maching vortec heads
12-30-2010, 05:38 PM
#11
its a 350ho vortec with msd ignition 8.5 wires 8m blue ignition box holley 650 edlebrock performer rpm intake and revolution marine 4inch aluminum wet exchaust with a gaffrig air cleaner the motors only has about 15hours on it and i got a set of ss full roller rockers for it to put on
01-11-2011, 10:55 AM
#12
Here are some flow numbers from a stock head:
Lift....................CFM....................... CFM
Intake EX
.2......................127.....................10 1
.3......................185.....................13 8
.4......................222.....................14 9
.5......................216.....................15 5
.55....................215.....................157
The intake port peaks at .4 and looses air after that point.
The exhaust poops out at about the same lift. Meaning there is an 11 cfm increase between .3 and .4lift and a 6 cfm increase between .4 and .5.
After some port work with the same valve:
Lift..............CFM...............CFM
Intake Exhaust
.2...............126.................111
.3...............191.................152
.4...............236.................178
.5...............242.................184
.55.............246.................186
.6...............248.................187
If I were to go to a 2.02 I would expect a gain on the intake at .4 and higher but would need extensive bowl and short turn work. Not a bad gain for stock valves. An added gain would be to increase cam lift to .550 to take advantage of the extra airflow at higher lifts.
Lift....................CFM....................... CFM
Intake EX
.2......................127.....................10 1
.3......................185.....................13 8
.4......................222.....................14 9
.5......................216.....................15 5
.55....................215.....................157
The intake port peaks at .4 and looses air after that point.
The exhaust poops out at about the same lift. Meaning there is an 11 cfm increase between .3 and .4lift and a 6 cfm increase between .4 and .5.
After some port work with the same valve:
Lift..............CFM...............CFM
Intake Exhaust
.2...............126.................111
.3...............191.................152
.4...............236.................178
.5...............242.................184
.55.............246.................186
.6...............248.................187
If I were to go to a 2.02 I would expect a gain on the intake at .4 and higher but would need extensive bowl and short turn work. Not a bad gain for stock valves. An added gain would be to increase cam lift to .550 to take advantage of the extra airflow at higher lifts.
Last edited by JimV; 01-11-2011 at 11:00 AM.
