how much top end>>

Discussion in 'Performance Modifications' started by NO HEMI, Jul 3, 2013.

  1. NO HEMI

    NO HEMI Viper Owner

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    How much top end speed do i lose from going from the stock 3.07 to 3.55's on a basically stock viper?, can i go up to 190 mph in 6th instead of 5th?, or will i need more torque to do it?? Thanks!!
     
  2. Steve M

    Steve M Viper Owner

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    Here's a good gear ratio calculator to play around with:

    http://xse.com/leres/ss/calculator.html

    Just put in your tire size, change the redline (6250 for a Gen III, 6400 for a Gen IV), and adjust the rear end ratio and you'll have your answer.
     
  3. NO HEMI

    NO HEMI Viper Owner

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    I tried it and it showed 189 mph in 5th!!??, and about 164 in 4th??, right now i top at 150 in 4th!!.. Maybe I'm doing something wrong.
     
  4. dester243

    dester243 Enthusiast

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    Ya, I don't think that calculator is 100% correct.

    I did 3.07 FD
    added 28.7" tall tires (due to my DRs)
    6200 rpms
    and it says 6th can do 344.8 mph. Ya I don't think that's right....
     
  5. SquadXX

    SquadXX Enthusiast

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    I have 373s with 18 inch wheels and i hate that gearings. Good for the track but highways it sucks. im topped out in 5th at 156. I will be going back to 307s.
     
  6. NO HEMI

    NO HEMI Viper Owner

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    but squadxx, don't you have enough torque to keep pulling in 6th?
     
  7. AZTVR

    AZTVR Enthusiast

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    What horsepower, torque and coefficient of drag did you put in the calculator to get your cars top end speed?

    The calculator only tells you how many miles in one hour the tires would cover when the engine turns at the RPM given. No consideration for friction losses, cd, air temperature, wind direction, inclination of road surface, etc.
     
  8. TowDawg

    TowDawg Viper Owner

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    I put 3.33's in mine and I think I actually gained top end because I can keep pulling in 6th. I ran an indicated 197-198 in 6th gear with the 3.33's and still had more to go, but ran out of road (in Mexico of course). I know speedos aren't necessarily all that accurate up high, but it's all I have to go on.
    I've got the revised 5th and 6th in the transmission now, but I haven't had a high speed run with them.
     
  9. Steve M

    Steve M Viper Owner

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    What year is your car? I've used this calculator many, many times, and it is always right on the money provided you put in the right set of variables.
     
  10. NO HEMI

    NO HEMI Viper Owner

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    I have a totally stock( for now ;)) 2006 conv.
     
  11. NO HEMI

    NO HEMI Viper Owner

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    That was my 2 nd choice tow dawg, but looks like it might be my 1st !!
     
  12. 345s-bspinnin

    345s-bspinnin Viper Owner

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    What drag radials are you using that are 28.7" tall? I wanted a taller rear tire, and the 345/35-18, 28" M/T Drag radials I bought are only about 27.5" tall when mounted.
     
  13. 345s-bspinnin

    345s-bspinnin Viper Owner

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  14. NO HEMI

    NO HEMI Viper Owner

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    Thanks andres, it helped alot, and with my mods i think i'll go with 3.55's and 3.33's when i go FI!!!
     
  15. spartan

    spartan Enthusiast

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    ndres, seeing as in the future i am looking to replicate your motor setup, what gearing are you using on your car? what would you recommend? it will be a street car with some strip/roadcourse time.
     
  16. 345s-bspinnin

    345s-bspinnin Viper Owner

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    Spartan, I am using the complete stock Gen III gearing. I believe its perfect for the power I am making. My gearing setup has worked well in standing mile and half mile events. Some folks complain that 5th gear is too long, but I was still able to hit 195mph in the stand mile.Its not optimal for the 1/4 mile, but I was able to get into the 10s on a very hot/humid day. It works well in the road course too, but you have to learn how to steer with the throttle. The generous torque will make the tail come around very quickly if not cautious. Lastly, the stock gearing works great for hwy cruising. I am still able to get over 25mpg on a long drive.
     
