Part #: PH 12700
Gasket: DSF 82LE
Air Con: Yes
Primary Pipe: 1⅝" (41mm)
Oxy Sen: N/A
Secondary Pipe: 2" (51mm)
Outlet: 2½" (63mm)
Y Branch: N/A
Fitting Time: 1½ Hrs
For over a quarter of a century, Pacemaker has been innovating, designing and manufacturing some of the highest quality exhaust headers in Australia.
What is the difference between a TRI-Y and a 4-into-1 design? A 4-into-1 design is perhaps the most traditional design. This design is common to the US market and is well used within the drag race fraternity. The basic principle behind the design is that the scavenging effect within the collector cone effects the three remaining pipes (in a V8 half), instead of limiting the pulse to the very next pipe in the sequence. This generally results in a header that performs very well in the mid-range to top end of the engines performance.
A TRI-Y on the other hand splits the firing order evenly and uses the secondary pipes as sequential collectors. This results in generally a greater scavenging effect due to the fact that scavenging is achieved at 2 different points in the header design, firstly at the primary to the secondary collector and secondly to the secondary outlet collector. Generally, this improves torque in the lower to mid-range performance of the engine.
Both designs are usually more efficient than a standard manifold and both offer distinctly different advantages.
What is scavenging? Scavenging is one of the most critical parts to a design of a header. The tubes volume (diameter and length) is chosen to represent a discharge of spent fuel or pulse being discharged from the engine at a given rev range (usually mid to top end), without competing with the next charge. This pulse then enters the collector cone with a greater volume than the surrounding connected pipe(s). This creates a low pressure (or vacuum) at the exit of the next pipe. This vacuum then, in turn, sucks at the next pulse traveling through the next pipe in the sequence, vacuuming or scavenging the cylinder bore clean. This aids towards an unpolluted cylinder bore, ready for the next clean dose of air fuel mixture.
· Place anti zapper across battery terminals
· Disconnect air intake from throttle body & remove air cleaner canister lid and filter
for easy access
· Remove engine pipe back to flange connection (100 series exhaust system cannot be removed with out being cut)
· Remove exhaust manifold
· Undo solitary bolt holding solid heater line to block (this can now swivel a little to
allow easy placement of header)
· Now is the time to check & repair or replace any broken studs
*Important if you are working on a 100 series Landcruiser, place base into
engine bay from the top, before headers are fitted. Base may not be able to be
fitted from underneath
· Place sealant onto gasket & slide onto studs
· Place rear half of header onto studs & replace all nuts (do not tighten yet)
· Replace heater line to original position & bolt up tight
· Place front half of header onto studs & replace all nuts (do not tighten yet)
· Using sealant & gaskets, connect base to headers & bolt up tight
· Return to top of vehicle & bolt up headers to tight
· Reconnect to original exhaust 75 & 80 series only. (For 80 series see Fig 1)
· Reconnect remaining air induction devices
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