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Cruising Engine RPMs, Gears & Gas Mileage

Discussion in 'SRT10 and SRT10 Coupe Discussions' started by IDM, Nov 24, 2012.

  1. IDM

    IDM Enthusiast

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    I have only had the 05 Viper for 1 week today. Have already put on over 400 miles, now up to 7200! My job is only 4.5 miles each way so it's been a lot of cruising and giving rides to family and friends.

    This is my daily driver and only car.

    I would like to know what the lowest but safe cruising rpm is? It seems like the gears are set up in an interesting way where I am never able to go the speed limit and be in a gear which is low rpms but is not bogging the car down.

    I would love to maximize my gas mileage and wear on the engine by using 5th in the city and 6th on the highway but don't want to bog down the engine and possibly strain or damage it. So what is the magic lowest safe rpms for flat roads cruising? Obviously if I need to go up a bridge or hill I would downshift for power.

    Once I know what the correct lowest cruising rpms are I can try it out and see if a gear swap is necessary.

    Thanks very much in advance for your advice.
     
  2. robiferretti

    robiferretti Enthusiast

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    Lower RPM= less fuel. So just above the stall point would be using the least amount of gas.
    But you bought a Dodge Viper as a daily driver. Lets not discuss gas mileage. :)

    Your better off buying a daily driver for the same money you would spend on a gear swap if fuel usage is a concern.
     
  3. IDM

    IDM Enthusiast

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    Not to be rude but what you wrote wasn't useful as I covered the basics in my mind LOL!

    I was hoping to learn what the lowest RPM is safe to cruise at. Thanks!
     
  4. robiferretti

    robiferretti Enthusiast

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    What in your mind equals a "safe RPM"?

    You've question and logic make no sense to me, sorry I could be of more help.
     
  5. happy56

    happy56 Enthusiast

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    We cruised for hours in 6th gear at 1500rpm and got 21mpg. 2000GTS
     
  6. denniskgb

    denniskgb Enthusiast

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    Seriously?/
    Do yourself a favour and get a beater to drive daily. As much as you love eating candy if you eat it every day you are going to hate it. Gas mileage?!!!! Ok the only way you get good gas mileage if you put it in NEAUTRAL and roll it down the hill with the wind.:rolaugh:
     
  7. TrackAire

    TrackAire Enthusiast

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    If you want to protect the engine, the worst thing you can do is cruise it at very low rpms under load when the oil and coolant is cold. With your 4.5 mile commute, the motor will not have enough time to heat up and burn off condensation and contaminants out of the oil. Trying to drive at a low rpm and lug it along to save mpg's for such a short communte isn't going to help, in fact is is harder on the gears in the transmission since you're putting more load on them without the lube being brought up to temp.

    Doing a gear change will take about 5 to 6 years of driving to pay off in mileage gains (I'm being way generous).

    The rpm isn't going to determine mileage as much as engine vacuum....if you put a vacuum gauge on the car you'll find that under certain conditions, lugging the car will give you worst mileage. If you can keep the car under load with the highest amount of vacuum, then you'll get the best mileage. For city type driving, your first four gears give you more than enough flexibility to do this.

    Driving the car "aggressive" vs lugging it for better mileage on a 10 mile trip would equate to less than $1.00 per day in savings.

    Enjoy your new ride, you're fortunate to be able to use the Viper as your daily driver.

    Cheers,
    George
     
  8. Steve737

    Steve737 Viper Owner

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    I think I know what your asking and I don't like to cruise at much less than 15-1800 rpm. Morgen at tombal dodge Said luging these things is really hard on the engine. I bet you would like a 355 or 373 rear end much better. Steve
     
  9. Steve737

    Steve737 Viper Owner

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    Oh and I would consider getting another car to help subsidize the snake. I'm sure you could get something cheap to drive on crappy days! Steve
     
  10. BlknBlu

    BlknBlu Enthusiast

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    Dodge Viper=bad gas mileage

    Bruce
     
  11. Allan

    Allan Enthusiast

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    I drove mine daily as transportation when I got it. Did that for about a year. Then finally realized that a Corvette is a much better street car. My Viper is now just a toy for track days. As much fun as these things are, you need an alternate ride for slumming around day to day. It also helps the Viper experience to be more intense.
     
  12. Mopar-man

    Mopar-man Enthusiast

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    Tow it with corvette and you'll get great milage
     
  13. IDM

    IDM Enthusiast

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    George thanks a lot for the technical response. I didn't realize that swapping gears is so expensive in this car.

    I could get a daily driver but I dont like having to worry about two cars as far as storage, insurance, maint. etc.

    I am lucky the job is close! Thanks Steve and all else. Looks like I will just leave as is for now and make sure to stay above 1500rpms
     
  14. tattooed

    tattooed Viper Owner

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    IDM, as others have suggested, you shouldn't be focused on gas mileage and economical driving styles if you're driving a Viper. I also use my Viper as a daily driver (2010 ACR), and have put 5000+ miles on it in 6 months. I *always* drive it the way it is supposed to be driven, and fill it up with 93 octane when it gets below 1/4 tank. I've never bothered to measure the fuel economy. I've got an Escort 9500ix + Escort Live + Laser Interceptor 4 head unit, so I haven't noticed any issues with gearing and speed limits. ;)
     
  15. IDM

    IDM Enthusiast

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    I am only trying to get used to the car and want to take care of it correctly.
    The mileage is bad but I want to be able to optimize it, that's all. My car doesn't warm up before going to work so I have to baby it.
    It also doesnt feel very fast to me so I have less desire to punch it a lot, I came from a vette like in your signature. The Viper is an amazing and unique car for the money though and I am enjoying it thoroughly.
     
