Darren Porter – to Feel Again

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   '63GT Well-Known Fellow member

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   We ended the first installment finding the Int port hitting 257 cfm.
   Not bad for a port just virtually anyone could duplicate in their garage.

   Although I was happy to hit this mark, without anything elaborate, it besides meant the Exhaust side had information technology's piece of work cutting out for it.
   A lifetime ago, it was thought frazzle port menstruum percentage of seventy% was all one would needed.
   Every bit conventional wisdom prevailed, this percentage jumped in 5% increments over the years, to the point of 80% in many circles. At least in the magazines.
   Reher & Morrison, as well as many others however contend 60% is plenty.
   I'one thousand sure at that place are some on this forum who may have differing opinions on this as well.
   And that'due south ok ! I want to hear their opinions too !
   I think the central matter here is keeping the apples away from the oranges.. A race merely awarding may exist ok with, say 70%, but one who is running a street bargain with closed exhaust may get a bump from a higher percentage.

   How does the Magnum Exh port faire? Well, in OEM form, near 73%. Wow, that's cool. This could be why so many are getting adept to great results with Cat backs and such on their Mag ability trucks.
   I used to own a beautiful 2001 Dakota RT that responded very well from a well crafted DIY Y-pipe.
   Ok enough of that !

   Every bit in the Int test, I freshened up the Valve Task first.
   This is what I concluded up with.. pass-able.
   
   Magazine Exh baseline OE port./ 35°back cut .125 wide .090 seat
   .050 31.two /27.0
   .100 55.8 /59.9
   .150 80.7 /84.iii
   .200 104.9 /108.iv
   .250 124.9 /126.2
   .300 138.8 /138.0
   .350 146.six /148.three
   .400 151.3 /152.three
   .450 154.0 /154.5
   .500 155.eight /157.two
   .550 156.nine /156.5
   .600 157.4 /157.3
   As you can see in the Baseline Exam, this port is starting to flatten out even at .350 lift, and almost completely by .450. Information technology actually could be better, only at 73%, it gets by.
   But, we're at 257 cfm @.500 on the Int. We NEED more, even just to striking 70% of that! which is 180 cfm. Preferably at .500 elevator.
   The BC valve helped in the lower lifts to about .300. The .050 elevator point was really noisy. probably due to the ledges in the chamber. We'll fix that later.
   Before nosotros get to step two, I'd like to point out a few things..
   The Cyberspace valve area is 1.984 sq in (valve area - stem expanse =1.984)
   The Bowl area (OE) is 1.430
   A rough approximation of area betwixt the SSR and guide is less than ane.25 (yes ane.25)
   Port area at the gasket (cease port 1,7, 2,8) is 1.640 (the centre ports are smaller due to the bending on the ports lower one-half and flows about five cfm less )
   Obviously, in that location'southward a major disparity in CSA in a span of simply 2.3" of port length.
   The merely saving grace in this port (in my view) is the generous SSR. Even though the bulk of port flow is upon the roof.
   Seems dismal, doesn't it ? Let's press on.
   Let'south open up the bowl up. There's a factory counter bore below the VJ, only only visible 2/iii the mode around. Do the best you can to follow this the whole style around. take it all the way down to the guide. I used a 1/ii" Oval burr hither.
   Something like this:
   
   You tin run into a fractional shadow of this counter bore.
   Test 2 opened bowl.
   .050 28.0
   .100 64.3
   .150 88.5
   .200 110.1
   .250 127.8
   .300 143.7
   .350 155.five
   .400 161.half dozen
   .450 164.half dozen
   .500 166.9
   .550 168.9
   .600 170.1
   Well, that was a pretty handsome gain, given the major pinch in the SSR/Guide area !!
   I'one thousand encouraged ! 13 more cfm, and nosotros'll have hit our target of 180.
   Now let'due south thin the guide some. Near like this (pitiful, information technology'southward a flake nighttime):
   
   .050 28.6
   .100 65.4
   .150 91.four
   .200 112.ane
   .250 130.five
   .300 147.v
   .350 160.7
   .400 167.5
   .450 170.2
   .500 172.i
   .550 173.9
   .600 175.2
   Ok, this is getting fun now !
   Like most Exh ports, the roof has a problem. A hump, like you see here:
   I scratched out a parameter here with a layout pencil.
   This hump (sorry difficult to come across) needs to exist gone.
   Problem is, we don't know how thick it is here. Then, in another port I previously ported, I found out. Run across beneath:
   That's correct, I drilled a hole. My apologies over again, its hard to brand out only, that pigsty is approximately .125 (1/8") deep/thick. (I'll tap it 1/iv-twenty and put a set screw in information technology for future testing)
   With that, grind away! just brand it apartment. Remove about .080" at the apex.
   Roof made flat exam:
   .050 28.iv
   .100 64.8
   .150 90.5
   .200 112.1
   .250 131.2
   .300 149.two
   .350 162.7
   .400 170.1
   .450 173.six
   .500 176.0
   .550 177.9
   .600 179.9
   A proceeds, merely smaller than the concluding test. Our restriction is in another expanse.
   My judge information technology'southward in the manufacturing plant type Valve Job. Like with the Int, I'yard going to use a much larger stone to clean upwards some of the ledges in a higher place the manufacturing plant top cut.
   I will also move the seat out to a diameter of 1.590. .030 smaller than the valve. Then a 60° bottom hopefully .080 wide and finish cutting of lxx°
   Deplorable, got all excited and forgot to have a pic. (I know, I"m fired)
   .050 28.0
   .100 57.0
   .150 92.9
   .200 116.0
   .250 135.8
   .300 153.0
   .350 165.vi
   .400 171.3
   .450 173.8
   .500 176.four
   .550 178.8
   .600 180.two
   The gains are slowing down... still a problem elsewhere.
   The noise in the low lift came dorsum.. Let'south debur it.
   
