CFM on the 500 EFI Heads?
01-04-2016, 06:11 PM
#3
Registered
iTrader: (3)
.300=197/150
.400=233/174
.500=258/184
.600=280/187
.700=287/187
ERRONEOUS NUMBERS. THROW THESE OUT THE WINDOW. REFER TO CALLING MERCURY RACING TECH LINE, OR MARINE KINETICS TO SEE WHAT A STOCK 500EFI HEAD FLOWED ON THEIR FLOW BENCH BEFORE PROCEEDING
Everyones flow numbers will be different. Those numbers were tested on a 4.500 bore, no pipe on the exhaust. Gives you an idea. Going to a Dart, AFR, Brodix, RHS, Trick Flow, etc, is a sure way to see power increases. Those old Merc Iron heads, were pretty poor stock, compared to a modern Hi performance aftermarket head.
When comparing flow numbers, keep in mind the bore size the heads were flowed on, whether or not the exhaust had a pipe on it, etc. Also, was it an actual out of the box head, or did it have a trick valve job for magazine promotion, etc .
Last edited by MILD THUNDER; 01-05-2016 at 10:50 AM.
01-04-2016, 07:53 PM
#4
Registered
iTrader: (4)
http://users.erols.com/srweiss/tablehdc.htm
Last edited by Rookie; 01-04-2016 at 07:58 PM.
01-04-2016, 09:13 PM
#5
Registered
iTrader: (3)
.200=149/117
.300=197/150
.400=233/174
.500=258/184
.600=280/187
.700=287/187
Everyones flow numbers will be different. Those numbers were tested on a 4.500 bore, no pipe on the exhaust. Gives you an idea. Going to a Dart, AFR, Brodix, RHS, Trick Flow, etc, is a sure way to see power increases. Those old Merc Iron heads, were pretty poor stock, compared to a modern Hi performance aftermarket head.
When comparing flow numbers, keep in mind the bore size the heads were flowed on, whether or not the exhaust had a pipe on it, etc. Also, was it an actual out of the box head, or did it have a trick valve job for magazine promotion, etc .
.300=197/150
.400=233/174
.500=258/184
.600=280/187
.700=287/187
Everyones flow numbers will be different. Those numbers were tested on a 4.500 bore, no pipe on the exhaust. Gives you an idea. Going to a Dart, AFR, Brodix, RHS, Trick Flow, etc, is a sure way to see power increases. Those old Merc Iron heads, were pretty poor stock, compared to a modern Hi performance aftermarket head.
When comparing flow numbers, keep in mind the bore size the heads were flowed on, whether or not the exhaust had a pipe on it, etc. Also, was it an actual out of the box head, or did it have a trick valve job for magazine promotion, etc .
01-05-2016, 05:26 AM
#6
Registered
.200=149/117
.300=197/150
.400=233/174
.500=258/184
.600=280/187
.700=287/187
Everyones flow numbers will be different. Those numbers were tested on a 4.500 bore, no pipe on the exhaust. Gives you an idea. Going to a Dart, AFR, Brodix, RHS, Trick Flow, etc, is a sure way to see power increases. Those old Merc Iron heads, were pretty poor stock, compared to a modern Hi performance aftermarket head.
When comparing flow numbers, keep in mind the bore size the heads were flowed on, whether or not the exhaust had a pipe on it, etc. Also, was it an actual out of the box head, or did it have a trick valve job for magazine promotion, etc .
.300=197/150
.400=233/174
.500=258/184
.600=280/187
.700=287/187
Everyones flow numbers will be different. Those numbers were tested on a 4.500 bore, no pipe on the exhaust. Gives you an idea. Going to a Dart, AFR, Brodix, RHS, Trick Flow, etc, is a sure way to see power increases. Those old Merc Iron heads, were pretty poor stock, compared to a modern Hi performance aftermarket head.
When comparing flow numbers, keep in mind the bore size the heads were flowed on, whether or not the exhaust had a pipe on it, etc. Also, was it an actual out of the box head, or did it have a trick valve job for magazine promotion, etc .
plus,I guess at rebuild time,you should get a trick valve job like all the after market heads get .
01-05-2016, 05:36 AM
#7
Registered
Question, say you are at refresh time and decide on a set of aftermarket heads, do most raise the exhaust port changing your exhaust pipe location? Meaning same headers but new tails?
01-05-2016, 06:06 AM
#8
Registered
most do raise the exhaust port.but sometimes,trimming the hole a little bigger gets the pipe thru.its a matter of trying after committed to new heads.
01-05-2016, 07:18 AM
#10
Banned
BB Chevy heads have two different intake ports and the "good" port is always the advertised port. The "bad" port can be 20+ cfm below the "good" port through mid lift numbers. Just a valve job on those heads can be worth 20 cfm so comparing these flow numbers with another set of the same heads is pointless. A pipe on the exhaust will also make a big difference on the flow bench.
