Crude Intentions

iTrader: (1)

I understand you don't "want" a bigger blower but heat will kill an engine in short time. Makes the budget build worthless if you don't make it across the lake.

ezstriper

Ok, seeing that I don't know anything, you might call holley tech line, they just might...I have built a couple of the simular setups and talked with them several times, and no the 177 and 174 are not the same, the 174 was built for small block use. You asked for opinions, you got them, don't be a dick...

89Force235

Have you had a 177 or 174 on any of your set ups or any experience with how quickly they heat up?

The Hawk/Merc 525SC's were known for being extremely reliable motor's despite running 174s and 177s. This is well documented. I'm sure there's an awful lot of boaters on here that have made upgrades and increased boost while still having a reliable combo. Maybe I need to make a pulley change or add a chiller/water methanol injection to keep the temps down or maybe I need to limit my wide open throttle rpm but I'm really not looking to go all out with this set up.

Truth be told, I'm mostly interested in the potential benefits of a head/cam change.

89Force235

Found this thread on the site today with a google search for "525sc dyno results".

There's a guy here claiming 8# of boost , 300 hours, 92 octane,and no chillers!

http://www.offshoreonly.com/forums/g...4-525sc-4.html

phragle

iTrader: (3)

Are you looking for opinions or are you looking for somebody to approve/validate your game plan?

Your sticking a blower, cam and heads on a 330 two bolt with a cast crank. Several people have mentioned the small builder making heat if you spin the blower. Heat will cause detonation. You have a bottom end that will not tolerate detonation. it is not going to ping and knock and give you hints that its not happy, It is going the spit pieces of crank along with pretzeled rods into your oil soaked bilge.

Merc went with a forged crank, bigger rods and 4 bolt block on ALL its motors making 30 hp more than your bottom end started life handling and Merc will cut a corner and save a nickle and chance they can.

You said your at 7000 some feet, You can build what at sea level would be a nice happy 400 hp naturally aspirated motor and use the little blower to get you back to atmospheric pressure. If you think your going to spin that little blower hard enough to make 525 hp at 7000 feet when you need about 3 pounds over atmosphere just to get to the 330 you have at sea level, the general consensus here is that you will be going into the scrap metal business.

89Force235

In my experience hitting the 500hp mark isn't really a stretch for a two bolt main 454 with a cast crank. As long as the rpms are kept in check, good bolts are used, and detonation is avoided. My neighbor ran his 22 scarab, an 80mph boat at Havasu, for nearly a decade with a two bolt main and cast crank. To my knowledge its still running.

I'm not looking for anyone to validate what I'm trying to do. But I would like some advice on what others have actually done with similar set-ups. I think the key to getting some tech out of this thread may be discussing a safe rpm range, boost level, and how to avoid detonation.

So far, to avoid detonation I'm getting;
-Keep it cool, I'm thinking running the cross over cooling I already have without a thermostat should help with this, I'm hoping engine temps stay under 140.
-Run conservative timing
-Dial back the boost if I'm seeing my temps creep up
-From what I read aluminum heads generally also lower detonation threshold as the aluminum runs cooler and is a better heat conductor.

89Force235

Another thread I found on a cam suggestion for Hawk 525sc

http://www.offshoreonly.com/forums/g...uggestion.html

And another thread concerning cams in merc 525sc's there's also some basic info on a build with a 174 blower.

http://www.offshoreonly.com/forums/g...-cam-info.html

Here's an interesting post on the 496 mag manifolds/risers I'm using.

http://www.offshoreonly.com/forums/g...rformance.html

vintage chromoly

iTrader: (3)

Certainly sounds as if you've got it all figured out.

mike tkach

iTrader: (3)

ez gave good advice and he is correct.good luck getting advice from anyone else!don,t forget,you came looking for advice,just saying.

SB

iTrader: (1)

The '721' was actually the HP500 cam. But, what do I know.

Merc HP500 Carb
Grind#HR-284-2S-10IG
Adv 284º, 292º at .004” (68º Overlap)
276º, 284º At .006” (60ºOverlap)
222º, 230º At .050” (6ºOverlap)
At .200” 141º,150º
Lift with 1.7 .576” , .598”
ICL 105º, ECL 115º
LSA 110º

Events at .004"
IVO 33°BTDC IVC 71° ABDC
EVO 77°BBDC EVC 35° ATDC