Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Big Block for towing
View Single Post
  #33 (permalink)  
Old 12-31-2012, 11:16 PM
my87Z's Avatar
my87Z my87Z is offline
Join Date: Mar 2009
Location: maryland
Age: 33
Posts: 1,729
Wiki Edits: 0

Thanks: 10
Thanked 18 Times in 18 Posts
Originally Posted by vinniekq2 View Post
I found no peanut portheads that had flow numbers lower than 226 cfm. My info was based on 156 and 236 peanut port heads?weakest exhaust ratio was 64%

Factory 156 peanut port heads with 195cc intake runners have a max flow of 226cfm at .600 and then 227cfm at .700" and their efficiency rating is 70.8%. The 236 peanut port heads with 208cc intake runners have a max flow if 235cfm at .600 and .700", their efficacy rating is 70.6%.

To put those flow numbers into perspective a pair of 906/062 vortecs with 170cc runners flow about 227cfm at .500" from the factory. These nor the BBC peanut port heads in factory form can support 500hp. A general rule of thumb is that what ever your max flow cfm is, multiply that by 2 and that will give you the absolute max hp those heads can support, and that is with an engine with pretty much 100% VE. Most decent street engine only have about 85% VE. So take the 236 208cc peanut port heads which flow 235cfm at .600, under 100% VE they could make 470hp max but considering most decent street engine on have about 85% VE that number is more realistically 415-425hp.
Reply With Quote