Skunk2 has some secrets to share and it's ready to tell the world. Divulging secrets is an anomaly in an industry characterized by closely guarded shops and companies that don't want even a whiff of their production practices publicized. After all, if company Y discovers how company X makes power, then company Y will copy company X and steal its business. There's some truth to it, but it nonetheless makes for a competitive environment without much unity or cooperation. Where's the love?
Skunk2, a company with a long-standing history of innovation, is throwing caution to the wind and releasing its secrets for the B-series engine. Skunk2 is revered for its horsepower-producing, all-motor vehicles, particularly those using the Honda B-series platform. People have long wondered how Skunk2 puts down such impressive dyno numbers, all the while on naturally aspirated engines in this age of turbo power.
The company is now ready to face the world and explain its strategies. Turbo was fortunate enough to soak up this knowledge and pass it on to our readers. Skunk2 is confident of its products and racecars and isn't afraid of revealing industry secrets; it's not known to back down from such risk-taking ventures.
Our day began in the farmlands of Norco, Calif., at the headquarters of Skunk2 Racing. For those who think the Los Angeles area is all fake tans and convertibles, drive an hour out of town and you can hang out with the cows as if you're in Wisconsin. By the time we rolled up to Skunk2, we were thanking the air conditioning gods because the weather was scorching.
Frank Balogh, the marketing director, and Dave Hsu, the managing director and Skunk2 mastermind, took us straight to the workshop. Engineers were working furiously on the yet-to-be-seen RSX racecar. Also in the facility were the DC2 front-drive racer and the Civic RR, which were at various stages of build.
We sat down with Dave and pumped him for all the information he had on the B-series engine.
Turbo: Dave, why share Skunk2 B-series secrets with the racing community? Are you guys leaving racing?
Dave: That is so far from the truth. We've been in hibernation, but have been busy at work building a new RSX racer. Also, we're comfortable with our development with the B-series engine and we've moved on with development on the K-series engine.
T: So will the original DC2 racer still be using the B-series engine or the K-series engine?
DH: Both the RSX and DC2 will be using the K-series engine.
T: Where do you get your inspiration for building a high-output, normally aspirated engine?
DH: The obvious inspiration is F1. For example, most of us are revving our normally aspirated drag race engines at about 10,000 rpm. The F1 guys are taking their engines to 19,000 rpm. And they're generating 300-hp per liter compared to our World Challenge engine that makes about 150-hp per liter. So we're quite a ways off from F1 standards.
T: Since you brought it up, let's first start with Skunk2's B16A Speed World Challenge engine. Does the B16A utilize all stock parts?
DH: Yes, we use factory pistons, connecting rods and crankshafts. However, all the components have been thoroughly massaged.
T: What do you mean by massaging?
DH: For starters, any endurance engine must start off with a good bottom end. We balance and blueprint the entire bottom end, check all the clearances on the bearing and usually try to build a slightly looser-than-stock-specification engine.
The pistons' valve pockets are fly-cut to allow for greater valve clearance so we can run larger cams. Not many people know this, but the factory Honda pistons are incredibly durable and the piston-to-wall clearance is extremely close, about .0015-inch, compared to many forged pistons that require much more clearance.
The key to building a high-output engine is containing all the compression gases within the combustion chamber prior to ignition. The ring tension is only about 10 pounds so trying to contain several hundred psi of compression with 10 pounds of ring tension isn't that easy. The next logical choice is to run extremely tight piston-to-wall clearances. The cylinder walls must be extremely cylindrical so the pistons ride smoothly along the walls. We usually outsource the coarse machine work and perform the final machining in house.