Rectangular/Oval port debate.
Racer
Joined: Jul 2004
Posts: 254
Likes: 1
The addition of tumble to the port some feel atomizes the fuel and air better. Laminer flow is the under current of air that "carries" the air fuel along the port. It's like riding a skate board. Some will allow a ledge on the floor of the port where the intake meets the head. The head side will have about a .125" tall ledge. This ledge ramps up the laminer flow mixes the air and fuel allowing for "tumbling" of the air fuel molecules. This mixed up air makes better power. This line of thinking is especially used in methanol based engines.
Drifting
Joined: Oct 2005
Posts: 1,527
Likes: 148
From: East London/SW Essex UK
The addition of tumble to the port some feel atomizes the fuel and air better. Laminer flow is the under current of air that "carries" the air fuel along the port. It's like riding a skate board. Some will allow a ledge on the floor of the port where the intake meets the head. The head side will have about a .125" tall ledge. This ledge ramps up the laminer flow mixes the air and fuel allowing for"tumbling" of the air fuel molecules. This mixed up air makes better power. This line of thinking is especially used in methanol based engines.
Racer
Joined: Jul 2004
Posts: 254
Likes: 1
Very interesting - I can see the logic where 'wet' alky based fuels are concerned - oddly my lad is building-up a 390 cu in Ford engine for his Tbird and debating whether to use original low riser 427 heads or - Edelbrock heads which have far smaller intake ports than CJ or 427 heads and therefore a port mismatch which seems to be far more significant than what we have been discussing. He will be using an early dual quad FoMoCo inlet with one reverse mounted Holley. Surprisingly this is dual plane! - wonderfully complex casting which by nature of its design must have quite high port velocities unlike open dual quad manifolds.
If you want an opinion, go with the Blue Thunder heads. AT has a killer piece.
