Head flow #'s
Thread Starter
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Head flow #'s I have been looking at a lot of different Cathedral port heads. I noticed most are pretty close in the intake flow #'s but Tony Mamo and Ai seem to have way higher exhaust flow #'s. I was just curious why that is?
LS heads don't have that great of exhaust flow and these heads could use extra help in that department. Thats why a lot of LS cams have bigger duration numbers for the exhaust side. In the "old days" I remember that head porters tried to get the exhaust to flow 85% as much as the intake. Now, too many people just look at intake flow when buying heads, just looking for that "big number".
LS heads don't have that great of exhaust flow and these heads could use extra help in that department. Thats why a lot of LS cams have bigger duration numbers for the exhaust side. In the "old days" I remember that head porters tried to get the exhaust to flow 85% as much as the intake. Now, too many people just look at intake flow when buying heads, just looking for that "big number".
OP, what you've also pointed out is one of the benefits to aftermarket castings. They can be designed to accommodate different things - line more direct port designs, larger exhaust ports, different angles. There are limits to the stock castings.
And there's a reason Tony gets such crazy numbers on his heads
Most ported cathedral heads will flow in the 220's-230's at .600" depending on what head you are looking at and what version.
When you add a 1-3/4" pipe the port flows another 20-40cfm again version dependent.
You need to pay attention to many factors when looking at flow numbers
What bench were they flowed on
last time bench was calibrated
bore size head was flowed in
was a pipe used in testing(before and after;what size)
flowed @28?
it's tough to do apples to apples without having the heads you are looking at being tested at the same independent qualified facility.
Flow numbers do not always tell the tale it's another piece if data to base the rest of your parts selection on.
The bottom line is how repeatable a cylinder heads shops work is on vehicle after vehicle.
When you add a 1-3/4" pipe the port flows another 20-40cfm again version dependent.
You need to pay attention to many factors when looking at flow numbers
What bench were they flowed on
last time bench was calibrated
bore size head was flowed in
was a pipe used in testing(before and after;what size)
flowed @28?
it's tough to do apples to apples without having the heads you are looking at being tested at the same independent qualified facility.
Flow numbers do not always tell the tale it's another piece if data to base the rest of your parts selection on.
The bottom line is how repeatable a cylinder heads shops work is on vehicle after vehicle.
Just make sure you get the cam spec'd for the particular heads you get, and the flow numbers of those heads. Matching the correct cam to the heads is a major part of the game, regardless of what heads you get.
Trending Topics
Thread Starter
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Most ported cathedral heads will flow in the 220's-230's at .600" depending on what head you are looking at and what version.
When you add a 1-3/4" pipe the port flows another 20-40cfm again version dependent.
You need to pay attention to many factors when looking at flow numbers
What bench were they flowed on
last time bench was calibrated
bore size head was flowed in
was a pipe used in testing(before and after;what size)
flowed @28?
it's tough to do apples to apples without having the heads you are looking at being tested at the same independent qualified facility.
Flow numbers do not always tell the tale it's another piece if data to base the rest of your parts selection on.
The bottom line is how repeatable a cylinder heads shops work is on vehicle after vehicle.
When you add a 1-3/4" pipe the port flows another 20-40cfm again version dependent.
You need to pay attention to many factors when looking at flow numbers
What bench were they flowed on
last time bench was calibrated
bore size head was flowed in
was a pipe used in testing(before and after;what size)
flowed @28?
it's tough to do apples to apples without having the heads you are looking at being tested at the same independent qualified facility.
Flow numbers do not always tell the tale it's another piece if data to base the rest of your parts selection on.
The bottom line is how repeatable a cylinder heads shops work is on vehicle after vehicle.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
