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Supercharged Fhead

Discussion in 'Builds and Fabricators Forum' started by Jrobz23, May 2, 2020.

  1. May 2, 2020
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    So I'm bored and waiting for my shop to get built (still not yet building season here), so my mind is wandering to fun toy projects. I figured this was the best forum choice for this sorta thing, in case this actually happens.

    I started looking at very small Superchargers that might work for the venerable but power-impaired FHead. First off, I like the idea of a Supercharger better than a Turbocharger, on the FHead, due to it's oiling setup. A roots type blower has it's own oil so I don't have to mess with much on this front or integrate into the OEM oiling system.

    My goals are very mild (aka realistic/achievable). I'd like a similar power curve (stock cam) to the FHead but about 80HP usable instead of about 60HP. This should make the vehicle more overall usable. A goal of traveling 60 MPH and towing a small trailer with a mild load (1000 lbs). I'd like to run stock spark setup and a clifford header. Nothing crazy.

    My chassis is already rigged for propane (top end of about 100HP supply - "1BBL"), so this will actually greatly help the spark side (not overly worried about ping with such high octane fuel if I keep advance conservative) and remove any worry about corrosion on a draw through Supercharger setup.

    The charger I'm looking at is a tiny 80s/90s model AMR500. This will produce 500cc air per rev. If my fudge math is correct, I can produce about 6 PSI with about a ~2.3 pulley ratio and still be below 10k RPMs on the SC (16k redline). So I figure I'd run like a 2.5 ratio pulley and play with a overboost valve.

    Thoughts? Math corrections? Flames?
     
    Desert Runner and ITLKSEZ like this.
  2. May 2, 2020
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

    USA
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    Do it! Sounds cool.
     
  3. May 2, 2020
    OzFin

    OzFin Vintage Jeep Guy

    Michigan
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    Please do it, I would like to see his as well ! :watch:
     
  4. May 2, 2020
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    I'm partial to Judsons myself but wasn't there a thread on here last year about these things?
     
    Alan28 likes this.
  5. May 2, 2020
    Alan28

    Alan28 Well-Known Member 2022 Sponsor

    Châtillon en...
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    I remember that there was something on this subject but probably something too powerful for the engine. A CJ5 is not a sport car so it must be adapted to the vehicle...:whistle:
     
    fhoehle likes this.
  6. May 2, 2020
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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  7. May 2, 2020
    fhoehle

    fhoehle Sponsor

    Harford Township, PA
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    :poke:Will there be a dyno run?
     
    Jw60 likes this.
  8. May 2, 2020
    Twin2

    Twin2 not him 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Virginia Beach, VA
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    save your money . build a shop
     
    dozerjim likes this.
  9. May 2, 2020
    garage gnome

    garage gnome ECJ5 welder

    Western MA
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  10. May 2, 2020
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    [​IMG]
     
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  11. May 2, 2020
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    That $ is totally separate from play $ to build a derp SC Fhead lol. Don't you worry.
     
  12. May 2, 2020
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    IDK. Not sure if there is a dyno within 100m of me.
     
  13. May 2, 2020
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    I've followed a lot of turbo / supercharger threads and I've had one myself. I think you're #8

    M38a1
    Life is good (dynoslip)
    Jwjeep60
    sabb turbo and propane about 6years ago
    We had a turbo 2bbl at the fall reunion
    Garage gnome was looking last year
    Unclemoak on the 2apage is building one now.

    I think you need to focus on blow thru and your build quality.

    Basically these are engine multipliers. They will make a good engine great and a bad engine go boom.
     
    Alan28 likes this.
  14. May 3, 2020
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    If I had a spare engine *cough cough* :whistle:

    I will say boost seems great but a powerful NA engine gets my attention...
     
  15. May 3, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    If you are thinking about supercharging, pick one that is efficient.
    I've been driving my Eaton M45 powered Mini Cooper since new in late '02, and is on SC#3. It works well enough that I haven't done anything other than a 17% pulley. The latest Eaton has soft coated rotors that makes a noticable difference, but its still a Roots design, but it will get to 11 psi on the top end.
    I also play with BMWs, and have a centrifugal blower for a 2.8 engine. It takes a total re-map of fuel and spark to get the most out of it, and keep it safe. The biggest issue is it makes more power the higher you spin it. Under 2500 rpm, You don't even know its there. Probably not good for a Jeep.
    Now on to my recommendation; find a twin screw! I also have another BMW with a TS and its a whole different story. It has a small Lysholm pump (same as Whipple) and it only makes about 7 psi, but its all-in by 2000 rpm as far as torque is concerned. Read up on twin screws. They are a more efficient design and do more for making torque down low than other style superchargers. To get the most out of it, I still need to upgrade to an intercooler because of my warm weather, but these units are impressive. Yes, a re-map and tune are required.
    There are usually some twin screws available on eBay from the Japanese and Korean market cars that might be about right for your project. My best guess is you should be looking at least a 1.2 - 1.6 liter displacement TS for an F134.
    -Donny
     
  16. May 3, 2020
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    I’m not looking for a rocket, just an augmented power curve and nice clean tight packaging. I’m most interested in a solid mid range boost.

    If this actually happens and works, and the FHead stays together, I might play a little harder ;)
     
    dane71 likes this.
  17. May 3, 2020
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Fwiw I used a turbo for a 1.6l Mitsubishi colt. It's redline × displacement was the same as the 134.
    You are basically looking for a motorcycle supercharger.
     
    Jrobz23 likes this.
  18. May 3, 2020
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Yeah that’s exactly what I found. The AMR500 seems like a good fit.
     
  19. May 3, 2020
    Desert Runner

    Desert Runner Member 2024 Sponsor 2022 Sponsor

    Hickory, Pa
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  20. May 3, 2020
    Keys5a

    Keys5a Sponsor

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    Those AMR's are Roots style superchargers, similar to the Eaton on my Mini Cooper S. They can make good boost, but its dependant on the engine spinning up to high rpm, not what a 134 is generally happy with.
    Please read up on what a twin screw supercharger is.
    The Roots units are "pumps" that that move air from side-to-side, relying on the resistance of the cylinder head to build boost, whereas the twin screws are compressors where the air is compressed in the supercharger. The roots units make more boost the higher the rpm. The twin screws build full boost at reletivelty low rpm, like 2000 rpm.
    You can tell a twin screw because the air enters the unit on an end and exits at the other end on the top or bottom. In Roots style, the air enters on top, and exits directly opposite on the bottom.
    I have cars with all three type superchargers (centrifugal, roots, and twin screw) and I can tell you that the twin screw style are far and away a much more efficient design, giving an extremely flat torque curve from approx 1800-2000 rpm all the way to 5000+ rpm. These are much better suited for a low rpm Jeep engine.
    -Donny
     
    ITLKSEZ likes this.
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