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Low RPM torque charts?

Discussion in 'The Garage' started by koldsimer, Apr 12, 2006.

  1. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    Hey everyone, i've looked all over and I can't find the info I need. I'm looking for tq/hp graphs for these three motors; zz383, ht383 and the ramjet 350. All the graphs that I find show nothing below 2k rpm. I'm real interested in seeing how these engines do from 800-2,000 rpm. I end up lugging my engine a lot and I dont want to find that one of these unexpectedly cannot handle extreme low rpm use. From the info I can find, It looks like the zz383 has the flattest curve of them all from 2k up even though it seems to be designed for higher rpm use. The driveability of the ramjet at low rpm's should be awesome due to FI but I wonder if it has the cojones down low where it needs them? Realistically, i'm probably gonna get either the ht383 or zz383 because I already everything needed to make it work. So, any advice or tq/hp charts you guys know of that would help? BTW, I know the ht383 would be a stumpuller but the extra 100hp and 40lbs of torque of the zz sure are enticing.
     
  2. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    TTT. C'mon guys! Not even, "your a jackass for caring" or "go search"? How about any real world experiences with any of these motors?
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The one with the mildest cam will have the most off idle torque and best 'luggability'. Long stroke, FI, and a tame cam should be the combo that works best for you.

    Rene
     
  4. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    So what would you pick? the zz383 w/q-jet, the ht383 w/q-jet or the ramjet 350?
     
  5. dcubb

    dcubb 1/2 ton status

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    I have the HT383. with a 700r4, 35's and 4.10 gears it will pull overdrive with the converter locked practically any speed effortlessly. And that's at 4000' plus elevation. the motor's only got about 800 miles on it and I've yet to finilize tuning (carb jetting and ignition curve). It does seem a bit flat in the upper rpm range but it's great on the low end.
     
  6. HarryH3

    HarryH3 1 ton status Author

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    The zz383 will give up bottom end torque for high RPM horsepower. Great for a mud racer, but not so great for a rock crawler. The HT383 is cammed for bottom end torque and getting heavy trucks moving.

    Last fall I helped a guy swap the cam out of a GM HO350 because the powerband came on way too high for his rock crawler. It made power like mad up around 5K RPM, but was gutless off the line. We put in a much milder cam and he was quite happy with the throttle response afterwards. :cool1:
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Yeah, in general hotter cams make more peak power, but also move the torque peak farther up the power band at the expense of off idle/low rpm torque.

    Lots of cubes, long stroke, FI and a tame cam = crawlin' joy-joy.

    Rene
     
  8. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    I keep checking out the torque curves for the zz383 and ht383. The zz is dead flat from 2,000 up. The ht is building torque still at 2,000 and flattens out at about 2500. Am I correct in assuming that the zz 383 would fall flat quickly under say 1,500 rpm's? I know the ht383 would be an absolute stump puller which is what I want for my 4 speed. It just kills me that it only makes 330 hp. I really think it's my smartest choice at this point. Then there's the fi'd ramjet....
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'd sacrifice a bit of tq to have FI. Carb's are for chainsaw's and lawnmowers, and wheeling with one sucks. i know the Q-jet is better than most...but it still doesn't hold a candle to FI for driveability, throttle response, cold starting and wheeling at crazy angles.

    Rene
     
  10. Citizen Rider

    Citizen Rider 1/2 ton status

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    I wanna see a stroker in your beast!
     
  11. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    I hear ya. I am extremely happy with my q-jet 99% of the time but I want and need (to some degree) the fuel injection. I keep seeing myself at some horrible angle trying to start the truck and it not wanting to idle and having to rev it and just drop the clutch. If my ramjet was in the same situation, there would be no idle/running issues- this can be huge in a 4spd. Then again, I have a flywheel for a 400 and i'd have to buy a new fuel pump and tank for the ramjet. Dang, I wish I could make up my mind here. So much to consider.
     
  12. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    Me too... I keep wanting to hear that zz383 scream!
     
  13. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I gotta tell ya that I've done the 4 speed/carb/stupid angle thing for the last time a few years back. Good riddance IMO. I went another direction and dropped a 6.2 diesel in my Jimmy though. It only shuts off with a key and has no problems idling and running smooth at any stupid angle I care to be at. If I do have it shut off I can easily start it in gear in low range even at the same stupid angle. It starts within the first two rev's of the starter when hot, without any throttle input. It also buries any small block in the off idle tq department...and gets twice the fuel mileage on a bad day. :D

    Honestly, if you're crawling I'd go FI and never look back. As for a fuel tank I don't think you need anything special...just a good high pressure electric fuel pump and you should be good to go. It comes with the ECM and stuff...add 12 volts and you're pretty much done.

    Rene
     
  14. Moody

    Moody 1/2 ton status

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    You're running a 400SB right now right? Why don't you just slap some vortecs on it with a cam swap and a quadrajet and be done with it. A similar build in chevyhp made 471 ft./lbs of torque at 2300 rpm. I'm sure it would be making over 400ft/lbs down well under 2000rpm. I built a similar motor with a comp XE268 for under 2,500 bucks. It would be a lot less money than buying a new crate motor.
     
  15. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    My 400 is already bored at least .030 and it's starting to make a bad sounding noise. I foresee it dying pretty soon. Still runs strong and still has good oil pressure though so who knows.
     

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