Engine Tech Feature: Aftermarket Blocks are More Versatile than Ever

Engine Tech Feature: Aftermarket Blocks are More Versatile than Ever

Many of today's new parts offer benefits not found on the old pieces. And in many cases, those old pieces just cannot offer what the new ones can in the way of performance possibilities.

mance and availability factors. As it has undergone design improvements and upgrades, the base engine has essentially moved away from the original Hemi design and specs and morphed into a hard core racing block.

Marine usage is obviously going to be different from off-road, considering one is run in the water and one is run in dirt, rocks or mud. Even the way the engine will be run is different. Typically, off-road racers are on and off the gas, going up and down the rev range. Boat racers tend to run flat out for short periods of time, much like drag racers.

When a block manufacturer is starting with a blank piece of paper to serve a particular market, features that are more or less exclusive to that genre of racing are given priority. Lesser known but popular engines are also being reproduced as they have been proven to have more than just a casual following. These models are not obscure by any means but border on an almost cult-like following of enthusiastic supporters who want only “their” engine for whatever the use. Even in the modern era of engines, aftermarket block manufacturers are looking over the current designs, throwing in more than a few perks and bringing them to market.

As with anything, the best way to get a good read on the market is to ask the man who’s in it. Frank Beck of Beck Racing Engines, Phoenix, AZ, is quick to point out his affection for the new aftermarket blocks. “I was so glad when we quit using old cores,” says Beck. “What a nightmare! They had a 53 percent rejection rate. Of course you wouldn’t find the problems until after you beat them apart, drilled out every galley plug, thermal cleaned and magged them, many dollars later.”

Reinventing a Winner
The winner and still champion, the small block Chevrolet engine block, is available from Brodix, CN Products, Dart Machinery, Donovan Racing Engines, Engine Parts Warehouse with their PBM and Erson Cams brands, World Products and others. With both small block and big block blocks in iron and aluminum, the features available seem to be endless.

Bill Mitchell Jr. of World Products says most of his blocks are available in high density cast iron and 357T6 aluminum. Mitchell says, “All of our blocks are designed from the inside out in CAD using SolidWorks design software to improve any short comings of the originals.”

Dart Machinery’s Ted “Bud” Keating expands on the improvements companies have made to these legendary engine blocks. “Dart and Dick Maskin fixed the problems with OE blocks that made them more adaptable for use in the performance aftermarket. Improvements have included expanded water jackets for additional cooling, redesigned and unrestricted oil system circuitry for more oil flow to the main saddles, relocated and expanded cam tunnel for use with large stoke engines and larger diameter cam cores, thicker and Siamese cylinder bore walls for larger over bores and bore stability, thicker deck surfaces, heavier main webbing structure with splayed four bolt main caps, oversized and taller lifter bore bosses for more stability and availability to use larger diameter lifters.”
Some of Dart's improvements over OE blocks have included expanded water jackets for additional cooling, redesigned and unrestricted oil system circuitry for more oil flow to the main saddles, relocated and expanded cam tunnel for use with large stoke engines and larger diameter cam cores, thicker and Siamese cylinder bore walls for larger over bores and bore stability, thicker deck surfaces, heavier main webbing structure with splayed four bolt main caps, oversized and taller lifter bore bosses for more stability and availability to use larger diameter lifters.
Jason Brotherton of Brodix, which offers a 4.500˝ bore space small block, says, “We have reinforcements across the lifter valley and a whole list of options as well. For example, we have added more deck height options and more cam journal options. We even have some lightening programs that we can do to the blocks.”

CN Blocks’ Chris Nuytten says his company offers, “Spread bore spacing, almost unlimited cam and lifter positions, racing specific oil systems and racing specific cooling/water systems.”

Since Chevy engines have been around so long, there has been plenty of time for improvements over the years, say experts. Dick Boyer of Engine Parts Warehouse/PBM says a wide variety of features are now built into different variations of aftermarket iron and aluminum blocks. “Our iron small block Chevy raised cam iron blocks feature American-made high density cast iron castings with a .134˝ raised camshaft location.

