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From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Which pistons should I use?
Engine's out of the car, the heads and oil pan are off so now I'm thinking maybe I should just go ahead and do it right the first time. All the pistons are OK, the cylinder walls are a little scuffed but nothing you can feel. Haven't measured the cylinders for round yet but I'm thinking at least hone the cylinders, new rings and pistons, polish the crank, all new bearings and freeze plugs. With new heads and cam I'd basically have a new engine and the machine shop will warranty it.
So what pistons? We're shooting for a comp. ratio of 10 to 1 or slightly less. It's an L82 4 bolt main. And I'm seriously considering changing my choice of cam from Comp's XE268 to their roller 270HR. I was trying not to spend a whole bunch of money but I should have known better. Same with the pistons, I suppose you can spend about whatever you want but I'm still on somewhat of a budget.
I'm not trying to build a fire breathing beast, just something that's fun to drive. So what sayeth the C3 engine gurus?
Looking for a brand recommendation, Keith Black, TRW, etc, than a specific piston.
Last edited by Capt. Shark; Apr 2, 2017 at 10:41 AM.
Reason: clarification
shouldnt that be a discussion with your machince shop? Your aiming for a 10:1 compression so knowing the size of your cylinder head chambers, deck height, head gasket thickness all come into play along with your piston choice.
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Originally Posted by MelWff
shouldnt that be a discussion with your machince shop? Your aiming for a 10:1 compression so knowing the size of your cylinder head chambers, deck height, head gasket thickness all come into play along with your piston choice.
Yes, that certainly will be a discussion with the shop. Guess I wasn't too specific. Was looking more for a brand recommendation than a specific piston. Keith Black, TRW etc.
First you need to decide on the type of piston - forged, hypereutectic or cast. I listed them in decreasing cost and quality. I believe your L82 had forged pistons from the factory.
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Originally Posted by BKbroiler
First you need to decide on the type of piston - forged, hypereutectic or cast. I listed them in decreasing cost and quality. I believe your L82 had forged pistons from the factory.
I believe you're right. That's what I would prefer to go back with.
I'm betting those are out of my budget Are all hypereutectic hyper junk?
I did mine twice because I thought the hyper would be ok--busted 2 of them have forged now and floating rods----more now usually equals less later...my 2 cents
From: Las Vegas - Just stop perpetuating myths please.
Do you even need new pistons? Did you do the usual tests for condition - compression and leakdown? What were the results/numbers?
With only 65k miles in it from your profile you shouldn't need anything in the bottom end. Throw a bigger cam in it and better heads w/ tighter compression. That's the advantage of the L82 that already has good forged pistons, 4 bolt main and I believe a forged crank to.
IMHO your expectation that it needs an overhaul at 65k mi is totally wrong unless you have data to back it up (compression and leak down).
Owners that do premature engine rebuilds usually don't have the patience to tune what they have correctly and find blame in the motors condition. The L82 short block is one of the best Chevy made. It just needs to breathe better with good cam and heads. And of course an accurate tune.
Sorry if this sounds blunt but to me tearing that low mi L82 apart is backwards if you're trying to save money on a budget and go faster to. The sbc is the cheapest motor on the planet to buy performance with and the possible combinations are countless. That's my advice and you can take it or leave it as I won't say anything more unless you ask me to. I don't want to ruin your thread but I believe your suffering a severe case of while I'm at it itis.
Good luck.
Last edited by cardo0; Apr 2, 2017 at 01:44 PM.
Reason: Stupid autocorrect!
I agree, if you are putting new pistons in then put em in fresh cylinders. Go .030 over. Hypereutetics are good, but they don't tolerate detonation at all so be very careful on your compression ratio.
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Originally Posted by cardo0
Do you even need new pistons? Did you do the usual tests for condition - compression and leakdown? What were the results/numbers?
With only 65k miles in it from your profile you shouldn't need anything in the bottom end. Throw a bigger cam in it and better heads w/ tighter compression. That's the advantage of the L82 that already has good forged pistons, 4 bolt main and I believe a forged crank to.
IMHO your expectation that it needs an overhaul at 65k mi is totally wrong unless you have data to back it up (compression and leak down).
Owners that do premature engine rebuilds usually don't have the patience to tune what they have correctly and find blame in the motors condition. The L82 short block is one of the best Chevy made. It just needs to breathe better with good cam and heads. And of course an accurate tune.
Sorry if this sounds blunt but to me tearing that low mi L82 apart is backwards if you're trying to save money on a budget and go faster to. The sbc is the cheapest motor on the planet to buy performance with and the possible combinations are countless. That's my advice and you can take it or leave it as I won't say anything more unless you ask me to. I don't want to ruin your thread but I believe your suffering a severe case of while I'm at it itis.
Good luck.
Not at all, I appreciate the advice. You're exactly right....I do have a severe case of while I'm at it. It ran fine before with no issues so I should probably just leave it the hell alone and put it back together with the new heads and cam like my original plan.
