Harper220

Anybody tried out Whipple's Stage 2 kit yet? I'm just looking to wake up my 496 HO's a bit, so I can jump from stock 30 bravo's to 32 bravo labs on my 28 daytona. I'm mainly looking to increase mid-range cruise speeds between 3000-4000 rpm. Whipple claims 8-10% increase which amounts to 34-42 hp. I believe this system sells for $795 and I believe they did away with the k&N flame arrestor to keep it at this price. Any input? Waste of time or worth the money?

Stage 2 $995
The Whipple stage 2 maximizes the power output of the stock engine by running 91 octane or better, increasing the maximum spark advance, increased ignition power from the individual coils, denser air charge from the low temp thermostat, maximized air-fuel ratio in each individual cylinder and increased air flow from the hi-flow filter. Calibration increases torque levels throughout the entire rpm curve while making more peak hp for increased speeds.
Key features:
• Hi-performance ECM calibration
• Low-temp thermostat
• Hi-flow K&N filter
• 5450 RPM limit
• 8% - 10% power increase over stock
• Increased plaining ability with increased torque output

CMG

Do some checking first if motors not new, I read somewhere that early generation 496s aren't so blower friendly. Bottom end not as strong as newer models. (forged crank)

Harper220

There's no blower involved, I added the stage 2 contents to my original post. Re-read and it explains what's involved.

boatfreak

CMG, I believe you have that backwards. The very early ones were said to have a forged crank.

Hydrocruiser

Nodular cranks have 42% the strength of forged. Straight off a GM website. A cast crankshaft is “weaker” because it is made from cast or nodular cast iron, not really because it is cast. It is cast because the material is very castable, but is impossible to forge. The pistons are hypereutectic coated cast aluminum which is a fancy way of saying aluminum. Rods are forged steel (1141SAE shot-peened and magnafluxed with 9mm diameter bolts). Main Bearing Caps: 4-bolt cast iron. Pushrod actuated overhead canted valves ( 2 valves per cylinder ). Oil Pan Capacity: 8 qt . (7 quart fill level after system charge) . Block: Cast iron. Cylinder Head: Cast iron . H.O 525 horsepower and more than 500+ lb-ft of torque. No replacement for displacement! Coil-near-plug ignition includes crankshaft sensor, camshaft sensor, Electronic Spark Control (ESC) sensors and eight ignition coils. Roller timing chain provides improved durability at marine engine speeds. High-torque marine camshaft with hydraulic roller valve lifters provides maximum performance. Marine-specific two-bolt flanged external water crossover (no seawater in intake manifold). Though the heads are iron they are of a good design but heavy. Supposedly less prone to insults in the marine environment.

I have discussed this engine with a few good mechanics and they all feel that this engine is fine at 425-475 HP with the internals being what they are. This engine has a mix of very high performance duty parts and "regular duty" parts. Not a bad mix and a great price. Beyond that it's time for Raylar and forged parts with or without a blower. This "stage 2" kit makes the most sense of all for the engine as it's an easy way to get to 460 HP and going up a pitch or two on the prop ought be good for a few more MPH and more torque. Beyond that I personally would go with a 525 EFI or Ilmor Viper V-10. I think you will reach a cost/benefit point that leans in that direction. The 496 has potential for some easy less costly mods and potential for some costly mods. Pushing the envelope too far gets expensive with this engine.

The Whipple stage 2 is as was mentioned earlier:
Key features:
• Hi-performance ECM calibration
• Low-temp thermostat
• Hi-flow K&N filter
• 5450 RPM limit
• 8% - 10% power increase over stock
• Increased plaining ability with increased torque output

http://www.gm.com/automotive/gmpower...3_brochure.pdf

Headers and a more flowing air filter are good choices too!

Harper220

That was a hell of a reply "Hydrocruiser", very informative. I assume then, that the stage 2 kit will add roughly 35 ponies? I'll take 460 reliable, turnkey hp to the prop anytime! Dam that's almost a 500EFI...

