496 ho with 525hp

[***boater#1]

ive heard that they are comming out with a new 496 H.O. it is supposed to have 525h.p. does this sound right? the guy at mercury said he didnt know anything... nut in powerboating is said they were thinking about it? anybody heard of this?

[LV-Advantage]

Whipple is coming out with three packages stage 3 has 525hp. I think it is cmi exhaust,recalibration,cams and a filter.

[LV-Advantage]

Here is a pic of the 525hp http://free.***boat.net/gallery/Gearhead_Garage/Motors_and_Drives/tn_525hp.JPG
[ October 14, 2002, 07:38 PM: Message edited by: LV-Advantage ]

[shockwaveharry]

I just saw Merc Racing's 525HP in the box last weekend. It looked just like a 500HP. It has closed cooling but I didn't get a close enough look to tell if it was based on the 496 or the old 502. I've seen pictures of the Merc 525 in Powerboat and it was a 496 painted red with long tube CMI's.

[Havasu Hangin']

From what I understand, it's a recalibrated 500EFI, based on the 496 block.
The old 525SC is now a 575SC EFI...

[shockwaveharry]

I'm standing here thinking about it and have come to the conclusion that the Merc 525 efi that I saw is based on the old motor because it uses the old intake with siamised runners. The 496 has symetrical ports. It uses a completely different manifold.

[Havasu Hangin']

shockwaveharry:
I'm standing here thinking about it and have come to the conclusion that the Merc 525 efi that I saw is based on the old motor because it uses the old intake with siamised runners. The 496 has symetrical ports. It uses a completely different manifold.Could be. I gotta wonder where they are getting the parts, though. I heard they moved away from the old 502s...but I'm not an expert.

[Steamin' Rice]

According to the specs on their website, the HP525EFI from merc racing is a 502ci motor. I believe that it's essentially an HP500EFI with closed cooling, different exhaust, different throttle body, and different computer.
I don't think that merc racing has announced a motor based on the 496......yet

[Craig]

I thought I read it also has Edelbrock heads on it.

[Steamin' Rice]

You're probably correct...I can only read so many words and then my brain locks up.... :D

[shockwaveharry]

Now I remember! The 525 you can get NOW is based on the gen 6 502. The next 525 should be based on the 496. GM calls it the Vortec HP3 8100 (HP1 is the 375 hp 496 MAG, HP2 the 425 hp 496 MAG HO). GM is running 9 teams in APBA offshore Super Vee Light, Super Vee vLight Twin, etc. and they're winning everything. GM will offer the engine to their marine OEM's in 2003. I've been looking for pix on the net but can't find any. There is a pic in Powerboat mag from a few months ago.
Found it! http://www.sae.org/ohmag/techinnovations/10-2002/05.jpg
[ October 16, 2002, 07:47 PM: Message edited by: shockwaveharry ]

[shockwaveharry]

More info:
As part if its 2003 marine engine lineup, GM Powertrain is introducing a high-performance Vortec HP3 8100 V8 that will produce the highest output ever offered by a GM Powertrain production engine. Based on the largest light-truck cylinder block in its lineup, the Vortec HP3 is targeted for the performance recreational marine market. It produces more than 525 hp (390 kW) at 5200 rpm and 560 lb•ft (760 N•m) at 4000 rpm.
The HP3 is GM's third marine powerplant designed from a common 8.1-L architecture. The Vortec HP1 and HP2 marine engines produce 375 and 420 hp (280 and 313 kW), respectively. The Vortec 8100 offered in both the Chevrolet Silverado and GMC Sierra produces 340 hp (255 kW).
Performance features specific to the Vortec HP3 include a virtually seamless, precision-matched intake manifold and cylinder head ports for optimum flow characteristics, providing improved power and torque for hole shots and acceleration maneuvers when boaters need it most. Other features of the HP3 include steel camshaft and crankshaft timing sprockets; a five-bearing crankshaft with four-bolt, cast iron bearing caps; a high-volume oil pump with weld-reinforced shroud, pickup tube, and screen assembly; double roller timing chain; coated cast aluminum; and port and starboard 12-mm drain plugs.
The fuel delivery system includes a 75-mm (3-in) marine throttle body unit with an HP3-specific, 400-kPa (58-psi) fuel rail, providing a pressure increase of more than 30% over the standard Vortec 8100 production engine. The engine's bore and stroke are 4.25 x 4.37 in (107.95 x 111 mm). Computer ignition and fuel management parameters are calibrated to provide the best possible performance characteristics across the entire powerband.
The Vortec HP3's valvetrain features a high-lift and high-duration camshaft; premium race-style valve springs; 1.7:1 ratio roller rocker arms; dedicated rocker arm studs; and an intake and exhaust push rod exclusive to the HP3. Performance is also enhanced with a dedicated HP3-tuned harmonic balancer and individual ignition coils for each of its eight platinum-tipped spark plugs.
The HP3's performance comes from a naturally aspirated design based on a stock truck engine block. Information gained from automotive engine development was applied to the marine engine. In turn, knowledge gained from marine engine development, where conditions are much more severe, was driven back to automotive engine development for improved product quality.
The new engine will also be available with a remote oil cooling system with all connections and system wiring, a dedicated marine fuel system, and a marine-specific alternator, starter, flame arrestor, and 142°F (61°C) thermostat.
HP3s have a 9.1:1 compression ratio and are designed to run on regular unleaded fuel. The engines are manufactured at GM's engine assembly plant in Tonawanda, NY, and then shipped to Innovation Marine in Sarasota, FL, where they are modified, tested, and sealed before being assembled into the race boats.
In the 2002 American Power Boat Association (APBA) Offshore Racing Series, Vortec HP3-powered boats captured first- and second-place finishes in the APBA race in April in Daytona Beach, FL. Three weeks later, in the second APBA race in Marathon, FL, HP3-powered boats went on to capture a first- and two second-place finishes. In the third and most demanding APBA race, held in June on stormy Atlantic seas off Cape Cod, HP3-powered boats took two first- and two second-place finishes.
- Jean L. Broge
--------------------------------------------------------------------------------

[Ric 232]

See, if you're patient you eventually get the right answer.
And yes, Merc also has the new HP525EFI which is a 502-based motor. It is the same as the HP500EFI except with closed cooling, aluminum Edelbrock heads, a "monoblade" throttle body and better headers. I suspect this engine will have a short product life with the HP3 coming online soon.
Ric