This allows the engine builder to use up to a  4.000˝ stroke crankshaft and retain a standard base circle 50 mm camshaft, 50 mm roller bearing or 55  mm Babbitt cam bearings, bushed lifter bores, .842˝ or .904˝ lifter bore diameter, billet steel or nodular cast main caps, dedicated main oiling, four bolt main caps in all locations, 1/2˝ main studs and  standard small block Chevy oil pan, machined to clear a 4.000˝ stroke crank with H-beam steel rods.”

Aluminum small blocks are just as feature-packed, Boyer says, a claim echoed by other block manufacturers as well. In the unlimited or open types of racing, blocks serving that market are flush with features as well.

One of the oldest names in that field is Donovan who offers a 417 cid dry block based on the 392 Hemi for drag racing. All Donovan blocks are cast, B356 ingot aluminum using a strontium modifier and proprietary heat treat. Donovan offers blocks with anodizing finish for marine use or hipped for highest performance uses.

More racing blocks come from CN blocks, which also offers billet aluminum BBC in 4.840˝, 4.900˝, 5.000˝, 5.200˝, and 5.300˝ bore spacing. CN offers SBC in 4.400˝, and 4.500˝ bore spacing as well as Hemis such as their 4.800˝ Chrysler block that is similar to a stock replacement (without water) like Pro Mod cars use.

Alan Johnson Performance Engineering (AJPE) offers hard core racing parts such as the AJPE TFX 2002 Hemi, based upon the original 426 Chrysler Hemi. The TFX is a forged billet 6061T-6 block and include features like ductile iron dry sleeves and a .250˝ raised cam location. Bores range from 4.187˝ for Top Fuel/Nitro, all the way up to 4.467˝ for Blown Alcohol. TFX Deck heights are available from 10.725˝ Std deck, 10.825˝ +.100˝ Tall deck, down to 10.225˝ -.500˝ Short Deck.

Lifter spacing is wider than the stock 426 hemi, available as either 1.900˝ (+.100˝ spread) for TF cylinder heads or as 2.00˝ (+.200˝ spread) for typical blown alcohol cylinder heads. Big 2.125˝ Babbit cam bearings are standard, with 60 mm Babbit cam bearings available as an option.

Another AJPE block is the 481-X block, an exclusive AJPE design loosely based on the company’s earlier generations of AJPE KB Oldsmobile/BBC blown alcohol engines. The 481-X is a purebred racing engine, designed by Alan Johnson and John Rodeck to be the ultimate engine for Blown Alcohol racing and features both Chevy and Chrysler bell housing bolt patterns and dowel locations.

Other aftermarket blocks include small block Fords, available from World Products, Dart and others. More current engines, such as the Chevy/GM LS series come reproduced from World, Racing Head Services (RHS) and ERL. The new style Hemi blocks are available from companies such as World and CN Blocks.

But it’s not only the Big Three performance motors used in the more recognized racing classes that are available in the aftermarket today. Specialty blocks are popular (well, that’s a relative term, perhaps) as well. World offers an iron Chevy “W” block for 409-style fans. Donovan goes back even further and offers Model D (Ford inline) 4 cylinder block for vintage use.

One specialty block that covers both street and hard core racing is the series of MR-1 blocks coming out of K&M Performance and Kauffman Racing Equipment (KRE) of Glenmont, OH. But don’t bother looking for Chevys or Fords. K&M makes only Pontiac blocks in cast iron, aluminum and billet aluminum in numerous configurations. Steve Kauffman says the materials of choice are: “Certified 30 gray iron, the cast Aluminum is T356 and the billet Aluminum is 6061 T6.”

For upgrades K&M blocks offer a bigger cylinder bore up to 4.400˝, leaving the stock block that allows only 4.210˝. Kauffman says, “With the larger cylinder bore, we have added more wall thickness in the water jacket area – up to .250˝ thickness with a 4.350˝ bore.”

