Photographers have an oft-used saying: "It's not the camera, it's the photographer." We would like to adapt that saying to the world of performance engines, ergo: "It's not the engine, it's the builder." Readers of Super Chevy magazine may already be familiar with Smeding Performance and the 572 big-block that was built for the Project American Heroes 1957 Chevy, or the more recent July 2008 cover, which featured one of Smeding's blown crate small-blocks.
But that's yesterday's news. Recently Ben Smeding teamed up with the legendary Bill "Grumpy" Jenkins to build and produce a limited number of street-ready 572 big-blocks. Every Chevrolet enthusiast, young or old, is undoubtedly familiar with "da Grump." Since the 1960s, this Super Chevy Hall of Famer stomped the competition with his innovations and won championships with Chevrolet power.
When we first became aware of the Jenkins/Smeding crate engine, we were champing at the bit to be the first to cover this story, and we did just that. This monster-cubed 572 is in direct competition with the GM ZZ572 crate engine, but is this just another crate engine on the market? The short answer is no. Through the collaborative effort of Jenkins and Smeding, the street-ready 572 has patented piston redesigns, as well as numerous hours of dyno-proven R&D, testing and tuning by Jenkins and the Smeding crew. It's this R&D, testing, tuning and the results thereof that make this engine what it is. The test results at times were quite surprising. Various cam swaps, larger carburetors and larger intakes didn't necessarily yield larger results on the dyno, putting to bed the "Bigger is better" mentality that exists in most of our minds.
The bottom end of each 572, whether it is the fuel-injected or the carbureted version, is built in the same manner. The rotating assembly consists of a custom 4340 forged-steel, internally balanced crank, custom 4340 forged-steel H-beam, lightweight 6.535-inch connecting rods with full floating wrist pins, and custom-designed pistons by Jenkins and Smeding.
Take a look at the piston redesign that Jenkins and Smeding came up with. On the right in the first photo is the custom forged piston; on the left is the forged stock-style piston.
The piston main trusses have been moved inward to be more inline with the major thrust of the skirt to substantially reduce flex. At the same time, this acts as a heat conductor, allowing the piston to run much cooler. With the cooler running piston we are able to run a half point higher compression without the danger of running into detonation.
The block is a Dart Big M with a standard 9.800-inch deck height, splayed four-bolt mains, CNC-machined 4.630-inch cylinder bores with scalloped water jackets, and a Canton oil pan. The crosshatch pattern and honing done with the torque plate is accomplished with studs rather than bolts. The studs minimize twisting of the block. They use a plateau hone, which is a rougher hone, then switch over to a real fine grit stone, and make three passes with it. Honing a cylinder leaves microscopic peaks and valleys on the cylinder wall's surface. The reason for this style of honing pattern is to remove peaks (which reduces friction) but leave the valleys for better oil retention.
Bill Jenkins and Ben Smeding inspect and discuss the various parts that are to be used in the 572 build. Among these are the all-important cylinder heads. The custom-made, high-flowing AFR 335 heads are completely CNC machined with 2.30-inch intake valves, 1.88-inch exhaust valves, and 121cc combustion chambers.
The intake valves used in this build are re-ground to 52 degrees in order to comply with the seat . Most valves contain a 45 degree angle. The theory behind the 52 degree grind is when using a higher lift cam (such as the one in this engine) there is more flow during the intake stroke.
Custom-made Scorpion full roller aluminum rockers are used on all the 572s for increased valvetrain stability.
Perhaps the most important part of this build is the amount of R&D that went into it. The R&D consisted of carburetor swaps, intake swaps, cylinder head swaps and even a cam swap.
In this photo Ben and Bill are discussing the various carburetor and intake differences.
Test 1. The first version of the 572 seen here on the dyno with the AFR 335 heads, Edelbrock Victor Jr. intake, custom-built Quick Fuel Technologies 950cfm carb, Petronix Flame Thrower billet distributor and a cam with 248 degrees/258 degrees duration (at .050) and .613-inch valve lift (intake and exhaust) was actually the best of the six different combos tested. Maximum torque was 730 at 5,100 rpm while the maximum horsepower was 748 at 6,000 rpm. Not content to leave well enough alone, more swaps and testing were done just to see what they would do.
Test 2: The second test version of the engine consisted of the same AFR 335 cylinder heads and same cam. What changed was the swapping out of the Quick Fuel 950cfm carb for that of a Quick Fuel 1050cfm carb and the Victor Jr. intake was exchanged for that of the Dart 4500 series intake.
This second combination yielded nearly the same results as the first combo. The maximum torque was 736 at 4,800 rpm and the maximum horsepower was 747 at 5,800.
Test 3: This test mule version is very much like the first build. This time around Ben Smeding had a theory and wanted to test it. Ben had taken a set of the AFR 335 heads and reshaped each combustion chamber wall nearest the intake valve. The hope was to take advantage of the reground 52 degree valves at maximum lift.
So off came the old heads and on went the experimental cylinder heads. The Victor Jr. intake was put back on as well as the Quick Fuel 950cfm carburetor and the same cam was used. Maximum torque was 688 at 4,500rpm while maximum horsepower was 673 at 5,500rpm. So much for that theory and those reshaped combustion chambers. It was back to the drawing board.
Test 4: Version number four was similar in every way to the very first configuration except for the Dart intake manifold and a custom-built 1050cfm carburetor that Bill Jenkins had brought out with him. The maximum torque was 736 at 4,700 rpm and the horsepower 726 at 6,000rpm. Definitely a step in the right direction compared to the previous test, but still not as good as the first version.
Test 5: This version of the 572 was a simple manifold comparison test. The engine combo is much the same as the first version, except a Dart 4150 intake was used with the smaller Quick Fuel 950cfm carb. Maximum torque was 737 at 4,700 rpm and maximum horsepower was 738 at 5,900.
Test 6: This last and final test was very much the same build as the first test version. The same Victor Jr. intake with a Quick Fuel 950cfm carb, the same cylinder heads, only this time a cam swap took place. The new, bigger cam that was installed had more duration (258 degrees int/268 degrees ex at .050) and more lift (.658/.672).
It proved that bigger is not always better. Maximum torque was 725 at 4,800 and maximum horsepower was 736 at 5,800.
Two different versions of the Smeding/Jenkins 572 engine will be available and rated at 760 horsepower at 6,000 rpm and a torque rating of 740 at 5,100 (improvements were made after we caught our flight back to Southern California). Cost for the carb'd 572 is $17,995. A fuel-injected version complete with the ACCEL Thruster EFI wide band O2 controller, computer, and harness will be available as well with the same cam, cylinder heads and bottom end build as the carbureted version.
The carbureted version will have all the parts that ran in the first test, but with a 1050cfm Quick Fuel carb rather then the 950cfm. Both engines have a compression of 10.4:1 and are built in limited numbers for street cars. There are other varied upgrades available, but you would have to call Smeding Performance about that.