What are the differences? I've heard the only difference is the new ZZ4 has a forged crank while the old ZZ4 had the nodular iron crank. Are the rods and pistons still the same (powdered metal rods and hypereutectic pistons)? What about the old ZZ3 motor?

Thanks,
Stephen

------------------
1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

 

To my knowledge, the ZZ4 always had a forged crank. The ZZZ-ZZ3 all had forged cranks. However the crank in the current ZZ4 is balanced to connecting rods (PN 10108688) and piston (PN 10159436).

Hope this helps a little,

Jason

 

yes the newer zz-4 engines have a forged steel crank in them but other than that I don't think they have changed anything.

 

The ZZ3 did not have hypereutectic pistons or PM rods. The drain plug was SAE, went to metric with the ZZ4.

Block, cam, heads, intake, etc., all the same.

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4, 2300 stall TC. Ported World 305 heads, Crane PowerMax 2050 cam. ZZ3/4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster 80. 2.93 limited slip. Spohn SFCs waiting to be installed. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
57 Bel Air, my 1st car. '66 396, 9.7:1 forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 700 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).