Another area of concern on any block is the lifter bore area and K&M blocks are solid compared to the stock block being open in the center with minimal bracing. The K&M block also offers main webbing that is thicker than stock blocks. “The three center main caps are 4 bolt splayed (outside bolts are at an 18 degree angle), which is a far superior arrangement to the four bolt straight main caps used on the stock blocks,” says Kauffman. The cam tunnel can be opened up for a 55 mm cam where the stock block does not have enough material at the rear of the block to allow that size of opening and be able to still insert the correct cam plug. Along with the wide range of options for Pontiac fans, stock pieces will bolt up to MR-1 and MR-1A (Aluminum) blocks.

Those looking for aftermarket blocks serving the demands of the import arena  won’t be disappointed. Dart manufactures a Honda B18 block that is capable of hitting 2.2L due to its expanded cylinder bore and taller deck configurations. Elsewhere, ERL sleeves and machines OEM cast aluminum blocks of Honda, Toyota, Mitsubishi and Nissan engines.
For these aftermarket blocks, the question comes down to their rebuildability factor. Are they designed for as long a lifespan as, say, the original 350 Chevy? “Every bit the same if not more,” says Mitchell Jr. “We build our blocks for horsepower and durability. They may not be as light as the originals but then the originals were never designed to do what our blocks are capable of. The originals were all thin wall blocks so there is no real way to accomplish both lightweight and strength.”

Dart’s Keating says he’ll happily put his trust in the durability of his company’s castings, thank you very much. “Our cast iron products have properties that promote multiple rebuilds, overbores and repairability. That’s what’s called recurring value.”

Nuytten, too, says: “Our blocks are used in extreme situations. The lifespan usually depends on tune up and parts breakage. With a proper tune up, these blocks last many seasons. They are also easily repaired if the need arises. The sleeves are easy to change and re-machine and the block is also very weldable in the case of catastrophic parts failure.”

Durability is, of course, directly related to maintenance. “As long as it is taken care of the block should last forever,” Brotherton says. “One advantage of an aluminum block is the repairability. You can replace the sleeves easily and if you have some damage to the block, chances are we can weld it up and remachine it to like new condition.”

And we’re not just talking three or four racing seasons, say our experts. “Depending on the build, maintenance, and tune, the length of service for a Donovan aluminum engine block is quite long. We have seen 30 year old blocks in recent sprint car competition,” Kathy Donovan says.

“The materials we use today are far superior to those used in the early years,” explains Kauffman. “All of the components used in today’s engines have much finer tolerances than those used in the ’60s, ’70s or ’80s due to CNC machines. Computer designs on all the parts are much more precise. This is one of the reasons, as most can see, even the new cars and trucks of today offer way more warranty miles than in the past.”

Sean Ragains from ERL says, “This is the great thing about using the new OEM blocks because these blocks have come a very long way since the old 350 Chevy. All the engineering that we have put into our Superdeck system is to only improve on the durability and strength of these blocks. We are seeing these blocks last longer under heavier strain.”

RHS’s Jennifer Lee agrees. “The OE blocks in the last couple of decades have concentrated on lightweight castings for cost savings in the manufacturing process and lighter finished package. However, this sacrifices strength in an endurance and/or performance application. Aftermarket blocks as a whole have a longer life span than the OE blocks, because they have been engineered to add the material and strength required even if the resulting block is a little heavier.”

Never one for blushing sentimentality, when it comes to using new blocks over old ones, Beck says, “That’s the way I would prefer to do it with new, better designed parts that aren’t worn out, patched and blown up.”

Picking an aftermarket block today is a lot like a trip to the grocery store – you’d better make a list. You’ve got a lot to choose from!

Article courtesy of Engine Builder magazine.

For a complete list of cylinder block suppliers and manufacturers, visit Engine Builder’s Online Buyers Guide at www.enginebuildermag.com/buyersguide.

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