When installing a new knock sensor today, I failed to get a face full of coolant. Surprised, I tried to stick my finger in the hole. No go. Although I did not specify it, my new block is filled, with a very firm but less than rock-hard light gray material. I could stick a dental pick in about 1/16 inch. Aside from increased dimensional stability, what are the pros & cons of having a filled block in a DD street/strip car. Any drawbacks?

Should block fill be rock-hard?
Does it affect the knock sensor performance?
Reduce cooling?

 

I might be wrong but I have heard of people pouring concrete in the block, why I have no idea.

 

a partial fill shouldnt hurt you any, about the only thing i've ever noticed is a slight increase in oil temps under some fairly extreme driving conditions. basicly all the heat that the engine makes is in the heads and the bottom of the water jacket doesnt do a whole lot besides maybe cool the oil.

 

Thanks guys. Another thing I found was that the old sensor was really driven into the fill, crushing and deforming it a bit. Probably not ideal for the KS, as it should load on the threads when torqued, not the end of the probe part. New sensor didn't change anything anyways.....

 

Some people run an external oil cooler if the block is filled. Watch the oil temp if you can to determine if you need to do anything.