What is a port stuffer? Do I want them in my 408 stroker 4V closed heads , Strip dominator intake. Bill
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There are Pros/Cons with port stuffers depending on who you talk too? If your engine runs good and your happy with the performance I wouldn't mess with them. But thats just me!
Good Luck
Curt
Good Luck
Curt
If you're using a Strip Dominator intake, you should not use intake port stuffers. The Strip Dominator was designed to work with a full size 4V intake port.
An intake port stuffer is designed to fill in the lower portion of the Cleveland cylinder head intake port, usually to be used in conjunction with an intake manifold that has matching filled runners. The Parker FunnelWeb and TFC intake manifolds are two examples of such intake manifolds. However, the ramp in the bottom of the 4V intake port was placed there for a reason, to guide the air flow in the port towards the roof of the port, and thus make the port behave as a higher port (i.e. improved air flow). This same port design was employed in the 1965 427 FE engine's "medium riser" cylinder heads to give them similar air flow performance as the 1964 "high riser" cylinder heads. The SVO C302B cylinder heads also incorporate this ramp in the floor of the intake ports. By filling in the floor of the Cleveland intake port that aspect of the engineering that went into the design of the port is disabled, air flow shall most definitely be reduced. Filling the port also reduces the volume of the port, which has a detrimental effect upon one of the Cleveland's trademark properties, the ability to supply sufficient air/fuel mixture to a very large intake valve.
Although the iron 4V intake port entrance is large, the port is not that size throughout its length. The intake port's entrance has a cross-sectional area over 4 square inches, but the port's "average" cross-sectional area is about 2.9 square inches. The port has an irregular shape ... this is true ... but it is not too large. The size of the entrance is visually misleading. The port volume of an un-ported iron 4V head's intake port is only about 242cc even with the large entrance! The port is tuned for peak horsepower at 6000 rpm, right where it should be for a high performance street engine.
Obviously making the port smaller is intended to increase mixture velocity within the port, which should result in better throttle response. But if you perform the port velocity calculations you'll find the port stuffers do not change port velocity that much. As far as I'm concerned stuffing the intake port has never been proven to make more horsepower. I would describe a port stuffer as a trade-off designed to gain throttle response at the expense of horsepower. But does throttle response need improvement? I do not believe so. Not if the compression ratio is high enough and the camshaft is designed properly.
The concept of port stuffers is dated, designed by people who wrongly believed the 4V port is too big for a 351 cubic inch street motor. It was a "fad" before the days of CHI and AFD stuffed 4V port (aka 3V port) cylinder heads and before the days of inexpensive Chinese cast stroker crankshafts. The CHI and AFD cylinder heads were inspired by the fad of port stuffing, they incorporate stuffed ports in their design, and they are a better way to go in my opinion. But ... for those who like the stuffed 4V port/3V port concept, Scott Cook's new stuffed port head will take the whole concept a step further ... and in the right direction. Scott's new cylinder heads shall incorporate constant cross-section intake ports, proper port volume to feed a large 2.19" intake valve, and a port tuned for a good power band (like the iron 4V head). Air velocity shall be where it should be. Air flow will be achieved with good design and CNC porting, rather than a ramp built into the port's floor.
Finally, a 408 stroker will pull hard enough on the intake ports to make the need for velocity improvement via stuffers a moot point. You won't need them with your stroker Bill.
-G
An intake port stuffer is designed to fill in the lower portion of the Cleveland cylinder head intake port, usually to be used in conjunction with an intake manifold that has matching filled runners. The Parker FunnelWeb and TFC intake manifolds are two examples of such intake manifolds. However, the ramp in the bottom of the 4V intake port was placed there for a reason, to guide the air flow in the port towards the roof of the port, and thus make the port behave as a higher port (i.e. improved air flow). This same port design was employed in the 1965 427 FE engine's "medium riser" cylinder heads to give them similar air flow performance as the 1964 "high riser" cylinder heads. The SVO C302B cylinder heads also incorporate this ramp in the floor of the intake ports. By filling in the floor of the Cleveland intake port that aspect of the engineering that went into the design of the port is disabled, air flow shall most definitely be reduced. Filling the port also reduces the volume of the port, which has a detrimental effect upon one of the Cleveland's trademark properties, the ability to supply sufficient air/fuel mixture to a very large intake valve.
