Is this adequate gain with the SCJs

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Is this adequate gain with the SCJs

Post  ED468 on March 18th 2016, 11:33 am

Ok, now i'm not concerned with what the bench max numbers are because it is stingy it seems, but with widening and a fair amount of SSR work without loosing any low to mid numbers I feel pleased with the modest effort. Gains started slightly at 250 lift, by 450 was up 10cfm and by 500lift 18 cfm 550 was + 25cfm, 600 was 39 cfm, 650 was 54 cfm where the stock scj fell off pretty bad. Held the max flow till 700 lift pretty much, but was a little turbulent. His bench only showed 360 cfm but too many heads have showed this bench on BBFs about 25 cfm lower. Air speed was at 295 cfm on the short Turn which he thought was about right. Hope I made a DECENT improvement since this was my first CJ port head and tried to Raise air speed in port but it still wasnt great. Didnt take a reading stock , wish we would of. This compareson was same day same bench, bench just calibraded on a rainy day which i would think even in a basement would be heavy air. Would like oppinions on flow numbers, this is for a 501 with a lunati 270-276 cam with 720 lift on 110 drag race cam, exhaust was around 255 cfm. Could of used more split, but he was in a hurry to by cam. Only need a tenth and he didnt want to restall converter so i played it kinda save i think on heads. Thanks..,Ed P.S. Head before and after numbers where both with a 30 degree 88 thousands backcut.

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Re: Is this adequate gain with the SCJs

Post  rmcomprandy on March 18th 2016, 6:10 pm

It certainly looks like what happens when initially porting an SCJ head; that's simply how they act.

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SCj

Post  ED468 on March 18th 2016, 6:41 pm

I did a little more widening on the short turn today, maybe .075. Not going to retest, hopefully it helped it some. So Randy are you saying You would do more? I really don't want to take a chance at hitting water! I dont really care to start trading mid numbers for high, wouldnt think it be worth the work to do that.

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Re: Is this adequate gain with the SCJs

Post  rmcomprandy on March 18th 2016, 11:09 pm

ED468 wrote:I did a little more widening on the short turn today, maybe .075. Not going to retest, hopefully it helped it some. So Randy are you saying You would do more? I really don't want to take a chance at hitting water! I dont really care to start trading mid numbers for high, wouldnt think it be worth the work to do that.

That is a major reason, (with any head), that maximum air flow numbers are a bad judge of how any cylinder head is gonna run.

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scj porting

Post  ED468 on March 19th 2016, 2:03 pm

Well ok, I'll let you guys know how it actually ran, he real anxious to get it back together. I think I might of picked a good place to stop. Thanks..,ED

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Test and tune

Post  ED468 on July 23rd 2016, 10:22 pm

cars picked up a solid tenth and half in the heat and MPH dropping off. Looks like one holley pump might not be enough.

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