In the first installment of our Castrol Syntec Top Shop Challenge engine build, we started with some fancy-pants textbook design and geometry considerations for our Cosworth-built, naturally aspirated VQ35DE. We didn't get much past the bottom end, since there was too much background theory to go over. In Part Two, we skipped the tech and opted to talk smack on our competitors. This time we're back to see how Cosworth assembles our engine.
After machining, the final 0.004-inch of bore material is diamond-honed off. This machine is set up to hone in consistent strokes, ensuring removal of the exact same amount of material throughout the length of the bore. The deck plate is used in boring and honing to simulate the strain placed on the block by the heads and head bolts.
The thing about Cosworth is that this operation is altogether different from the tuners and shops we're used to working with. The company is an engine manufacturer that designs and builds race motors. Everything is constructed in-house, except for the nuts, bolts, and block and head castings. Reputation and enigma aside, it's hard not to be impressed as soon you step into Cosworth's Torrance, Calif. facility. How many shops have you been to that require signing in and proof of citizenship before going beyond the security doors?
There aren't any cars in the garage either, just endless rows of engines, machines, and barely identifiable tools. Inside the temperature-controlled engine build room are workbench cubicles broken down into various sub-assembly departments, manned by clean-fingered craftsmen wearing aprons on top of their crisp Cosworth uniforms.
We spent an entire week here to witness the step-by-step machining and assembly of our Castrol Syntec Top Shop Challenge motor, hoping to learn the secret(s) behind assembling a race-worthy engine. We didn't get anything-at least nothing tangible. Every question we posed was met with: "Well, it depends." But that's really the best real-world response anyone can expect.
Our Cosworth pistons are one-off, lighter, higher-compression units made specifically for this shootout. They feature the patented anti-detonation/anti-contact bands that reduce friction and minimize detonation in the ring-land area and the accumulator groove in the second ring land for additional volume to trap oil blow-by.
The guys at Cosworth are smart and honest enough to know that there isn't a concrete answer in engine design and manufacturing. Everything is a variable-design, prep and machining, and tolerances. Any alteration in one aspect of the engine reflects everywhere else. And when we asked what one parameter depends on, we were given several more open-ended answers, like an impatient grandfather would reply to an annoyingly inquisitive 2-year-old.
The reality is that even the pros at Cosworth, who build Indy, F1, and Formula Atlantic spec race motors, don't have some magical secret to building a motor. It's still nuts, bolts, rings, and lube, but what sets them apart is the vast knowledge base and wealth of experience the entire team possesses. This all ties into the decision-making process of re-engineering an engine. Engines are built on a rolling production line where each specialist works on their dedicated portion. Custom tools and jigs are regularly designed and fabricated by their in-house fab shop. This is how they crank out crate after crate of spec race engines throughout the breakneck pace of an entire racing season.
Cosworth's H-beam rods are single-piece forgings machined to minimize weight and have stress risers around the rod bolts. They also have lightening pockets in the rod face.
From the outset, senior engineers and technicians get together to examine a motor thoroughly and formulate a game plan. This encompasses everything from speccing out new bottom-end dimensions, head, piston, and manifold design, to identifying structural weaknesses of the existing block, machining strategies, and assembly tolerances. Much of this is based purely on years of experience. In the case of the VQ program, the Cosworth guys are up-front about the fact that it's still under development. They're prepared to tear down and update any section of the engine if there are further improvements to be had. The only parts set in stone-having already gone through the R&D process-are the heads, intake manifold, and pistons. Our particular motor will be the equivalent of a qualifying motor, compared to production crate motors, which means one-off pistons, as well as different tolerances. We're willing to trade longevity for more engine speed and increased horsepower.