hello...just got back from flowing another Chevy 250-292 big chamber head I have been working on....Very surprised with exhaust flow-not much work and GREAT results so far.... this test what performed on a SF600 Super Flow Machine located in Nashville area at Revolutionalry Performance Machine, LLC.....

this test used the PES aluminum Bot-In exhaust port plate(it raises the floor of the exhaust port).....I was very surprised how these plates worked with how the port was enlarged-here are results....tests Done for racing performance only...
@.500 lift 57% = 180 cfm
@.600 59.5% = 188 cfm
@.700 61.5% = 195 cfm
@.800 62% = 200 cfm

use 316.3 for factor- (ie, 316.3*.57=180)

I also tried without plate

@.500-800 58% = 184


mmmm interesting huh? and very little chamber work done.....
tests continue


the PES bolt-in Intake head on my 292 drag project is ...(194 head)

264 cfm @ .700 lift Intake
177 cfm @ .700 lift Exhaust


these plates work wonders!!!!!!! ...seems raising ports works very impressively on these heads just like most performance heads-start by looking at Performance V-8 heads and see what these heads look like.......Ever seen an Allen Johnson Solid SBC head?

Lee

lee, it good to see your getting some good flow numbers. can you also give numbers for smaller lifts such as .100,.200,.300,.400. i thankyou for your work.

hello...well it depends on what valve you use, not just size, but how its designed, what port work is done, what port pocket size is used,what chamber work has been done and what head is used>> 194 or 230/250/292...here r a few ranges for exhaust(depending on what combination)from.100-.400

.100 47- 55
.200 90-111
.300 120-141,
.400 144-163