VOL. 10, NO. 1, JANUARY 2015 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 370 MULTISTAGE TURBOCHARGING SYSTEMS FOR HIGH ALTITUDE FLIGHT WITH COMMON RAIL DIESEL ENGINES Luca Piancastelli and Leonardo Frizziero Department of Industrial Engineering, Alma Mater Studiorum University of Bologna, DIN - viale Risorgimento, Bologna, Italy E-Mail: leonardo.frizziero@unibo.it ABSTRACT A Fiat 1.9jtd diesel engine has been extensively reviewed to output 300HP. This paper introduces a multiple stage turbocharging system that uses commercial turbocharger, taken from the catalogue of a popular manufacturer. The calculation method and the problem connected are widely discussed. Along with the problem that may arise in using these off the shelf unit. The quite heavy result advice the user to adopt ad-designed turbochargers for this task. Keywords: INTRODUCTION The research in the field of engines is aimed to the design and implementation of engines with increasing power to weight ratio, with reduced costs and with the restore altitude higher possible. In this context the project of the conversion of the Direct Injection Diesel (DID) FIAT 1.9 Jtd 8V (8 Valves) is a very interesting. Thanks to the innovations made in recent years in the compression- ignition engines, the power to weight ratio of these engines has been greatly increased. This fact, together with their very good efficiency has led to a great interest for aerospace applications. For all the above factors, but particularly to enable a higher restoring altitude, it was decided to study a multistage turbocharging system. This solution has the drawback of a greater complication and higher total mass. In this paper we intend to proceed with the design of a supercharging system that can guarantee full power restoration even at very high altitude for HALE (High Altitude Long Endurance) UAVs (Unmanned Aerial Vehicles). It 'should be noted that the commercial offer in this field, it is very scarce and it is largerly non-compliant with fuel economy requirements for a long duration of flights. For this reason, the system proposed in this paper, once designed and developed, may prove to be satisfactory in a field where the concurrency is nearly absent. Evolution of the project In this section we briefly summarize the various stages of evolution of the project to develop a DID, based on the 1900 FIAT JTD engine, capable of a power output of 300 HP. Clearly, this development had to comply with certain constraints imposed by the type of engine choice. The engine displacement (1910 cc) and the in-line arrangement of the cylinders should be kept as well as the same cast iron crankcase of the original engine, for obvious economic reasons. This choice imposes to keep similar dimensions of the main crankshaft journal bearings and consequently a certain difficulty is to obtain consistent lightening of this organ. Fortunately maximum power output is required at high rpm so journal bearing loads due to combustion are partially reduced by inertia load. However the use as many original components, in particular pistons and connecting rods. may lead to important economic advantages, but reduces the maximum allowed pressure the combustion chamber since the original piston resist up to a maximum 180 bar. Initially the aim of the project was only a new design of a special steel crankshaft 300 M, able to reach the required power of 300HP at 3800 rpm. This result an be achieved by using the new bimetallic pistons can withstand a peak pressure in the combustion chamber of 240 bar (see Figure-1). Figure-1. New bimetallic piston. Also the connecting rods have been redesigned. The H-beam design is substantially stronger and lighter than the T-shaped OEM equipment, allowing the engine to rev quicker and hold up to the demands of high boost applications. The new titanium alloy rods have a mass of 0.457 kg instead of the original 0.653 kg (Figure-2).