A simple Cylinder Head Question
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More Turbo
Joined: Jun 2001
Posts: 572
Likes: 1
A simple Cylinder Head Question
I have two different sets of FE heads. They both have the same size valves, but one set had lower cc's. you may get more compression with the lower CC heads, but since they are smaller wouldn't that make it harder for the engine to breath than it would with the larger CC heads.
One set of heads has about 64cc and the other about 72cc(if I remember right)
Thanks,
One set of heads has about 64cc and the other about 72cc(if I remember right)
Thanks,
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
A simple Cylinder Head Question
Port & Valve size is what is going to determine how the head will breathe. The amount of air/fuel mixture the engine will suck in is going to be the same no matter what size combustion chamber. Think of it this way. Lets say you have V8 with a 4 inch bore and a 4 inch stroke. Each cylinder is going to TRY to suck in 50 cu. in. of air/fuel no matter how big the combustion chamber. Now on forced induction engines the air/fuel would fill the entire combustion chamber and cylinder because the engine is not using its own sucking force to get the mixture in, it is being forced in. I hope you can understand this explanation. I'm sure someone else could have worded it a little better.
Laughing Gas
Joined: Oct 1999
Posts: 1,188
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From: yes
A simple Cylinder Head Question
The engine will try to suck enough air to fill the cylinder, but valve shrouding will play a factor. if the combustion chamber/cylinder wall is too close to the edge of the valve you wont see as much of a improvement as you'd like, just deshroud the valves a little if it really concerns you. I guess the illustration I'd use is have a 1 1/4 inch tube and a 1" valve it will probably flow more air than a 1 and 1 1/8" valve because there is more room around the end of the valve for the air to flow around. I can see no major problem from running the smaller CC heads, but going zero deck height pistons would probably be a less detonation prone way to get your power.
Guest
Posts: n/a
A simple Cylinder Head Question
For each head determine what the compression ratio will be with a near zero piston deck height. Compression ratio is the real issue. Either head would be fine if the compression ratio is OK for the worst grade of gas you expect to buy.
Bob
'66 7 Litre Convertible, top loader, 3.25 Traction-lock, 427 Sidewinder Intake, 780 Holley, Windage tray, SCJ Exhaust manifolds, H-pipe, MSD, Line-lock, AM/FM/8-Track/CB
'88 F150 XLT Lariat, 302, 5 speed, 3.08
'98 Mustang, 3.8, 5 speed
'99 Ranger, 3.0, 5 speed, 3.73 posi
Bob
'66 7 Litre Convertible, top loader, 3.25 Traction-lock, 427 Sidewinder Intake, 780 Holley, Windage tray, SCJ Exhaust manifolds, H-pipe, MSD, Line-lock, AM/FM/8-Track/CB
'88 F150 XLT Lariat, 302, 5 speed, 3.08
'98 Mustang, 3.8, 5 speed
'99 Ranger, 3.0, 5 speed, 3.73 posi
