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Centrifugals, bearing wear, and crank snouts

 
Old 05-11-2010, 12:26 AM
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Default Centrifugals, bearing wear, and crank snouts

Why is it that some people can run a procharger setup (I'm using procharger as a general reference for centrifugals in general) for thousands of miles without any problems, while others have front main bearing wear and break crank snouts after just a few thousand miles, if that? Is it just because some people adjust the belt too tightly? What are the biggest / most common reasons for these failures?

YES, I searched the forums, and found failures and successes for the setup, but couldn't really find the cause for it in the first place. Maybe because the answer is so common that everyone already knows it...I don't know.

I have a forged 370ci built for boost, and I'm getting close to buying an F1 procharger to obtain around 800rwhp, but I keep reading these horror stories and I have no clue how to prevent mine from doing the same thing. I know I would like a cog setup, but from what I've found, nobody currently makes a cog kit for the F1 (but they do for the F2 I believe).

I know everyone says to pin the crank, but sureley that can't be the only fix...and I'm sure that doesn't prevent bearing wear either.

While I have the engine still on a stand, what other precautions can be taken to prevent excessive wear from a centrifugal? I know the old school guys put a BBC snout on, but I haven't read any lsx guys doing that (maybe they have a better cast crank?). That reminds me, I'm using the factory crank, which I've been told should support my power goals. I'm trying to study for finals but this keeps driving me crazy in the back of my head, so I said screw it I gotta make a new post :-) Hopefully it'll help others as well.

Anyways, main questions:

What are the biggest / most common reasons for the crank bearing / snout failures?

What other precautions can be taken to prevent excessive wear from a centrifugal? (Or hell, even roots blower for that matter, though I don't read about as many failures from the roots)

I
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Old 05-11-2010, 06:40 AM
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I haven't seen any failures with LS engines, if there are any out there, it certainly is not a common problem. Bob
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Old 05-11-2010, 07:33 AM
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I'm sure [email protected] Speed will chime in on this as he has seen several LS cranks twisted in two from high output cog drive procharger setups. With cog setups you don't need much belt tension. Also, besides crank pinning, you should do coated bearings.
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Old 05-11-2010, 07:44 AM
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i have run about 30 blower cars, s/b's, b/b's, now a couple LS engines-i have run F2's, 871's, on s/b's, b/b's-i have never had a failure
the belt gets tighter when hot, so adjust it hot-i always have the balancer hone fit if needed to the crank (if aftermarket balancer)
i know some guys used a snout brace
i have heard of a couple s/b's breaking, hard to say what cont. to it, although there is a lot of pressure on it
i pinned a stock crank, ATI 8 rib balancer, when i pulled it off, it was hard to get off, the pin dug into the balancer groove a little, so they will try and turn
we used to double key the s/b's, b/b's, or one long key-prob not a bad idea on L/S engines, esp a cog setup
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Old 05-12-2010, 03:35 AM
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93 - What type of coating are you suggesting for the bearings?

forcd ind - how long would your engines last usually. Meaning, did you rebuild them often (race-only) or were some of them daily drivers? So it sounds like pin the crank and with proper belt tension, the snout should be fine, but what about the front main caps wearing? I take it you didn't experience any type of premature wear from them? Or were the rings/bearings etc replaced often?
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Old 05-12-2010, 12:15 PM
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Originally Posted by zeeboost View Post
93 - What type of coating are you suggesting for the bearings?
Don't have the specific name of the coating but make sure you order "thermal coated bearings" that's what they call them.
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Old 07-06-2010, 09:30 AM
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Originally Posted by forcd ind View Post
the belt gets tighter when hot, so adjust it hot-i always have the balancer hone fit if needed to the crank (if aftermarket balancer)
i
I thought stuff expands when its hot...?
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Old 07-06-2010, 12:34 PM
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^ Thats what i thought as well..
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Old 07-06-2010, 12:36 PM
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What the hell do coated bearings have to do with this topic? Enlighten me.

