Dart SHP "Pro" block over bore size options

[Dragsinger]

Question, are the 4.00" bore and the 4.125" bore the same blocks? That is to ask, can the 4.00" block safely be bored to the recommended max of 4.165?

[pdq67]

Whose block will bore to 4.200"?

And isn't there one that will bore to 4.250"?

pdq67

[Frankshaft]

Dart and World race blocks will go 4.200 no issue. They both will actually run at 4.250 just fine. Felpro makes a 4.250 head gasket. Not much room between cylinders, but I have seen it done a few times with zero issue on NA stuff. Not sure how it would work if you hosed it down, or boost. THe shp block, I would limit to 4.185. I hear guys all the time talking how you can't do this or that, bore size is one of them. going from .030 to .060 for example, your making the cylinder wall .015 thinner, not .030. Going from .030 to .040, is only .005 thinner. Food for thought. Also, world products used to sell a 4 inch stroke, 454 sbc. It was 4.250 bore. Kinda dumb to buy the engine max bored with a brand new block. If you had to do it to get a few more years out of it, that's one thing.

[Zmechanic]

Specifications are a transfer of liability. They are only as good as the manufacturer is willing/able to accept the end user relying on them as a limit. And because businesses are in business to make money, they have to be conservative. Max bore is no different. It depends heavily on your use. There is no way Dart can guess how much stress you will put it under.

Not chiding anyone, just speaking as someone who is frequently on the spec setting side. Every product that goes out the door, there is likely many ways it could be pushed past it's defined limits with probably no noticeable effects to the user.

[bigjoe1]

I run the SHP block at 4.170 and 925 HP--- NO PROBLEMS




JOE SHEREMAN RACING

[ProPower engines]

Question, are the 4.00" bore and the 4.125" bore the same blocks? That is to ask, can the 4.00" block safely be bored to the recommended max of 4.165?

They are not both the same but I have at a customers request gone to 4.250 on a 4.00" block before they had a 4.125 block in production or was available I can't remember which way it was at that time but they do make a 4.125 std bore block now I have gone .125 over with. That block I did had a 400 main size although we used a spacer set.
I believe they sell a block with 350 main size and a 4.125 bore now.

You may want to look at that option if you don't already have the block at this time.