omc8

iTrader: (7)

Like to get some input from experienced head porters on certain areas that gain good returns. The area in question is the intake port floor and wall
just preceding ssr . Are there any gains in this area , buy moving the straight wall out and knocking down the floor slightly ?

A.R. Shale Targa

iTrader: (2)

do not ever drop the port floor at the ssr !!!!!!!!!!!!!!!!!!!
cartridge roll blend is about all even if opening up for bigger valves

omc8

iTrader: (7)

In general the floor is a area not to mess with, agreed. But I've read some guys have seen flow gains in the area encircled in green .

A.R. Shale Targa

iTrader: (2)

Well. Since the GM engineers used hundreds of air speed monitors in the runners; I'm of the mindset that getting a head to flow more air is only part of the equation since engines run on air/fuel mixture. So the shape that they came up with is to promote tumble and turbulence without too much of either.
Keeping the mixture atomized on its way to the cylinder is what burns cleaner faster and makes more power.

G Atsma

^ You been listening to that guy Mamo again??? Yeah. So would I...

99 Black Bird T/A

iTrader: (4)

Lowering or hogging out the port floor can show gains on a flow bench in some cases however that almost never translates into an actual hp gain on the dyno according to an old friend that ported beads.

If one was to go back to the early LS days in 1997-2001 one could find certain shops that lowered the floor to pump up flow numbers.

omc8

iTrader: (7)

Well here is a quote from the past , a experienced porter' on here.

"Jantzer98SS , 12-07-2006 03:33 AM
Focus on the straight side especially around the ramp area and up into short side. That side shows a lot of gains the 2" before the short turn. Pull the ramp down, but don't try to remove as it will get thin. You'll see huge gains there. Also the front rocker bump can be removed, I'm sure you know that. I would do chamber work on the 5.3's as well. Unshroud the valves and roll over the sparkplug boss."

KCS

iTrader: (20)

I knew some head porters that swore flattening out the SSR there helped, but I don't know if they were talking about gains on the flowbench or dyno.

There is a lot of power in reshaping the short turn, but you can shoot yourself in the foot if you don't know what you're doing. I was taught that that part of the port has what we call a "bias", meaning that the port leans one way or another with respect the the valve centerline. The air is going to flow though the port and try to turn to the center of the bore as it approaches the valve. In your picture of the port, the air will be turning towards the bottom left area of the port.

The idea here is that if you have a flat SSR with a tight radius corner, the air will crowd there and cause very high localized velocities, which is bad. However, if you bias the port and lean that port floor, the air will spread out and remain stable to higher average air speeds. It's kind of like the embankments on a NASCAR oval track.

A.R. Shale Targa

iTrader: (2)

Even removing the intake bowl ramp does spike flow numbers but dramatically changes what the engineers were trying to achieve. Carl Wagner here in Wisconsin has done an awful lot with the LS stuff over the years and right from his mouth was "I simply can't get 300 CFM from a cathedral head while keeping the swirl ramp. I modify it but refuse to remove it"

KCS

iTrader: (20)

That may be true, but the design goals of GM engineers and racers are different. Where GM worries about fuel efficiency and emissions, drag racers don't. If I'm not mistaken, Wagner does a lot of circle track stuff, so reducing tr amount of refueling stops may be more important to them and their clients that making the most power possible.