496/8.1 Performance handbook
01-16-2020, 09:58 AM
#1
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Thread Starter
496/8.1 Performance handbook
I'm in the process of building up a forged internals 496HO with a Whipple. I've spent days scouring OSO etc to find out the details on the 496, which is kind of a mystery motor compared to the typical big block Chevy. It seems only a few really know the 496 well, and I thank you guys for the valuable info which has guided me on my build.
I found this 496 performance handbook on Amazon back in October so I pre-ordered it. It finally showed up yesterday. I wish I would have had it months ago, it answered so many questions I had. I'm going to read it cover to cover before I start assembly of my engine this weekend.
I'm not here to promote this book as I have nothing to gain here, I just thought fellow 496 owners who are rebuilding or modifying their engines could benefit from it.
The book has lots of pictures and they are in color.
I found this 496 performance handbook on Amazon back in October so I pre-ordered it. It finally showed up yesterday. I wish I would have had it months ago, it answered so many questions I had. I'm going to read it cover to cover before I start assembly of my engine this weekend.
I'm not here to promote this book as I have nothing to gain here, I just thought fellow 496 owners who are rebuilding or modifying their engines could benefit from it.
The book has lots of pictures and they are in color.
01-16-2020, 11:20 AM
#2
Registered
Nice find!
The OSO 496/8.1 Performance Handbook reads as follows:
Step 1: List complete takeout 496 for sale in Swap Shop
Step 2: Scour Swap Shop and Classifieds for 502 based engine
The OSO 496/8.1 Performance Handbook reads as follows:
Step 1: List complete takeout 496 for sale in Swap Shop
Step 2: Scour Swap Shop and Classifieds for 502 based engine
01-16-2020, 11:51 PM
#3
Platinum Member
Platinum Member
I was under the impression that ALL GM 496 motors have nodular iron cranks, forged steel rods, and hypereutectic cast pistons.
Forged pistons would be a no brainer for a whippled motor, and I would think upgraded rod bolts (and big-end resizing) would be high on the list. The nodular crank might be okay for low boost and <5,000 rpm usage, but as lots of folks say, the 502 comes with a beefy forged crank and forged pistons (although early units used a metric ring that is pricier than standard sizes).
Additionally, the larger bore of a 502 eliminates the need for bore notching to unshroud the valves.
A 496 is a fine motor, but I honestly wouldn't bolt $4,000 worth of Whipple on top of it and lean on it. And by the time you throw parts at the 8.1, you are usually better off to freshen a 502 Magnum or MPI and spend your money on heads and valve train.
Forged pistons would be a no brainer for a whippled motor, and I would think upgraded rod bolts (and big-end resizing) would be high on the list. The nodular crank might be okay for low boost and <5,000 rpm usage, but as lots of folks say, the 502 comes with a beefy forged crank and forged pistons (although early units used a metric ring that is pricier than standard sizes).
Additionally, the larger bore of a 502 eliminates the need for bore notching to unshroud the valves.
A 496 is a fine motor, but I honestly wouldn't bolt $4,000 worth of Whipple on top of it and lean on it. And by the time you throw parts at the 8.1, you are usually better off to freshen a 502 Magnum or MPI and spend your money on heads and valve train.
01-17-2020, 06:26 PM
#4
Registered
So i dont know how much it costs to "build & whipple" a 496, the parts prices or procedures involved,
nor do i know how far you may be into it. Definately not saying dont do it, nothing like diy
but screenname Igetwet has a whippled 525 and scx drive combo for trade in the swapshop,
i bought his 496 mag ho and it was everything he said it was.
my opinion, a phone call wouldnt hurt to see if you guys can come to a deal or not,
Plus he did it (whippled a 525) so you might be able to get some insight.
nor do i know how far you may be into it. Definately not saying dont do it, nothing like diy
but screenname Igetwet has a whippled 525 and scx drive combo for trade in the swapshop,
i bought his 496 mag ho and it was everything he said it was.
my opinion, a phone call wouldnt hurt to see if you guys can come to a deal or not,
Plus he did it (whippled a 525) so you might be able to get some insight.
Last edited by outonsafari; 01-17-2020 at 06:29 PM.
01-17-2020, 06:49 PM
#5
Registered
I was under the impression that ALL GM 496 motors have nodular iron cranks, forged steel rods, and hypereutectic cast pistons.
Forged pistons would be a no brainer for a whippled motor, and I would think upgraded rod bolts (and big-end resizing) would be high on the list. The nodular crank might be okay for low boost and <5,000 rpm usage, but as lots of folks say, the 502 comes with a beefy forged crank and forged pistons (although early units used a metric ring that is pricier than standard sizes).
Additionally, the larger bore of a 502 eliminates the need for bore notching to unshroud the valves.
A 496 is a fine motor, but I honestly wouldn't bolt $4,000 worth of Whipple on top of it and lean on it. And by the time you throw parts at the 8.1, you are usually better off to freshen a 502 Magnum or MPI and spend your money on heads and valve train.
Forged pistons would be a no brainer for a whippled motor, and I would think upgraded rod bolts (and big-end resizing) would be high on the list. The nodular crank might be okay for low boost and <5,000 rpm usage, but as lots of folks say, the 502 comes with a beefy forged crank and forged pistons (although early units used a metric ring that is pricier than standard sizes).
