L82 power limit
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L82 power limit
I've searched this a little already and have found many different answers so here goes if I rebuild my l82 short block with boost in mind, by that I mean keeping the stock forged crank, stock lt1 style rods, and stock forged pistons but opened up the ring end gap and doing some stuff like that to help it survive under boost. Then put aluminum heads and a different cam and intake on it trying to keep the CR around 9:1 how much boost could I run with 93 octane and how much power will that short block handle before it gives way.
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
About 8-9 psi and 550 horsepower on those rods....that is an estimate...really depends on how hard you beat it.
Look at the Eagle SIR or Scat I-beam.....either are about 5 times stronger for $200 a set.
Stock block stuff is limited to just past 600 horse anyway as the webs like to move around....splayed caps are needed and by the time you do that, just buy a Dart block. Why you say? For one VERY important reason.....Dart/World blocks are priority main oiling.......it oils the crank first, stock block oils the cam first.......you will run out of oil on a stock block before anything happens but starved for oil with webs moving around is the kiss of death.
Jebby
Look at the Eagle SIR or Scat I-beam.....either are about 5 times stronger for $200 a set.
Stock block stuff is limited to just past 600 horse anyway as the webs like to move around....splayed caps are needed and by the time you do that, just buy a Dart block. Why you say? For one VERY important reason.....Dart/World blocks are priority main oiling.......it oils the crank first, stock block oils the cam first.......you will run out of oil on a stock block before anything happens but starved for oil with webs moving around is the kiss of death.
Jebby
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Your question has too many variables on the boost question. Thing like intercoolers, boost controlled timing retards, water/methanol injection, and EGT limits. the list goes on Thermal piston top and chamber coatings...…..
As to the amount of power that a ARP studded, billet main cap, 397 casting high nickel 4 bolt block can withstand is not just a HP number, but RPMs also. Those kind of motors were used in 360 ci sprint cars and were able to make reliable 800 hp. Boosted power is lower rpm and those L-82 parts might hold together in a built up block to 600 hp.
IMO you want to protect your investment. So quality all forged H-beam rotating assemblies of the most ci are the way to go.
As to the amount of power that a ARP studded, billet main cap, 397 casting high nickel 4 bolt block can withstand is not just a HP number, but RPMs also. Those kind of motors were used in 360 ci sprint cars and were able to make reliable 800 hp. Boosted power is lower rpm and those L-82 parts might hold together in a built up block to 600 hp.
IMO you want to protect your investment. So quality all forged H-beam rotating assemblies of the most ci are the way to go.
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
if you're going to boost, why buy more heads?
had a set of brand new SIR rods...right out of the box big end not round not sized right … some round, others not. Seems during manufacture they were not torqued properly before they were honed-sized. Regardless, always cycle the bolts & measure; don't assume.
had a set of brand new SIR rods...right out of the box big end not round not sized right … some round, others not. Seems during manufacture they were not torqued properly before they were honed-sized. Regardless, always cycle the bolts & measure; don't assume.
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
Jackson is right. Boost means the head flow is less of an issue. You can always turn up the boost to make up for head flow issues.
L-82 cam is not bad for boost so maybe you can keep it.with a modest amount of boost ;~D
All your decisions really hinge on your bore condition. If you can reuse the bores, the bottom end could (should) be saved. Boost based on the existing pieces.
If the bores are too far worn for reuse, you are buying oversized pistons at a minimum. Better rod bolts on resized rods would be a good investment. The SCAT rods are also good choice but you can flip a coin here and be right either way.
New pistons means a different HP goal is possible.
L-82 cam is not bad for boost so maybe you can keep it.with a modest amount of boost ;~D
All your decisions really hinge on your bore condition. If you can reuse the bores, the bottom end could (should) be saved. Boost based on the existing pieces.
If the bores are too far worn for reuse, you are buying oversized pistons at a minimum. Better rod bolts on resized rods would be a good investment. The SCAT rods are also good choice but you can flip a coin here and be right either way.
New pistons means a different HP goal is possible.
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
TRW forged pistons that came with the L-82 will way outlast the stock rods........Stock pistons should be good for 10 psi boost or better.
Boost will crutch a bad cylinder head but at some point that charge needs to leave the cylinder.......cramming boost into an engine with crap exhaust ports creates its own problems.
Jebby
Boost will crutch a bad cylinder head but at some point that charge needs to leave the cylinder.......cramming boost into an engine with crap exhaust ports creates its own problems.
Jebby
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So it sounds like the pistons, the block and the crank are good to around 600hp but the rods would have to be upgraded for that kind of power and It sounds like I'd be good to 10psi or less on pump gas?
Team Owner
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From: Reno Nevada
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From: raleigh N.C.
sorry it's a long read, and definately an exception, but you would be suprised how tough the old smallbocks are.
https://www.theturboforums.com/threa...o-come.305001/
[QUOTEOk, on a short nitrous pull it made 609 whp and 694 ft. lbs torque][/QUOTE] page13
cant remember how much more he got out of it.
fatigue can cause a part to fail, but its usually improper tune/setup or excessive rpm.
https://www.theturboforums.com/threa...o-come.305001/
[QUOTEOk, on a short nitrous pull it made 609 whp and 694 ft. lbs torque][/QUOTE] page13
cant remember how much more he got out of it.
fatigue can cause a part to fail, but its usually improper tune/setup or excessive rpm.
Melting Slicks
Joined: Mar 2008
Posts: 2,666
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From: Spring Park MN
TRW forged pistons that came with the L-82 will way outlast the stock rods........Stock pistons should be good for 10 psi boost or better.
Boost will crutch a bad cylinder head but at some point that charge needs to leave the cylinder.......cramming boost into an engine with crap exhaust ports creates its own problems.
Jebby
Boost will crutch a bad cylinder head but at some point that charge needs to leave the cylinder.......cramming boost into an engine with crap exhaust ports creates its own problems.
Jebby
I agree with Jebby on the rods too. The Scat I beam rods are a nice piece rated for 750 HP and 7500 rpm. They are fairly light too besides being inexpensive.
I think the stock block setup properly would be good for 550 to 650 HP on a street engine. With splayed caps and main stud girdles they can handle more. I would run the main bearing clearance a little on the loose side to give it room for the flexing under boost and run a heavier oil like 20/50.
The tune on a boosted engine is what will make the difference between long engine life or instant death.
Mike
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From: altered state
St. Jude Donor '05
Assuming your piston to wall clearance isnt excessive you could run a miniblower say like the weiand, 4-6 lbs the stocker will take it for a long time. Yes, regap
Better heads=more power less boost.
Better heads=more power less boost.