447 HP Vortec Small-Block Build - Budget Sledgehammer

There are many different ways to build an engine, and when the object is a 350 Chevrolet, it would seem they've all been tried. We've seen or read about our share of "low-buck" builds, so the very concept is nothing new. The challenge was to try to do it better. To us, the essence of a low-buck build is creating value, and our yardstick for that is power for the money. Making the most under these criteria takes very careful parts selection, beginning at the engine core itself, and an eye on the overall combination. To get to the punch line, our 350 made 447 hp on Speed-O-Motive's DTS engine dyno, and when every greenback we doled out was accounted for, we had change left over from $3,500.

Anytime such an undertaking is carried out, there will be some who will claim that they can make even more for less, and that may be. As we point out in our price list, there are a few areas where the budget could legitimately be trimmed here and there, and if you can save over our example, we'd congratulate you on a job well done. We list full retail on all of the parts used, including the cost of the carb, distributor, plug wires, and all those little items that usually get lost on some engine cost price lists, including the cost of the basic engine core. We stayed away from the trickery of the sweetheart deals, like claiming $25 for a swap meet carb, or a set of ported heads that a buddy was giving away while sweeping up under his workbench. Sure, those deals come along, and if you're lucky enough to find them, that's great. However, the retail prices we quote are what it takes for anyone to buy the parts we used, at least at the time this story was written. It can be argued that an individual engine build could be done cheaper, but we can say for sure that many have spent far more and ended up with far less power for their money.

The Build

A successful engine build comes down to planning, and for us, that began at square one-the basic engine core we used as our foundation. Chevy 350s were produced for decades, but we had a specific idea of what we wanted and why. Our core, purchased from AA Midwest, is a late-model truck Vortec or Gen II small-block 350. GM sufficiently refined the engine package to offer many improvements in quality. These late-model blocks can commonly be had with the robust four-bolt main bottom-end configuration, with an excellent factory windage tray arrangement. There is no debating the Gen II's superior gasket sealing systems, reducing the possibilities of oil leaks. Those features are nice, but the real advantage in our low-buck power plan is the factory hydraulic roller cam configuration these engines are designed to accept. With a factory hydraulic roller cam engine, we would gain the advantage of a roller, be able to re-use the factory lifter retention yokes and spider, the pushrods, and even re-use the lifters themselves. These items alone represent the potential for a significant cost savings, while reaping the roller cam's power and durability benefits.

We've seen scads of these late-model engines torn-down, and are always amazed to find remarkably low wear in the key components. Decades ago, the typical engine core would normally be worn to the hilt, rendering it unusable without extensive machining. In contrast, late-model engine cores routinely come in with negligible bore wear, and serviceable cranks, rods, and even pistons. We've heard many theories proposed to explain the readily apparent improvement in OEM engine durability, but what makes sense to us is the use of improved, lower-friction rings, closer control of engine tolerances and machining, better fuel management with fewer internal deposits as a result of EFI systems, and lower rpm with overdrive transmissions.

Our engine came direct from a core-supplier, and was simply plucked from inventory with no special selection involved. Once torn down, it proved to be a good example of what is normally found inside late-model blocks, showing negligible bore wear, and serviceable journal surfaces. There was some staining of the cylinder walls where the rings rested during storage, but our inspection confirmed that the engine was in good overall condition.

Knowing the condition of our engine, we had our starting point, and could decide on the course for our buildup. We could've fully rebuilt the engine, grinding the crank, and boring the block to fit oversize pistons as a matter of course, but the excellent condition of the core opened another possibility-that of an old-school rings/bearings/gaskets engine overhaul, rather than a full all-new buildup. There was no doubt that a simple overhaul would be more in keeping with a budget approach, and even represent what could be achieved by someone with a totally stock engine in very good original condition. The biggest downside to this route would appear to be the factory dished pistons, which could hamper the compression ratio enough to compromise output. We weighed the cost benefits, and decided to keep the bottom end stock, and would target the rest of our component selection around making the most of the freshened factory short-block assembly.

