FRiCK

iTrader: (7)

In your opinion, is there any power to be had by removing the intake port swirl vein or swirl dam on an LS7 head? If so, how much on a 243/259 cam motor, 11.8:1?

Che70velle

iTrader: (6)

If your looking to be a dyno hero, and want every last number, yes.
If you want to have a little more driveability, just clean it up.

pantera_efi

iTrader: (1)

Hi FRiCK, my typical reports ARE based on fact, you judge the case.

The Case Engine is a LS-482 Endurance Engine with a RHS TALL block AND 4.5" Stroke.
The LS-7 heads were ported BY KAYTECH with the original "flag" left in place.
The HP output was 650 @ 6200 RPM. (Wheel)
The heads needed replacement due to age, the castings became soft after many seasons of operation.
A set of used replacement ported (WCH) heads were found, NO "flag" in the port.
I do not know if West Coast REMOVED the ""flag" or if it was another person.
These heads were installed when the engine was freshened for the next year races.

The engine was tested, same rolling road dyno, same time of year.

The results were 630 @ 6200 RPM with the replacement heads, no
"flag".

Lance

Che70velle

iTrader: (6)

I like the comparison Lance, but there are a lot of possible variables in that scenario, that would change the outcome, during a rebuild.

My Mamo LS7’s flow 410-412 cfm, and the “vein” is still there.
There are many, many variables at large here, such as overall port shape, CSA, bowl design, camshaft choice, desired rpm, etc, that will determine how well the “vein” works, or does not work.

But from what I’ve observed, the LS7 heads that flow the most out there, usually don’t have the “vein”, due to the porter looking for max flow/power.
Personally, I was looking for driveability more than power, but was hoping for both. So far so good...

KW Baraka

iTrader: (7)

If Tony left it there then I would think the squeeze ain't worth the juice.

In other words.....leave 'em alone.

KW

lowcountry

iTrader: (1)

From a fluid dynamics perspective, a small amount turbulence may help by keeping the air & fuel mixed proportionally.

A.R. Shale Targa

iTrader: (2)

The Sperry brothers would be very happy to read this
IMO. dead on
Tumble AND turbulence by design. Even though it sacrifices a few CFM of dry air flow

Double06

Is the swirl vein in the chamber or is it by the valve guide above the intake valve head.

Che70velle

iTrader: (6)

By the guide, right above the valve seat.

FRiCK

iTrader: (7)

Double06

Thanks that explains it.

DB Z28

The swirl vein From all the testing from the flowbench to the dyno the Vein did very little for swirl how ever it produced a lot of tumble in the cylinder which helped with mixture motion and emissions . Removing it got a lot more flow to look good for CFM numbers on the flowbench . But removing it caused the engine to get lazy on the dyno due to lost mixture motion and lost power. We spent a long time looking at this.

A.R. Shale Targa

iTrader: (2)

Must be from that shop in Markesan....

DB Z28

From that area

Double06

Well looks like I have the vein in mine. Heads flows pretty good port stock LS7 head 400 cfm at .650

FRiCK

iTrader: (7)

Chad, we've spoke before, yes it's a PRC head........ and your pic looks to be cathedral, Mamo right?....

FRiCK

iTrader: (7)

Double06

That seems about right the cfm actually drops to like 385 or so at .700 lift.

Fivethree twinturbo

I've hand ported few LS7 heads. Some heads i leave the vein and some heads i removed it. Every time ports where i removed them flowed better. Stock LS7 was 372 cfm at our Flow bench and hand ported are somewhere in 390-400cfm.

pantera_efi

iTrader: (1)

Hi ALL, many here look at MAX LIFT flow, with NO RESPECT for flow at LOWER LIFTS.
I Graph the Flow Area with GREATEST concern in the Low Lift areas.
AS WE ALL KNOW the Valve spends 2x(+) the time in the Low Lift Area.

ALL Data reports are great, well given, I see no reports posted here of lower lift flow with/without the Swirl Vein.

Valve Seat Angles have a great effect on flow with NO REPORTS provided ?

Lance