Resoundingly defying conventional wisdom, small-blocks dominated the field at the 2006 Jeg's Engine Masters Challenge-the first year which allowed big-blocks and small-blocks to compete side-by-side. Even more astonishing, only one small-block Chevy showed up to the fight, while five of the six finalists hit the pump with small-block Fords. What those five front-running Blue Ovals shared is what proved to be this year's deadliest combination: a Windsor block topped with CHI Cleveland-style cylinder heads.
Running that exact setup was the School of Automotive Machinists, finishing Sixth overall in its maiden voyage into the Engine Masters Challenge. Founded by Judson Massingill, the School's curriculum encompasses the art of building hardcore race engines. The SAM graduates work in the top ranks of NHRA Pro Stock, NASCAR Nextel Cup, and the IRL, and are eager to share cutting-edge trade secrets with their old teacher. Naturally, the luxury of engaging in such covert dialogue with the industry's greatest minds most certainly inspired some of the unique design elements in the SAM 434-ci Ford.
While the SAM's resume includes everything from record-holding NHRA Stock Eliminator motors to race-winning NMRA Hot Street Mustangs, EMC's scoring system averages horsepower and torque from 2,500-6,500 rpm. Consequently, the SAM's biggest challenge was focusing less on maximum horsepower than it normally would, and more on low- and mid-range grunt. Ultimately, while the SAM's 434 posted the third highest horsepower total (690) in the finals, a shortage of low- and mid-range horsepower and torque is what precluded a stronger finish. Here is a closer look at how the School's combination came together.
Clevor InfluxRacers will be racers, which means stretching the rule book to get a leg-up on the competition. Since only production-based cylinder heads were allowed, the SAM opted to mate Ford Cleveland-style heads to a World Products Windsor block. Due to the 351C's extremely brief production run in the early '70s, very little is known about it outside of the Ford camp. Nevertheless, with 9.5-degree valve angles featuring a 4-degree cant, the Cleveland's "semi-hemi" cylinder heads were absolute monsters. "There are no 23-degree small-block Chevy heads on the market that can touch a canted-valve Cleveland head, airflow-wise," says Judson. "Since the rules didn't allow purpose-built race heads, it was an easy decision to go with CHI's Cleveland heads."
Bore And StrokeThe first step in designing the short-block was determining what bore and stroke dimensions to use to achieve the maximum-allowed displacement of 434 cubes. While the SAM typically employs oversquare cylinder dimensions in most of its high-winding race motors, it opted for a larger stroke than bore this time around. "I despise undersquare motors when it comes to making power, but to boost output at 2,500 rpm we didn't have a choice," says Judson. "The four-degree cant of the Cleveland heads helps de-shroud the valves, which is more advantageous in a small-bore motor. With the heads on the flow bench, we installed smaller and smaller sleeves until it started hurting airflow, and came up with a 4.061-inch bore. We combined that with a 4.185-inch stroke to get 434ci."
Short-BlockAnchoring the 434's internal and external bits is a World Products Man O' War block. Although it's technically a 351 Windsor block, it features 2.75-inch Cleveland mains for reduced bearing speed and friction. World also offers blocks with 302-style 2.25-inch mains, but the SAM opted for the larger Cleveland mains to increase crank journal overlap. The pre-prepped block required no additional grinding to clear the rod bolts, and was ready to go after a cleanup bore and hone. Despite an ultra-slick finish (6-8 RMS value) with no crosshatching, blow-by was non-existent, even with unbaffled valve covers.
The rotating assembly comprises a Winberg crank, Manley 6.000-inch rods, and Wiseco pistons. Although it required adding a fair amount of heavy metal to balance, the crank's relatively short counterweights cut down on windage. In fact, there is no windage tray at all, and that's just how Judson likes it. "From our experience, unless an engine combination is really messed up to begin with, windage trays are never worth any power," he says. On the other hand, Judson hoped to eek out a few extra ponies by running concave dish pistons instead of the more common reverse domes. "A concave dish sacrifices some quench compared to a reverse dome, but the Nextel Cup guys have been using them for years and say they're good for an extra 3-4 hp."
Top EndExpectations for a cylinder head run high when it boasts canted valves situated at an angle quite conducive to flow, and the CHI 218s didn't disappoint. Out of the box, they flowed 330 cfm, and the SAM's porters massaged that figure to 370/250 cfm, when all was said and done. The biggest surgical procedure involved welding the chambers shut and reshaping them. Doing so allowed a reduction in chamber size from 62 to 48ccs, and reshaped them to more closely follow the flat contours of the pistons. "With the 10.5:1 compression limit, reducing chamber size lets you run a bigger piston dish, which in turn moves the spark plug closer to the center of the chamber," explains Judson. "The top of the piston then essentially acts as part of the chamber itself."
Feeding the heads is a NASCAR-style Edelbrock/Yates Racing intake manifold, and getting it to fit involved some creative installation. The manifold's flanges were cut to get the roof of the runners to line up properly with the intake ports, and epoxy was then added to the heads so that the intake runners and ports would mate up just right. After slotting the manifold's bolt holes, the final step was fabbing up a custom lifter valley plate, since the Yates manifold is a "bottomless" design.
Lessons LearnedReaching the finals and finishing Sixth overall is quite respectable for your first trip to the Engine Masters Challenge. Nonetheless, even before it loaded its 434 back on the truck, the SAM was already investigating ways to improve its performance. "If you want to win races, no one is going to build a motor that gives up 50 hp up top to pick up power at 2,500 rpm," says Judson. "Be that as it may, we knew what this competition was all about beforehand, and everyone had to play by the same rules and points system. We just flat out got beat by the other finalists in the low-rpm range."
While the School competes to win, lessons learned on the dyno and at the track serve as precious educational material for its students. The team thinks that its combination may have been a bit too conservative. "We were the only ones in finals with small valves and runners," explains Judson. "That was supposed to help out down low, but it didn't. We were going to play around with bigger valves and runners, but ran out of time. Despite having a cam with the least amount of duration, tightest LSA, and most advance of all the finalists, we posted the third highest peak horsepower numbers." The team also suspects that the Yates intake manifold (every other SBF in the finals used a CHI intake) was oriented too much for high-rpm operation.
Now back home at its Houston, Texas-based shop, the SAM is contemplating this year's EMC rules so that it can get to work scheming up its next engine combination. Based on the School's excellent finish in its EMC debut, the entire PHR staff looks forward to seeing what Judson and crew bring to the party this October.
434-ci SMALL-BLOCK FORD
|RPM ||TQ ||HP ||RPM ||TQ ||HP |
|2,500 ||471 ||224 ||4,600 ||577 ||505 |
|2,600 ||483 ||239 ||4,700 ||585 ||523 |
|2,700 ||492 ||253 ||4,800 ||594 ||543 |
|2,800 ||500 ||267 ||4,900 ||601 ||561 |
|2,900 ||501 ||276 ||5,000 ||606 ||577 |
|3,000 ||497 ||284 ||5,100 ||610 ||593 |
|3,100 ||495 ||292 ||5,200 ||614 ||608 |
|3,200 ||494 ||301 ||5,300 ||614 ||620 |
|3,300 ||495 ||311 ||5,400 ||615 ||632 |
|3,400 ||494 ||320 ||5,500 ||613 ||642 |
|3,500 ||488 ||325 ||5,600 ||609 ||650 |
|3,600 ||481 ||330 ||5,700 ||604 ||656 |
|3,700 ||478 ||337 ||5,800 ||598 ||661 |
|3,800 ||480 ||348 ||5,900 ||593 ||666 |
|3,900 ||493 ||366 ||6,000 ||587 ||671 |
|4,000 ||507 ||386 ||6,100 ||581 ||675 |
|4,100 ||520 ||406 ||6,200 ||576 ||680 |
|4,200 ||537 ||429 ||6,300 ||570 ||684 |
|4,300 ||553 ||452 ||6,400 ||565 ||688 |
|4,400 ||562 ||471 ||6,500 ||558 ||690 |
|4,500 ||569 ||487 || || || |
Chi Mops UpWhile everyone is going cuckoo over the wild valve angles and flow numbers exhibited by GM's Gen III and IV small-blocks, their performance is just now matching what Ford accomplished with the 351 Cleveland nearly 40 years ago. Its 9.5-degree valves with a 4-degree cant were unheard of for a production motor back then, and still unheard of today. One shortcoming of the Cleveland heads, however, is that they were often better suited for high-rpm race motors than street applications. Likewise, with an extremely short production run of less than a decade, they are becoming increasingly difficult to find. And, with street motors displacing more cubes by the day, demand for them is going way up. That's where Australia-based CHI comes in, which offers a line of top-notch aftermarket Cleveland castings.
