Twin Turbo Myths [Archive] - Subaru Legacy International
EJ swap ECU question Third Generation Legacy ( - ). Since the two turbo's meet up at the intercooler. . rueben i may need your help with this motor swap so dont lose you internet anytime soon!. Find For Swap in Auto Parts & Tires | Find parts & accessories for sale in Ontario. Fix up a RAM, JDM SUBARU LEGACY GT-B EJ 2STAGE TWIN TURBO SWAP S10 Auto Parts - Can deliver in/near Barrie Swap Meet Friday.
Two small turbos can be better than one 'equivalent' if they provide sufficient boost and they are connected to the cylinders such that the exhaust pulses are evenly spaced.
A twin-scroll single turbo approximates 2 separate turbos wrt exhaust pulse splitting while giving greater boost due to the larger compressor. A twin-scroll has a single turbine wheel but 2 volutes inside the turbine housing.
EJ swap ECU question - Subaru Legacy Forums
Unfortunately the banked arrangement of the turbos on the H4 means that when the turbos are working together in secondary mode, effectively in parallel, each turbo sees 2 exhaust pulses close together partially overlapping followed by a long gap and is not optimal.
The Syms headers that GTauto nearly bought were designed for proper pulse phasing in a full-time parallel operation. Having said all that our turbos are still short of boost regardless of the finer points of pulse phasing.
My first thought was to swap exhaust housings, in effect making the low RPM turbo the main one and letting the smaller one supplement it at high RPM.
That ought to shift the boost threshold up but also narrow the VOD. You wouldn't get more peak power but even on a 2.
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An EJ would be horribly strangled with the 2L twin-turbo setup. You'd have the power curve of a turbo-diesel without the economy. I'm sure the VOD can be reduced but you have to accept that Subaru tried to optimise it for years with many changes of turbos etc and eventually ditched it, so its not going to be an easy fix. This eliminates the clearance that was available between the piston at TDC and the fully opened valve.
Piston pin offset has been changed to 0.
Subaru EJ engine
Piston to cylinder wall clearance has been reduced by increasing the piston diameter. Another source of high engine friction is the valve train. Hydraulic lash adjusters HLAs are always in contact with the valves. The hydraulic pressure of the lash adjuster must be overcome during operation and during the most critical time of engine start.
To overcome this situation and to contribute to the total reduction of friction loss, and later SOHC engines have solid valve adjusters. SOHC engines now use an adjustment screw to adjust valve clearance. Engines with the earlier HLA are recommended to use 10W30 or 10W40 oil year-round; 5W30 can be used at very low winter temperatures.
The roller rocker cam follower system that was introduced on the Impreza engines, is installed on all model year and later engines. The roller assemblies are not serviceable separately, but the rocker arms may be serviced as individual units.
The carbon composition head gaskets with integrated o-rings are interchangeable from left to right on to NA engines only. Other Engine Modifications The intake manifold has been reshaped to increase the airflow mass and speed, contributing to improved low and mid engine speed operation. Components located on the intake manifold have been relocated as compared to the models. All engine for are the Phase 2 design. Changes in the Phase 2 engines are as follows: Additional Phase 2 Engine Features: