Crate engine specs
Race Director
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From: Science Bitch! Mississauga, Ontario
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Le Mans Master
Joined: Oct 2007
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From: Tennessee/Rhode Island
A crate ZZ4 engine probably has around 290-300 NET HP, at best. As an example, the 71 LT-1 rated at 330 Gross HP in 1971, was rated at 255 Net HP in 1972-same exact motor with the 2 different rating systems.
Instructor
Joined: Dec 2007
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From: Crystal Lake IL
Instructor
Joined: Dec 2007
Posts: 184
Likes: 0
From: Crystal Lake IL
Crate engines like the ZZ4, not originally installed in a GM vehicle, like the crate engined LS7, are rated at GROSS HP/TORQUE, NOT NET HP, like production engines today.
A crate ZZ4 engine probably has around 290-300 NET HP, at best. As an example, the 71 LT-1 rated at 330 Gross HP in 1971, was rated at 255 Net HP in 1972-same exact motor with the 2 different rating systems.
A crate ZZ4 engine probably has around 290-300 NET HP, at best. As an example, the 71 LT-1 rated at 330 Gross HP in 1971, was rated at 255 Net HP in 1972-same exact motor with the 2 different rating systems.
Safety Car
Joined: Oct 2004
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From: Youngstown Ohio
The crate is rated net, the same as if installed in a Vette with accessories. If it was rated the same as dyno musclecar engines (gross HP, as we are used to seeing), it would be higher...perhaps 530 HP or so.
Le Mans Master
Joined: Oct 2007
Posts: 7,441
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From: Tennessee/Rhode Island
The point of the discussion to make folks aware that taking a ZZ4 crate engine and installing it in a C3 does not result in an instant 355HP like say a C5 corvette with 350 NET HP from the factory. They are different! Like I stated before a ZZ4 at best is probably producing around 290-300 Net HP in today's terms like today's production cars. just an FYI.
Instructor
Joined: Dec 2007
Posts: 184
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From: Crystal Lake IL
As already stated, since the LS7 was installed in a production car, the Z06, it is rated at the NET HP rating as all production cars are, as a crate motor. Any crate motor NOT installed in a production vehicle is rated at GROSS HP, not NET. Most crate motors are rated at Gross HP since they were never installed in a production GM vehicle-a 383 for example. Hope that helps!
The point of the discussion to make folks aware that taking a ZZ4 crate engine and installing it in a C3 does not result in an instant 355HP like say a C5 corvette with 350 NET HP from the factory. They are different! Like I stated before a ZZ4 at best is probably producing around 290-300 Net HP in today's terms like today's production cars. just an FYI.
The point of the discussion to make folks aware that taking a ZZ4 crate engine and installing it in a C3 does not result in an instant 355HP like say a C5 corvette with 350 NET HP from the factory. They are different! Like I stated before a ZZ4 at best is probably producing around 290-300 Net HP in today's terms like today's production cars. just an FYI.
Le Mans Master
Joined: Jan 2000
Posts: 8,721
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From: Canada
As already stated, since the LS7 was installed in a production car, the Z06, it is rated at the NET HP rating as all production cars are, as a crate motor. Any crate motor NOT installed in a production vehicle is rated at GROSS HP, not NET. Most crate motors are rated at Gross HP since they were never installed in a production GM vehicle-a 383 for example. Hope that helps!
The point of the discussion to make folks aware that taking a ZZ4 crate engine and installing it in a C3 does not result in an instant 355HP like say a C5 corvette with 350 NET HP from the factory. They are different! Like I stated before a ZZ4 at best is probably producing around 290-300 Net HP in today's terms like today's production cars. just an FYI.
The point of the discussion to make folks aware that taking a ZZ4 crate engine and installing it in a C3 does not result in an instant 355HP like say a C5 corvette with 350 NET HP from the factory. They are different! Like I stated before a ZZ4 at best is probably producing around 290-300 Net HP in today's terms like today's production cars. just an FYI.
and well put! This helps explain why so many vintage GM owners (not just vettes) have gone with the Ls swaps. They are very good bang for the buck these days.
Safety Car
Joined: Jan 2009
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From: New York
Technical Notes: GM Crate Engines are horsepower rated to SAE Standards.
HP ratings are at the crank.
The SAE standards eliminated "Gross" hp results years and years ago and mandated "Net" hp. You can not use an example from 1971 to explain hp ratings of today's testing requirements.
Now lets go further , because it is made as a drop in anything pre 1985 a zz4 if configured as GM has it on the dyno with the same headers , carb and accessories it will produce the advertised power pretty closely.
Add to that the many many people who have actually run there ZZ4 on a dyno who can show a drive train loss of 15 to 20% over advertised and it pretty well confirms GM ratings as accurate.
From all my searches I have to say 355/405 at crank is an accurate HP rating not inflated by "Gross" testing standards of the long ago past.
HP ratings are at the crank.
The SAE standards eliminated "Gross" hp results years and years ago and mandated "Net" hp. You can not use an example from 1971 to explain hp ratings of today's testing requirements.
Now lets go further , because it is made as a drop in anything pre 1985 a zz4 if configured as GM has it on the dyno with the same headers , carb and accessories it will produce the advertised power pretty closely.
Add to that the many many people who have actually run there ZZ4 on a dyno who can show a drive train loss of 15 to 20% over advertised and it pretty well confirms GM ratings as accurate.
From all my searches I have to say 355/405 at crank is an accurate HP rating not inflated by "Gross" testing standards of the long ago past.