Main bearing clearance questions?
Main bearing clearance questions? I'm going to build a 346ci LS6 with the stock crank, forged rods and pistons. This motor will be used with a power adder (supercharger) and see about 15-16 lbs of boost. The main and rod bearings will be clevite.
I have read that lsx aluminum blocks expand more over iron when at operating temps. Also, it seems GM has much tighter tolerances for these motors.
When at full temps won't your clearances reduce? Or should I build it with tighter specs assuming expansion will get me to the target numbers?
Any suggestions as to what shoot for on the main and rod bearings?
Thanks
I have read that lsx aluminum blocks expand more over iron when at operating temps. Also, it seems GM has much tighter tolerances for these motors.
When at full temps won't your clearances reduce? Or should I build it with tighter specs assuming expansion will get me to the target numbers?
Any suggestions as to what shoot for on the main and rod bearings?
Thanks
I'm going to build a 346ci LS6 with the stock crank, forged rods and pistons. This motor will be used with a power adder (supercharger) and see about 15-16 lbs of boost. The main and rod bearings will be clevite.
I have read that lsx aluminum blocks expand more over iron when at operating temps. Also, it seems GM has much tighter tolerances for these motors.
When at full temps won't your clearances reduce? Or should I build it with tighter specs assuming expansion will get me to the target numbers?
Any suggestions as to what shoot for on the main and rod bearings?
Thanks
I have read that lsx aluminum blocks expand more over iron when at operating temps. Also, it seems GM has much tighter tolerances for these motors.
When at full temps won't your clearances reduce? Or should I build it with tighter specs assuming expansion will get me to the target numbers?
Any suggestions as to what shoot for on the main and rod bearings?
Thanks
TECH Apprentice
Joined: Dec 2008
Posts: 372
Likes: 1
From: Kinston North Carolina
I'm going to build a 346ci LS6 with the stock crank, forged rods and pistons. This motor will be used with a power adder (supercharger) and see about 15-16 lbs of boost. The main and rod bearings will be clevite.
I have read that lsx aluminum blocks expand more over iron when at operating temps. Also, it seems GM has much tighter tolerances for these motors.
When at full temps won't your clearances reduce? Or should I build it with tighter specs assuming expansion will get me to the target numbers?
Any suggestions as to what shoot for on the main and rod bearings?
Thanks
I have read that lsx aluminum blocks expand more over iron when at operating temps. Also, it seems GM has much tighter tolerances for these motors.
When at full temps won't your clearances reduce? Or should I build it with tighter specs assuming expansion will get me to the target numbers?
Any suggestions as to what shoot for on the main and rod bearings?
Thanks
TECH Apprentice
Joined: Mar 2006
Posts: 361
Likes: 1
From: australia
[ With that said, as far as bearings and clearances. I would definitly run a H series bearing, which stands for hardened and they have added clearance made in. Clevite is good but if it were mine i would go with a ACL race bearing. As far as clearances optimal for your build would be .0025 at a minimal preferably .003 on the mains and no less than .003 on the rods.
a few corrections here...
H series does not have added clearances...
" HX " , has to be ordered to have the extra .001' clearance
a few corrections here...
H series does not have added clearances...
" HX " , has to be ordered to have the extra .001' clearance
Trending Topics
on oil even all the "diesel" oils now which basically mean any 15w-40 oil such as shell rotella, mobil delvac, or chevron delo, technically do not have extra zinc and phosphorus as anti-wears because they are all meeting the API-SM spec, check the bottle. There is tons of emission bullshit on diesels now, including catalytic converters.
The diesel oil has more antiwear additives or it protects better is becoming a common misconception. But I do agree it is a better oil, based on price and it's viscosity range; the synthetic label is a bunch of crap.
can there be a clarification on the words tolerance vs clearance ?
It seems those two words get used in place of each other, more so tolerance for clearance.
Am I correct in saying that tolerances have tightened up (which is a good thing and is due to a better manufacturing process) but clearances for the most part have not changed?
