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Head Flow Comparison |
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Flow bench #s can be deceptive. If you have a set of heads flow benched and they don't match advertised cfm it can be from testing methods and differences in the benches. Possibly newer benches are more accurate but could also be the manufacturer padding the #s of their product to make it look better.
You be the judge
Stock Magnum 5.2/5.9 hds vs Heavy Duty heads
& RT 2.02 Mopar heads
Hughes Engines and EQ Cylinder head sell the Heavy Duty heads (flow chart from Hughes)
www.hughesengines.com/heavyduty
www.eqcylinderheads.com/flow.html
Valve
LiftIntake
Exhaust
OEM
Heavy
DutyR/T
OEM
Heavy
DutyR/T
1.920"
1.920"
2.02"
1.60"
1.60"
1.650"
0.100"
51.2
68.2
61.4
55.1
57.2
65.9
0.200"
121.1
124.1
119.2
109.0
114.1
120.2
0.300"
181.5
179.6
169.3
148.4
155.3
153.7
0.400"
207.5
213.8
211.0
170.8
180.0
168.0
0.500"
209.0
227.0
220.6
176.2
187.3
174.0
0.600"
208.4
233.1
220.6
178.4
188.7
176.0
Stock Magnum 5.2/5.9 hds vs Edelbrock Performer RPM alum 2.02heads
INTAKE PORT CFM
LIFT
STOCK
EDELBROCK
0.100
60
62
0.200
120
119
0.300
168
175
0.400
195
225
0.500
202
251
0.600
194
260
EXHAUST PORT CFM
LIFT
STOCK
EDELBROCK
0.100
59
52
0.200
113
105
0.300
142
142
0.400
148
169
0.500
150
185
0.600
151
190
Info source
EDELBROCK Corp.
2700 California St., Dept PHR
Torrance, CA 90503
(310) 781-2222
www.edelbrock.comFlow benches all show different #s on the out of the box Eddy heads depending on the machine shop. Here are what some got for the base flow rates @ 550Lift & 28" though Ill be running .580 lift on the intake side with the new cam.
Edelbrock got 256/187cfm approx
Hughes Engines got
236/186cfm @ 550
My machine shop got 200/156cfm
My Eddy heads out of the box flowed 200in/156cfm @550 lift before porting This is how the Eddy heads now flow after stage III porting, gasket matching & 3 angle valve job & decked. Before and after port work flow gains are 23% on the intake side and 36% on the exhaust side. That is a pretty large increase in flow over out of the box. Based on Hughes Flow bench that is 290/253cfm, on the Edelbrock bench these heads would flow 317/254cfm!
