor vehicles are; The exhaust gases generated by the internal combustion engine are noise and vibration. The effect of these factors can be reduced thanks to the fully efficient and regular operation of the engine. The most important part affecting the efficient operation of the spark plug ignition engine is the spark plug. Spark plug failure; emission, noise and vibration values increase. These negative effects reduce vehicle comfort and increase travel costs; it also causes more damage to nature. Vehicles are designed and manufactured to ensure optimum operating parameters during production. However, changes in these parameters occur as the vehicle is used and different types of parts are used during maintenance. In this study, spark plug nail spacing; Emission, noise and vibration effects and determination of optimum nail spacing. In the experiments, iridium spark plug was used as ignition spark type. The spark plugs wear out because the engine fires continuously during operation. This wear increases the distance between the center electrode and the electrode cap and changes the resulting spark quality. According to the experiments; When the iridium spark plug nail spacing is 0.8 mm, the noise is optimum at different revolutions, the vibrations in the 0.9 mm nail spacing increase at low revolutions, and the hydrocarbon value is minimized at high revolutions in the 0.8 mm spark plug nail spacing.

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In the experimental study, the effects of diesel-methanol-dodecanol blends on en-gine performance and smoke emission in a single-cylinder, four-stroke, water-cooled, normally aspirated compression ignition engine were investigated. Fuel blend ratios in the study; Diesel (D100), diesel-methanol (D90M10) and diesel-methanol-dodecanol (D89M10D1) were used. In order to solve the phase separation problem in the diesel-methanol blend, 1% by volume of dodecanol was added. The test engine was oper-ated at four different loads (6, 12, 18 and 24 Nm) and constant engine speed (1800 rpm). The performance parameters such as brake specific fuel consumption, brake specific energy consumption and brake effective efficiency for each blend at various engine loads are calculated based on the experimental data. The results indicated that methanol adding diesel lead to worsens specific fuel consumption but improve BTE. A significant improvement was observed in smoke emissions with the addition of both methanol and dodecanol compared to diesel.

There are many factors that affect the operation of vehicle engines. Not working regularly of an engine causes a decrease in the performance; on the other hand, an increase in the fuel consumption, the vibration and the HC emission. These adverse impacts reduce vehicle comfort and increase travel costs, and also damage nature much more. Vehicles are normally designed in such a way that they provide optimum operating parameters. However, as the vehicle is used, these parameters negatively change. In this study, it has been experimentally investigated that the effects of spark plug gap on vibration, noise and HC emission in a gasoline engine. It is a fact that, the spark plug is abraded in a certain amount because it is continuously ignited. This abrasion increases the distance between the center electrode and the electrode head, and changes the quality of the composed spark. In experiments, it has been detected that, when the spark plug clearance and the number of revolutions are increased, the vibration and noise increase proportionally; on the other hand, the exhaust emission (HC) value increases at 0.7 mm, 0,8 mm and 1.0 mm plug gap and decreases at 0.9 mm plug gap. As a result, setting the standard spark plug gap in the gasoline engines to 0.9 mm instead of 0.7 mm can provide a significant reduction in exhaust emissions; thus, an improvement in performance can be achieved.

ÖzetTitreşim, içten yanmalı motorlu araçlarda konforu etkileyen en önemli faktörlerden birisidir. Doksanlı yıllarda üretilen dizel araçların, benzinli araca göre daha titreşimli çalıştığı bilinmektedir. Son teknoloji dizel araçlarda ise titreşim seviyesi azalmıştır. Bununla birlikte dizel araçların titreşim seviyesi benzinli araçlar seviyesine indirilememiştir. Bu çalışmada; benzinli ve dizel motorların farklı devir sayılarındaki titreşim ölçümleri ivme cinsinden (g) yapılmıştır. Her iki motorun maksimum ve ortalama titreşim değerleri kendi içinde ve karşılıklı olarak kıyaslanmıştır. Bu karşılaştırma sonucunda, ortalama ivme dikkate alındığında, dizel motorun benzinli motora göre rölanti devrinde (1000 dev/ dak) 42.2 kat daha titreşimli çalıştığı tespit edilmiştir. Her devir aralığındaki titreşim oranları değerlendirildiğinde ise iki motorun da maksimum torkun ulaşıldığı devire kadar titreşim oranı azaldığı, bu devirden sonra arttığı tespit edilmiştir. AbstractVibration is one of the important factors affecting the comfort of vehicles with internal combustion engines. It is known that diesel vehicles produced in the 1990s runs with more vibration than the gasoline engine. On the other hand, the high technology diesel engines produces less vibration. Although there are significant developments in the vibration levels of diesel engines, it is obvious that the vibration level of gasoline engines are better than that of diesel engines. In this study, the vibration level of gasoline and diesel engines are measured as acceleration (g) in their different revolutions. The maximum and average vibration values of these two engines are compared first inside each kind of engine itself and finally with each other. According to this comparison, in terms of average acceleration, the vibration level of the diesel engine is higher (42.2 times) than that of gasoline engine in the idling state (1000 rev/min). In terms of the vibration rates in the range of each revolution for both two engines, it is observed that the vibration rate decreases until the revolution at which the maximum torque is reached, and the vibration rate increases after that revolution.