Additionally, the larger bore of a 502 eliminates the need for bore notching to unshroud the valves.
A 496 is a fine motor, but I honestly wouldn't bolt $4,000 worth of Whipple on top of it and lean on it. And by the time you throw parts at the 8.1, you are usually better off to freshen a 502 Magnum or MPI and spend your money on heads and valve train.
The original poster is adding a forged rotating assembly, replacing the weak part of the 496HO. I would have no worries "leaning" on it. I will argue it will be more reliable than an earlier 502 of comparable build. More headbolts, symmetrical cylinder head runners, dry intake, far better windage setup, revised firing order, and closed cooling.
The stock intake/heads suck for making N/A hp, however, his Whipple will make up for their shortcomings. The 8.1 marine platform will always be limited as long as one is running the 555pcm. Only a few can tune it. The auto 8.1 side can use newer LSX PCM's and tune via HP tuners. There is a huge market available for this platform auto side vs just a couple years ago.
01-18-2020, 12:06 AM
#6
Gold Member
Gold Member
...I dont even comment on 496 threads anymore. A lot of haters say "just swap out a 525" but many stuck to the Gen 7 platform with success Ryan00TJ, I did it, SD Fever did it and many others. It was simple and cost-effective for this power range. It can be done for the same cost or better. You can easily make up to 750 HP pretty easily with proven setups like baking a cake. Everybody says the 496 platform is a joke, but look at all the threads about somebody building a 502 with a cam and head package they bought off OSO and the boat runs worse or other mechanical problems. There's dozens of cams with screwed up durations, mis-sized push rods, messed up runner sizes, bla, bla, bla. Then there is an 80 page post about how to fix the messed up cam and heads. Raylar/Larry has a pretty easy pick and choose parts list that can be arranged for most budgets and for 450 to 750 HP. Pick your parts, install them, and you get the advertised horsepower.
01-18-2020, 08:18 AM
#7
Registered
496 great motors just leave them alone! My 02?
01-18-2020, 08:58 AM
#8
Registered
So i dont know how much it costs to "build & whipple" a 496, the parts prices or procedures involved,
nor do i know how far you may be into it. Definately not saying dont do it, nothing like diy
but screenname Igetwet has a whippled 525 and scx drive combo for trade in the swapshop,
i bought his 496 mag ho and it was everything he said it was.
my opinion, a phone call wouldnt hurt to see if you guys can come to a deal or not,
Plus he did it (whippled a 525) so you might be able to get some insight.
nor do i know how far you may be into it. Definately not saying dont do it, nothing like diy
but screenname Igetwet has a whippled 525 and scx drive combo for trade in the swapshop,
i bought his 496 mag ho and it was everything he said it was.
my opinion, a phone call wouldnt hurt to see if you guys can come to a deal or not,
Plus he did it (whippled a 525) so you might be able to get some insight.
The 496s were/are great motors imo. Yes definitely less info on them and not great internals for making more power, but that’s not what GM or mother mercury intended for them. More to run hundreds to thousands of hours with little to no maintenance. Ask many who own a coveted Merc racing 502 motor how many hours before the valve train has to be upgraded...
01-22-2020, 05:35 PM
#9
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Thread Starter
I spent months figuring out which way to go here, meaning build up my 400hr reliable 496HO or swap in a 502. In my case the 496 build made more sense $ and time wise, as I do everything myself (except the machine work). The Whipple is an expensive kit ($7,600), however it's beautifully engineered and has a great high end fuel system and plumbing. It's nice knowing I'm getting a complete new fuel system to replace the 400hr stuff.
The 8.9:1 forged pistons I chose have the top ring lower than stock (.300" vs .200" on stock), and the Scat rods are tough with ARP bolts. It's all balanced too, and of course Cometic MLS gaskets. The heads were redone and comp cams valve springs and hardware were used to give 130# seat pressure. I'm running Raylar rockers and a Raylar blower camshaft. I'm going to run a mild 7psi and Whipple thinks it should be in the neighborhood of 650HP. That's plenty for me as I want it reliable, plus I'm really easy on the sticks. In addition to your standard gauges on the dash, I've added boost, water pressure, fuel pressure, oil temp, and a wideband AFR. I should have the engine back together in about a week or so. Time will tell if I've made the right choice with staying with the 496 platform. FYI I'm at $13k for this project all in.
Here are a couple pics of the build.
The 8.9:1 forged pistons I chose have the top ring lower than stock (.300" vs .200" on stock), and the Scat rods are tough with ARP bolts. It's all balanced too, and of course Cometic MLS gaskets. The heads were redone and comp cams valve springs and hardware were used to give 130# seat pressure. I'm running Raylar rockers and a Raylar blower camshaft. I'm going to run a mild 7psi and Whipple thinks it should be in the neighborhood of 650HP. That's plenty for me as I want it reliable, plus I'm really easy on the sticks. In addition to your standard gauges on the dash, I've added boost, water pressure, fuel pressure, oil temp, and a wideband AFR. I should have the engine back together in about a week or so. Time will tell if I've made the right choice with staying with the 496 platform. FYI I'm at $13k for this project all in.
Here are a couple pics of the build.