The guy that owns the machine shop did say it looked fine to him.
Measure up the cylinders. Who knows they may still be within specs for taper and roundness. My L48 was at 60 some thousand miles. That was 10,000 miles ago and one rebuild with stock spec cylinders.
If they are still in spec then you could use a ball hone and re-ring the existing forged pistons and use smaller chamber heads to get the compression up. Are new heads part of the plan?
The original 9.0:1 advertised CR is probably more like 8.3-8.5:1 or so if the heads are at all like the L48 in consistancy and advertised chamber size.
If you intend on going to 10:1 then new rings may be desirable to eliminate the possibility of making an oil burner.
I rebuilt my OEM L-82 in 2014 when I had 66,000 miles on the motor. I went with a .030 bore, Forged JE Racing Piston/rings (I would not use Hyper's)...Total compression 10.2:1 with 9:1 JE pistons, Howards Roller cam (.525/.525 Lift, duration 219/225, LSA 110), AFR 180 aluminum heads and LTH's. I did reuse the L-82 forged rods, L-82 forged crank..reconditioned. The L-82 has very similar components to the LT-1's and the bottom is 4 bolt and all forged. Its a great motor with all the goodies for high performance. Go Roller cam all the way..forget a flat Tappet cam, in my opinion.
Had the L-82 355 out just today..holy smokes does it have serious b**lls after the rebuild..it simple amazing. BTW- I know what fast is, I have a 10C6Z06 for comparison.
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Originally Posted by REELAV8R
Measure up the cylinders. Who knows they may still be within specs for taper and roundness. My L48 was at 60 some thousand miles. That was 10,000 miles ago and one rebuild with stock spec cylinders.
If they are still in spec then you could use a ball hone and re-ring the existing forged pistons and use smaller chamber heads to get the compression up. Are new heads part of the plan?
The original 9.0:1 advertised CR is probably more like 8.3-8.5:1 or so if the heads are at all like the L48 in consistancy and advertised chamber size.
If you intend on going to 10:1 then new rings may be desirable to eliminate the possibility of making an oil burner.
We're certainly going to measure them tomorrow. New heads are going on. Dart iron 72cc that the shop is going to take some off the top. Honed and new rings seems like a reasonable course of action.
Thanks
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Originally Posted by jb78L-82
I rebuilt my OEM L-82 in 2014 when I had 66,000 miles on the motor. I went with a .030 bore, Forged JE Racing Piston/rings (I would not use Hyper's)...Total compression 10.2:1 with 9:1 JE pistons, Howards Roller cam (.525/.525 Lift, duration 219/225, LSA 110), AFR 180 aluminum heads and LTH's. I did reuse the L-82 forged rods, L-82 forged crank..reconditioned. The L-82 has very similar components to the LT-1's and the bottom is 4 bolt and all forged. Its a great motor with all the goodies for high performance. Go Roller cam all the way..forget a flat Tappet cam, in my opinion.
Had the L-82 355 out just today..holy smokes does it have serious b**lls after the rebuild..it simple amazing. BTW- I know what fast is, I have a 10C6Z06 for comparison.
I've been up and down that road more than once about this. Aluminum vs. iron, roller vs. flat tappet, etc. Finally decided that if I can wake it up a little and have some fun with it, I just really don't need a 12 second car. It's not going to the strip, just the cruise ins so that's where I'm at.
I'm sure your's is a blast to drive, though
Just saw your pics.......sweet. However I told the shop you better not paint the block that damn blue
Last edited by Capt. Shark; Apr 2, 2017 at 06:51 PM.
I've been up and down that road more than once about this. Aluminum vs. iron, roller vs. flat tappet, etc. Finally decided that if I can wake it up a little and have some fun with it, I just really don't need a 12 second car. It's not going to the strip, just the cruise ins so that's where I'm at.
I'm sure your's is a blast to drive, though
Just saw your pics.......sweet. However I told the shop you better not paint the block that damn blue
I went roller cam to avoid the dreaded cam lobe wipe issue and the better area under the power curve plus with the aluminum AFR's. I wanted to take advantage as much as possible of the increased air flow from the AFR's. The aluminum heads also enable me to use 89 octane fuel with no detonation with 10+:1 compression. With the 4 speed and 3.70 gears, I have no doubt that I could achieve high 12's in the 1/4 if I raced it at the strip which I don't. The blue GM paint was part of the theme to make it look, be, and feel as much L-82 as reasonably possible with 425+ Gross HP. The intake manifold in the picture is the OEM L-82 intake cleaned up and slightly ported and I still use the dual snorkel GM cold air air intake assembly as well. The engine looks and sounds pretty much like the OEM L-82...until I step on the gas.......
I have seen more motors rebuilt twice, than I can count.
because they were to cheap, to buy forged pistons the first time.
Hypertec pistons are a waste of time and money, in a performance engine.
if you already have forged pistons keep what you got and run it.
Which pistons should I use?
