G2: DIY: Engine Swaps: C35 Swap

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3.5 Engine Block Differences

Block & Displacement Increase

The biggest reason to upgrade to the 3.5RL motor is, of course, for the increased displacement of 3.5 litres (from 3.2 litres). This increase is from a 7mm longer piston stroke from 84mm to 91mm making the block slightly under-square for low end torque improvement. The same cylinder bore of 90mm was used. Aluminum block casting with cast iron cylinder liners and 6 bolt mains. To compensate for the increase stroke the height of the block deck was raised ??? mm.

Forged Crankshaft

The crankshaft is made of forged steel for bullet proof reliability. Larger main bearing journal supports are used. Journals are micro-finished. The bearing surfaces use a pyramidal structure for better oil retention, durability and lower friction. Stroke increased to 91mm.

Forged Connecting Rods

A special block forging method is used for precisely measured and balanced connecting rods.

Full Floating Piston Pins

For engine noise reduction, full floating pins are used. Tolerances between the piston and pin were tightened.

Balance Shaft

A rotating balance shaft helps to dampen vibrations inherent to 90 degree V6 motors. The balance shaft, mounted on the passenger's side of the block, is driven by a separate toothed belt and tensioner mounted directly in front of the timing belt. It is theorized that the balance shaft also helps reduce the engine harmonics that cause the well-known head gasket failures with the 3.2 block.

Dished Pistons

Dished Piston Comparison - 3.2 Left, 3.5 Right

Since the combustion chamber size (in the head) is the same, and the stroke increased, dished pistons are used to maintain the same compression ratio of 9.6:1.

Oil Pump

The engine oil pump casting is different; the area where the engine oil cooler is on the 3.2 is now occupied by the balance shaft drive and belt.

Water Pump

The water pump no longer has the two auxiliary outlets for the differential cooler or engine oil cooler. This area is occupied by the balance shaft drive belt and is now covered by a larger lower timing cover.

Timing Belt and Pulleys

Cam Gear Comparison 3.2 Left, 3.5 Right

The 3.5 uses a thinner timing belt to make room for the balance shaft and also for quieter running. The cam pulleys, crank pulley, tensioner and water pump pulley were also made thinner. The timing belt is also 1 tooth longer than the 3.2's due to the increased deck height.

Cylinder Head Differences


Head Casting Comparison

To compensate for the taller deck surface, the location of the intake runners was changed so that the same size and mounting points of the 3.2's intake manifold could still be used


Camshaft Comparison - 3.5 Left, 3.2 Right

The 3.5 has a lower overlap, "mild cam" which helps to increase low end torque production. Valve overlap is the amount of time (in degrees) the intake and exhaust valves are open at the same time at TDC. The higher overlap cam found in the type II permits better breathing at high RPM sacrificing low end torque production. The mounting journals are the same, so type I or type II 3.2 cams can be used in a 3.5 head.

Rocker Arm Assemblies

Rocker Arm Assembly Comparison - 3.5 Top, 3.2 Bottom

The 3.5 continues to use hydraulic lifters in the rocker arm assembly. Unfortunately, two center solid supports were eliminated in the rocker assembly (as well as the mounting points in the head) and replaced with retaining springs. This design downgrade was most likely due to the lower redline of 3.5 at 5900rpm. Some sort of solid spacers should not be difficult to machine.


The intake and exhaust valves are the same size and part number as used in the Type I Legend. The Type II used a 1mm larger intake valve.

Engine Mounts

The motor mount system used on the 3.5RL is different from the Legend.

Mid Mounts

The RL utilized a different location of the mid mounts, moving them from the 3.2's transmission bell housing to the rear of the 3.5's engine block. These mid mounts were computer controlled. At idle, the 3.5's engine computer activated a fluid bypass solenoid for increased damping and a smoother idle. Fortunately, the mounting locations for these mounts are not used and do not interfere with the legend swap.

Front Mount

Front Mount Comparison - 3.2 Left, 3.5 Right
Custom Fabricated Hybrid Mount Front View
Custom Fabricated Hybrid Mount Side View

The 3.5 front motor mount brackets or "legs", are angled and oriented in a completely incompatible way. Fortunately, the driver's side 3.2 Legend motor mount bracket bolts directly to 3.5 block. The passenger side bracket, on the other hand, is the major issue and it will not bolt up. A specially fabricated "Hybrid" mount needs to be constructed. This is due to the balance shaft occupying the area where the mount was before.

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