The diesel oil has more antiwear additives or it protects better is becoming a common misconception. But I do agree it is a better oil, based on price and it's viscosity range; the synthetic label is a bunch of crap.
can there be a clarification on the words tolerance vs clearance ?
It seems those two words get used in place of each other, more so tolerance for clearance.
Am I correct in saying that tolerances have tightened up (which is a good thing and is due to a better manufacturing process) but clearances for the most part have not changed?
Last edited by 1 FMF; Jan 19, 2009 at 11:44 AM.
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perhaps you should do some more research before making a post like that.The stock ls1 crank is incredible strong and has been in 1000+hp cars with no issues.Theres no reason to upgrade to an aftermarket crankshaft unless you purely want more cubes from stroke.Check out the Forced Induction section and do some reading/searching.
TECH Apprentice
Joined: Dec 2008
Posts: 372
Likes: 1
From: Kinston North Carolina
[ With that said, as far as bearings and clearances. I would definitly run a H series bearing, which stands for hardened and they have added clearance made in. Clevite is good but if it were mine i would go with a ACL race bearing. As far as clearances optimal for your build would be .0025 at a minimal preferably .003 on the mains and no less than .003 on the rods.
a few corrections here...
H series does not have added clearances...
" HX " , has to be ordered to have the extra .001' clearance
a few corrections here...
H series does not have added clearances...
" HX " , has to be ordered to have the extra .001' clearance
TECH Apprentice
Joined: Dec 2008
Posts: 372
Likes: 1
From: Kinston North Carolina
on oil even all the "diesel" oils now which basically mean any 15w-40 oil such as shell rotella, mobil delvac, or chevron delo, technically do not have extra zinc and phosphorus as anti-wears because they are all meeting the API-SM spec, check the bottle. There is tons of emission bullshit on diesels now, including catalytic converters.
The diesel oil has more antiwear additives or it protects better is becoming a common misconception. But I do agree it is a better oil, based on price and it's viscosity range; the synthetic label is a bunch of crap.
can there be a clarification on the words tolerance vs clearance ?
It seems those two words get used in place of each other, more so tolerance for clearance.
Am I correct in saying that tolerances have tightened up (which is a good thing and is due to a better manufacturing process) but clearances for the most part have not changed?
The diesel oil has more antiwear additives or it protects better is becoming a common misconception. But I do agree it is a better oil, based on price and it's viscosity range; the synthetic label is a bunch of crap.
can there be a clarification on the words tolerance vs clearance ?
It seems those two words get used in place of each other, more so tolerance for clearance.
Am I correct in saying that tolerances have tightened up (which is a good thing and is due to a better manufacturing process) but clearances for the most part have not changed?
TECH Apprentice
Joined: Dec 2008
Posts: 372
Likes: 1
From: Kinston North Carolina
perhaps you should do some more research before making a post like that.The stock ls1 crank is incredible strong and has been in 1000+hp cars with no issues.Theres no reason to upgrade to an aftermarket crankshaft unless you purely want more cubes from stroke.Check out the Forced Induction section and do some reading/searching.
Not sayin thats what you said but thats sure how it seems up here. And not knocking stock LS1 cranks, but your comparing a cast oem crank to a forged crank. You do the math. I guess its all about peace of mind. But again to each his own. 
9 Second Club
Joined: Jan 2006
Posts: 457
Likes: 1
From: Kinston, NC
Haha ok... Just cause ole Jo Blow's car made 1000 hp on the stock crank dont mean that its a proven piece and is what every body should run. Hell i suppose that anybody who buys an aftermarket forged crank for a LS1 is just insane in that case. I bet if callies knew that the stock cast crank was so strong then they would drop all there LS crank manufacturing for the stock stroke. Yea anybody can make a 1000 HP on stock stuff, but if im not badly fooled here the whole idea is to make power and make the engine live. Everything with a beginning has an ending. And i promise you that a cast crank will fail before a quality forged crank will. So if you wanna save you 5 or 6 hundred dollors now to spend 3 or 4 thousand dollors later then go right ahead. Its not my motor. You know its funny how when you try to help someone up here, some forum goddess chimes in with a "1000" post and tells you you dont know nothing because you only have 50 post. Not sayin thats what you said but thats sure how it seems up here. And not knocking stock LS1 cranks, but your comparing a cast oem crank to a forged crank. You do the math. I guess its all about peace of mind. But again to each his own.
