Anniversary 427 install questions
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Instructor
Joined: Feb 2006
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Anniversary 427 install questions
We got our Anniversary 427 Aluminum installed and running last week. To baseline it, I wanted to see if any of you guys had done this swap and more specifically if anyone dyno'd theirs. I have some initial numbers with little run time on the engine.(approx 3hrs)
Looking to see something to compare by. I think it's a little low at 338hp to the tires. The GM Performance rep that I spoke with told me that the engineering department wouldn't proceed with a "claim" unless the engine had 5000mi or the appropriate run time on it. We're just concerned that 40-60hp won't magically show up during the remainder of the break-in time. Any real evidence is appreciated.
Looking to see something to compare by. I think it's a little low at 338hp to the tires. The GM Performance rep that I spoke with told me that the engineering department wouldn't proceed with a "claim" unless the engine had 5000mi or the appropriate run time on it. We're just concerned that 40-60hp won't magically show up during the remainder of the break-in time. Any real evidence is appreciated.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I had to look this up to comment. Yes, a broke in motor will gain some HP. Not a lot. I haven't run a dyno comparison to give you a number.
I don't follow your figures? 338 RWHP could be right up around the claimed 430 hp due to power losses of auto tranny. You hear all kinds of loss figures comparing crank hp to RWHP. Lets just call it 15% for a manual tranny and 20% for an auto.
This motor is a very mild, no frills, low compression, low valve lift. Lets say that it makes 440 crank when broke in. Minus 15% That give you something like 374 RWHP possible. Poor timing and tune will drop this number down. Restrictive exhaust??????
This is not a hot rod like the modern Vette LS7 with 505 HP.
Based on an exotic aluminum block, the ZL1 offered only the best components from the L88 engine including a high compression piston, high flow aluminum heads and intake, and a bombproof bottom end. To celebrate the 50th anniversary of the Chevrolet big-block, GM Performance Parts has brought back a modern version of the ZL1 for your chance to relive musclecar history. The Anniversary Edition 427 starts with the ZL1 aluminum block using the tooling that helped create this legend in 1969. The block offers a full-strength structure, thick deck surfaces and 4-bolt mains. Building on that foundation, the short block contains a forged steel crank, forged steel rods, and forged aluminum pistons for a 10.1:1 final compression ratio. Aluminum oval-port heads and matching high-flow aluminum oval-port intake are paired with an 870-cfm carburetor. The camshaft is a hydraulic roller with valve lift numbers of .510" on the intake and .540" on the exhaust. We even added 1.7:1 aluminum roller rockers. Like the original ZL1, the Anniversary 427 comes grossly underrated at 430 horsepower. Once you purchase an Anniversary 427 big-block crate engine, you enter a very exclusive club because only 427 of these engines will ever be produced. A special owner's kit includes official Anniversary 427 emblems to place on your car, as well as an engine data plaque and certificate of authenticity that share a matching serial number with the valve covers. Only 427 of these crate engines will ever be produced, and then the ZL1 tooling will be retired forever.
I don't follow your figures? 338 RWHP could be right up around the claimed 430 hp due to power losses of auto tranny. You hear all kinds of loss figures comparing crank hp to RWHP. Lets just call it 15% for a manual tranny and 20% for an auto.
This motor is a very mild, no frills, low compression, low valve lift. Lets say that it makes 440 crank when broke in. Minus 15% That give you something like 374 RWHP possible. Poor timing and tune will drop this number down. Restrictive exhaust??????
This is not a hot rod like the modern Vette LS7 with 505 HP.
Based on an exotic aluminum block, the ZL1 offered only the best components from the L88 engine including a high compression piston, high flow aluminum heads and intake, and a bombproof bottom end. To celebrate the 50th anniversary of the Chevrolet big-block, GM Performance Parts has brought back a modern version of the ZL1 for your chance to relive musclecar history. The Anniversary Edition 427 starts with the ZL1 aluminum block using the tooling that helped create this legend in 1969. The block offers a full-strength structure, thick deck surfaces and 4-bolt mains. Building on that foundation, the short block contains a forged steel crank, forged steel rods, and forged aluminum pistons for a 10.1:1 final compression ratio. Aluminum oval-port heads and matching high-flow aluminum oval-port intake are paired with an 870-cfm carburetor. The camshaft is a hydraulic roller with valve lift numbers of .510" on the intake and .540" on the exhaust. We even added 1.7:1 aluminum roller rockers. Like the original ZL1, the Anniversary 427 comes grossly underrated at 430 horsepower. Once you purchase an Anniversary 427 big-block crate engine, you enter a very exclusive club because only 427 of these engines will ever be produced. A special owner's kit includes official Anniversary 427 emblems to place on your car, as well as an engine data plaque and certificate of authenticity that share a matching serial number with the valve covers. Only 427 of these crate engines will ever be produced, and then the ZL1 tooling will be retired forever.
