Engine life

I know that there are alot of variables, but what type of life can be expected out of a mild 540 BBC blown making about 750 hp before it needs to be freshened up?

Too many variables...rpm and tune up have a lot to do with it. But here is what I do every 2 seasons or every season if I run it a lot.
Remove all spark plugs.
Leakdown test. TDC. Record % leaking. Note where leaking from. Through intake is intake valve...exhaust, etc..
Now I am picky...anything over 10% leakage and I am going in there. But 20% or more is probably more the norm.
Leakdown test #2. Remove the rocker arms and leak test again. Let the piston push down to bottom of cylinder. Now hold you thumb over spark plug hole of cylinder(s) next to the one you are leaking. Feel air pressure? Head gaskets are leaking between the cylinders if you do.
Remove intake manifold and roller lifters. Inspect them.
Remove oil pan and check bearings. Main concern is always the main bearings.
Not saying that you go to all this...but is what I do.
You don't want to go to all that....then leak it down and then remove the oil filter..cut the oil filter open and look for metal.

In english: unless you run it like a complete idiot, or buy something from an automotive shop(they don't understand the differences between car and boat motors), or just plain shop cheap prices, 3-6 years is normal. Also, don't detonate it! You really need to talk to someone who does blower boat motors! There is much to learn. Talk to the guys that have them or build them, listen to all and consider the source, or call me during business hrs, and I'll try to help. I have one, and I build them. TIMINATOR 623-877-8553

Looking for a ball park idea of how many hrs before they need to be freshened up.

40-300 hrs. it really depends on who built it,how you run/maintain it etc.etc. my 600+horse n/a engine was running awsesome at 300+hours when i pulled it out. my blower engine i got rid of after 40hrs and is still very strong. but i change the oil every 10hrs or after it smelled bad whichever came first. if you still havent built it go with a very reputible builder no matter the cost. try larry's engines in tucson az.lot's of my buddies use him and i've never pulled them back with a broke engine.

Im looking to buy a used boat and trying to guard against big surprises. I live in western Ny and used performance boats are not that common in my area. I have seen several boats that Im interested in but they are on the other side of the country AZ or CA. A test ride and inspection is complicated. Is there any marinas that do any type of documented inspections?

if ya gotta ask... how much power you want? :p

I'm not as picky as a lot of people, but I have 4 hard racing seasons on a blown 540 and it still runs the same E.T. and MPH it did when new. I'd say it's seen about 200 full throttle passes under 10-15 lbs. boost and 7500 rpm. I tore it down a year ago, pretty much a waste of a gasket set. The bearings were flawless, no cylinder wear at all. Not to say that my environment compares to long hours under heavy load, but if the clearances are right and quality parts are in it, as long as the compression is up and plugs don't read oil consumption you are good for a long time, 300 hours at minimum.
DJ

detriot...that sounds good!....obviously you did it right with the right parts the first time.

if ya gotta ask... how much power you want? :p
Thanks That was really helpfull.

I'm not as picky as a lot of people, but I have 4 hard racing seasons on a blown 540 and it still runs the same E.T. and MPH it did when new. I'd say it's seen about 200 full throttle passes under 10-15 lbs. boost and 7500 rpm. I tore it down a year ago, pretty much a waste of a gasket set. The bearings were flawless, no cylinder wear at all. Not to say that my environment compares to long hours under heavy load, but if the clearances are right and quality parts are in it, as long as the compression is up and plugs don't read oil consumption you are good for a long time, 300 hours at minimum.
DJ
Did you do a leakdown test before you tore it down? Thanks for your post.

Thanks That was really helpfull.
sorry banzer...but a blown 540 and you want 750 h.p.?
in my opinion that is a very easy and reasonable goal...and it should last a very long time before refreshening...make sure it has good components but most importantly have it or you put it together well and it should give you years of service.... :)

Tbanzer,
Check your PM's. I sent you one.
Jim

sorry banzer...but a blown 540 and you want 750 h.p.?
in my opinion that is a very easy and reasonable goal...and it should last a very long time before refreshening...make sure it has good components but most importantly have it or you put it together well and it should give you years of service.... :)
That what Im looking for . Decent power, something that wont kill drives and last for years without being a timebomb.