   That'southward better!
   Debur test:
   .050 28.7
   .100 56.0 (humm)
   .150 93.3
   .200 117.1
   .250 141.0
   .300 158.2
   .350 168.6
   .400 172.9
   .450 175.four
   .500 177.7
   .550 179.5
   .600 180.five
   Some dainty gains in the mid lifts.. Only still not responding like we demand information technology to. We're sooo shut.
   We haven't touched that SSR. It's crease time. I'thousand non ready to punt, however..
   This is what I did:
   
   The low-cal green is where I started to grind, the darker greenish is where I removed about .035" worth of SSR, and the longer green is showing the boundary line I ground to while I also widened the port some.
   The Hail Mary to 180 cfm exam:
   .050 29.0 (?!)
   .100 57.8
   .150 94.5
   .200 118.six
   .250 141.2
   .300 158.2
   .350 168.7
   .400 173.7
   .450 176.6 (feeling better..)
   .500 179.1
   .550 181.1
   .600 182.2
   Simply in the nick of time! are y'all feeling the love correct now?!
   In the back of my mind, Maxwell Smart is proverb, '..missed it by THAT much!'

   More flow probably could be had by getting after that roof some more than, Definitely the pinch between the SSR/guide surface area.
   Taking a intermission for now. Let me know what yous recollect.
   I"g just glad we met the goal.

   Last edited: Jun 25, 2020
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   '63GT Well-Known Fellow member

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   I saw your other post... Thinking on getting a bench?

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   '63GT Well-Known Member

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7. 

   pishta I know I'm right....

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   Oooh, OOoh! Do some LA's next!

8. On exh flow ratio, theres ideal then there is what works, then at that place is handicapped. You can exist pretty far below ideal and make big ability. In that location are ford BB heads that when total ported...are as low equally 50% ..and make 900hp on 470+cid. Could it make more.. yes... but it'due south still making 900. A serenity non turbulent exh port is something not a lot talk about. That'southward of import besides. Mayhap more so. Cracking thread, nosotros needed ane on these.

   Last edited: Jun 25, 2020

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9. No, sir you don't get to do that. I pulled out the popcorn for keeping track of the first post. I volition not be left standing alone waiting in the theater. I could have missed this and been broken heart'ed. Waiting, waiting for your return. Similar a lost beloved thing later the allies won the war. Do you accept no feelings sir for you faithful audience? I feel so used and cheap.... I'm gonna need shower and a Brillo pad.

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10. Not bad post! Thanks for taking the time to share.

    • Thanks! x ane

12. Lack of emojis make for very dry humor.
    Nevertheless humor none the less. Lol

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    '63GT Well-Known Member

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    Well, maybe.. I don't accept a donor head to scratch on.. (I don't retrieve..)
    I have a set of 906's I NEED to finish, every bit well equally a set of 452's (?) I may do something there..
    I have a carb project I shelved for ... appetite to kick in.

14. Super threads '63GT

    Edit
    That goes for the intake and frazzle threads.

    Last edited: Aug xix, 2020
15. 

    '63GT Well-Known Member

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    Thanks !! catch the Exh port thread as well?

    Edited: Int port ! not exh

    Final edited: Aug nineteen, 2020

16. I wish I could modify some of you lot guys thinking on exhaust menstruation.

18. I'd like to hear your accept on it also.

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19. What is your take on exhaust flow?

20. 
    Words out of the mouth of a head porter way amend and smarter than I will ever exist. (Darren Morgan)
    Flow numbers mean nothing on an frazzle port. Air speed should be at least 325 FPS in the port.

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    '63GT Well-Known Member

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    I remember I have a SpeedTalk interview with Darren Morgan.. I'll have to see if I could dig that up and come across exactly what he's proverb.
    That could be sliced a number of dissimilar ways.. A larger valve with the correct shaped port would hit 325 earlier in the lift cycle, than a smaller ane. Which would dramatically change 'accident-down'. Non to mention the effect on 'overlap'.
    Interesting, still. He's no dummy.

22. Just throwing this out there only my inexpensive azz small block Speedmaster Caput has airspeed over 325 FPS with a little port and shortside shaping. It was then good I refused to touch the valve chore. It was also one of the calmest sounding after market pocket-sized block head I accept ever tested out of the box. Information technology shocked me.

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    '63GT Well-Known Member

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    I noticed that on mine as well.
    Was the valve job concentric, at to the lowest degree, on the exh ?
    I did a gear up of Edelbroke E Street heads for a buddy last week... some of the seats were out .009

24. 
    Heck as wide as those exhaust seats are they could probably be out .030 and seal upwardly. Lol.

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Source: https://www.forabodiesonly.com/mopar/threads/magnum-head-porting-for-the-beginner-pt-ii-exh.466679/

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