Thread Starter
Instructor
Joined: Feb 2006
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It's a 4 speed car, the plugs look good and we've went up and back down with the timing. The first pull netted 300 at the tires. I realize it's not as good of a platform and don't know of any pump gas big blocks that impress me with old school heads and no turbo. This is my dad's car and he gave up on the whole hotrodding process 25 or so years ago. This was the first thing he has done an engine swap in a very long time. I just don't want him to be disappointed with it. It is under-performing at this point and we have realistic expectations. I initially said 380rw and had my fingers crossed that it would be higher. GMPP even said it should be around 400 or maybe a tad over at the tires.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
It would take 450 - 475 crank hp to make 380 - 400 RWHP I just don't think that this was the intended outcome of these 427 motors.
But let's look at the happy side. light weight, looks great, and if it comes up 20 hp at breakin those 427 ci put out nice TQ figures and it wiil be fun to drive.
But let's look at the happy side. light weight, looks great, and if it comes up 20 hp at breakin those 427 ci put out nice TQ figures and it wiil be fun to drive.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
We got our Anniversary 427 Aluminum installed and running last week. To baseline it, I wanted to see if any of you guys had done this swap and more specifically if anyone dyno'd theirs. I have some initial numbers with little run time on the engine.(approx 3hrs)
Looking to see something to compare by. I think it's a little low at 338hp to the tires. The GM Performance rep that I spoke with told me that the engineering department wouldn't proceed with a "claim" unless the engine had 5000mi or the appropriate run time on it. We're just concerned that 40-60hp won't magically show up during the remainder of the break-in time. Any real evidence is appreciated.
Looking to see something to compare by. I think it's a little low at 338hp to the tires. The GM Performance rep that I spoke with told me that the engineering department wouldn't proceed with a "claim" unless the engine had 5000mi or the appropriate run time on it. We're just concerned that 40-60hp won't magically show up during the remainder of the break-in time. Any real evidence is appreciated.
Thread Starter
Instructor
Joined: Feb 2006
Posts: 113
Likes: 0
It would take 450 - 475 crank hp to make 380 - 400 RWHP I just don't think that this was the intended outcome of these 427 motors.
But let's look at the happy side. light weight, looks great, and if it comes up 20 hp at breakin those 427 ci put out nice TQ figures and it wiil be fun to drive.
But let's look at the happy side. light weight, looks great, and if it comes up 20 hp at breakin those 427 ci put out nice TQ figures and it wiil be fun to drive.
What driveline % loss do you have in mind? 20%? It's a manual transmission.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
475 X .15 = 71.25 slightly over 400 RWHP
450 x .15 = 67.5 slightly over 380 RWHP
Kind of like asking you what carb size? When I already posted the GM quoted engine specs of 870 carb. Or where you said that the dyno people tried different timing and when they found the best timing the power came up from 300 to 338. It is amazing to me how little people listen or comprehend when you tell them something.
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Racer
Joined: May 2008
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I recall reading, once upon a time, that this "grossly underrated" claim was really just urban folklore. What raises my eyebrows here are the cylinder heads: Your description says these use oval ports. IIRC, ZL1s used big rectangle port heads. That, and as already noted, the compression ratio is way down from the original ZL1, which was not (and is not) really a streetable motor. I don't think it's fair to assume this motor will necessarily perform even as well as the original. The roller cam is a nice update, but the rest of the package may very well not make up for it. I wouldn't be surprised if those RWHP numbers are about right for an automatic.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Part of the problem on getting an answer is that only 427 of these motors are going to be built and at the @ $25,000 price tag it is not something the general population of hot rodders would even invest in.
The ZZ427 with 480 hp is 1/2 the price for a 200# maybe weight penalty. It specs with a bigger H-roller cam and maybe bigger aluminum heads.
I was maybe even low balling the 15% drive train loss.
IMO - you bought a very nice low production motor not made for performance. Maybe call them up and say you got duped and get one of the many higher hp crate motors. But these rare motors are just bought by so few people that it would be hard to get a comparison.
Intermediate
Joined: Dec 2020
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Block Casting Numbers
I know this is a very old post but Does anyone know the block casting number range for the anniversary 427? I am looking at buying one but the seller has no proof its a anniversary 427. The casting number is 3946058.
