tx911

The guy building my shortblock is primarily a drag race engine builder, Flame away, but he has done some boat motors and has been more then willing to follow manufacturer directions on raw water cooled motor. He had to bore the block to 4.565 to clear the cylinders and I already ordered custom pistons. He said if it was a drag motor he would fill the block, has anyone tried this on a marine application? He did not suggest it, he just brought it up, but said he had no experience with it on a marine application. I know it would make the block heavier, but beside that are there any other problems. I run a crossover with no thermostat so I dont think heat would be an issue, actually it may help. Any thoughts or opinions would be helpful. Even thought about doing a partial fill to stablize what are boarder line cylinders walls.

dennis r

iTrader: (1)

I would not use it it will not cool very good but I guess it all depends how far he fills it.

GPM

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Ghostrider

From what know, filling is done in certain parts of a DRAG engine to allow circulation to only go to certain areas so that the engine can generate heat faster so it doesn't need to warm up as long, it also lessens the burden on water circulation because drag motors normally run electric water pumps or underdriven pumps to save HP. The block isn't totally full, it just reduces the coolant holding capacity and block certain areas deemed less necessary.

NOT something I would EVER consider in any motor designed to last more than 10 seconds total between rebuilds!

Drag race engines take every HP shortcut known to man. If it makes more power, they'll do it. I once raced at Mission raceway in Canada with no power steering, alternator or water-pump belts, and I even plugged my brake booster vacum for one run... DUMB idea, you try stopping a 470hp El-Camino at the end of 1/4 mile on manual brakes!!! (rookie mistake).

niceguy

As others have said... bad idea on marine apps. On drag motors back in the day, they primarily used the block fill to stabilize the cylinder walls due to extreme bore sizes. Nowadays, we have much thicker casting blocks and hard-fill is not used much at all anymore, especially in the mega HP motors.

tx911

They do not stategicaly fill certain parts of the block, They fill it from the bottom up on one side with the deck level, then when it dried fill the other side. It is not filled full, the top of the deck is where the heat is generated and that is where the water is left to circulate. He builds a lot of very competitive drag motors and says it is common place for him to fill blocks, even on new dart blocks. He said that they even do it on some dirt track motors and they stay cool just fine, a lot longer then 10 sec run. It is not done to decrease cooling capacity, it is done to add torsional rigidity to block and support the cylinders. I am not saying this is a good idea and neither is the builder, It just came up that if it was a drag motor that is what he would do, I just wanted to have some opinions from poeple that know out of sheer curiousity.

tx911

I way there the other day and he was working on a 565 for some girl running in the 7s with a door slammer, new dart block and fill. Like I said, I dont know much about it, I was intrigued because I have problems with the motor staying too cool because I dont run it that hard, and lack of thermostat.

niceguy

I hear ya on the drag motors, although I am surprised to hear people still doing that especially to Dart blocks... but I've heard far more stranger things. LOL.

Keep in mind though, heat is also tranferred throughout the block which is why the water passages go that deep in the block.... to pull heat out. So I still say it's a no go for marine, but ultimately it's your choice.

tx911

I dont feel like being the guinea pig at this time, I was just curious what others thought, or if anyone had tried it.

niceguy

I don't blame ya on that!!! Too much work pulling these things out.