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Thread: Lightened Crankshaft advantages/disadvantages?

  1. #1
    Garrett booster
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    Lightened Crankshaft advantages/disadvantages?

    Looking at a built (never run) engine that is for sale and it has a "lightened" (by 9lbs) crankshaft (its on a 2.4 and supposedly a DCR piece). The advantage of it revving faster is obvious, but from what I have read about lightening the rotating assembly it becomes a bit of a bear to drive with a manual tranny. Also what about the engine balance, do you need to lighten the rods/pistons to offset the material removed from the crank? Any thoughts appreciated.
    Last edited by 83rampage; 07-31-2016 at 12:33 AM.

  2. #2
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Inline 4 cylinder Engines are in a natural state of balance as to bob weights.

    No need to lighten rods/pistons to match the crank as they just have to match each other, but they can be lightened.

    Reducing the size of the counterweights on a 4 cyl can be dicey strength/vibration wise so where the weight was removed could be an issue.

    Hopefully someone who has experience with a lightened 2.4 crank will chime in with real world experience.

    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
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  3. #3
    turbo addict
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    Re: Lightened Crankshaft advantages/disadvantages?

    9 lbs? Can we get some pictures?
    The 88 cast 2.2 crank I have is 33lb and 6oz.

  4. #4
    turbo addict
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    Re: Lightened Crankshaft advantages/disadvantages?

    Interesting topic- subscribed!

  5. #5
    turbo addict
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    Re: Lightened Crankshaft advantages/disadvantages?

    I haven't done a crankshaft but love the extra lightness of my aluminum flywheel and UDP. So to me the lighter you can get things and still keep the strength up the better. Even on my heavy ShelbyZ and my friends heavy minivan 5spd the lighter rotating assembly is nice. Yes you have to change your driving style a bit but it becomes 2nd nature.

  6. #6
    Garrett booster
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    Re: Lightened Crankshaft advantages/disadvantages?

    I had kind of dismissed looking at this engine because I thought the crank would be more of a disadvantage. Decided to go check it out since no one has thrown any red flags.

    Since I haven't actually looked at the engine yet I don't have pictures, but hopefully will in a few days, so Ill grab some pics. The engine is assembled so not sure what you will be able to see.

    It is a Darryl Cox crank so I assume it is a quality piece since he has a good name (albeit expensive) in the SRT world. Good news that it doesn't affect the balance.

    Keep the comments coming! Ill hopefully have more info in a few days.

  7. #7
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by tryingbe View Post
    9 lbs? Can we get some pictures?
    The 88 cast 2.2 crank I have is 33lb and 6oz.
    I re read my first post and realized I gave some misconception. The crank was lightened by 9 lbs.

  8. #8
    Super Moderator Turbo Mopar Staff contraption22's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by 83rampage View Post
    It is a Darryl Cox crank so I assume it is a quality piece since he has a good name (albeit expensive) in the SRT world.
    Don't make that assumption. Not saying it's not good, but the DCR name is not a guarantee.


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  9. #9
    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    I had about 6.5 lbs taken out of the non-common-block-converted-to-common-block forged 2l IMSA crank Im going to run(someday) in the 9500RPM Masi Motor. The project is nowhere near ready (tho I do have a bunch of the parts,still need rods/pistons made) and I waited A YEAR for that shop to finish modding that crank. One of the reasons was that they do all of DCR's cranks. About once a month I would go in to 'check on the progress' and there were always a half dozen cranks that said DCR on them. It's a well respected shop in Santa Fe Springs, CA. Surprisingly primitive in there but if they have the tooling and the knowhow, good parts can be built I suppose. Before visiting the shop a few times I never knew that cranks are 'trued up' on a jig with a hammer and a brass punch. Looks really brutal but they just hit the thing, turn it over in the jig by hand and read the measurements on the dial indicator.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    AJ (no More Alan) 84 Rampage RT TIII/568 Quaife 87 GLHS dealer optioned Red 16V Masi/568/Quaife
    90 Masi 16V White/Ginger/Black
    89 TC Masi 16V Red/Ginger/Black
    86 GLHS #110 RoadRace Built 89 CSX-VNT Recaro Car
    89 Turbo Mini 'Woody' 85 GLHT 'RedBox'
    2014 Explorer DD'r 3.5Twin Turbo Ecoboost AWD and 500HP
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  10. #10
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    340 V8 cranks were drilled through the rod journals. Anyone try that with a 2.2 crank?

  11. #11
    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by ajakeski View Post
    340 V8 cranks were drilled through the rod journals. Anyone try that with a 2.2 crank?
    Look closely at the pic I posted Andy...

