Screw Funnycar Injector Styles

Discussion in 'InsideTopAlcohol.com Tech Questions' started by TOL, Apr 10, 2019.

  1. TOL

    TOL Active Member

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    Dumb question for the day......

    When I look at recent videos I notice something interesting.

    Some teams still run the old school open bottom FC hats of various shapes and forms and sizes. Whether they have internal dividers I can't tell.

    A lot have switched to the JBR type front load carbon injectors that feed only the front portions of the screw.

    I've noticed a movement away from the big throttle blade MK16 carbon front load injector which used to be really popular in the past couple of years (yes it is a couple inches taller). I wonder why? Visibility?

    Still, all of the teams seem to have about similar performance. So I gather from this that front loading a screw may not be all that it is touted to be worth at 92% ?

    I would have anticipated a bigger disparity between the styles, but I'm just not seeing it?

    Thoughts?.........
     
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  2. blowntuner

    blowntuner New Member

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    if you switch from a standard PSI magnesium funnycar injector to a jbr, you will get 2-3% more power
     
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  3. Andy C

    Andy C Member

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    We had our PSI C dyno tested at Hammer Supercharges – testing multiple hat designs. The JBR front loading, also tested 3 round hole full open bottom, also had few spacer. Each one performed differently. One set up had more boost on the hit, the other had little less at the hit, change the spacer less at the hit more at top end. When it’s all said and done, we are only talking about max 1-2 lbs of boost difference on top end. The bottom line is, how your tune is up? Each hat design will need a slightly different tune. We didn’t see any tremendous gains worth bragging about between the best and worst hat we had.
     
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  4. TOL

    TOL Active Member

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    Thanks Andy, that was very helpful. What sort of overdrive were you testing at? 1.92? 2.28?
     
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  5. Luke G

    Luke G New Member

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    I'm a roots blower guy so I have a pretty good handle on how changes to the top opening change the boost characteristics on a roots but I'm not sure I understand how a front loader hat works on a psi with the helix being the opposite of a roots blower, is it just closing the the top opening or is it to do with where the air is directed?
     
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  6. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    The front loading injector tends to make more boost at the hit. The full open hats tend to do a little better at the top of the gears and on the back 1/8.

    Last year they banned any kind of divider or insert that goes below the injector mating surface, so that kind of hurt the PSI mag injectors.

    TOL, you like engineering type stuff - so here's one thing that I think helps the mag injectors - the "ice." Very rarely do you ever see a carbon hat ice up. I think a mag injector cools the air better than a carbon hat, so that may be something that helps them.

    I think the newest JBR is a little better. I think to claim 3% across the board is a little steep.

    The lowest common denominator here is the blower. Obviously an injector can only be better than another injector if the latter is restricting flow. I think the mag D port injector is pretty efficient at 92 over at feeding the blower.

    Most TAFC's nowadays don't have full power ramped in until 8500-9000, so it really marginalizes any 'at the hit' advantages.

    I haven't ran one back to back, so I just speak from personal experience. I think the new carbon hats are a little better, but not a huge step.
     
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  7. TOL

    TOL Active Member

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    Thanks Will.

    So let me ask a loaded question if I may, and if anyone wants to reply offline that is fine.......

    Has anyone tested the Bohr PM/FC low profile carbon hat (open) against others, and how did it compare?

    I am down to deciding between either it or a CGC carbon MK16 front load hat. Both are fairly low profile, which is what I need.

    Maybe it's just me, but my thinking is that a well designed open design, maybe moved up and forward 1.5x1.5" with a decent short side radius into the blower housing makes a bit more sense than a purely front load hat design which forces all the air perpendicular into the front cavity of the blower and then forces a significant portion of the air to then turn 90 degrees to run along a flat plate and fill the tails of the rotor voids behind? Assuming no insert/deflector plates.

    I have no data one way or the other to support either. Just a lot of time staring down into my "C" as I unwind from the day and think about the airflow characteristics.
     
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