Power Parts

We knew the cylinder head choice would be critical to the our effort's success, and carefully considered the choices available in terms of cost and power potential, as well as how these possibilities would dovetail with the components we already had, and our goals for the finished engine. We selected the cast-iron CH350C Lightning cylinder heads from Enginequest. These heads are essentially Vortec replacements, sharing many features with the excellent OEM Vortec heads, but sufficiently improved in ways that would help achieve more power than the stock Vortecs. The Enginequest heads are aftermarket iron castings, designed with good airflow and power in mind. The intake ports feature 180cc runners, which is sized right on target for a 350-cube engine, for good torque production and port velocity. We liked the compact 62cc chambers, which would help boost the compression ratio with our factory dished pistons. In fact, with moderate milling (25 thousandths), we were able to achieve slightly over 10:1 compression with 58cc chambers, which is right were we'd want to be for serious pump-gas street performance. The intake ports flow in the neighborhood of 230 cfm, which is enough to produce well into the mid 400hp range, based on common measures of power potential versus airflow capacity. The key for us would be to take maximum advantage of the available flow, extracting all the power these heads are capable of. As a point of interest, Shaver Racing Engines performed our flowbench testing and head assembly prior to our engine's assembly at Speed-O-Motive. Shaver offers EQ Vortec heads in assembled form, starting at $860.50 for a pair.

Of course, our avenue for taking advantage of the head's potential lies right in the heart of our engine's short-block; the camshaft. With a hydraulic roller cam, we'd have the potential to safely employ much more lift than we would dare use with a flat-tappet cam on the street, and still keep the overall duration at a moderate level. This would help generate strong torque in the engine's intended operating range of approximately 6,000 rpm. By maximizing the torque production, we're also maximizing the horsepower the engine will deliver in its operating range. We had frequent PHR contributor David Vizard spec our cam, and he selected a custom COMP Cams hydraulic roller single-pattern grind, with 224 degrees duration (at .050) on the intake and exhaust lobes, and 0.352 inch lobe lift. David specified a relatively tight 108-degree lobe separation angle, which would serve to bring the torque on hard, and preserve cylinder pressure compared to a similar cam with a wider spread.

We knew the cam would make hard-hitting torque, but questioned whether it would have the legs to run up the rpm range, which would be vital to making big horsepower upstairs. In fact, we questioned whether the 224 degrees of duration would allow the engine to make peak power anywhere near the 6,000-rpm range, an rpm capacity we know a 350-cube engine would require to make over 400 hp. When questioned, Vizard reassured us by stating confidently, "I've been speccing cams for well over 20 years, and haven't been wrong yet, but maybe I'm due." Complementing the cam, we increased the rocker ratio from the stock 1.5:1 to 1.6:1 with a set of COMP Magnum rockers, bumping the valve lift delivered by our cam from 0.528 to 0.563 inch in the process. The high lift delivered by this combination would be a big help in high-rpm power. We didn't skimp on valvesprings, since power production only continues as long as the valvetrain is under control. We used COMP's high-tech beehive springs, which significantly reduce valvetrain weight, and resist the onset of power-limiting valvespring surge. Prior testing had shown that the beehive springs extend the rpm potential of a hydraulic roller system.

With this, our engine's internals were essentially determined, and all that remained were the supporting parts. There was no misunderstanding that we needed an effective induction system with enough capacity to make power up top and a layout that would encourage torque as well. As a nod toward value, we went with a Professional Products Crosswind two-plane intake manifold. We know this intake manifold configuration delivers the best overall power from engines operating up to 6,500 rpm, and prior testing has shown the Professional Products' piece is a worthy unit. To top the manifold, we used a new Holley 3310 750-cfm vacuum-secondary carb, probably the most universal high-performance carburetor ever offered. With 350 cubes to feed, the 750 cfm offered by this carb looked like plenty to keep the engine happy up into the 6,000-rpm range, and it is very hard to beat this carburetor on the basis of airflow per dollar spent. With the addition of a Summit HEI distributor and MSD wires, we had our 350 combination established.

