the ins and outs of an SC block

Kevin Leitem

Registered User
After sonic testing the cylinder walls on the SC and mustang blocks. I learned that the mustang block has thicker walls. But there were still a couple spots that were only .080 thick. I talked to my engine builder about sleeving all six holes and going to at least a 3.9 bore. He wanted to see if I could section a block to see what was going on so he could chose the appropriate sleeve. So after searching for a shop that had a big enough band saw and many people looking at me as though I had a third eye , I finally found one to do it. Here are a few pics.

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Was that a stock bore block? If so, that is remarkably thin between the cylinders. It looks to me like siamese sleeves would be necessary to get any decent amount of overbore. Either way, it looks interesting, and I'm curious to see the results if you do this.
 
Kevin, how thick is that at the thinnest part between the bores? Had that block been bored or was it stock?
 
That block is a .020 overbore SC block. Yes , it would have to be siamesed. But it will be filled with hard block too. Cooling is of no concern as there will be no cooling system anyways.
 
www.youtube.com/watch?v=z2oYFu7uVFYWow not much there! Hey Keven fixed the smoking Lighting new valve seals, but before that I ran a 12.0 blew the pipe off the supercharger about 1/2 track and we did not get a time from the first run. Beat the Chevy 2 times it had a ls6 D-1 Procharger 2 stage "50 shot he clamed:rolleyes:" DR's and a bunch more. This is the second run I think he got excited and jumped on the second stage too soon and blew the tires off, the guy clamed to run pro bike?
 
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The thinnest part of the cylinder wall is .080 on a .020 bored block.

Man I would hate to actually see how thin my walls are since it has been bored .040over. Obviously the last time this block can be done! .060 at my thinnest point:eek:

That is rather scary to think about now! :confused:

Makes me wonder how much those side walls between the bores flex under full load and 18lbs of boost!
 
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Man I would hate to actually see how thin my walls are since it has been bored .040over. Obviously the last time this block can be done! .060 at my thinnest point:eek:

That is rather scary to think about now! :confused:

Makes me wonder how much those side walls between the bores flex under full load and 18lbs of boost!

Provided that this disected block and your block had the same wall thickness to begin with, and the disected block has a .080" wall thickness with a .020" overbore, you'd have .070" wall thickness with a .040" overbore. A .060" wall thickness would equate to a .060" overbore.
 
All castings will vary but what this shows is that there is minimal overboring youll want to do. So do we have sections of a later model block?
 
All castings will vary but what this shows is that there is minimal overboring youll want to do. So do we have sections of a later model block?

I don't have an extra mustang block to section. But when I sonic tested both blocks the mustang one was considerably thicker but one cylinder was still just as thin.
 
I picked up another 2001 mustang 3.8 block and had it cut. The thinnest spot is .130 versus .080 on my .020 overbore sc block. So essentially it would have been .090. Also on these blocks the head studs go much deeper in the block so there would be less distortion of the deck once the heads are torqued down.

Mustang

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Supercoupe

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