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Questions About All Motor Hf

Discussion in 'Engine Building' started by theantiriced, Jan 15, 2003.

  1. theantiriced

    theantiriced Junior Member

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    im new to hondas and i am thinking about getting an 88-91 crx. i was reading that hf all motor buildup and i have a few questions. first, how much torque (approximately) will those mods give me? also, how big are the hf motor's rods compared to a dx? are they the same? also are the hf's gear ratios really that bad for an all motor setup? it says the car will pull on si's, and even gsr's?! is this realistic?
     
  2. prawjEKt Cx

    prawjEKt Cx Senior Member

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    building an HF motor???????? how about you give me 20 dollars and i shoot you in the foot and we call it a day
     
  3. theantiriced

    theantiriced Junior Member

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    thanks for the intelligent response. now can someone answer my questions?
     
  4. TotallyRandomDriver

    TotallyRandomDriver Junior Member

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    Honestly dude, I've driven an HF and its the slowest thing I've ever driven. The gears are extremely long, shoot I could read a friggin book while I waited for it to redline. As far as the head swaps and all that stuff..... sure its cheap, but I honestly find it hard to believe that an HF with those mods could pull on a gsr and si. You are better off doing a mini-me or getting a sir1 b16 from hondamotorsline. good luck
     
  5. punx04

    punx04 Member

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    if your gonna keep the hf motor then atleast get a d series si tranny examlpe y, my second gear goes to 60.....my 3rd gear basicly tops out at the same speed as fifth
     
  6. Dr.J.

    Dr.J. Junior Member

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    Hi,

    The key to the HF build up is car weight. HFs have the lightest weight of any CRX at 1916 lbs. Now if you do the math, a GS-R on the street is around 2760 lbs (ignoring driver in both cases). Most stock GS-Rs (94-96 cars) dyno at around 142, 152-160 with the usual bolt-ons.

    Let's do some math:

    HP = Vehicle Weight * (Trap speed/234)^3

    or

    Trap Speed = 234 * (HP/weight)^1/3

    For the cars to have equal trap speeds set the two equations equal to one another for the CRX and GS-R, with x being the hp the CRX needs to match the GS-R:

    234 * (142/2760)^1/3 = 234 * (x /1916)^1/3 --- divide both sides by 234

    (142/2760)^1/3 = (x/1916)^1/3 --- cube both sides

    (142/2760)=(x/1916) --- now it is simply a function of power to weight

    x = 98.6 hp!


    Now as someone pointed out the the gearing of the HF sucks which is not reflected above. The HF build-up in the articles section is not meant to give you a car that will beat a prepped Civic Si, GS-R or Type-R. Is is meant to be a quick and cheap way of getting a inexpensive car (~$1500) to be reasonably quick for a little wrenching and a few bucks ($500). I think it is a great starting point for anyone just getting into Hondas and doing their own motor work, as the cost-benefit and cost-screw up ratios are not that much. If you make a mistake you're out a few hundred bucks, try that starting off with a B-series motor in the aforementioned cars and you see why this is meant to be "fun", not to give you a 13-second car.

    I say do it...have fun, then use this quick little miser to go the the parts store for a nice B-series project... :D

    Cheers,

    Michael
     
  7. theantiriced

    theantiriced Junior Member

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    thanks for the insight.
     
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