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24* vs 12* vs dr17*

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  • 24* vs 12* vs dr17*

    Any idea how much et difference there would be between similarly built 615-632 engine with a good 24* head and say the 12* raptor heads? Also the dr17 heads, not seeing any info on these at all. The dr17 says conventional (style) what does that mean? Are the exhaust ports same height and angle as a 24* or what makes it conv style? Lets say a race weight of 2500.

  • #2
    "Conventional" describes the original GM big block engine design of valve location.

    A very easy way to tell at a glance is the intake runners. Are there two pairs of runners between the carb and head, or 4 evenly spaced runners?

    In theory, the aftermarket spreadport design is more efficient, thus making more power.

    I reality, well, they will make more power, but conventional head design sure has come a long way!

    TRUMP 2020!

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    • #3
      https://frankensteined.net/shop/edelbrock-dr17/#details They say these flow 565 and 370. That seems crazy to me. I wonder if same headers would work with these as a conventional head?

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      • #4
        Originally posted by Inferno camaro View Post
        https://frankensteined.net/shop/edelbrock-dr17/#details They say these flow 565 and 370. That seems crazy to me. I wonder if same headers would work with these as a conventional head?
        Headers should work.

        I would specifically ask them the following.....

        Do the heads require special intake manifold, valvetrain, pistons.

        One drawback of the SR20 heads is that they require all of their own components....

        565int./370ex. is absolutely HUGE! I do not recall the numbers, but I doubt my modified 12 degree raptors flow more than that! Goneracin probably knows.....
        TRUMP 2020!

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        • #5
          I have not heard much about the DR17 heads, going to be interesting to hear what Bob has to say about them and if Madcap is running them on any of their sportsman engines.
          Impressive numbers for sure.
          Steve

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          • #6
            Well I messaged him and he said he has a set that are not good and didn't flow well. They were from different a porter so not apples to apples I guess. What I've read the dr17 has to be ported so I suppose the porter has a lot to do with it but I really have no clue.

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            • #7
              Inferno are you still thinking about the 20* heads and combo? Seems like the 20* combo is what a lot of sportsman engine builders are turning out with success. Even running on alcohol.

              Steve

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              • #8
                That's what I was planning to do but couldn't find a builder that has much out there running on alky in the 20* stuff. Some say it should work but haven't found the builder that says oh I have that combo out there running good no problem. TRE is the only one that says they have several running alky and really works well. I've gotten really mixed reviews on TRE so not sure I want to go down that road. Really don't know what the heck I'm going to do.

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                • #9
                  One thing for sure with the Eddy 17 head is you wont have to use big time off set rockers.

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                  • #10
                    There is a thread over at DRR in regards to 20* heads albeit Brodix- Dart vs spread port design head interesting comments. One of our members Al Alguire is also in on the conversation maybe he will see this thread and comment!

                    Steve

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                    • #11
                      As was mentioned, we tried some 17 degree heads, actually maybe the first ones in the country...lol. They were not good for us. I ran them on the same platform as our 20* stuff, same cam, same compression, same rocker manufacturer and ratio etc. They were heavy, and were down a significant amount to my 20*. Not from Frankenstein, but from a guy who ive had success with in the past with some 24*. If you do go down the 17* road, i have some pistons and valvetrain id sell you, as im done with the project. If they truly flow 565 from FED, they will make power. BTW, my last 20* 615 made 1250 with an APD 1250 carb FWIW. Same bracket combination as the rest of our stuff. I think my 20* stuff flows like 530-540 ish

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                      • #12
                        Do you have a program for the 20* heads or you have a guy you get them from? Assume that was on gas? What are the pistons that you have for the 17's ?

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                        • #13
                          we have our own program that someone runs for us. yes, on gas. pistons are like 15.5 ish for the 17 degree. diamonds.

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                          • #14
                            Called about the 17* heads and they say they are nearly impossible to get castings but recommends an AFR 3708 18* head. Say it takes the same pistons and intake as sr20 so assume my intake would work with spacers. 2.45 int and 1.88 exh valve. Have never ran AFR heads but seem to have good reviews.

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                            • #15
                              These are the flow numbers and they say these should work better on methanol than their 20's.
                              Last edited by Inferno camaro; 01-21-2020, 06:55 PM.

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