Initial planning includes...
Initial planning includes performance targets and key engine parameters and specifications. In the case of this 383 cubic-inch circle track engine, a key goal was to achieve approximately 500 horsepower and 500 ft-lbs. of torque in an rpm range best suited to circle track racing. Here Brian Divis (right) explains to Dru Freese some of the block, piston, and connecting rod specs that will form the basis of this new engine.
With the need tentatively established in the first couple of meetings, engineering was tasked with creating an engine that would meet the entire target criteria -- horsepower rating, torque rating and price. "At BluePrint Engines all initial development work is done on computer using various software packages from companies like Audie Technology and Dynomation," explains Pabian. "The initial design is done on the "Dynomation " simulation software, but later in the process we can tie together the simulation software, with our "Cam Pro Plus" machine and our flow bench, using "Pro Flow" software and controls. Everyone knows that the key to power is in the heads, cam and manifold. Tying all this together early on in the process enables us to see what we need and even check multiple parts to see if they will deliver the output, all before we ever assemble the first prototype."
"Our research and development team is then charged with building up a prototype engine that we subject to exhaustive testing for power, durability and practicality. One of our five dyno cells is dedicated to testing performance and prototype engines, and it really got a workout with this particular project. Our engine development program typically involves extensive parts interchange before we ever get down to tuning for every last horsepower. We spend a lot of time with cam profiles, whether the final configuration calls for solid or hydraulic flat-tappet cams, or roller camshafts. Depending on the desired configuration, we also experiment with different types of OE and aftermarket cast iron and aluminum cylinder heads. And of course we'll try a variety of combinations of intake manifolds and carburetors, as rules or customer needs allow, to see which performs best in the desired rpm range," says John Nickel, BluePrint R&D Supervisor.
"After trying four different cylinder head designs on this particular circle track engine, we were actually able to achieve about 522 horsepower with one particular head configuration," adds Nickel. " However durability concerns caused us to request a change in the casting that resulted in a small but surprising drop in power. We tested other heads and still found, that even with the small drop in hp, our first choice was still the best choice. A little hp was sacrificed but durability and longevity were increased, and the engine is still a great investment for dollars spent and hp gained.
Horsepower and torque come...
Horsepower and torque come from the right combination of intake, heads and camshaft. BluePrint Engines will test several brands of heads and camshafts to come up the best combination. By connecting the flow bench software to the "Cam Pro" machine and then downloading all data into the engine simulation software program we can accurately predict the results and dial in the best likely combination of parts before ever building an engine. In the case of this 383 cubic-inch circle track engine, a key goal was to achieve approximately 500 horsepower and 500 ft-lbs. of torque in an rpm range best suited to circle track racing.
"It was only at this point that we actually got down to tuning to extract the most power possible. This process typically includes experimenting with a variety of carburetor jets, cam timing, ignition timing, and spark plug heat ranges. It may also include trying different types of intakes, and even different types of ignition systems, depending on the class rules. Incidentally, we sell a substantial number of performance engines with aftermarket fuel injection systems installed. All of this testing involves the monitoring of oil pressure, fuel pressure, EGT's on each cylinder, A/F ratios, brake specific fuel consumption, and engine vacuum, as well as constant observation for oil, fuel, coolant and vacuum leaks. Compression and cylinder leak-down tests are also part of the protocol," continues Nickel.
This process included repeated teardowns and examinations for wear, clearances, compatibility, break-in, and other indicators of normal or abnormal interaction between all of the parts. "Tear-downs allow us to validate our R&D work, and also assure proper break-in and wear patterns for cam lobes and lifters, rings and cylinder walls, bearings and crank journals, and other critical finishes, clearances, and surface wear patterns," notes Nickel."
"After many pulls on the dyno, we finally reached a point where we believed we had a workable model, with satisfactory and repeatable output in the 505-510 hp range, assuring that we could deliver to our customer an engine that actually exceeds advertised hp and torque," adds Nickel.
"At this point we passed the project along to our production, purchasing, parts and accounting people who determined that producing this particular engine would be practical, profitable, and affordable," notes Kirk. "A few final adjustments were made, and a decision was made to include this configuration in our product line."
"The final design made 500 horsepower at 6,200 and 475 ft-lbs. of torque, and the torque band peaked at a very usable 4,800 rpm, making it ideal for the type of circle track racing for which it was designed," explains Kirk. "Plus, we were able to achieve the cost and pricing goals we had set, allowing us to offer the engine we wanted at a price that racers would find quite fair for the power and performance offered by this engine configuration. So the entire process for this particular engine was a win, win, win."