Gen IV block question
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02-07-2011, 08:38 AM
#2
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You can take a standard production 396/427/454 and bore/stroke it to get 500 CI. But it is not the same block as say a 502 production block.
As for the newer 8.1L 496 merc/gm engines, I dont believe they based off either the 454 or 502 block. I think they are their own breed so to speak. I Could be wrong on that.
What is it you are trying to do?
As for the newer 8.1L 496 merc/gm engines, I dont believe they based off either the 454 or 502 block. I think they are their own breed so to speak. I Could be wrong on that.
What is it you are trying to do?
02-07-2011, 11:38 AM
#3
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Yea, some people are confused on all the CI numbers out there. To answer your question NO the blocks are different. A 502 is a bigger bore than a 454. You can bore and stroke either engine and make them bigger. A 454 can be made into either a 489 .030 over pistions and 4.25 stroke or 496 with .060 over pistons and 4.25 stroke.
But the newer 496 Big Blocks are completely different.
But the newer 496 Big Blocks are completely different.
02-08-2011, 11:39 PM
#4
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Chevy Mystery motor and the 8.1
These are two different GM engine family lines you are discussing.
The "Mystery Motor" as it was first called made its debut at NASCAR in 1965 and was a unique engine design that started at 396 CI and went to 427 CI then 454 CI then 502 CI. This motor included hemi type valve layout and wedge shaped combustion chamber in a way that was never tried before. ?They called it the Chevy "porcupine" engine. This high power engine was made in a complete aluminum form in the 1960's model L-88. Corvette versions featured tripple two barrel Holley Carburators and made 425 hp.
Later bigger Chevy cars needed more power so the engine went to 454 CI. The 502 CI version was not used in passenger cars but was developed for street racing and Marine use. All of these high performance versions used the big Holley four barrel while most common versions used Rochester Quadra Jet carburator. Late Mercury models used Carter Aluminum Four Barrel carb made by Webber in Italy.
Mercury bought into the GM engine line after flirtation with Ford and used the Mystery Motor first in 427 CI and later as 454 CI. They all made around 310 horsepower or 380 horsepower depending on the camshaft and were basically unchanged from the 1980's through 2002.
In the late 1990's younger GM engineers realized that a few new ideas could be incorporated into the aging engine design and with the advent of computer aided design created a completely new engine line to replace the old Mystery Motor. This is the 8.1 V-8 also called the 496. The 496 engine had better water flow internally and also changed to crankshaft triggerd ignition advanced computor and fuel injection. It was mostly used in pickup trucks, high performance and marine applications. It is a shame they did not develop it with overhead camshafts because the changes they made really did not merit a completely new engine product line. Yes the new engine was slightly more powerful but did not have the long history and development which the Mystery Motor had. Like many things GM was doing at the time it was simply excessive.
In 2008 when GM was in crisis they dropped all production of the big V-8 engines and Mercury Marine had to find another engine suppler. They decided to build the GM 502 Mystery Motor themselves in house and so the new 8.1 (496 CI) went the way of all things. It was a very short lived albeit slightly better engine design.
DART and other companies are producing new carburator and distributor setups for the 8.1 496 as I am sure the first thing that will be unavailable is the complex computer, ignition and fuel injection setups which are no longer being made. If you take away the fuel injection and crank triggered ignition from the 8.1 what do you have but a retro 502 and not a good copy at that. Go figure.
The "Mystery Motor" as it was first called made its debut at NASCAR in 1965 and was a unique engine design that started at 396 CI and went to 427 CI then 454 CI then 502 CI. This motor included hemi type valve layout and wedge shaped combustion chamber in a way that was never tried before. ?They called it the Chevy "porcupine" engine. This high power engine was made in a complete aluminum form in the 1960's model L-88. Corvette versions featured tripple two barrel Holley Carburators and made 425 hp.
Later bigger Chevy cars needed more power so the engine went to 454 CI. The 502 CI version was not used in passenger cars but was developed for street racing and Marine use. All of these high performance versions used the big Holley four barrel while most common versions used Rochester Quadra Jet carburator. Late Mercury models used Carter Aluminum Four Barrel carb made by Webber in Italy.
Mercury bought into the GM engine line after flirtation with Ford and used the Mystery Motor first in 427 CI and later as 454 CI. They all made around 310 horsepower or 380 horsepower depending on the camshaft and were basically unchanged from the 1980's through 2002.
In the late 1990's younger GM engineers realized that a few new ideas could be incorporated into the aging engine design and with the advent of computer aided design created a completely new engine line to replace the old Mystery Motor. This is the 8.1 V-8 also called the 496. The 496 engine had better water flow internally and also changed to crankshaft triggerd ignition advanced computor and fuel injection. It was mostly used in pickup trucks, high performance and marine applications. It is a shame they did not develop it with overhead camshafts because the changes they made really did not merit a completely new engine product line. Yes the new engine was slightly more powerful but did not have the long history and development which the Mystery Motor had. Like many things GM was doing at the time it was simply excessive.
In 2008 when GM was in crisis they dropped all production of the big V-8 engines and Mercury Marine had to find another engine suppler. They decided to build the GM 502 Mystery Motor themselves in house and so the new 8.1 (496 CI) went the way of all things. It was a very short lived albeit slightly better engine design.
DART and other companies are producing new carburator and distributor setups for the 8.1 496 as I am sure the first thing that will be unavailable is the complex computer, ignition and fuel injection setups which are no longer being made. If you take away the fuel injection and crank triggered ignition from the 8.1 what do you have but a retro 502 and not a good copy at that. Go figure.
02-09-2011, 01:00 AM
#5
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These are two different GM engine family lines you are discussing.
This high power engine was made in a complete aluminum form in the 1960's model L-88. Corvette versions featured tripple two barrel Holley Carburators and made 425 hp.
Mercury bought into the GM engine line after flirtation with Ford and used the Mystery Motor first in 427 CI and later as 454 CI. They all made around 310 horsepower or 380 horsepower depending on the camshaft and were basically unchanged from the 1980's through 2002.
.
This high power engine was made in a complete aluminum form in the 1960's model L-88. Corvette versions featured tripple two barrel Holley Carburators and made 425 hp.
Mercury bought into the GM engine line after flirtation with Ford and used the Mystery Motor first in 427 CI and later as 454 CI. They all made around 310 horsepower or 380 horsepower depending on the camshaft and were basically unchanged from the 1980's through 2002.
.
Mid 80's Mercury had the "Cyclone Series", 400, 440, 460 hp versions of the big block. The 460 was a 1/4" stroker making it 482 cu. in.'s.
'91 ended the Mark lV and the new model Gen V started being produced.
