19 August 2011
Project Silvia was a Krylon superstar. Back in the heady days of Sport Compact Car and paper magazines, it was our most popular project, and when we launched MotoIQ, dusting off the Silvia was one of our first stories. The rebirth of this project series was looking so promising, and then...
The problems all started in turn 3 at Streets of Willow, where the Disco Potato-boosted S13 junkyard engine didn't spool quite early enough to lug out of the corner in 3rd gear, but was too responsive to control if you dropped into 2nd. The same thing happened again in turns 4 and 5, and again on the skidpad. It made for a frustrating lap, and a lot of scolding from the drift-hating corner workers.
So I decided to fix the problem the only way I knew how. With junk I had laying around. I had a non-turbo S14 cylinder head just sitting there that hadn't cost me a dime. S14 heads share the low intake port position with the later U.S. SR20DE that most of us consider inferior, but the ports are actually larger than the front-drive heads, and total intake flow is actually about the same as the high port heads. Most importantly, for my purpose, the S14 head has variable intake cam timing. Advancing the intake cam boosts low-rpm torque. This better breathing creates more exhaust energy, which spools the turbo sooner too. Adding additional low-rpm cam advance on EVO IXs really wakes up their boost response, and I was hoping to achieve the same thing with the S14 head.
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