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LT-5/ZR-1 CYLINDER LINER AND PISTON/LINER ASSEMBLIES:

(These items are currently no longer available from General Motors.)


CONTENTS:

A.  Why Use OEM Cylinder Liner Replacements Vs. Aftermarket Liners?

B.  LT-5/ZR-1 Cylinder Liner Unit

C.  LT-5/ZR-1 Complete Piston and Cylinder Liner Assembly

D.  Break-In of OEM Liners With Aftermarket Pistons and Rings

E.  Break-In of OEM Piston and Nikasil Cylinder Liner Assemblies


A. Why Use OEM Cylinder Liner Replacements Vs. Aftermarket Liners?

The LT-5 /ZR-1 engine assembly is a "wet sleeve" engine.  This means the piston liner sleeves are exposed to the engine's internal lubricants and any contaminants which might ultimately build up in those lubricants (such as water and combustion by-products) .  Wet sleeve engine components are subject to an effect called "dissimiliar metal galvanic contact corrosion"  when different metallic components come into physical contact with each other in the presence of moisture, acids and other contaminates.  Essentially, very small electric currents can be generated which result in corrosive metal effects between different metals.

The LT-5/ZR-1 engine block is aluminum, and the OEM piston liners are made of forged aluminum coated with an extremely hard and durable Nikasil piston ring contact coating.  Since the liners in the LT-5/ZR-1 Engine are aluminum, the same material as the engine block, the possibility of galvanic corrosion effects are virtually eliminated. 

Most, if not all, currently available "aftermarket" LT-5/ZR-1 cylinder liners are made of cast iron or machined steel.  These alloys are subject to galvanic corrosion effects when placed in contact with the aluminum engine block and exposed to the internal fluids circulating in the engine.  Only if the aftermarket liner engine block contact surface is coated with an appropriate protective/isolation coating will the prospect for corrosive effects be minimized.  Unfortunately, increased bore sizing for the LT-5/ZR-1 engine can only be achieved using these aftermarket iron/steel sleeve assemblies.  Larger bore forged aluminum/Nikasil liners are not currently available.  When purchasing an aftermarket iron /steel liner, use only appropriately coated liners and use extreme care when installing the units to avoid damaging the protective coating.


B.  LT-5/ZR-1 Cylinder Liner Unit

1990-1995 OEM Mahle Forged Aluminum Nikasil Cylinder Liners.  These liners were never available separately from General Motors, and their production as part of the complete piston/liner assembly has been discontinued.  We have a limited number of these brand new cylinder liners available, priced individually and in sets of eight.  These liners may be used with OEM and aftermarket piston units.

1990-1995 OEM LT-5 Cylinder Liner (New):

       $135.00 Each, plus Shipping/Handling/Insurance

1990-1995 OEM LT-5 Cylinder Liner Eight-Piece Engine Set (New):

       $1000.00 Per Set of Eight Liners, plus Shipping/Handling/Insurance

Contact: Rueben Hanson at humagengroup@gmail.com for product purchase and payment options. This is a temporary clearing and distribution mailbox to be used while the security of our communications systems is being substantially improved.


C.  LT-5/ZR-1 Complete Piston and Cylinder Liner Assembly

1990-1992 OEM Mahle LT-5 Piston and Liner Assemblies.  These assemblies are no longer available from General Motors.  Original GM P/N 10146287.  These units are different from 1993-1995 assemblies in a number of design parameters.  The 1990-1992 assemblies must be "broken in", and the rings seated, using premium blend non-synthetic motor oil, as specified for the original engines which came in the cars from the factory.  Synthetic based motor oils may be used in the engine after the equivalent of approximately 12K-13K miles of use.

The Piston/Liner assemblies are available in either OEM factory production "A" or "B" specification.  An "A" or "B" is stamped on the top of the piston, near the edge.  Carbon deposits may need to be removed to see this designation.  Most engines were built using the "A" designation assemblies. See D and E below.

The Piston/Liner assembly includes the preassembled fitted piston with complete ring set installed in the forged aluminum Nikasil liner, wrist pin and wrist pin retainer circlips.

1990-1992 OEM LT-5 Piston/Liner Assembly (New):

       $235.00 Each, plus Shipping/Handling/Insurance

1990-1992 OEM LT-5 Piston/Liner Assembly Eight-Piece Engine Set (New):

       $1760.00 Per Set of Eight Assy's, plus Shipping/Handling/Insurance

Contact: rueben.hanson@humagen.com for product purchase and payment options.


D.  Break-In of OEM Liners With Aftermarket Pistons and Rings

The stock OEM forged aluminum piston liners may be used with non-OEM piston and ring assemblies.  However, if synthetic oil is used as an engine lubricant during break-in, ring assembiles which will seat properly against the hard Nikasil coating using a synthetic oil must be specified.  These ring assemblies typically exhibit higher tensions and use slightly different materials than rings designed to be used with non-synthetic oils.  The reason for the ring tension and material differences, is that synthetic oils typically have a much greater ability to protect against wear.  Combined with the extaordinary hardness of the Nikasil coating, this enhanced wear protection can prevent the necessary break-in for improperly spec'd rings to seat and seal properly in a reasonable amount of time.  1990-1992 LT-5 ring assemblies were designed to seat effectively using non-synthetic oils; 1993-1995 LT-5 ring assemblies were designed to seat effectively using synthetic lubricants.  The 1993-1995 OEM ring assemblies, and similarly spec'd aftermarket rings, will seat effectively regardless of the type of oil used during break-in. 

E.  Break-In of OEM Piston and Nikasil Cylinder Liner Assemblies

The piston/liner assembly will fit all LT-5 engines from 1990-1995.  However, it is strongly recommended if replacing any assemblies in 1993-1995 engines with one or more of the above units, all eight original units be replaced at the same time (The 1993-1995 assemblies are no longer available from General Motors, and no known volume supplier for the 1993-1995 OEM product is known to exist).  The piston rings in the 1993-1995 assemblies were designed to  "seat in" using synthetic oils (necessary when the factory switched to a single synthetic oil fill, Mobile 1, to be used for all the engines coming off the Corvette line starting in 1993); the piston rings in the 1990-1992 assemblies should be "seated" using premium blend non-synthetic oils or a non-synthetic/synthetic blend oil for best results.  After the "break-in period" of approximately 12K-13K miles, synthetic lubricants may be used exclusively.  Some newer synthetic oils may provide similar ring seating characteristics as premium blend non-synthetic oils.