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Hurricane F134 Driveability

Discussion in 'Early CJ5 and CJ6 Tech' started by schneedrache, Jul 5, 2016.

  1. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    It's mostly about wind resistance. Wind resistance increases with the square of velocity, so it takes roughly 4x the amount of power to go twice as fast. The F134 has peak power at about 3500 RPM. Above or below that, power falls off. The gears were chosen so that the maximum forward speed against the wind is at peak power. Change the gearing to make the engine run slower, and you lose top speed. Change the gearing to make the engine run faster, and the torque curve falls off and ... you lose top speed. Same thing into a headwind. Same thing up a hill. Same result. You can't squeeze blood from a stone.
     
    eti engineer likes this.
  2. eti engineer

    eti engineer Member

    Ron,

    My CJ has adjustable stops to keep this from happening. If you have issues with oversize tires, you can adjust these stops to keep that from happening. I am running 31's and they seem to be a happy medium all the way around. I still have a turning radius that's respectable, they don't totally rob my power and they give me some clearance. I like them. I also have wheels with an offset, but since they come from the PO, I don't know how much of an offset I have.
     
    Last edited: Jul 8, 2016
  3. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    I love the f-134 around town in a rural village, and on trails. Personally I consider 50mph to be my comfortable top end limit, on the original engine.

    On state roads with conventional traffic, there is a lot of pyschological pressure to over-rev the Jeep so as to not be leading a parade.

    That can quickly hurt an engine that is not in new condition... and anyhow, it's no fun.


    tumblr_n0z1k7xX7c1svfy0eo1_500.jpg
     
  4. eti engineer

    eti engineer Member


    I ran mine with the windshield down the other day and it is amazing how much drag that windshield creates. Very noticeable. However, in the psychotic state of CA, it is illegal to drive with the windshield down.
     
  5. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor


    i consider driving with the windshield up to always be a real drag, regardless of speed. :D
     
    eti engineer likes this.
  6. eti engineer

    eti engineer Member

    Me, too, Pete, but State Troopers frown on the "hi-speed/lo drag" mode around here. Welcome to the over-regulated, psychotic state of CA...
     
  7. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor


    That sucks. When I was a kid listening to the Beach Boys, I thought California must be the cooolest place in the world

    New Hampshire = "Live Free or Die."
    :)

    "The right to be let alone is indeed the beginning of all freedoms."
    William O. Douglas
     
    eti engineer likes this.
  8. BobH

    BobH Member

    What about more CFM's from the carb. Would that help? I think that if you do the math (there was a thread about this) 150 cfm is good (?).
     
  9. ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Except for that whole state inspection BS. ;)
     
  10. Glenn

    Glenn Kinda grumpy old man Staff Member

    ETI engineer has the 2 barrel Weber on his.
     
  11. ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    I ran a 2 Jet on my F-head for a while with ported intakes and a high compression head. The upper RPMs really opened up quite a bit, but the off-idle lug-ability really suffered.

    It's a game of compromises.
     
  12. Daryl

    Daryl Sponsor

    This thread explains exactly why most engines get swapped and Dana 25 and 27s give way to a Dana 30.
     
    GillaFunk likes this.
  13. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Huh. When I lived in California, I drove around the burbs with the windshield down all the time and nobody bothered me. Of course, this was 1973, so maybe that matters.
     
  14. 47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

    The 134 will be fine to 55 mph as it is with 5.38's. Anything more will be asking a lot. Its ok because if you don't upgrade the steering and brakes you won't want to go faster.
     
  15. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Very true.

    a) It is easier with antiques. No emissions test.
    b) It is a whole lot easier if you live in a small town.
     
    eti engineer and ITLKSEZ like this.
  16. Glenn

    Glenn Kinda grumpy old man Staff Member

    That is true and a very good point. Intended use is the key and thus dictates what form of reality check one needs.
     
  17. Bajatransit

    Bajatransit Member

    I have a 67 cj6. Hurricane motor. After reading a ton for about two months I think I'm leaning toward doing the 4.3 v-6 conversion. Nice to hear others are going through the same deliberations. Probably throw in the Muncie sm420 as well.
     
  18. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    What's your intended use for the jeep? You can read all sorts of opinions on what a jeep needs to Be A JEEP but what is , or isn't required/a good idea depends on what you'll ask t to do, & to a very large extent on your driving style.

    Before you get started on any major mods I'd suggest driving it for a bit, finding any issues with things like brakes or steering and fixing those then seeing how well it works the way it is for what you want to do with it.

    Welcome :)

    H.
     
    Bajatransit likes this.
  19. PierreDnepr

    PierreDnepr Member

    100% agree -

    I have a 66 CJ5 completely stock with the F134. I live in an area mostly flat with small hills - the F134 is good at 50mph - 55mph. I have done 60 mph but only on good pavement with a tail wind but I do realize its pushing it. I have the 9" brakes without the star wheel adjuster. So each pads are adjusted individually with an eccentric. They are not that easy to set them perfectly right and you learn to leave a lot of distance between the guy in the front. If I had a minimum amount of money to spent - I would put them on the brakes (11" drums) first since I am happy with the motor as it is.
     
  20. 1960willyscj5

    1960willyscj5 Well-Known Member

    I am very comfortable with the F134 in my '60. No trouble running 50-55mph with occasional 60 mph stretches.
    Being retired, I am in no hurry to get anywhere, so 50-55 mph is fine with me.