    AJ (no More Alan) 84 Rampage RT TIII/568 Quaife 87 GLHS dealer optioned Red 16V Masi/568/Quaife
    90 Masi 16V White/Ginger/Black
    89 TC Masi 16V Red/Ginger/Black
    86 GLHS #110 RoadRace Built 89 CSX-VNT Recaro Car
    89 Turbo Mini 'Woody' 85 GLHT 'RedBox'
    2014 Explorer DD'r 3.5Twin Turbo Ecoboost AWD and 500HP
    My profile page has over 20,000 views, I'm somebody LOL

  12. #12
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by 2.216VTurbo View Post
    Look closely at the pic I posted Andy...
    Nice looking crank!!!!

  13. #13
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by 2.216VTurbo View Post
    Look closely at the pic I posted Andy...
    You're ahead of the times. Was that part of you're lightening process or was it made that way?

  14. #14
    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    This crank started life as a non common block forged 2.2 that the IMSA team had welded, destroked to 2l (offset ground to reduce stroke) and balanced. When I bought it off FWD Perf years ago with the intention of building a 5000RPM-9500RPM screaming Masi Motored 2l, I took it to Castillo Crankshaft in Santa Fe Springs CA to have it lightened and modified to have it fit into a common block motor. Yes, they bored the rod journals out as part of the weight reduction as well as semi-knife edging the bobb weights (counterbalances) They also turned down the front crank seal area and rebroached the Woodruff slot, balanced, trued, cryo'd, surface hardness treated and all the other little tricks they do to a crank expected to survive near 10K RPMS. It took them a year but the broaching tooling had to be special ordered and there were a couple other hurdles I don't recall right now. It's my first $1800. crank and hopefully I'll never need another one 2l project keeps getting pushed back by other TM and non TM projects but it's in the que

    AJ (no More Alan) 84 Rampage RT TIII/568 Quaife 87 GLHS dealer optioned Red 16V Masi/568/Quaife
    90 Masi 16V White/Ginger/Black
    89 TC Masi 16V Red/Ginger/Black
    86 GLHS #110 RoadRace Built 89 CSX-VNT Recaro Car
    89 Turbo Mini 'Woody' 85 GLHT 'RedBox'
    2014 Explorer DD'r 3.5Twin Turbo Ecoboost AWD and 500HP
    My profile page has over 20,000 views, I'm somebody LOL

  15. #15
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    So then I'm going to guess the rods and pistons are lightened or lightweight pieces to match the bob weights?

    I'm asking because I have a forged 2.2 CB crank that may need some substantial work and my machinist is the crank specialist of our area. Maybe I'll look into doing this...

  16. #16
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    Re: Lightened Crankshaft advantages/disadvantages?

    AJ, your crank makes me jealous...and I'll NEVER say that to another man again! LMAO!

  17. #17
    turbo addict
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    Re: Lightened Crankshaft advantages/disadvantages?

    AJ??? now how do we know who's who? AJ socal or AJ arizona?

  18. #18
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by ajakeski View Post
    So then I'm going to guess the rods and pistons are lightened or lightweight pieces to match the bob weights?

    I'm asking because I have a forged 2.2 CB crank that may need some substantial work and my machinist is the crank specialist of our area. Maybe I'll look into doing this...
    Bobweights don't apply to inline 4/6 cyl Engines, they are applicable to V6 and V8.

    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
    89 Turbo Minivan
    83 Turbo Rampage : SOLD
    Edmonton,Alberta,Canada

  19. #19
    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Quote Originally Posted by ajakeski View Post
    So then I'm going to guess the rods and pistons are lightened or lightweight pieces to match the bob weights?

    I'm asking because I have a forged 2.2 CB crank that may need some substantial work and my machinist is the crank specialist of our area. Maybe I'll look into doing this...
    Yeah, what Randy said, doesn't matter on a 2.5/2.2/2.0 balanced/lightened crank is it's own entity. Im gonna use Pauter rods and Wiseco(or maybe Diamond) pistons. Unless it's drag motor(mine isn't) the lighter the rotating assembly is the better. Ziiingg...

    AJ (no More Alan) 84 Rampage RT TIII/568 Quaife 87 GLHS dealer optioned Red 16V Masi/568/Quaife
    90 Masi 16V White/Ginger/Black
    89 TC Masi 16V Red/Ginger/Black
    86 GLHS #110 RoadRace Built 89 CSX-VNT Recaro Car
    89 Turbo Mini 'Woody' 85 GLHT 'RedBox'
    2014 Explorer DD'r 3.5Twin Turbo Ecoboost AWD and 500HP
    My profile page has over 20,000 views, I'm somebody LOL

  20. #20
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: Lightened Crankshaft advantages/disadvantages?

    Hey Alan, do Masi cranks fit a regular common block??

    I really like the full counter weights, even if they weigh more.

    2.4 crank is looks almost fully counter weighted but they probably don't fit common blocks??

    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
    89 Turbo Minivan
    83 Turbo Rampage : SOLD
    Edmonton,Alberta,Canada

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