Quote:
Originally Posted by DavidVizard-GFN
Funny this port should crop up at this moment in time as we have a set of those 7 liter (litre for those back home in the UK) head going through the shop at this moment in time.
The port dam does not appear to promote swirl in the normal manner but acts more as a vortex generater. This should be good for faster combustion and for breaking up any fuel stream there may be in the system. However there should not be too much fuel wash as this is an injected engine and there is some 45 psi to break up the fuel just a short ways up from the intake valve.
Although the dam may be good for vortex generation it certainly is not that good for flow. At present the bench is showing the more that comes out of the dam the better the flow and the swirl.
Some Cup car heads were done this way about 10 -15 years ago but refinements in carburation and the ports themselves lead to the dam becoming smaller and smaller until it eventually disappeared.
The real issue here is that it is a great talking point as the number of people looking at this combustion thread has shown. Still got to get to that article I promised. Right now the tach is pretty much redlined here getting the front cover done and the two lead tech stories out for the PRI edition of Stock Car Racing. but I will get to that combustion feature just as soon as I can.
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Some Cup car heads were done this way about 10 -15 years ago but refinements in carburation and the ports themselves lead to the dam becoming smaller and smaller until it eventually disappeared.
i discovered the same thing or had the same results
on the Dyno and the DragStrip.
Worked with 3 Teams, 1 was ProStock Truck
another B/ED , another was A/ND , and then a LS-7 Engine .
With that Vortex-fin the Flow CFM gained between 15 to as much as
25 CFM -VS- without that Fin.
But in all the above Test Cases...the extra Flow CFM gains showed
zero MPH and ET gains down the DragStrip.
On the B/ED they did a A-B-A Dyno + DragStrip tests
results were no real differences in ET or MPH,
it was as if you did absolutely nothing to the Cylinder Head,
even though the Vortex-generator fin was increasing FlowBench CFM
by 15 to 25 CFM !
When you ground out that Fin..you lost FlowBench Dry Flow Numbers,
but the RaceCars ran the same.
When you put back the Fin..you gained FlowBench Dry Flow Numbers,
but the RaceCars ran the same.
Basically a great waste of time that only resulted in
FlowBench Bragging Rights
..., but no DragStrip ET/MPH differences