smokinZX14
Needs a life
Posts: 10197
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posted September 11, 2010 08:20 PM
quote:
quote:
This is the best artitcle on porting I have seen in 35 years of porting, written by Jim MacFarland , he worked with Smoke Yunick for 40 years. Read it 2 or 3 times ?? Also sometimes you have to FILL, not make bigger??
http://www.circletrack.com/enginetech/ctrp_0806_mc_part_5/index.html
Gotta make it easy on people here. 
http://www.circletrack.com/enginetech/ctrp_0806_mc_part_5/index.html
Good stuff! However, I would bet that most won't make it past Page 1 ...................
I read all of it .. And was looking for more ...
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Smokin Performance Cycles..
Tampa Bay , FL .. Brocks Performance Dealer ..
Gen 2 ZX14R Best ET 8.43 , Best MPH 164.95
  
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wrongway
Pro
Posts: 1078
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posted September 12, 2010 05:51 AM
If you are really interested in measuring flow at the valve you may need one of these..
http://rtstooling.com/pdvalves?s=
the valve is the probe ....
not sure where that SB2 head came from....
Roy
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted September 12, 2010 06:43 AM
Its true that some carbureted engines like rough floors in the plenum and part way into the port on the floor.
Fuel injected engines are different thou due to the the way the fuel is delivered.
A carbed street V8 engine has to start cold with a choke on and depends on a vacuum signal to draw fuel from the boosters. The fuel comes out in very large sized droplets when the choke is on and it puddles on the plenum floor. This is a very different scenario from a modern 4 valve injected engine warmed up to operating temp and running at 10,000 rpm plus. The dynamics are completely different in every way. I could go on for pages about this.
Our SB 2.2 heads that we do for SCCA Trans AM have very different features in the ports. Let me just tell you one thing amazing. Most of the fuel and air that a particular cylinder ingests on a sb 2.2 engine comes from the other intake runners, not in a straight line from the closest carb throat like you would expect. The air and fuel are going in any out of all the runners back up into the plenum and back down into other cylinders.
One of our customers running a 820 hp sb 2.2 engine sucked in a screw from the squirter that came loose. The engine felt funny but they kept running it and finished the race. When we took the engine apart that screw had gone into every single cylinder at least once before it either went out the exhaust or got pulverized into nothing. It was never found. It gives you an idea of how violent it is in that intake manifold.
We also use strobe lights and cameras on the dyno to watch whats going on down in there.
On webber carbed engines you will see the atomized fuel cloud come right up and out of the individual velocity stacks about 1-2" and then get sucked back down in as the rpms sweep threw the power band. This is cause by the sonic waves being out of phase at those particular rpms as the engine sweeps threw the sweep test.
Any way every engine is different on what a port texture should be depending on its use etc.
So these web sites that say that this or that is good or bad, are making generic statements that don't apply to every engine and configuration.
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Y2KZX12R
CompetitionCNC.com
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1badzx12r
Needs a life
Posts: 8321
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posted September 12, 2010 08:48 AM
 Edited By: 1badzx12r on 12 Sep 2010 16:50
when we gonna see your gain chart roy . i still say 0 well maybe a ponie or 2 but no gains at the track ..it will run the same .. but we are getting better air in ,so hurry while its hot
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http://www.youtube.com/watch?v=S06nIz4scvI
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wrongway
Pro
Posts: 1078
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posted September 12, 2010 09:44 AM
quote:
when we gonna see your gain chart roy . i still say 0 well maybe a ponie or 2 but no gains at the track ..it will run the same .. but we are getting better air in ,so hurry while its hot
I am not gonna put it on till after the maxton race on the 25th ... Just incase it does go backwards :-)
Roy
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Shane661
Needs a life
Posts: 11494
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posted September 12, 2010 09:49 AM
quote:
I am not gonna put it on till after the maxton race on the 25th ... Just incase it does go backwards :-)
Roy
I bet you get that hat this time! Good luck! 
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