amh44
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- May 21, 2016
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dose anyone know anything about the merc racing hp500 bulldog 540 motors my new boat has one in it?
how good of a motor are they mine is running about 700hp naturally aspirated
The Bulldog was offered at the same time as the carb'd 500hp.
Both Bulldog and 500 were rated at 500hp at the crank and 470 at the prop.
The 500 was based on the Gen V block and the bulldog on the Tall Deck.(I'm not hip on my GM alphanumeric bs,they may be the same block??)
The 500 was 502 cid(4.47" bore x 4" stroke) while the bull dog was a 540 (4.44 bore x 4.375 stroke).
Both used Crane cams and valve train.Both had the same 2.25x1.88 valve sizes in the same open chamber GM iron heads.
The 500 was 8.75:1 comp the bulldog 8.6:1, both ran on 87 octane fuel.
The 500 ran a GM forged crank,GM rods and JE pistons with GM rings and a GM oil pump with a GM stamped steel pan.
The Bulldog ran a Lunati forged crank,Manley forged rods and Weisco forged Pistons with Speed Pro rings and a Melling Oil pump with a cast aluminum Mercruiser pan.
Both ran Gil/Merc cast aluminum exhaust.
Both ran Carter high performance belt driven fuel pumps.
Both ran Holley 800 cfm carbs,both ran Dart single plane intakes.
Both ran Merc Thunderbolt IV ignition w/rev limiter.
Both were offered with Bravo 1 drives,but the Bulldog was also offered in Bravo 3 and 5 drives and came with a modified Borg Warner Model 62 transmission.
I'm not sharp shooting, but I thought the 540's were 4.500" bore and 4.250" stroke. Guess the math works out either way though. I do know the Bulldog was a Tall Deck block.
If it's making 700hp, it's not really a 500hp Bulldog. What else has been done to it?
Easiest way to tell is the Gen V timing cover has same bolt pattern as the Mark IV, a stamped steel cover, and 10 bolts. Gen VI is a cast cover and 6 bolts.Just read the oil viscosity thread. Mention of valve train maintenance reminded me of this thread. Everything I've read says that the 500hp is a gen 5 but mine has a cast timing chain cover which leads me to believe it's a gen 6. It's a 1997 also.The only service manual I could find is for the gen 5 version.
Anybody have any insight?