CHI offers heads with port volumes ranging from 190 to 258ccs, but its 225-cc units were the hot ticket at this year's EMC. Dubbed 3V, since its port volume falls right in between Ford's 4V and 2V heads, the CHIs offer several key improvements over the factory castings. "From a standpoint of architecture and airflow, Cleveland heads are the ultimate small-block heads from the factory, but that doesn't mean they can't be improved," explains John Konstandinou of CHI. "The biggest improvement we made is in the port sizing. Our 3V heads are like factory 4V heads but with smaller, and better-flowing ports. What a lot of people do is epoxy factory 4V heads, because the ports are way too big for street applications, so we eliminated the need to do that."
The concept of moving a large volume of air through the least amount of cross-sectional area as possible works quite well at the EMC, where low-end output is critical. CHI's 225-cc heads flow 340 cfm, despite a modest 2.4-inch cross section. "If you have a motor with small ports that flow enough air but then increase port size, you'll pick some more horsepower up top but give up a lot down low," says John. "Too often people get cylinder heads and grind on them, but very few street motors see more than 6,500 rpm, where smaller ports really help out." Other features include revised combustion chambers and hand-blended valve throats. The heads are compatible with all standard Cleveland intakes and valvetrain components, and bare castings can be found for $2,200. As good as a set of heads may look on paper, at the end of the day people want dragstrip numbers. John informs us that a 740-hp pump gas 427 with CHI heads has propelled a 3,500-pound car to 9.90s at 135 mph in the land down under. -Stephen Kim
|SCHOOL OF AUTOMOTIVE MACHINISTs |
|434-CI SMALL-BLOCK FORD |
|Bore: ||4.061-inch |
|Stroke: ||4.185-inch |
|Displacement: ||434 cubic inches |
|Compression ratio: ||10.3:1 |
|Camshaft: ||COMP, solid roller |
|Cam duration: ||248/253 degrees at .050 |
|Valve lift: ||0.830-inch |
|Rocker ratio: ||1.8:1 |
|Lobe separation: ||104 degrees |
|Installed centerline: ||99 degrees |
|Top ring: ||0.043-inch |
|Top ring gap: ||0.015-inch |
|Second ring: ||0.043-inch |
|Second ring gap: ||0.035-inch |
|Oil ring: ||3mm |
|Piston: ||Wiseco concave dish |
|Quench clearance: ||0.035-inch |
|Block: ||World Products iron |
|Crankshaft: ||Winberg, forged |
|Rods: ||Manley 6.000-inch |
|Main journal: ||2.75-inch |
|Main bearing clearance: ||0.0015-0.002-inch |
|Rod journal: ||1.8885-inch |
|Rod bearing clearance: ||0.0015-0.002-inch |
|Bearings: ||Clevite |
|Cylinder heads: ||CHI aluminum |
|Intake valve dia.: ||2.125-inch |
|Exhaust valve dia.: ||1.625-inch |
|Intake manifold: ||Edelbrock/Yates Racing |
|Carburetor: ||Holley 1,000 cfm |
|Ignition: ||MSD |