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Thread: 3.7L down for the count again

  1. #1
    I'm magical... verified Feedback Score 0 Trevor's Avatar
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    3.7L down for the count again

    First off...after adding up all the money in the car (you would NEVER believe how much!) there's no way I can just sell it for what I could probably find a buyer for. So breathe easy...I'm keeping it and I apologize for scaring you guys. I'll give whatever time I have but it's just going to move down the priority list a little.

    So...shortly after this awesomeness:
    http://www.3sgto.org/showthread.php?...-lbft-15.8-psi
    ...I am yet again stuck with a hurt car. I lost 14-15 psi of oil pressure at 2000 rpm after a pull. This isn't the first time either. Last time it happened at just 19 psi and hardly any timing (before I even started advancing it). I pulled the pan down and found the center mains had wear all the way around (but weren't smashed). The crank journals were fine. I replaced all the main bearings with ones that were tighter for more support (I went to stock 6G74 clearances), switched from 0w-40 to 5w-50 oil for more film strength, dropped the rev limiter from 8340 to 7100 (I thought maybe the high RPM was the issue), and dropped the boost from 19 to 16 psi to start tuning. After getting it back together I took note of the oil pressure at 2k (64-68 psi at 2k) so I could watch it very closely. I thought I was out of the woods and was pretty psyched after hitting 600 tq but obviously I wasn't. I'm sure this time once I pull the pan again I'll find center main bearing wear again.

    Now I was thinking that maybe the 6G75 cranks are weak and it was flexing from power. On the other side...in the back of my mind I was thinking that Italo Grasso did 774 tq on the same crank so WTF.

    I talked to Ray P just now and he had a good point. He's wondering if maybe my old school machine shop didn't balance the assembly properly. It makes sense since it's 360 degree bearing wear and not just wear/smashing at the bottom.

    So where to now? Well...obviously this crank is probably cracked all to hell. I could have the balance checked by another reputable shop and just get another (properly balanced) stock crank if it checks bad. Or I could just go with a custom 4340 grade forged steel crank made by one of our pioneering vendors that will be announced soon. Stay tuned!
    2011 CTS-V Coupe

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    Forum User Not Verified Feedback Score 1 (100%)
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    w00t! He's keeping it! You'll get it going better than ever.

    Subscribed.

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    Forum User Feedback Score 0 pos-vr4's Avatar
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    the way you describe the issue, kinda sounds like a bent crank.

    BTW when my machine shop dose the 6g72 balance my invoices always say V6 "split throw" balance on them. makes me wonder what they need to do differently Vs a regular balance job.

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    1st ever COTM and COTY verified Feedback Score 9 (100%) green-lantern's Avatar
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    I'm glad your keeping it man!

    Sorry about the crank problems though.

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    Jeremy

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    Thumbs up

    glad to hear your keeping it !

    sorry for the problems
    Last edited by mb7050; 09-30-2010 at 02:52 PM.

  6. #6
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    glad to hear you are sticking with it. I'd send the shortblock to ray and see what he can do for you, it may be cheaper and a lot less headache in the long run.

    Parting 6 speed
    Pampena 3.5 Stroker, TiAL DR750s, AEM Series2, oohnoo SMIC, DN Hardpipes, ID1000s, Walbro 416/485, aermotive fpr, Dejon intake pipes, Tial QR, DN Precats, 3sx Single Pass Rad, Samco Hoses, Stoptech 332mm fronts, Tein S-Techs, Bilstein HDs, Spec 4+, JDM 6 Speed, Billet shift forks, Pampena brace

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    DR750's cool kid club! Feedback Score 0 TT Eric's Avatar
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    Sorry and happy at the same time! I'm glad you keep your car, you're and outstanding member.

    Eric


    DR750's, DR stage III heads, DR Boost cooler stage 2, Denso 660cc, TE37SL +273'S Z1 , KWv3, Stedebani suspension buschings, SCE 13'' Stoptech, 2G rear brakes, Forged shortblock, 3SX cam gears, SCE racing oil pan, PST CFDS, RPS 6 puck, RPS Flywheel, ETS FMIC, 3'' custom quad tips catback, new leather seats heated, SCE center diff, Quaife, brand new tranny/tcase, Billet casings, Chrome ECU, Swaintech...

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    Forum User Feedback Score 0 JasonY's Avatar
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    I believe Matt M is selling his stroker that was just refreshed...

    Glad to see you sticking it out with the car but sorry to hear about the problems with it.

    Jason

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    Forum User Not Verified Feedback Score 2 (100%) jba3's Avatar
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    Quote Originally Posted by Forest Gump View Post
    glad to hear you are sticking with it. I'd send the shortblock to ray and see what he can do for you, it may be cheaper and a lot less headache in the long run.
    My thoughts exactly. If you don't have the time, put a little money into Ray's hands, and he'll get you running even faster than the already ludicrous speed you have.
    1995 VR4 Coupe

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    #1 Glad your keeping your car
    #2 So I take it you're going to help out with this?
    Quote Originally Posted by Trevor View Post
    Or I could just go with a custom 4340 grade forged steel crank made by one of our pioneering vendors that will be announced soon. Stay tuned!

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