Engine displacement measurements???

[Carbo]

Hey guys, how do you measure an assembled engine sitting on an engine stand to determine its true displacement? I would like to play with one to see if I can measure it accurately. I'm assuming you can remove the oil pan and take measurements from the bottom but not sure how to measure or where (specifically on the crank for the stroke)?

[Yelcamino]

You'll need to remove the cylinder heads to measure the bore diameter. You'll also need to remove the crank so you can measure the stroke (center of main journal to center of rod journal). Then the formula is: bore x bore x stroke x .7854 x no. of cylinders.

A 350 cid for example would be:

4" x 4" x 3.5" x .7854 x 8 = 351.85 cubic inches.

[andrewb70]

You'll need to remove the cylinder heads to measure the bore diameter. You'll also need to remove the crank so you can measure the stroke (center of main journal to center of rod journal). Then the formula is: bore x bore x stroke x .7854 x no. of cylinders.

A 350 cid for example would be:

4" x 4" x 3.5" x .7854 x 8 = 351.85 cubic inches.

Can't the stroke be measured from the top? Half the distance between TDC and BDC?

I also know that various sanctioning bodies measure the displacement with some sort of pump, without pulling the heads.

Andrew

[Yelcamino]

Can't the stroke be measured from the top? Half the distance between TDC and BDC?

I also know that various sanctioning bodies measure the displacement with some sort of pump, without pulling the heads.

Andrew

Hey Andrew! Yeah I didn't think of measuring the stroke from the top, probably accurate enough to figure out what the engine displacement is. As for the pump, I'm sure the sactioning bodies have that ability.

[Carbo]

Hey guys, thanks for the info. I was actually able to take some measurements and saw some stampings and have determined that the engine is a 427. I did forget to add that this is an LSX as well. According to the crank it has markings that read 4-LS1-4000-61. When I look that number up it's Scat and a 4 inch stroke. For the bore I cut a metal strip and placed into the center part of the bore (not the most accurate I'm sure but I knew it would put me in the ballpark). It measured 4.125 so this calculates to 427. Now, here is why I'm extremely pissed about this. I purchased an LSX 454...so I thought. I know my measurements on the bore aren't the most accurate but I know this block was a 427 before and the engine builder told me he would have it bored out and have the proper crank installed for a 454. I'm trying to get a hold of the builder now and see what he has to say about this. He did tell me the engine has .030 quench when I first got it, would that change the displacement at all?

[Joe87MonteSS]

I don't think quench has any affect on displacement. As for your crank, the rod journals can be cut in a way to increase stroke. I'm not saying that this is the case, but it's a possibility. Being that it's almost been 3 weeks, did you find anything out?

[Carbo]

Yeah, I talked to the builder and he's sending me the build sheet. He said he believes its a 4.185 bore with a 4 inch stroke which would put it right around a 440. He couldn't confirm at the time because he wasn't at the shop when I spoke to him. Once I get the build sheet I'll be able to verify it. I'll let you know when I get it. Don't know when that will be though.