358CI ROUSH YATES D3 FORD
> DEAN PERKINS, PUKEKOHE, NZ
NASCAR engines may look decidedly low-tech on the outside, but the specs speak for themselves. This Roush Yates D3 donk punches out 850hp at 9000rpm and 550lb-ft at around 7400rpm, with just 358 cubes, a flat-tappet cam and a single four-barrel 830cfm carby. No blowers, no turbos, no nitrous!
This particular engine is from the XD Falcon driven by New Zealander Dean Perkins in their Central Muscle Cars class, and it’s been quite successful.
“About three years ago my wife and I decided to go to North Carolina and head up to Roush Yates, north of Charlotte. We’d heard all about them and we purchased what they call a D3 flattappet NASCAR engine. At the time they were just about to phase them out to be replaced by the FR9 engine,” Dean says. “I brought it back to New Zealand, and it really started doing the job for us. We managed to wrap up the Central Muscle Cars series last year and we’ve just backed that up again this year.”
The D3 engine is loosely based on the Windsor, in that it will accept Windsor mounts and bolt into just about anything that will accept a Windsor V8, but the nine-inch deck height has nothing in common with any of the production engines. A 302 Windsor uses an 8.2-inch deck height and the 351 Windsor’s deck height is 9.5 inches; the Cleveland is closest with a 9.2inch deck.
The D3 Yates heads are an evolution of the Cleveland head, and they flow 390cfm with a 2.18in inlet valve and 1.65in exhaust. Jesel rockers with a 2:1 ratio maximise the lift, but the solid lifters and thick-walled pushrods are basic 50s tech – if you ignore the rollerised 55mm cam bearings and the 0.850in-lift cam. In fact the whole underside of the cam tunnel is sealed off to stop oil hitting the crank at 9000rpm, and to keep plenty of oil around the lifters.
With a ratio of about 12:1, the compression is on the high side for premium unleaded, but still workable for those who like to push the limits. The current fuel used by NASCAR is a 98-octane 15 per cent ethanol blend called Sunoco Green E15. The guys at Roush Yates don’t recommend trying nitrous with one of these high-rpm race engines if 850hp isn’t enough for you, because the top ring land is very close to the top of the lightweight pistons. It is best being used as the RY guys intended: naturally aspirated and singing its lungs out.
Dean has plans for a new motor and a trip to The Mountain in the near future. “Roush Yates is helping us stroke one of these out to about 410 cubes,” he says. “Out next mission is to head to Bathurst, and we think that will go really well.”