John B

jd 1,

No way! Going from a 500 to a 525 is like a 4 mph increase. From 500 to 575 is a 6 mph increase.

This is from the boat manufactures' tests.

JB

Whipple Charged

The 500 makes approx. 500-505hp on a true steady state run on an accurate dyno. THe 525HP EFI makes 540-545hp with the same test. Compression is the same, same pistons, crank, rods, etc. The 575SCI makes between 600-605 with the same test. Mercury Racing is always conservative on power ratings while Mercury Marine is usually off. Typically there so called prop hp's are the crank hps, example, the 496Mag HO makes 415-430hp depending on computer cal. The 502 Mags made 415-420hp.

Thanks,
Dustin

John B

Dustin, Thanks for the information. Back to the post.

DOES ANYONE FNOW THE CAM SPECS???

John.

Hessdk

John B,
Adivanman is correct. You can call Crane and they will verify P/N 16HR00004. I have a 525 HP and it is a very nice sounding cam, and still idles fairly well.

Adivanman

Thank you Hessdk,
Once again, specifications are:

Crane 16HR00004 BBC Hydraulic Roller
Duration (advertised) - 298/306
Duration (@ 0.050) - 234/244
Lift - .610 Intake, .632 Exhaust
Lobe Center - 114°

This is a purpose built marine camshaft.

John B

Thanks guys,
I put this cam into a program ( Engine analyzer v3.0) and it showed a 10 hp improvement over the 500 EFI.

scarabman34

The specs just given above are a crane 139741

Ric232

Actually, it's more like the 168741, except that the HP525 cam has a 114deg LSA instead of 112.

Adivanman

JohnB - Glad we could help.

Scarab________34,
Have you LOOKED at the specs for a crane 139741? Besides being hydraulic rollers and having the same lift the two cams don't share any specifications or applications.

Rick232 - as mentioned before, you are correct.

liquid lounge

Thanks for the info. Well that cam is bigger than I thought it would be, especially on the exhaust lobe! You would think since they are running a true header that they might back off of exhaust timing a bit in favor of cylinder pressure, especially since the cr is very conservative considering the aluminum heads. Maybe lowering cylinder pressures is their intent? They are the ones that have to warranty it. One thing for sure, the new Motorola ECM/sensors have it all over the old GM MEFIs'....making civilized big HP for this system a piece of cake. Take Care , Berg