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  #16 (permalink)  
Old 01-10-2013, 01:09 PM
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Quote:
Originally Posted by cobalt327 View Post
That's why they pay me the big... ah hell, you know better!

Richard, what do you make of the size of the primaries on this deal? I remember you used your software to show the output using bigger long tube headers was close to the 1-5/8 headers, and this was on a milder build than a 500-plus hp/ 7500 rpm engine.
Mark, you know that I'm no scientist, I'm just an old hot rodder sittin' on a stump with a pencil and paper. The things that I don't know or don't understand scientifically, I try to figure out with common sense and what seems real to me.

When I was doing the sims, I found that the breakover for primary tube size was around 6000 r's on a 383 or larger motor. A 350 at 6000 would still make max power with 1 5/8" primaries, but a 383 at 6000 made a little better power with 1 3/4" primaries.

Here's how I would try to figure out what you're thinkin'. Let's say that a 383 at 6000 passes 665 CFM uncorrected for efficiency. We might conclude that somewhere around 665 would be the breakover point for larger primaries, since they make more power on a sim. Now, a 331 buzzed to 7600 would pass 728 CFM uncorrected, so it would seem logical to me to use a larger primary tube for more power at the top.
I might be full of it, but that's how it looks to me, sittin here on this stump.
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  #17 (permalink)  
Old 01-10-2013, 01:48 PM
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Thanks for the input Richard. I see no flaws in your "stump logic".

I'm tryin to get my head around the recommendation from experts for a small primary, and in this application it just doesn't seem to jibe w/what I thought I knew. Makes me wonder all the more about what I'm missing here.
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  #18 (permalink)  
Old 01-10-2013, 01:59 PM
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You are generally correct. I still need tq to make hp though. Everything else on the setup is for hp. This is the ONE thing that isnt. F, i'm running a single plane
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Old 01-10-2013, 02:04 PM
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Originally Posted by cobalt327 View Post
Thanks for the input Richard. I see no flaws in your "stump logic".
Do dat make me a "stump logician"?
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  #20 (permalink)  
Old 01-10-2013, 04:24 PM
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thinking something like 750 plus CFM a/f management system,255 ish @ 050 timing on the intake,maybe 260 ish exhaust solid roller(probably 108 square). 280 plus CFM intake volume heads with 75% plus exhaust ratio. Jeres headers 11:1
rocker shafts a must
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  #21 (permalink)  
Old 01-10-2013, 04:33 PM
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Quote:
Originally Posted by techinspector1 View Post
Mark, you know that I'm no scientist, I'm just an old hot rodder sittin' on a stump with a pencil and paper. The things that I don't know or don't understand scientifically, I try to figure out with common sense and what seems real to me.

When I was doing the sims, I found that the breakover for primary tube size was around 6000 r's on a 383 or larger motor. A 350 at 6000 would still make max power with 1 5/8" primaries, but a 383 at 6000 made a little better power with 1 3/4" primaries.

Here's how I would try to figure out what you're thinkin'. Let's say that a 383 at 6000 passes 665 CFM uncorrected for efficiency. We might conclude that somewhere around 665 would be the breakover point for larger primaries, since they make more power on a sim. Now, a 331 buzzed to 7600 would pass 728 CFM uncorrected, so it would seem logical to me to use a larger primary tube for more power at the top.
I might be full of it, but that's how it looks to me, sittin here on this stump.
Tech,consider this engine might be used for road racing. note I posted previously 1 5/8 or 1 3/4.This is due to many factors that may be incorporated in road racing.The same header builder ,Jere Stahl, also made my headers.I thought I needed 1 3/4 with 2 steps was what I needed,he made my headers as 1 7/8 stepped to 2 inch. I didnt argue with him and Im happy now with the way my car runs.
500 HP engines can use 1 5/8 or 1 3/4,depends on,,,,,,many things.I think blight has good headers,unless he goes drag racing next week
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  #22 (permalink)  
Old 01-11-2013, 02:59 AM
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I'm built like an asian. I don't drag race, I road race.
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