3.5 Motor Swap DIY and Info

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-==3.5 Engine Block Differences(from 3.2)==+==3.5 Engine Block Differences==
[[Image:Piston_Compare.jpg|150px|thumb|right|Dished Piston Comparison - 3.2 Left, 3.5 Right]] [[Image:Piston_Compare.jpg|150px|thumb|right|Dished Piston Comparison - 3.2 Left, 3.5 Right]]
 +[[Image:Cam_Gear_Comparison.jpg|150px|thumb|right|Cam Gear Comparison Showing Wider 3.5 Cam Gear and Timing Belt- 3.2 Left, 3.5 Right]]
====Block & Displacement Increase==== ====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 undersquare 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. 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 undersquare 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.
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====Water Pump==== ====Water Pump====
The water pump no longer has the two auxillary 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. The water pump no longer has the two auxillary 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 Pullies====
 +The 3.5 uses a wider timing belt for increased durability and longevity. It also helps to reduce noise. The cam pulleys, crank pulley, tensioner and water pump pulley were also made wider. The timing belt is 1 tooth longer than the 3.2's due to the increased deck height.

Revision as of 00:56, 24 May 2007

Contents

3.5 Engine Block Differences

Dished Piston Comparison - 3.2 Left, 3.5 Right
Enlarge
Dished Piston Comparison - 3.2 Left, 3.5 Right
Cam Gear Comparison Showing Wider 3.5 Cam Gear and Timing Belt- 3.2 Left, 3.5 Right
Enlarge
Cam Gear Comparison Showing Wider 3.5 Cam Gear and Timing Belt- 3.2 Left, 3.5 Right

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 undersquare 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 microfinished. 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 damp 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 headgasket failures with the 3.2 block.

Dished Pistons

Since the combustion chamber size (in the head) are 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 auxillary 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 Pullies

The 3.5 uses a wider timing belt for increased durability and longevity. It also helps to reduce noise. The cam pulleys, crank pulley, tensioner and water pump pulley were also made wider. The timing belt is 1 tooth longer than the 3.2's due to the increased deck height.


Cylinder Head Differences

Head Casting Comparison
Enlarge
Head Casting Comparison
Camshaft Comparison - 3.5 Left, 3.2 Right
Enlarge
Camshaft Comparison - 3.5 Left, 3.2 Right
Rocker Arm Assembly Comparison - 3.5 Top, 3.2 Bottom
Enlarge
Rocker Arm Assembly Comparison - 3.5 Top, 3.2 Bottom

Casting

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

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

The 3.5 continues to use hydraulic lifters in the rocker arm assembly. Unfortunetly, 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.

Valves

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 completly different from the Legend.

Mid Mounts

The RL utilized a different location of the mid mounts, moving them from the 3.2's transmission bellhousing 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. Fortunetly, the mounting locations for these mounts are not used and do not interfere with the legend swap.

Front Mount

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

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