[slh0616]

I know from talking to an old Porsche and GTR mechanic that some of the engines in those cars are "hotter" than others. Apparently some stock C2S 997 Porsche engines have wildly variable horsepower numbers.

Is this something to look out for in the LT4? I know it is a mass produced engine (unlike the Nissans GTR hand-built motor) but since there is so much power in this small block will one ZL1 or Z06 make more power (stock) than another?

Thanks for the comments!

[SJFGTO]

The idea of a “factory freak” is an urban legend...I can hear all the “yeah but” comments already. The materials, specifications and manufacturing process are so precise, there is minimal room for variation, absent the random defects that can occasionally occur. Safety, emissions compliance, cost of warranty claims etc demand minimal variation from standard.

[19Nasty1le]

I was told the LT4 are hand built in Kentucky at the Corvette plant and then sent out from there.

[Sakudog]

My car has had two motors, the GM warranty replacement motor is making exactly the same power as the original motor. I will say many LT4 cars come with air in the supercharger system from a bad factory bleed. Everyone should bleed this system when they get their car, it is very easy to do. When I got the car back from GM and took it out, it was 9 mph off its typical top speeds at my local track. After bleeding the system, it was back to the exact same speeds. Food for thought.

[SFV1LE]

Peak power will generally have a maximum that engines in good condition will all achieve under similar conditions--same octane, altitude, ambient air temp, AIT, engine temp, etc.

It is common for engines to under-perform due to issues like bad ring sealing leading to excessive blow-by, low compression, cylinder leak-down (poor sealing valves, rings, or head gasket). There are many other potential issues like carbon buildup on pistons causing hot spots and knock, supercharger issues, boost leak, etc. Any of this type of stuff can result in lower power than the average LT4.

[drfeelgood]

The Gen 6 ZL1 was ordained by God, and he doesn't make mistakes. Thus, every LT4 will be the exact same and produce the same power

[bobby35ny]

Originally Posted by Sakudog

My car has had two motors, the GM warranty replacement motor is making exactly the same power as the original motor. I will say many LT4 cars come with air in the supercharger system from a bad factory bleed. Everyone should bleed this system when they get their car, it is very easy to do. When I got the car back from GM and took it out, it was 9 mph off its typical top speeds at my local track. After bleeding the system, it was back to the exact same speeds. Food for thought.

We don't need a special tool for that?

[rlarsen462]

Originally Posted by Sakudog

My car has had two motors, the GM warranty replacement motor is making exactly the same power as the original motor. I will say many LT4 cars come with air in the supercharger system from a bad factory bleed. Everyone should bleed this system when they get their car, it is very easy to do. When I got the car back from GM and took it out, it was 9 mph off its typical top speeds at my local track. After bleeding the system, it was back to the exact same speeds. Food for thought.

Do you have a link to this process? I will definitely check that out.

[Stealth7]

GM OEM SAE-certified Power; I believe it is a standard feature from GM now.

As noted above, modern mfg. tolerances are very precise.

[Stephen12ZL1]

the hp differences are mostly from variables like octane and IAT2. The factory IC circuit is a POS and really needs a reservoir. An aftermarket reservoir is hardly a "mod" but a necessary addition for any tracked ZL1. Bleeding the system isn't perfect unless the system is purged using the factory procedure which uses a vacuum.