The stock mesh flame arrestor seems to flow better than the K&N replacement. Is there something else out there that flows better than the stock arrestor? Do you know of anybody that has installed this kit and actually noticed a difference? Thanks for the great information...

Raylar

Harper220 & Hydrocruiser:
Thought I would drop in the thread here and try to clear the air and line out some more 496 facts and insights. First the 496 engine in 496HO early versions came with a 1038 micro-alloy forged crank that was forged by a GM subcontractor. The 1038micro-alloy in forged is stronger than a conventional cast nodular iron crank. GM provided this crank in the marine engines in 2001 and erly 2002 versions because it was the only crank they tested up to that time that would provide enough safe stength for the 425HP loads. In 2002 GM perfected a new micro-alloy cast crank with new dimensions and strenghts that just about equaled the earlier forged cranks and was a moderate cost savings(bean counters still rule!) and meet durability levels for 500+ HP, so they made the switch to these new micro-alloy cast cranks in mid 2002. The new cast crank has knife edged counterweights on all crank throws, rolled fillets and treatments that make it far stronger than conventional cast cranks. This crank has been pushed hard by both Raylar in over 80-5500rpm dyno pulls, by Dustin at Whipple, Tyler Crocket, Paul Pfaff and Flagship marine in like uses and I have not heard of one major cast crank failure. Some stock 496 engines in trucks and boats have had bearing and rod failures, but the numbers are relativly small and are usually related to improper bearing fit and clearences in original factory assembly. The truth is that the bottom ends of the 496 engine are quite strong and tend to be mostly trouble free. The weakest link in the block if their is really one is the hyper-eutectic cast piston. Hyper -eutectic cast pistons are basically cast pistons with metallic silicone additives designed to add strengh to a cast piston at a lower cost than aluminum forgings. The silicone additives add strength to the aluminum, however the even distrbution of the silicone alloys in the aluminum are not quite as uniform as some engineers would like to see and the effect of the silicone in strengthening the aluminum tends to make the overall piston more brittle and sometimes subject to a disintergration versus just cracking in overload situations such as detonation or knock events. Couple this with tight cylinder wall clearences to help with engine noise control and a realitivly thin top ring land above the top ring to eliminate emissions caused by the unburned gases in this area above the top ring during ignition, sometimes make this piston a canidate for failure. These failures sometimes tend to accelerate, especialy when the piston is subjected to high cylinder pressures and detonation caused by high boost pressures, poor fuel or timing thats been advanced to far. These failures will also appear a little more in high performance marine uses where sustained high loads and higher rpm blasts really push these pistons to the max. The Mercury ECM's have really conservative timing advance tables and adjust somewhat for poor fuel, high engine coolant and intake air temperatures and high loadings that overpropping in high performance boats that sometimes occur. When the engine shows evidence of detonation thru the knock sensors on the motor the computer will pull out a good deal of timing to try and avoid any serious internal engine damage and power levels may be reduced accordingly.
We have been testing and thrashing these engines for over two years as have others I mentioned above. Overall the 496 engines as produced by GM powertrain for Mercury and others exhibit greater strength and durability than the GM produced 454 and 502 shorter stroke motors. The longer stroke coupled with better GM parts have made these motors produce more power and torque than the 454 and 502 GM motors that have been rated sometimes with more crankshaft horsepower. This is one reason Mercury is dropping the HP500 motor next year.The 496 represents more power with great un-blueprinted construction and a better engine value than the current HP500EFI offering. Remember Mercury does not reassemble the 496 engine with special parts as it does the HP500 and HP525. Mercury uses the 496 engine assembly as shipped by GM Powertrain and accessorizes them for Mercury's package offering.
As for the stock iron cylinder head that all 496's come with, the head is a moderatly strong piece due to thick heavy valves, powdered iron exhaust seats, good reverse flow cooling and better than old iron casting processes.
(continued posting#2)
Ray @ Raylar

