filling block

Ok so i have decided to not to run a cooling system thanks to all the advice given. But my question now is should i fill my block if so to where or should i leave it empty to save on some weight? i have a dart big m block and am building a blown alcohol 540 shooting for around 1500 hp
thanks for any info
Simon

 

To fill or not to fill

I recommend not filling the Dart big M. It is a good stout block to start with and at 1500 hp you are not working it hard at all. We filled our big M and after four seasons racing feel it was not very good advice we recieved. The block holds to much heat and it is WAY heavy.

Cheers
Jim

 

If you are planning on getting a ton of passes out of the engine, just don't fill it.
The Darts are fairly strong already. A 4.500 bore leaves quite a bit of meat. But we have found that iron blocks that are filled are really hard on rings as there is no place to disperse heat on the bottom of the stroke. For alcohol, it does not matter quite as much, but with gas, we are seeing much less than half the ring life over a non filled block.
As for filler, I use vinylester fiberglass resin (With some extra styrene to make it flow better) and a fair dose of sawdust and talcum powder. Some put freeze plugs in and fill to the bottom of the water jackets, and some fill to the bottom of the freeze plug holes.
I just never liked the added weight, and don't like wiping out my expensive ring packages. But lots of people do it and really like it. Especially with stock blocks.

 

If your not detonating than there is no reason to fill the Dart Big M. We're doing it with 2 blocks with more than 1500 HP and no grief so far.

 

Stock block is a different story. I wouldn't fill the block that you have and I wouldn't run freeze plugs either (air is an insulator)

 

i agree leave the freeze plugs out and let it breath