  17. spartan

    spartan Enthusiast

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    ^excellent, exactly what im looking for. would 3.55 be too short of a gear? any idea how a 3.3 would do?
     
  18. dester243

    dester243 Enthusiast

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    Sorry I forgot about the thread.

    I have the 315-35-20 nitto nt05R DR.
     
  19. NO HEMI

    NO HEMI Viper Owner

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    so after all is said i guess even if the 3.07 are really good, if you do a bit more autocross and 1/4 mile than 1/2 mile events, and plan on going FI the answer would be to put in a 3.33 !.
     
  20. Tom Sessions

    Tom Sessions Enthusiast

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    Only problem with the 3.33s is they do not make them anymore. So if you can find a set grab them.
     
  21. NO HEMI

    NO HEMI Viper Owner

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    :Dohh didn't know that!!!!, i guess i'll start looking.!! :2tu:
     
  22. Richard Koch

    Richard Koch Enthusiast

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    I am heading to the Mojave Mile (and 1 1/2 Mile) event next week. I checked the gearing tables for my 3:55 gears and it looks like I could go 180 at 6,000 rpm in 5th. I realize that drag etc. will limit me. Does anyone have experience with using 6th gear with 3:55s above 150 mph and whether it will pull well enough to warrant the shift? I have a few mods on my 1999 RT-10 and it has pulled 443 rwhp, so I hope it will be a little faster than a stock Gen II.
     
  23. steve911

    steve911 Viper Owner

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    There are some 3.33's out there but they were made for the Vette Dana 44. The bearing on the pinion gear is smaller than on the Viper. Some will include a spacer to allow it to fit, but I have seen even stock Vipers twist off the the end of the pinion gear where the drive shaft yoke is attached to.

     
  24. NO HEMI

    NO HEMI Viper Owner

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    Hmmm, can I usea 3.55 on a 800rwhp car to try and squeeze all the mph I can on 1/2 or 1 mile run??, I know hooking will be hard on the 1/4, but i'll have big enough DR's(hopefully.)
     
  25. 345s-bspinnin

    345s-bspinnin Viper Owner

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    I would NOT recommend drag radials for any standing mile or 1.5 mile event. First of all, a hard launch will have little to no impact on final speed. Second, and most importantly, a drag radial is not designed for sustained high speeds. I have seen the blow outs. Some events like the Texas Mile don't allow drag radials at all. Just run a modern W/Y rated street tire and you will be fine.

    As for your gearing questions, don't shift into 6th. The 0.5 ratio will kill your acceleration. Just run 5th gear all the way out. Also, based on your power (443whp), you won't come anywhere close to 180 in 1 mile. Your power is on par with a Gen III, and those average about 140 in the half and 160 in the mile. That extra 1/2 mile may get you in the high 160s at most.

    Good luck, and keep us posted on your results.
     
  26. Richard Koch

    Richard Koch Enthusiast

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    Thank you for the information. I didn't think that 6th gear would be a viable option. I am hoping that in the extra 1/2 mile I can get into the low 170's, but running at 3,200 feet and the expected high 80's for temperature I think I may be a bit optimistic. I will let you know what the results are. By the way, I am running an almost new set of Toyo R-888's, which should be fine on the long runs.
     
  27. Cobraken

    Cobraken Viper Owner

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    I didn't think 6th gear was usable in any race/top speed applications in a stock Viper. So many comparos on TV and in magazines where the Viper would be leading until shifted into 6th and the other car catching up and passing (giving the appearance of the Viper running out of power or hitting a wall). Will going to lower gears (3:55 or 3:33s') allow a stock Viper to pull in 6th gear and attain a higher top end?
     
  28. Richard Koch

    Richard Koch Enthusiast

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    My post (#27) mentioned that I was headed to Mojave to run my 1999 RT-10 in the Mojave Magnum 1 1/2 mile competition. I run 3:55 gears and pull 443 hp at the rear wheels. I only got one fairly good run, but was pleased to run 175.3 mph. I think If I could do some fiddling I could improve on that with a better launch and better shifting. For a car that turned over 100,000 miles on the return trip I am fairly happy. It is nicely broken to be sure.
     
  29. Richard Koch

    Richard Koch Enthusiast

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