What Are Advantages of Longitudinal Engine?

Longitudinal engine means that the engine is vertical to front axle of vehicle. In brief, the engine is located longitudinally inside engine compartment. 

 

Advantages of longitudinal engine

In general, longitudinal engine is mainly applied on rear wheel drive. The power should be transmitted to rear axle. Transmission distance cannot be reduced. So, frequency of power direction transformation should be decreased as much as possible. If transverse engine is used, the crankshaft is vertical to driving shaft. Direction should be changed firstly so that driving shaft can transmit power. However, driving shaft is also vertical to rear axle. So the direction should be shifted again. Without doubt, efficiency of transmission mechanism is declined. Due to longitudinal engine, the shaft is parallel with driving shaft, reducing the frequency of transformation and power losses further. 

 

On the other hand, longitudinal engine allows position of transmission backward as far as possible. Core of power assemble is behind front axle. Nevertheless, forward and backward weight of car body is more average.  

 

For longitudinal engine, Audi is quite particular. Audi applies longitudinal engine on front wheel drive. Although Audi uses longitudinal engine for considering quattro, the engine can still bring excellent forward and backward weight ratio. The arrangement can locate engine longitudinally before front axle. Gear box connecting directly with engine is limited by engine compartment space. So, the gear box is located behind front axle. Both input shaft of gear box and shaft of engine rotate with the same axis. For front axle which bears weight of engine and gear box, the axis is like the pivot of balance. Engine and gear box are distributed forward and backward front axle. Although understeer still exists in front wheel drive, the weight ratio is more excellent than general transverse engine. For example, weight ration on Audi A4 which is front wheel drive can realize 55:45.