Although the iron 4V intake port entrance is large, the port is not that size throughout its length. The intake port's entrance has a cross-sectional area over 4 square inches, but the port's "average" cross-sectional area is about 2.9 square inches. The port has an irregular shape ... this is true ... but it is not too large. The size of the entrance is visually misleading. The port volume of an un-ported iron 4V head's intake port is only about 242cc even with the large entrance! The port is tuned for peak horsepower at 6000 rpm, right where it should be for a high performance street engine.
Obviously making the port smaller is intended to increase mixture velocity within the port, which should result in better throttle response. But if you perform the port velocity calculations you'll find the port stuffers do not change port velocity that much. As far as I'm concerned stuffing the intake port has never been proven to make more horsepower. I would describe a port stuffer as a trade-off designed to gain throttle response at the expense of horsepower. But does throttle response need improvement? I do not believe so. Not if the compression ratio is high enough and the camshaft is designed properly.
The concept of port stuffers is dated, designed by people who wrongly believed the 4V port is too big for a 351 cubic inch street motor. It was a "fad" before the days of CHI and AFD stuffed 4V port (aka 3V port) cylinder heads and before the days of inexpensive Chinese cast stroker crankshafts. The CHI and AFD cylinder heads were inspired by the fad of port stuffing, they incorporate stuffed ports in their design, and they are a better way to go in my opinion. But ... for those who like the stuffed 4V port/3V port concept, Scott Cook's new stuffed port head will take the whole concept a step further ... and in the right direction. Scott's new cylinder heads shall incorporate constant cross-section intake ports, proper port volume to feed a large 2.19" intake valve, and a port tuned for a good power band (like the iron 4V head). Air velocity shall be where it should be. Air flow will be achieved with good design and CNC porting, rather than a ramp built into the port's floor.
Finally, a 408 stroker will pull hard enough on the intake ports to make the need for velocity improvement via stuffers a moot point. You won't need them with your stroker Bill.
-G
> What is a port stuffer? Do I want them in my 408 stroker 4V closed heads , Strip dominator intake. Bill
There are port stuffers for both the intake and exhaust ports. What the stuffers
try to do is increase port velocity by reducing the cross-sectional area of the
port. Roush made inserts that raised the port floor of a 4V head to match that
of an A3 head/intake. Marino Perna makes something similar. Ideally, you'd want
the intake manifold ports to likewise be reduced. There are intakes from Australia
that have raised floors and Terry Parker makes an intake and matching spacer
combo. These intake stuffers are meant to be screwed in place and sealed with a
thin layer of epoxy (Z-spar or similar). MPG Heads makes a stamped sheetmetal
plate that sandwiches in between the intake and head that attempts to do the same
thing but is susceptible to leaks.
There are similar stuffers for the exhaust side that bolt in place. I've dyno
tested the exhaust side "Stinger" type with both Pantera and long tube Mustang
headers and they made a repeatable increase in average power.
Dan Jones
There are port stuffers for both the intake and exhaust ports. What the stuffers
try to do is increase port velocity by reducing the cross-sectional area of the
port. Roush made inserts that raised the port floor of a 4V head to match that
of an A3 head/intake. Marino Perna makes something similar. Ideally, you'd want
the intake manifold ports to likewise be reduced. There are intakes from Australia
that have raised floors and Terry Parker makes an intake and matching spacer
combo. These intake stuffers are meant to be screwed in place and sealed with a
thin layer of epoxy (Z-spar or similar). MPG Heads makes a stamped sheetmetal
plate that sandwiches in between the intake and head that attempts to do the same
thing but is susceptible to leaks.
There are similar stuffers for the exhaust side that bolt in place. I've dyno
tested the exhaust side "Stinger" type with both Pantera and long tube Mustang
headers and they made a repeatable increase in average power.
Dan Jones
a picture is worth a 1000 words
Old school late 1970s (Roush style?) stuffed intake ports.
What is not so obvious in this picture, the roofs of the
intake ports have been raised as much as possible, which
isn't very much. These mods were the prelude to the SVO
A3 aluminum cylinder head. These were drag racing
modifications, the goal at the time was not quicker
throttle response, but a more consistent port cross-section
which avoided the separation of fuel from the air at high
rpm.
-G
Old school late 1970s (Roush style?) stuffed intake ports.
What is not so obvious in this picture, the roofs of the
intake ports have been raised as much as possible, which
isn't very much. These mods were the prelude to the SVO
A3 aluminum cylinder head. These were drag racing
modifications, the goal at the time was not quicker
throttle response, but a more consistent port cross-section
which avoided the separation of fuel from the air at high
rpm.
-G
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