Q&A WITH TONY MCAFEE OF DART MACHINERY
CHP: How did this redesign start, Tony? Tony McAfee: It was time to upgrade the Iron Eagle and Pro 1 heads, so what we did was take the old design and played with the wet flow process we've been using on our Pro Stock heads, looking to make a better mousetrap.

CHP: What are the advantages of the wet flow process? TM: You're simulating a running engine more closely than on a dry flow bench. An engine doesn't run just on air. When you add fuel, the whole airstream becomes heavier; it does much more than dry air.

CHP: Like what?TM: When you see the fuel run, it runs in streams. You see the vortices in the combustion chamber. And no matter what, fuel attaches to the port walls... It's gonna happen.

CHP: And you can actually see this on the wet flow bench? TM: Yes. It can be seen in black light, through a half port made of clear plastic. You can see everything the mixture does, where it's at, how it moves. We've been able to see many things we couldn't imagine.

CHP: So what have you learned so far? TM: The combustion chamber should be thought of as an extension of the intake port, and the way it's shaped can improve air/fuel distribution around the valve. The plug is also moved toward the exhaust port; it's now in the same place as a Vortec head. Flame travel is one of the big positive sides to a Vortec head. Most people think it's airflow, but that's only half of it.

CHP: What other areas have you found to be important? TM: The cross section of the port, for one. We've also worked on the short turn and the diameter of the throat. They need to be a specific area based on valve size. Also the bowl and valve-seat area. We want it to gather loose fuel, rather than let it hit just the back of the valve. Once it leaves the valves, you have to make the mixture keep moving.

CHP: Once you've seen how the air/fuel mixture acts on the wet flow bench, how do you go about achieving the results you're looking for?TM: It's trial and error, using traditional methods: epoxy, grinding, and welding. We do anything we can do to make it flow better. I'm still trying to teach myself how to influence the mixture flow.

CHP: Really? TM: Wet flow technology is in its infancy. I don't know half of 1 percent of what we'll know in a few years.

GOING WITH THE FLOW
Dry Flow (@ 28 inches of water)
Pro 1 215Pro 1 215 Platinum
Lift (inch)Intake (cfm)Exhaust (cfm)Intake (cfm)Exhaust (cfm)
0.200128.0 114.8144.1107.0
0.300184.1142.8191.1139.6
0.400230.5165.8228.2 166.4
0.500260.0178.8258.1185.1
0.600260.0186.3265.3195.6
0.700260.9191.3268.2 199.9
Wet Flow (@ 55 inches of water)
Pro 1 215Pro 1 215 Platinum
Lift (inch)Intake (cfm)Fuel (lb/hr)Intake (cfm)Fuel (lb/hr)
0.200165.658.3174.058.9
0.300230.879.3228.678.8
0.400276.394.4278.695.4
0.500308.4106.4312.6111.9
0.600328.9113.7331.2113.9
0.700324.8112.4329.5111.1
383 STROKER SPECS
Displacement384.6 ci
Bore x Stroke4.040 x 3.750 inches
Rotating assemblySpeed-O-Motive cast crank and forged rods
PistonsMahle forged
Compression10.30:1
HeadsDart 215cc, 72cc chamber
Intake manifoldDart single-plane
CarburetorHolley 750-cfm Street HP
DistributorPertronix Flame-Thrower
CamshaftComp Cams hydraulic roller
Valve lift0.520/0.540 inch, intake/exhaust
w/1.6 rockers0.555/0.578 inch, intake/exhaust
Duration at 0.050236/248 degrees, intake/exhaust
Intake centerline108 degrees
Lobe separation113 degrees
DYNO DETAILS
Headers13/4-inch Hedman long-tubes with 18-inch extensions
Fuel91-octane unleaded
Jetting75 primaries, 80 secondaries
Timing37 degrees
Iron Eagle Platinum
Max torque464.2 lb-ft @ 4,600 rpm
Max power463.9 hp @ 5,900 rpm
Average torque425.4 lb-ft
Average power335.8 hp
Pro 1
Max torque473.1 lb-ft @ 4,700 rpm
Max power479.7 hp @ 5,700 rpm
Average torque432.3 lb-ft
Average power342.2 hp
Pro 1 Platinum
Max torque483.8 lb-ft @ 5,000 rpm
Max power503.2 hp @ 6,000 rpm
Average torque441.5 lb-ft
Average power351.0 hp
SOURCE
COMP Cams Federal Mogul(Fel-Pro Gaskets)
Dart Machinery
353 Oliver St.
Troy
MI  48084
248-362-1188
www.dartheads.com
Moroso
Guilford
CT
2-03/-453-6571
www.moroso.com
Denso Corp