RMRE Article on Blocks

This article by David Reher (Reher-Morrison) was in the National Dragster a couple weeks ago. Interesting information in light of the Buick block scenario.

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A strong, dependable block is the cornerstone of every racing engine. It's the foundation that supports all of your efforts to build horsepower. Yet as important as the block is in building a reliable and powerful motor, too many racers still insist on using a "good old block" as the starting point for a competition engine. In my opinion, that's a major mistake. The truth is that there aren't any good old blocks - at least when the subject is big-block Chevrolet V8s.
The big-block Chevy and its derivatives have become dominant in sportsman drag racing. There are armies of Rat motors marching through the staging lanes in the heads-up Super eliminators, Quick 32 and fast bracket categories. It's amazing that an engine that debuted 38 years ago is the powerplant of choice in our sport, but it's tough to beat the big-block's combination of performance, reliability, and affordability.

While the technology of drag racing has changed dramatically since the big-block Chevy was introduced in 1965, some racers remain stuck in the past. They still believe that an original 4.250-inch bore factory block is the ideal starting point for a big-block racing engine. Unfortunately, they're wrong - and that costs them time, money, and horsepower.

The fact is that aftermarket blocks from Dart and World and GM's heavy-duty Bow Tie blocks are vastly superior to the original production castings. They've got siamesed cylinder barrels that allow larger bore diameters
(up to 4.600 inches), stronger main bearing webs, thicker deck surfaces and improved oiling systems. It's simply throwing good money after bad to invest in a decades-old production block for racing when these modern alternatives are available.
The chief shortcoming of a production Chevy big-block is its limited bore diameter. The big-block's 4.250-inch cylinder bore diameter is a compromise even with stock heads - that's why the factory notched the tops of the cylinder bores for intake valve clearance in high-performance engines. Chevy engineers may have been concerned about the long-term reliability of siamesed cylinder bores when the big-block was designed. We know now, however, that siamesed bores work just fine in everything from street engines to Winston Cup and Pro Stock motors. Eliminating the water passages between adjacent cylinders is the key that opens the door to building big-inch big-blocks.

Increasing cylinder bore diameter improves engine performance in many ways. Within reasonable limits, a bigger bore is like getting free cubic inches. By that I mean that big-bore pistons aren't significantly more expensive than comparable small-bore pistons. The piston speed is the same regardless of piston diameter, and you don't invite the potential oiling problems and windage losses that come with long-stroke cranks. Most importantly, a large cylinder bore complements the big-block Chevy's combustion chamber design and valve spacing.

David Reher
Reher Morrison Racing Engines

 

Wow!

That's a lot of typing!!

Thanks for taking the time to share the article Jeff!

 

Well, actually I cut and pasted from their website (www.rehermorrison.com). They post all of David's articles from National Dragster on their website, also.

I think this article just reinforces our need for a new block. It's the last piece to the puzzle. Have fun.