540 vs 578 or 598
 

Looking to repower and want max reliability. Doesnt bigger mean more power at lower rpm? Which motor and source is the best all around choice? Goal is high cruise speed and awesome poker run performance without seasonal teardowns. Would you EFI or carb?

Keep in mind that bigger cubic inches need bigger cams. With bigger cams you need higher spring pressures and thus top end rebuilds become needed more frequently.

Lots of variables and I agree with the valve train issues. I still believe big cubes is the way to go. EFI if I had a choice. Rebuilds would also depend on how hard and how long you hold the sticks down also. :D

You could go turbines!

What great decisions to have to make!!! ;)

I disagree about the valvetrain. You can build say a 632 CID engine with a set of CNC ported heads, Brodix, AFR, Dart, World, your choice. Mild compression ratio of say 8.5 to 9 to 1. Use a very mild camshaft, something in the 230is or 240ish range and make an easy 600 to 650 HP. This type of power is easily done, is not stressing parts for this size engine, will run on 89 octane gas or whale blubber, and should be a very low maintenance engine with gobs of torque.

Same engine and you want 950HP, then yeah, you better have a good "wrench" on retainer.

Chris

It depends on which drives your using. A 632 connected to a bravo drive is pushing it. 700 hp 540 ci seems to be the best all around package for the bravo. We have seen 400 hours with no failures.

Konrad 540 drives with that engine package would eliminate drive failure and give you many years of low maintenance boating.

Have heard lots of good things about the Konrads. Just no real name recognition yet in the USA. They would probably be the perfect drive to combine with the power I am looking for.

I totally agree. 650 is not much of a squeeze for a 598 or 632 motor in my opinion. I was thinking he wanted more HP but really did not specify how much HP expectation was? :D Usually the first think needing attention is the valve train if everything else is right.

Konrad drive. REAL curious to see how Biggus retro works out! :)

JimV/Biggus,
I agree on the drives. You start getting over the 500#/ft torque mark and your Bravo is getting into dangerous territory. When building the engine power you better be ready to spend the bucks on that drive to hold it. 900HP Bullet ain't fast when she's sitting in dry dock with twisted shafts!!

Chris

Valvetrain issues are not there with hydraulic roller cams like they would be with solid roller motors. Figure to make @1.2 hp per cubic inch conservatively with today's head technology.