Originally Posted by 93formto98T/A View Post
I'm sure [email protected] Speed will chime in on this as he has seen several LS cranks twisted in two from high output cog drive procharger setups. With cog setups you don't need much belt tension. Also, besides crank pinning, you should do coated bearings.
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Old 07-06-2010, 03:50 PM
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Originally Posted by vmapper View Post
I thought stuff expands when its hot...?
it does, the brackets on the block get heat soak out of the block causing the growth
belts do get tighter, i destroyed two cog belts i made them to tight when the engine was cold
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Old 07-06-2010, 03:57 PM
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Originally Posted by helicoil View Post
What the hell do coated bearings have to do with this topic? Enlighten me.
Less friction, less resistance, less of chance to wear the bearing down and cause issues? Maybe? lol
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Old 07-06-2010, 03:58 PM
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(quote) I've found, nobody currently makes a cog kit for the F1 (but they do for the F2 I believe).

that is the same thing the f1 has the dual key way cut on the snout, just like the f2, mine WAS cogged, the belts are high dollar when you hurt one, pedaling kills belts and snouts with a cog drive, if you are a M6 you will pay for belts in the long run the up and down rpms over time hurt the belts
the bearings that where in my BBC where Teflon coated for the extra wear,
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Old 07-07-2010, 06:37 PM
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I used Calico Coatings on my Rod and Main Bearings.

http://www.calicocoatings.com/

My understanding allot of Cup Teams use this company.
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Old 07-07-2010, 06:47 PM
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Usually a lot of materials will expand when heated (most metals, concrete, asphalt....) but these objects have a positive expansion coefficient. Most rubbers, and I think latex, based materials have a negative coefficient of expansion so they shrink. They aren't that common, but that is why belts get tighter when the engines heat up.
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Old 07-08-2010, 04:18 PM
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Breakages are very rare.

If you want to increase strength, and reduce loads on both crank and blower bearings. Fit a brace between the two.

Its also interesting to see just what a belt has to endure on some systems. And how much they can stretch !! Check how much the tensioner moves

http://www.youtube.com/watch?v=WqyT8dYzAkM
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Old 07-08-2010, 05:08 PM
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I was just about to post that vid... I dont see hot bracket causing a 'tightened' belt there, perhaps its a different story with cog, but not sure how, no personal experience with Cog driven.
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Old 07-08-2010, 05:17 PM
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Originally Posted by vmapper View Post
I was just about to post that vid... I dont see hot bracket causing a 'tightened' belt there, perhaps its a different story with cog, but not sure how, no personal experience with Cog driven.
Care to explain how you would ever see a hot engine cause a belt to tighten, when the engine is already hot, the engine is running, and its an automatic tensioner ?

Now dont be silly.

When the engine gets hot, all the metal does expand. It is more of an issue with manual tensionsers as there is nothing to allow for this expansion.
And it will also depend on bracketry, and the distance the blower is from the crank.

That video shows only the stretch that the belt is seeing due to the load of actually driving the blower. And it is substantial. Testiment to the belt itself, that it returns to its original length when not under such loads !
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Old 05-10-2019, 12:42 AM
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Default Brand new built ls2 crank snout broke

So I am really in need of help I just recently had a ls2 built on a 06 ss trailbalazer that was procharged by a p1sc1 well I got a call from the mechanic who claims that the procharger locked up on dyno at 4700 rpms and caused the engine to cut off while also braking my crank snout and brand new high performance water pump what are the chances of a procharger locking up and causing this to happen I just dont see the belt having enough strength to brake a crankshaft snout it was a 12 rib pully on a ati dampener that house of boost recommends but was running a 8 rib belt till I upgraded head units I planned on upgrading belt what are the chances a procharger would lock up and cause all that damage I just find it hard the procharger caused that to happen he said it caused the engine to dead stop

Last edited by Klopez91; 05-10-2019 at 12:47 AM.
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Old 05-10-2019, 07:14 AM
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Originally Posted by Klopez91 View Post
So I am really in need of help I just recently had a ls2 built on a 06 ss trailbalazer that was procharged by a p1sc1 well I got a call from the mechanic who claims that the procharger locked up on dyno at 4700 rpms and caused the engine to cut off while also braking my crank snout and brand new high performance water pump what are the chances of a procharger locking up and causing this to happen I just dont see the belt having enough strength to brake a crankshaft snout it was a 12 rib pully on a ati dampener that house of boost recommends but was running a 8 rib belt till I upgraded head units I planned on upgrading belt what are the chances a procharger would lock up and cause all that damage I just find it hard the procharger caused that to happen he said it caused the engine to dead stop
Strange things can happen but I have never ever heard of that happening before. Bob
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Old 05-10-2019, 07:49 AM
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I feel like it's more likely the engine locked up and took everything else with it then procharger taking everything with it what would cause a crank snout to brake on a brand new built engine
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