Blower speed. Are pullied cars on borrowed time? Imp discussion

Discussion in 'SRT Hellcat Builds' started by Dr. SS, Aug 25, 2016.

  1. Dr. SS

    Dr. SS Silver Member

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    who knows the specs on the IHI blower? How fast can u spin these blower before they are at a higher risk to fail? Forget about power , heat, diminished efficiency when spun to fast...at what point will they fail?

    2.65/10% od pullied car tuned well on enough octane fuel (e85, or race has)

    How fast is the blower speed /spinning? Is it to much? Is the blower destined to fail? Is it out of its safe rpm
    Range?

    I daily drive my car .. 16k miles and I drive it mostly 99% on street and I'm a spirited driver
    Highway pulls here and there

    How fast is my blower spinning? 20?-23,000 rpm?

    W my mods and my car actually really being used as a daily driven car seeing a lot of use...is the blower on borrowed time?


    Trying to determine whether I should just go to a 2.85/along w 10% OD w the e85 or 93... For longevitys sake

    Would love to hear expertise and opinion below
     
  2. CanHP

    CanHP Silver Member

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    I think the blower spins at max around 14K from the factory, so it has lots of room, I think?

    The new Z06 blower is maxed out as I heard that from the factory it spins almost 20K.

    I may not be correct, but I think I'm in the ballpark.
     
  3. Racist Cat

    Racist Cat Gold Member

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    I thought hellcat max was 20k and factory was 19.5k

    As a daily driver there isn't much to worry about.

    Just take the max rpm the blower is designed to operate at, and with your overdriven pulleys, calculate at what engine rpm your blower rpm gets to its max, and in daily driving, don't exceed that rpm.

    Racing is racing though.

    Any piece of equipment spun faster than it's designed speed will live a shortened life. Speed costs, how fast you wanna go?
     
  4. CanHP

    CanHP Silver Member

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    The new supercharger, sealed for life with synthetic oil, has a drive ratio of 2.36:1 and a maximum speed of 14,600 rpm.
    So from the factory its maximum speed is 14600 at the engine's 6200 so there is room left in it.
    From:
    Supercharged 6.2 Hemi: “HellCat V8”
     
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  5. CanHP

    CanHP Silver Member

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    The 14600 is actually quite low compared to other cars so we are in good shape
     
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  6. Racist Cat

    Racist Cat Gold Member

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    On the surface this seems like a reasonable response, but, comparing our much larger supercharger to the smaller corvettes, is not the same.

    All we know at the moment is how fast the supercharger turns from factory.

    There's the limit where things explode, and the limit of a daily driver. We are searching for more in depth information.

    What does the supercharger manufacture state as me operating rpm?

    I could swear I read an article pointing we only had a small window of safe improvement.
    This didn't stop me from getting a 2.65 pulley, but OP has a viable point.
     
  7. Aaron Vogel

    Aaron Vogel Gold Member

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    Or is it a max of 14600 under factory conditions, not taking into account what the blower max speed really is.
     
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  8. CanHP

    CanHP Silver Member

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    Yes, it's 14600 for factory conditions. The blower is capable of more as we know these cars have been pullied

    Why I brought up the Z06 supercharger is from the factory it's already spinning around 20K. They can't go much higher or the thing (any supercharger) turns into a heat pump.
    Both the Z06 and Hellcat engine are 6.2L and in order to get the same 10psi on both cars the Z06 has to spin much faster as its a smaller unit 1.7L vs the Hellcat 2.4L. All things being equal a bigger supercharger will move more air when operated at the same RPM.

    That's why a lot of mustang guys replace their superchargers with a bigger Kenny Bell. Because they can only get so much volume out of a smaller supercharger.

    I'm probably getting off topic here, but the point I was trying to make was that with the Hellcats 2.4L blower only spinning at 14-15k there is room for more.
     
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  9. BULL

    BULL ________173.7mph_______ ___2016 Colorado Mile___ Gold Supporting Member HOTM Winner

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    I think I recall Dr. Buick making statements about SC critical speeds, I just don't recall what they were, but the point is that he may be your information source.
     
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  10. Dr. SS

    Dr. SS Silver Member

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    My car is daily driven w 16 k on it I am a spirited driver and I get on my car on Ramps and highways and have fun w it..no racing so I don't think it's abuse . However I drive it when it's hot out and on e85 w a 2.65/10% OD pushing 20psi likely (map only reads upto 17.5-18)

    On a blower being over spun likely to 20,000 rpm
    And higher and being used on the daily driven grind and in heat is it liable to fail lock up get to hot , melt , eat itself?

    It's already happened to me I've had one blower fail on me for unclear reasons only thing I can think of is maybe it's just being spun to fast and it manifested in my car because unlike a lot of people pushing 800-900rwhp I daily my car w 60-70 mile driving daily and I'm
    Spirited driver and have been running it in recent heat.

    I am on my second blower car runs like a beast but am I destined for the same fate again? I'm running same mods. Or was my original blower just one of the bad ones or had poor tolerance and over spinning it made it susceptible to failure?

    I don't know. I don't think anyone does.

    I am contemplating turning it down to 15 psi w a 2.85/10% lower to be safe. Sucks tho bc I love the sick power it makes now

    I talked to Steigemeyer to rebuild my original blower..he hasn't done any yet but after talking to him he is if the opinion my second blower could take a shit too bc he thinks it's just being spun to fast .. He said blower speed and what octane would determine where and when it fails .. Granted I am on e85 so I have the octane .. But for a daily hustled car (not a strip queen) am I just spinning this blower to fast?

    Anyone know if IHI has specs on how fast these blowers have been spun during tested and where they get critical and fail?

    I think we need to establish this as no one really knows
     
  11. Racist Cat

    Racist Cat Gold Member

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    Exactly. We need to know max critical, and technically high idle. The max rpm it can safely run and not be detrimental to lifespan.

    Also, it seems from a blower standpoint that the type of fuel would be irrelevant? I could understand a turbocharger...
     
  12. FFBOS

    FFBOS Senior Hellcat Member

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    I would say long lasting sessions of high rpm that cause extra heat will put strain on it. Spirited pulls here and there with appropriate cool down....it should last a long time.
     
  13. Dr. SS

    Dr. SS Silver Member

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    well mine ate it self with a 2.65/10% OD lower, pushing probably 20-22 psi
    and that is likely where we found the limit, I don't know what RPM that is but I assume >20K
    I plan on changing the upper to a 2.85 and limit boost to 15-17 psi and get the blower speed sub 20k I guess....
     
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  14. 19Dart69

    19Dart69 Silver Member

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    How much for a new supercharger ?
     
  15. sgoyal

    sgoyal Gold Member

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    Around 7-8K... I think
     

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