Thread: mopar w8 motor
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Old 11-14-2003, 11:58 PM
sanborn sanborn is offline
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Join Date: May 1999
Location: shelbyville,tn,USA
Posts: 2,880

Eric, I am an oval track racer- And, they are a little different from drag engines.

It has been my experience that a good, serious oval track engine will produce approximately 2.1HP per CFM of intake flow at maximum valve lift. This assumes a 4 barrel carb, precision assembly, matched ports, good intake manifold, aggressive camshaft, etc. And, you measure valve lift with a dial indicator on the retainer(remember SB Mopar don't really have the advertised valve lift because of lifter bore angles). And, CFM flow is measured at max valve lift.

The case of our 358" engine; the heads flow about 360 CFM multiplied by 2.1 = 756HP. The actual dyno numbers were 746HP- pretty close. We had a "limited" engine we used last year; the stock W2s flowed 250 CFM at the actual max lift of .615" lift. 250CFM multiplied by 2.1= 525HP. Actual Dyno results were 527HP. I could go on about other engines, the results are about the same. So if you compare two sets of heads, one flowing 40-45CFM more than the other, the higher flowing set will produce about 85-95HP more than the lesser set. The difference in a drag engine would be more because you can use more lift/duration than we do on oval tracks.

I say again, the W5s may be your best choice because of cost. Going to the W7,8 or9 heads is sort of like jumping off into the deep water. You got to spend "real $$$" to complete the job because everything required to finish the changeover is expensive-special rockers(jesel or T&D), intake(needs porting), valves(2.180/1.625-5.56" long-titanium preferred),
different valve angle/valve reliefs(maybe pistons), different headers, different pushrods, lifters, and in the case of W8s-different valve covers. Then you have the water plumbing(custom), valley cover and plumbing the oil return to the pan. Then you need the "R" block to take advantage of the 18 head bolts so you can use serious compression.

I'm not trying to be rude, crude, etc. I've been through it--------several times.
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