Raylar

Harper220 & Hydrocruiser: (first post continued)

The problems with the stock iron cylinder head are really heavy weight (94lbs.), poor midlift and high lift port flow characteristics, poor combustion chamber shape, size and fuel burn and heavy valve train and limited valve springs that combine for less than desirable power development. We took a clean sheet of paper design approach to our new aluminum cylinder head and corrected all these deficiencies and problems, raised the compression ratio possible even with standard 87-89 octane fuel from 9 to 1 to 10 to 1 which produces about 35 to 40 HP all by itself. Couple these changes with higher velocity-higher flow ports, awesome quality lighter valves and retainers, new technology variable rate high lift valve springs and a smooth "as cast" casting technology to produce a new aluminum cylinder head that only weighs 36lbs. needs no addtional CNC or machine work and out flows the stock head by 35% at lifts between .200 and .600 and you begin to see why we could not reproduce these results with $2200 to $2500 CNC, valve and spring replacement rework on the stock heads as some engine builders have done including the HP3 525HP motors. I am not trying to toot our own horn to loudly but when a 496 engine owner can buy our heads for about $2600 complete, take a 110lbs per motor off the back of the boat and ultimately produce more power it sort of makes the choice a "no brainer!"
As for Whipples ECM reprogram packages for stock EFI 496's, remember that the overall horsepower levels quoted are for peak rpm power levels, most likely in the 4800 to 5000rpm range. These do not mean you will receive these levels at mid rpm or speed levels. Also the increased rpm limits will most likely mean a re-prop or prop re-pitch or labing to achieve higher speeds at these higher horsepower and rpm range levels. Dustin at Whipple has done a great deal of dyno and on boat in the water testing with excellent results on his ECM reprogramming especially with his supercharger packages at moderatly low boost levels on this engine. Dustin at Whipple is the only one in the industry now that I know of who has this level of expertise and is duly licensed to flash reprogram the PCM555 -ECM computer that the Mercury 496 engine uses. As for horsepower from these type of reprograms, we believe and know from our testing that 25 to 30HP is probably the max that can achieved on a stock motor with just reprogram adjustments to fuel, spark and temperature levels.
Any addtional HP would only come from our heads, major stock head rework, intake manifolds, marine headers, cam, supercharger and bore & stroke modifications.
As for flame arrestors and K&N air filters the important thing to know on this issue is that a flame arrestor of the 496 type is a Coast Guard requirement. Our testing has shown that even a removed arrestor state produces no addtional power. Taking off an approved flame arrestor can be disastorus and dangerous in case of a backfire in an engine comaprtment. The resulting liability and fire danger is huge and uncalled for. Most boat insurance policies would not pay for the resulting loss in the event a flame arrestor is removed or not used. As for the K&N Coast Guard approved air cleaner, it will filter dirty air better than a stock flame arrestor but it will not add any power and may slightly restrict air flow over the stock arrestor. If you boat in a dirty or dusty area, probably not a bad idea for long motor life, but if you boat in clean areas like most of us do, save your money and spend it on more useful equipment.
We know that the 496 engine is a better version of the original big block, its long stroke, revised firing order, symetrical port head design, strong block and wide higher level torque band make it an excellent motor for high performance boating. We also know our new high performance parts as well as others in the marine aftermarket make this engine the marine Big Block of the future!
Well school is now dismissed! I have matriculated far to much but I hope I am helping with factual information about this engine and our findings!
Great High Performance boating to you!
Ray @ Raylar

NJDave

Harper what year is your 28 daytona? I have a 1999 with twin HP500's and I am spinning 30p bravo1 4 blades thru 1:36 gears. I was wondering what gears are in your drive's? Because if you are getting 4800-5000 rpms with those 496HO's thats pretty damn good. Let me know. Also are your props turning in or out?
what speed are you getting on GPS?

rv

Facts and more facts. It is great having people post that have useful information. Good job Raylar.

Rick