what's the opinion on doin a half fill on a jetboat block??

[IMPATIENT 1]

i've been thinking about doin a 1/2 fill on my next block for added strength since i'm gonna dump a buttload of nitrous into it. i thought about doin the block fill till its up level with the freeze plugs. good idea or bad idea??? do it before boring or after block has been cleaned and bored???
boat will see some cruising and i'll beat on it like it owes me money at times,lol.

[jimsplace]

depending on your block, is that above the drain hole?

[IMPATIENT 1]

depending on your block, is that above the drain hole?
i short fill would cover the drains.i always use nontoxic antifreeze for winterizing, so the drains mean nothing to me;)

[WannabeRacing]

I would go out and buy a good block. Even something like a merlin II or III, or an old bowtie, to be more cost effective. Get the strength there with thicker walls. Filling creates way more heat in the cylinder than running no water at all. So now you have more heat than even a car at 240 on the bottom of the cylinder and the boat problem of too little heat on the top of the cylinder. My guess is that the cylinder wall will not know what it is or where it is going
I have never done it, so I cannot say for sure. But it sure seems like a problem waiting to happen. Unless it is for a drag race only application where you are on the throttle for a few seconds then hours to cool down.
If you do decide to do it. Let us know how it goes.

[Warp Speed]

The 598 I just built for my jet boat ('99 cnc bowtie block) is filled a couple of inches up. I know this will help with the 4.600 bore I have, and haven't experienced any water temp or ring sealing issue's what so ever.
The added stiffness helped alot when honing (if you do go this route, definatly do it prior to final machining), and I don't think it is going to cause any heat problems as far as bore top to bottom. With the low water temp jets run, I think it may even help with the thermal efficiency.
This is the first big block I have built in 20 years, so maybe Steelcomp can add to this, but I don't see (or haven't experianced) any negatives so far.
Warp Speed ;)

[LakesOnly]

Pay attention to your oil temperature before and after you do the block fill; you'll probably observe that with the reduced water cooling due to the block filler that your oil temperature will have increased with the short fill.
LO

[OkieDave]

I have run several BBF strokers with filled blocks. not all the way up, usually an inch or so below the deck. never a problem except draining.

[jbone]

Does sand count. A a few trips in the shallow water at Martinez and my block filles up with sand.
I've tried keeping it flushed out in the off season, but it is not easly to get all the sand out without removing the engine.
J