Importance of Matching Injector Hat To Blower

Discussion in 'PSI Superchargers Tech Questions' started by Battleborn, Feb 3, 2020.

  1. Battleborn

    Battleborn Member

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    Does anyone have any dyno numbers showing the difference between a matched hat and blower opening vs a mismatched setup? Say using a 13.25 or a 15.25 hat on a 10.5 blower opening? Its on a tractor pull deal so its not a situation where the air is really being forced into the hat
     
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  2. Mike Canter

    Mike Canter Top Dragster
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    No but it is being sucked into that hat and goes down and hits a 3” ledge which causes a tremendous amount of turbulence. Like putting out a speed brake on an F-15 fighter. Also think about this. On a blown Hemi a pound of boost is worth about 150 hp. So if you even get a half pound boost increase that is worth about 75 hp.
     
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    Last edited: Feb 8, 2020
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  3. GregM784

    GregM784 Member

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    It's always been stressed to me, that the top side of a roots combo should have zero restriction. I would see a shelf like you describe as a restriction.
     
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  4. andy wilfong

    andy wilfong Active Member

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    Think of it as water being pour into the injector, what do you think it would be like if the water was hitting a flat surface instead of entering the supercharger
     
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  5. rhansenml

    rhansenml New Member

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    Just my opinion, it's more important for the intake of any pump to have a non-turbulent flow at the best angle to load the rotors, in the case of a small opening blower a 45 degrees looks right, and sized to accelerate the air to match the rotor speed, rotors at 11000 rpm have a tip speed close to 200 mph requiring approximately 30-32 square inches measured perpendicular to the throat of the injector. I believe the injector nozzles spraying fuel in on top of the rotors at 45 degrees causes a curtain effect and chaotic turbulent as the fuel is batted upward as it strikes the upward rotation of the rotors pushing fuel back up into the injector against air flow. I mount my fuel injectors at a 45 degree angle so the fuel enters the blower straight down at the edge of the opening, but I put the minimum amount of fuel in on top as I can to keep the blower happy and minimize unequal cylinder distribution, over 60 percent goes in the down nozzles, that right no port nozzles and yes this is bbc
     
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  6. Mike Canter

    Mike Canter Top Dragster
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    But surely if what you are saying about shooting less fuel into the hat gives you more power then the spray bar in the hat would be a waste of time but it is not. Over the years from experience and on a dyno we have learned that putting as much fuel into the hat as you can helps seal the blower and makes more boost, lubricates the stripes so the last longer, keeps the blower bearings cooler, and most of all cools the incoming air charge which changes the Density Altitude and allows more fuel to be burned thus more power
     
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  7. rhansenml

    rhansenml New Member

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    I have no doubt that misting nozzles can have an affect on the air temp if located far enough up stream, but putting 9 gpm instead of 5-6 gpm creates a sloppy stream of fuel that is difficult at best to control where and at what rpm its going to end up. once its in the port it's stuck to the walls along with a good portion fuel being sprayed in by the port nozzles ending up in the back of the valve bowl then blown over the valve seat washing the plug sealing the piston rings lubricating the piston and ends up cooling and lubricating the crank bearings JUST like it did in the blower.

    I prefer to put the 9 gpm through down nozzles with no defector directed at the back side of the intake valve with a high pressure straight stream, that way the only place the fuel can end up is in the middle cylinder as it gets shredded by 40-50 psi exploding into the cylinder, just my opinion
     
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  8. Mike Canter

    Mike Canter Top Dragster
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    You had better hope that the alcohol going into the cylinder is not sealing and cooling the piston rings and pistons because if you have that much unburned alcohol in the cylinder it is running super rich and washing down the cylinder walls and will cause piston skirt scrubbing and worn cylinder walls and rings. Don’t see how you are going to cool the main bearings with alcohol. If you have the correct fuel pressures and the right amount of nozzles in the top of the blower and in the hat then you do not have a sloppy flow. I have watched in on a flow bench and all is good.
     
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  9. rhansenml

    rhansenml New Member

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    I'm worry Mike I meant that as a sarcastic benefit of your theory more fuel the better in the top of the blower, I have no fuel in the rings, pistons or oil. I lube the blower with spray lube the rings pistons and bearings with undiluted oil :)
     
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    Last edited: Feb 11, 2020
  10. Mike Canter

    Mike Canter Top Dragster
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    Ok but it is not my theory it is the way most roots blown Promods are set up and tuned.
     
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    Last edited: Feb 11, 2020
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  11. nitrowannabe

    nitrowannabe Member

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    Google " Jeff Sitton FuelTech powered ". Great shot of spray bar working. Not what I thought I would see.
     
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  12. Mike Canter

    Mike Canter Top Dragster
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    I have a great picture of the spray bar on Adam Flamholc’s car while going down the track. It looks like a big cloud inside the hat just like the one in the Jeff Sitton video
     
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  13. nitrowannabe

    nitrowannabe Member

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    Seems to prove a theory. Most of the top efi roots cars seem to have all the hat fuel in the spray bar. Is most of the air fuel mix pulled into the set back rotor pocket ?
     
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  14. lucky devil

    lucky devil Member

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    I think the one word to remember in all this is "Flow"...… why create obstacles in the path of the air/fuel if it can be avoided. Just my own thoughts.
     
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  15. Battleborn

    Battleborn Member

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    Thanks for the input guys!
     
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  16. dragster156

    dragster156 Member

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    what if the injector hat is larger than the blower opening - I would assume that isn't that big of a deal? or is it?
     
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  17. Mike Canter

    Mike Canter Top Dragster
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    I think you accidentally worded that backwards. The problem is not as bad if the hat exit is smaller than the blower entrance. You are wasting blower potential
     
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  18. dragster156

    dragster156 Member

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    OK let me fix that.

    Let's say the hat has a larger opening than the top of the current spacer being used. the spacer to the blower is perfect. I hope that's better.
     
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  19. dragster156

    dragster156 Member

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    OK well I screwed that up again - smh.

    Hat opening is 9 1/4" in length
    Top of the spacer on the blower opening is 10"

    So to finally get my head of my ass the hat is 3/4 SMALLER than the top of the spacer on the blower. The spacer to the blower is a perfect match.

    Sorry for the confusion.

    it's a carbon hat, should it be matched perfect as well to the 10" or is it a minor detail?
     
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  20. nitrowannabe

    nitrowannabe Member

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    Can I ask what blower are we talking about. Hi-helix, mods, set back rotor ???
     
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