I’m planning another LTX stroker build in the future (S/R and more compression) and considering a “partial fill” with the block. I’m keeping it tagged and technically street-legal, however, it will not be driven on the street. Basically, a track-only LTX engine package.

Although, I don’t want to over-do the fill and cause heating problems at the track. So, I wanted to get some opinions here on the forum from people who have used block fill on an LT engine with reverse-coolant flow.

Specifically, what amount of fill is acceptable for an LT specific block (1/4, 1/3, 1/2) and a fill level reference on the block (bottom of the freeze plugs, Etc.) for each fill amount?

WD

 

I wouldn't do any fill. I have heard many recommendations against it.

 

I've filled several LT1 blocks, all for use on the drag strip. My own 4-bolt main Super Stock block has held the NHRA national record in the past and it has over 200 runs, many in the 9 second range, with no problems. All the blocks are filled to the bottom of the water pump. I've never had a broken cylinder wall on a filled block, a claim that I can't make in reference to unfilled blocks. Heating is no problem. I run a Meziere water pump, a stock LT1 radiator with the fan system taken from a V6 Firebird. I only turn on the fan after the car has crossed the finish line. I leave the line at about 120 degrees and usually turn off the track with the temperature at about 160. If I kick on the fan at the end of the run, the temperature will be back to 120 by the time I've passed the scales, picked up the time slip and coasted wherever possible on the way back to the pits.

If you are interested in the process I use to do the fill, PM me and I'll give you a step-by-step recap of the procedure.

c

 

Had mine half-filled when we clearanced for the 383 stroke.
I'm interested to see what people who've run theirs on the street have to say.

I've seen at least a few people talk about having theirs filled to just below the water pump.
No idea if they were street driven or not.

 

I have used 1/2 fill on the street, no problem.

Rich

 

My 383 is half filled and I intend to put more street miles then strip. I was told that cooling will not be an issue with a ~1/2 filled LT1.

If anything I consider it cheap insurance...sure the blocks are tough, but for the minimal added cost why not have the peace of mind?

 

Noob question but i have to ask. What/how do you fill an engine block? i know it strengthens the block but how? do you fill the block up with a compound in the water passages?

 

That's pretty much it. There are several commercially available products on the market but most people who fill blocks have a personal preference in terms of the material. One such product is known as "Hard Blok." It requires mixing a powder with water and pouring it into the water jackets of the block in a semi-liquid state. I've been doing it for at least twenty-five years on drag motors. In recent years manufacturers have been producing aftermarket blocks with substantially thicker cylinder walls and those would be obviously preferable. There is no reverse-flow aftermarket LT1 block so we have to make a choice between filling a stock block or adapting a traditional SBC block. Life is full of compromises!

 

Amen Mr. Norton...Amen!

 

Bringing this one back in hopes to answer a quick question on Hard Blok: Is the 'short fill' 12.5lb kit adaquate to fill an LT1 up to the bottom of the expansion plug openings?

Also the 28lb kit is only $10 more. Does that make any sense? That's 124% more material for 13% additional cost

Thanks,
Scott.