Not sayin thats what you said but thats sure how it seems up here. And not knocking stock LS1 cranks, but your comparing a cast oem crank to a forged crank. You do the math. I guess its all about peace of mind. But again to each his own.
u sir, are the mani got my turbos running my superchargers budday!
Haha ok... Just cause ole Jo Blow's car made 1000 hp on the stock crank dont mean that its a proven piece and is what every body should run. Hell i suppose that anybody who buys an aftermarket forged crank for a LS1 is just insane in that case. I bet if callies knew that the stock cast crank was so strong then they would drop all there LS crank manufacturing for the stock stroke. Yea anybody can make a 1000 HP on stock stuff, but if im not badly fooled here the whole idea is to make power and make the engine live. Everything with a beginning has an ending. And i promise you that a cast crank will fail before a quality forged crank will. So if you wanna save you 5 or 6 hundred dollors now to spend 3 or 4 thousand dollors later then go right ahead. Its not my motor. You know its funny how when you try to help someone up here, some forum goddess chimes in with a "1000" post and tells you you dont know nothing because you only have 50 post. Not sayin thats what you said but thats sure how it seems up here. And not knocking stock LS1 cranks, but your comparing a cast oem crank to a forged crank. You do the math. I guess its all about peace of mind. But again to each his own.
Not sayin thats what you said but thats sure how it seems up here. And not knocking stock LS1 cranks, but your comparing a cast oem crank to a forged crank. You do the math. I guess its all about peace of mind. But again to each his own. 9 Second Club
Joined: Jan 2006
Posts: 457
Likes: 1
From: Kinston, NC
Are you kidding me?SERIOUSLY do some research.Check out the stickies,check out the FI section,check out the nitrous section.The stock ls1 crankshaft is NOT the same thing as a regular small block crank.It has been proven time and again to handle ALOT of power, RELIABLY.And if by Joe Schmoe making 1000hp+, youre referring to MANY of the sponsors and moderators on this very site, THEN you would be correct.And, ps I have more than 1 stickie on this site as well, so you can shove the "well he's just throwing around his post count".You truely are acting like a newb.Maybe you should do your research before you try to give others advice.
maybe you should bother to read your buddies posts and then make a comment."Cast cranks werent intended for the torque you will be making with that setup."
1 thing i cant stand is some guy who comes on here giving advice when he doesnt have a clue.Im amazed at the level of knowledge in this thread.If either of you bothered to look at the setups/builds being done on a weekly basis, the majority of them are using a stock crank and make somewhere between 700-1000hp. Not to mention its been done reliably.Im done with this thread.Nobody seems to watch to do any research,even by what was said by GM themselves regarding the ls1 crank.peace
1 thing i cant stand is some guy who comes on here giving advice when he doesnt have a clue.Im amazed at the level of knowledge in this thread.If either of you bothered to look at the setups/builds being done on a weekly basis, the majority of them are using a stock crank and make somewhere between 700-1000hp. Not to mention its been done reliably.Im done with this thread.Nobody seems to watch to do any research,even by what was said by GM themselves regarding the ls1 crank.peace
9 Second Club
Joined: Jan 2006
Posts: 457
Likes: 1
From: Kinston, NC
well lets see, did u research before u built your motor? on a budget?, or did u just go a builder and say here is 10,000 build something that runs good. man i am no idiot, and yes this guy is my buddy. i AM on a budget and i do my homework. i dont think what i run is not half bad from two guys that built the car with a budget and 17 years old at the time.
well lets see, did u research before u built your motor? on a budget?, or did u just go a builder and say here is 10,000 build something that runs good. man i am no idiot, and yes this guy is my buddy. i AM on a budget and i do my homework. i dont think what i run is not half bad from two guys that built the car with a budget and 17 years old at the time.