On The Dyno

Anticipation was pretty high on dyno day, as dyno operator Jake Hairston mounted our sweet-looking small-block to the DTS dyno at Speed-O-Motive. Very few engines we've put together have ever drawn such widely varied "guesstimates" regarding the power outputs. Running the numbers on a variety of engine simulation software programs showed output nearly all of us regarded as outrageously optimistic. As the crowd gathered for testing, jawbones were working overtime. We had doubters who maintained that 400 hp would be a stretch [including the author, Steve Dulcich-ed.], while a few in the group figured the engine would be a little stormer. Jake couldn't be engaged in giving an opinion, stating, "We'll be up and running in a few minutes, and I'm just going to wait and let the engine tell the story." With the timing dialed in at a conservative 32 degrees of total advance, the engine was fired and brought to life. Before long, a few stabs of the throttle were made to gauge the carb mixture, and the raw torque numbers looked encouraging. We caught a few numbers flashing well over 400 ft-lbs on the torquemeter-it looked like this thing would make some power.

Our first power runs came on really strong, building torque to 430 corrected ft-lbs, but the power went awry at higher rpms, basically nose-diving just before 5,000 rpm. (Power maxed out at 4,900 rpm with just 400.5 hp registered.) The peak torque rpm of about 4,500 rpm indicated this engine would really run the number upstairs if everything was right, predicting a peak power number somewhere in the vicinity of 6,000 rpm. If that held true, there was no doubt about eclipsing the 400hp barrier, in fact it would be substantially past that point. Jake quickly detected that the high-rpm miss was ignition related, and went to work replacing the HEI module with a high capacity four-pin Dyna-Mod unit from Performance Distributors. With that, the tension in the test cell was higher than ever as the engine was once again loaded against the dyno. The module definitely solved any ignition-related problem, as the engine screamed to the 6,400 rpm upper limit set at the control console, never missing a beat. The power kept coming as the 350 reached a peak at 6,200 rpm, running up the range with even more fury than we had hoped for. We had over 440 hp on the read-out! This combination just kept hanging on as the revs built, and with peak output at 6,200, it was not really surprising that the peak number was well above expectations. Interestingly, the Holley 3310 showed an ideal air/fuel ratio right out of the box. We never cracked open a float bowl for a jet change.

Dialing-in the ignition timing through a timing loop, we achieved a repeatable 447 peak horsepower at 6,200 rpm, and equally impressive torque at 445 ft-lbs. Our cheap 350 proves that outstanding output can be had on a budget. Did we just get lucky on this one? The real magic is in selecting the combination to work together and get the most from the each component. No doubt, our well-planned 350 nailed that requirement.

Cylinder Head Flow

PHR would like to especially thank Shaver Racing Engines for performing the cylinder head flow testing and head assembly for us. Shaver is a dealer for EQ cylinder heads, and offers the Vortec EQ Lightning heads in bare or assembled form with a variety of spring and valve packages. (We suggest you call 310-370-6941, or check out www.shaverengines.com, for more information.) Our heads were assembled with cost-effective Manley budget performance valves (1.94-inch intake and 1.50-inch exhaust), a three-angle valve job, and COMP Beehive springs and retainers. That's all. No additional clean-up or port work was performed. As you can see, flow values for the EQ are better than stock, yet still relatively modest. It just goes to show that for a street engine, the amount of flow is a secondary concern to the quality of flow. Other than a .025-inch mill job to up the compression, our heads were box-stock.

On The Flowbench

Tested At Shaver Racing test depression 28-in. H2O

Budget Vortec 350-Turnkey Crate Motor

Speed-O-Motive helped us build our motor and can build you a near replica of our budget Vortec 350-the only difference will be an upgrade to stainless steel roller rockers, a Pertronix Flame Thrower HEI, and a Holley 750 double-pumper. The price of $5,450 includes assembly, dyno tuning, and free shipping. By comparison, a little shopping will uncover more than a few crate engine packages that cost as much or more and don't deliver the goods like this little number. Keep in mind everything that you are getting, including the carburetor, dyno-tuning, and shipping costs. Figure in the whole package, and this combination is quite a performance value. To find out more about ordering a budget Vortec 350 like this, go to www.speedomotive.com, or call 626-869-0270.

Dyno Results

TESTED AT SPEED-O-MOTIVE
DTS ENGINE DYNO

The Cost Breakdown

Machine Shop Labor Cost