Flow testing AFR vs Profiler

Discussion in 'High Performance Modifications' started by muscl car, Apr 21, 2021.

  1. camaro71/holland

    camaro71/holland Veteran Member

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    Not starting a pissing contest, just thinking out loud. It's looks odd that a 383cui drops off in the upper rpm range where it should pick up from larger intake runners. Is something in the combo choking it?
     
  2. G72Zed

    G72Zed Veteran Member

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    No pissing contest started here, I just posted this chart as I have seen this very thing happen so many times....both heads are very good quality pieces, if applied in the correct application and compliment the supporting actors as well.

    Sometimes getting everything to "dance" at the same time can be a little frustrating, and often times overlooked or ignored. But when you have a "better" head in many areas, both on paper and on the flow bench and the targets comes up short, that's when the finger pointing starts, the heads get the blame, and it's not there fault. Or the engine builder who chose the parts combo, in this case it was the owner.

    This is a classic case of a casting (Vortec) that achieved it's full potential and was a "great fit" for the combo, the Profiler was not allowed or able to achieve it's potential, and looks to have come up short, and that's not the case at all.

    Bolt the intake and carb on the head and flow them as a unit, the "choke" point becomes apparent, and factoring in the cubic inches, rpm and camshaft specs, the results are less than expected.

    Goes to show how important picking a cylinder head is, paying $235 per HP gain gets very expensive not to mention disappointing.
     
    jeff swisher likes this.
  3. firefighter_11

    firefighter_11 Member

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    That was the plan at least for me. I also like the brodix race rite 200 for sbc but I hardly ever see anything at all about them. I can get them and the profiler both bare and have them assembled by machine shop.
     
  4. 1980RS

    1980RS Veteran Member

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    A 383 will always have more valve shrouding over 400 SBC because of the smaller bore that's why the 4.155 bore has the advantage over 4.030 bore with the same head. More top end power due to better breathing.
     
  5. camaro71/holland

    camaro71/holland Veteran Member

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    Sure, but I'm referring to the dyno pull with both results from a 383. A well worked out 383 with good performing 195 heads should outbreathe a 170 head and make more power (not torque) in the upper RPM and it didn't. So I'm just wondering what went wrong there.
     
  6. biker

    biker Veteran Member

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    I think the graph colors are just mixed up. If you read his post, he said the new combo made 460 hp compared to 443 for the old combo. I think the point he is trying to make is that the guy spent lots of money for a 17hp gain because he plunked on a set of big heads without optimizing the combo for them, and the hp per available cfm tells you that there is a clog in the system somewhere, likely the cam. The old combo worked pretty good for what it was.
     
    Last edited: May 5, 2021
  7. G72Zed

    G72Zed Veteran Member

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    Fist off, I accidentally inverted my colours, GREEN is the NEW combo, and RED was the old combo. Sorry about that, my fault. And you're absolutely correct camaro71/holland in your observations and questioning the results. I assure you the core data is correct. The "cork" in the system is parts combo, cam upgrade choice and intake design to a point.

    Biker, your thinking is correct, I spend so much time on the data, forgot the proof read on colours, my bad.

    And your analysis is right on track as well I might add, the owner wanted a "bigger" cam for more power and sound, and this is what I see when too much duration split is used and focus on the exhaust, over scavenging the cylinder is not the way to make more power in the upper RPM's. I believe it's one of those cam's like the "thumper" series. And the Profiler has a good and well shaped exhaust port, in would actually need the opposite of what the owner chose for a cam.

    The "budget" rotating assembly with 5.7 rods and 5/64 rings don't help in that dept either.
     
  8. firefighter_11

    firefighter_11 Member

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    Seems like that cam and intake don’t really match the heads all that well? Just trying to read between the lines. Seems somethings a miss if he upgrades to better flowing heads but only gains a small amount of hp and loses torque. Throw a lunati voodoo cam in it from and see how it changes. Those were UD Harold grinds if I’m not mistaken.
     
  9. camaro71/holland

    camaro71/holland Veteran Member

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    Ok, that explains a lot. Thanks for clearing up. Believe me, I'm the kind of guy who prefers to make something cheap work over just throwing money at it. So I like the Vortec combo a lot. Still would like to make the other combo work too.
     
  10. G72Zed

    G72Zed Veteran Member

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    Correct, cam was not a good choice, tapped out early in the RPM range, not enough lift to get into the meat of what the head could supply, choked with a the dual plane intake, and at 5,700 rpm, the engine needs a MCSA of 1.83, not the Profilers 2.27 CSA, all about velocity to fill those cylinders. Your right, the Voodoo line lobes come UDharold. I have a Voodoo FT solid in my 10.8CR 362 sbc, but make an extra 80 hp with 21 less cubes vs this NEW 383 combo.


    Well, sorry for the error on my part camaro71/holland. That 305 Vortec headed combo worked real well, it was backed by the new TR6060 6spd and pulled great in every gear.

    Different cam, and a nice open plenum intake and another 1,000 rpm, it would of been a much better result, better piston rod combo would help as well.
     

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