Brand new 4-bolt main shortblock w/ ai 200cc heads. will it hold up?
04-26-2009, 12:22 AM
#1
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Join Date: May 2008
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Brand new 4-bolt main shortblock w/ ai 200cc heads. will it hold up?
Does anyone know if the LT1 4-bolt shortblock can handle 500hp for a long time? I have a pair of Advanced Induction 200cc TFS heads going on it with ported intake and upgraded valvetrain package. Should be around 500hp with full boltons (electric waterpump, long tubes, etc).
Should I just get a forged rotating assembly or will i be fine? Since the shortblock was only $800 it really wouldn't be a big deal if it went, but I don't want to ruin the heads if it blows.
Should I just get a forged rotating assembly or will i be fine? Since the shortblock was only $800 it really wouldn't be a big deal if it went, but I don't want to ruin the heads if it blows.
04-26-2009, 08:56 AM
#3
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Join Date: Feb 2004
Posts: 4,800
The main bolt count nothing to do with reliability of this since the rod bolts will allow cap wiggle and take out the rod bearings before the mains even become a concern.
Power level is NOT that big a deal either.
What you need to be concerned with is rpm. High rpms put tremendous tension on rod bolts, this tension can stretch them a little which lets the rod cap move which lets the crank and bearing get to know eachother better.
How high you looking to rev it?
People are quick to say "replace everything" but fact of the matter is to genuinely improve on things is not cheap. Lots of guys like to put in cheap HEAVY forged pistons with thick parasitic rings that eat the bores. While they are stronger I don't call that a step forward. A heavier piston also puts more tension on the rod bolts.
To genuinely improve the pistons and rods you are looking at probaly $600 Mahle Powerpak and a $300 Scat capscrew rods and a rebalance, at $900 already so might consider the "Budget 355 assembly" AI lists, does cost more but the Compstar rods are nice.
When looking at questions like this think about "How" and "Why". Like I said rpms kill stock shortblocks and it is rod bearing failures most likely due to bolt stretch.
You could always just get the stock rods rebuilt with good fasteners, with the piston pressing that would probably be $200 if you do the disassembly and reassembly yourself and that alone would keep things fairly safe to probably 6800. Without touching the shortblock you probably want to limit to to 6500.
Power level is NOT that big a deal either.
What you need to be concerned with is rpm. High rpms put tremendous tension on rod bolts, this tension can stretch them a little which lets the rod cap move which lets the crank and bearing get to know eachother better.
How high you looking to rev it?
People are quick to say "replace everything" but fact of the matter is to genuinely improve on things is not cheap. Lots of guys like to put in cheap HEAVY forged pistons with thick parasitic rings that eat the bores. While they are stronger I don't call that a step forward. A heavier piston also puts more tension on the rod bolts.
To genuinely improve the pistons and rods you are looking at probaly $600 Mahle Powerpak and a $300 Scat capscrew rods and a rebalance, at $900 already so might consider the "Budget 355 assembly" AI lists, does cost more but the Compstar rods are nice.
When looking at questions like this think about "How" and "Why". Like I said rpms kill stock shortblocks and it is rod bearing failures most likely due to bolt stretch.
You could always just get the stock rods rebuilt with good fasteners, with the piston pressing that would probably be $200 if you do the disassembly and reassembly yourself and that alone would keep things fairly safe to probably 6800. Without touching the shortblock you probably want to limit to to 6500.
04-26-2009, 10:29 AM
#4
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Join Date: May 2008
Posts: 82
Thanks 96 for the well typed post...I was actually only planning on spinning it to 6200 at the absolute most. I usually dont rev higher than 5800 or so on the street. I see you are running a stock shortblock so it must be able to handle the power pretty well then? I guess my plans of putting a 100 shot on top of the head/cam pkg is out of the question now..lol
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