  16. speedracervr4

    speedracervr4 Enthusiast

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    Why not let it warm up prior to leaving for work? I would suggest starting it about 5 minutes prior to heading out.
     
  17. ViperTony

    ViperTony Enthusiast

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    Toss the mileage optimization goal out the window. Forget the gears. Drive it. Since your commute is too short (4.5 miles) and your Viper isn't warmed up before going to work then I suggest you leave for work 15 minutes earlier and take the Viper for a warm up cruise, romp around a pre-planned route on your way to or around work. You'll get better gas mileage this way and warm up the Viper. More importantly, it'll put a s***-eating grin on your face when you arrive to work every morning. :D
     
  18. IDM

    IDM Enthusiast

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    I have actually done that every day after getting out of the shower until leaving. Still my temps dont get to 180-200 for a bit and it's okay with me to drive the car slow to work and back. During the weekends I can do some spirited driving. The car is not fast compared to previous cars so the excitement of beating on it is not prevalent. Im just happy to be in a Viper finally! I hope to see you guys out at some track events where I can actually do what Id like with it!
     
  19. JAY

    JAY Enthusiast

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    Highly recommend a second car. :)
     
  20. IDM

    IDM Enthusiast

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    Jay I just cant stand having multiple cars for a single guy. Plus work is close, and when I have a car like this I want to drive it and not be in the beater. I did this for the last several years with a nice corvette and was miserable not driving it and having two cars to handle.
     
  21. 345s-bspinnin

    345s-bspinnin Enthusiast

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    The old wives tales and non-sense on this thread are staggering.

    Why would need to be above 1500rpm at all times? This means that you will be in 5th gear all the way to 80mph with rpm at 2200+ rpm before a change to 6th gear (rpm is your requested 1500). You can cruise at 60mph in 6th gear with rpm at 1100. You are just loafing and cruising along. There is not need to be in a lower gear unless you are passing, there is hill, hitting late apex at a track, or you are in Mexico racing. Once up to operating temperature, nothing will happen to the engine at that rpm. Granted, you will need more "load" since being 6th gear multiplies down (by 0.5) your engine torque output. However, this does necessarily mean that you will burn more fuel.

    Let's now get serious and factual about engine load and how much you are terrorizing the engine at lower rpm. At 1000rpm, our engines only make about 80 horsepower (420 ft-lb * 1000rpm / 5250 = 80 hp). At that rpm, the engine is properly oiled, cooled, executing proper combustion mix, and well under its maximum operating capacity in virtually all aspects. I challenge anyone with any real technical information to come and proof to me how this dangerous to our engines.

    Please do come forward and I shall aptly retort. :eater:
     
  22. JAY

    JAY Enthusiast

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    I can appreciate your point . my approach for myself is a New Mustang Convertible for a Daily Driver , and Viper and 2 motorcycles for the FUN Activities .:drive:
     
  23. Gordonvi

    Gordonvi Enthusiast

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    I cruise for hours as well in the 08 SRT-10 6th ~1400 rpm 78 mph ~23 mpg
     
  24. Paul Hawker

    Paul Hawker Enthusiast

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    Your big V-10 can lug around pretty well, but it has little satisfaction driving it like that.

    Instead of watching your tach, instead feel how well it responds to throttle.

    If you add throttle, but the car does not seem to want to accelerate, then you are in a lugging situation. Changing down a gear will not effect your fuel economy, but make your engine much happier.

    If you notice bucking, also shift down a gear.

    Vipers are actually pretty fuel efficient when driven conservatively, and this is part of their engineering design, but they are not at their best at the lowest possible RPM's.

    Since you are driving in a warm climate, your engine will warm up pretty quickly, however no matter how conseratively you drive, you will not attain optimum fuel economy in such a short commute to work. WHen you start out, your engine will be running in a choked, or fuel enrichened state.

    If you are going to short shift around town to maximize fuel economy, you will do yourself and your Viper a big favor by taking it out on the freeway for an "Italian Tuneup" every once in a while.

    Hope you enjoy your new Viper. They are pretty remarkable cars.
     
  25. IDM

    IDM Enthusiast

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    Paul thank you very much, the car sure is remarkable. It's been my dream car since I knew anything about cars and I can't believe I have one. I unexpectedly pulled the trigger and got this one and it's more than I can imagine, Ive been high in the clouds for 9 days
     
  26. MtnBiker

    MtnBiker Enthusiast

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    Not sure what you mean by the car doesn't feel fast or isn't fast?! I just came out of an 09 Z06 and the Viper would kick it all day and every day.
     
  27. IDM

    IDM Enthusiast

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    Have had two cars before this one with more power, this is by far the fastest stock car, but it cant compete with forged motor and supercharger, or big turbos! Its fast but not anything out of control, just right and comfortable for me to enjoy.

    A lot of people have been saying get rid of the stock runflats and be careful on the throttle. So far the car is completely in control and stable. No issues with traction thus far, but not driving it like Im on a track or anything
     
  28. viperbilliam

    viperbilliam Enthusiast

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    Don't let it drop below 1000 rpm but you can cruise with gentle throttling just above that.
     
  29. IDM

    IDM Enthusiast

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    I cruised at 1375 rpms in 5th earlier and it was great. I guess these gears are okay after all once you get over the fear of bogging the engine. I can save the cash and my tires! Thanks guys
     
  30. ViperTony

    ViperTony Enthusiast

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    The advice about ditching the run-flats is more over safety rather than traction. If they're the original run-flats, they are probably old and hard. They most likely will bite you not necessarily during spirited driving but during an emergency maneuver. Be safe out there!
     

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