You can find guys who have been hitting their engines with 200 shots of nitrous while turning 6000rpm for years and having the hyper pistons survive. So, they aren't complete junk guaranteed to fail like some people claim. They can work well, they just don't have as much tolerance to doing something bad to the engine like a forged piston has.

 

Although this is entertaining, Let's get over it. the name small block is generally associated with the gen 1 small displacement motor. Gen 2 is the LT motor, gen 3/4 is the LS, gen 5 is the lt eco tech. if your talking similar displacement, then you are all talking small displacement, hence small blocks. If you want large displacement, then your either BBC or large displacement LS. There is an actual block size difference that gen 1 and the lage displacement LS motors share. I dont believe anyone is making a block the size of an old big block and a small displacement motor for the same cars anymore just boring out and resizing the same block

If you throw a similar roller cam in a gen 1 or a gen 3 with the same intake and equal heads you will get similar HP. These motors are just an air pump and all things the same, It will produce the same. You guys are getting off of the main topic, how about you leave this thread to the OP and you guys go argue your issues out in a new thread. Thanks for coming, theres the door
https://en.m.wikipedia.org/wiki/Chev...l-block_engine

 

Like I said, The issue with Hypers is they do NOT tolerate detonation well of any sort like a forged piston..No detonation issues and I would predict that Hypers are fine......

 

That is why hypers hold up in LS engines. Most REAL small blocks have no detonation sensors and computerized retard.

 

There's more than one flavor of forged piston. The two main flavors are 2618 alloy and 4032 alloy. 2618 is the piston everyone thinks about when they think "forged". Great resistance to detonation, but noisy due to big bore clearances and not as long a life as hyper cast due to poor wear characteristics. 4032 pistons are kind of halfway between hyper cast and 2618 forged in their characteristics. They have most of the benefits of hyper cast - tight bore clearances, good thermal stability, and long life - while also having most of the 2618 forged piston resistance to detonation. It's the alloy GM uses in the LS9, LSA, LT4, and even their performance parts engine, the LSX376 B15.

If you're not going to go with a forced induction engine that makes 4 digits worth of horsepower, the 4032 alloy is the way to go. Mahle has lots of 4032 pistons for the smallblock, as does JE in their SRP Professional line of pistons.

 

Great Info..Thanks

I would assume my LS7 in the Z06 then is the 4032 piston?

Not sure what the JE Forged Racing piston is in my L-82 355..it has zero piston noise/slap even when stone cold....4032 as well?

 

getting back to the original question.......
I would assume that possibly you lost a piston due to maybe detonation or the rod angle. 383 do not like high rpms. piston broke and the resulting carnage.
I know a lot of others have had good luck with the same combo but others haven't..... Its a combination I really don't like, like I said. I would tend to lean towards a 377 but just my preference.
Hopefully we can all get back on track to the op.
Flame away.

 

Nope, the LS7 uses hyper cast pistons. The modern ones are really very good. Titanium rods in the LS7 but cast pistons. That tells you just how good they really are. As far as the 4032 alloy goes, there are people making over 1,000 hp on stock LT4 and LT5 engines just by swapping out the blower. You really don't have to sacrifice the superior wear characteristics of the high silicon alloys for anything that will ever be driven on the street. Even the F1 cars use the 4032 alloy pistons because their race rules require that their engines last multiple races between rebuilds.

As far as the pistons in your L-82, if they're branded as JE pistons, they're probably 2618 alloy. If they're branded as SRP or SRP Professional, they're most likely 4032 alloy.

 

Thanks for the great info that is useful for most.

As far as the OP goes, not sure there is much more to be said at the moment until he determines the origin of his failure and decides what he wants to do now based on everything suggested so far concerning all his options......................

 

The OP is currently on the look-out for both an engine hoist as well as an engine stand. Also he needs to get his mother in law's Peugeot 106 out of the garage first (has a power leak somewhere draining the battery in a week or so).

 

That implies he also needs to get the mother-in-law out of the house as well.

 

My early flight training days were in the 70's when I was 14 - didn't finish until I was 42. Back in that era the instructors dressed much more formally - button down dress shirts, dress pants, shoes. Couple that with the early 70's style and my instructor, my uncle, would usually show up crisp and clean down to the white shoes. On one lesson as he went to hop in the C150 he noticed a brown stain on the seat. So he grabbed a rag out of the back, took a little gas out of one the fuel drain, and started cleaning. I asked him if it was chocolate. His reply - Either that or the last student scared the hell out of the instructor.

 

I second the motion.

Seems the debate here is on semantics. Does small block refer specifically to size or to generation of engines which were virtually identical except for the bore.

The real debate comes down to the old saying, there's no replacement for displacement. This is not true. If I said, all else being equal (to the extent theoretically possible), fuel, aspiration, exhaust flow, cam specs, redline, etc. etc., then it is true, you need more displacement to get more hp. But hell, torpedo engines produce several hundred hp on displacements more in line subcompact car engines. So is a torpedo engine a small block and a Pratt and Whitney R4360 28 cylinder 4,363 cid radial a big block? In the "all we're talkin' 'bout is size world", yes. In the automotive terminology world I'd say no - Chevy 396 / big block; Chevy 400 / small block.

Po-tay-to, Po-tah-to

 

PM sent.

DUB

 

On the ultimate topic of this thread, I just want to say the posts with relevant information (which exclude mine) are providing a wealth of information. As I look at some point dealing with my original L-82 it becomes clear to me that if I rebuild it I'll stick with new parts every bit as tough as those currently in it and which dealt with putting a brand new corvette in the hands of 21 year old who, thanks to the 1980's oil boom, had for the first time financial means which were greater than his self survival instincts (i.e. more money than brains). Or, should I go the replacement engine route, have it built with parts just as tough as the original L82 to be tolerant of variation which may be hiding in the parts or the build quality.

 

I have read this and it seems to me you are saying the same thing...rebuilding the engine with the same type of parts that to came with. or am I missing something.

DUB

 

But there is no replacement for displacement if you want to make big HP and still get lots of low end torque that makes the car fun to drive on the street. I wouldn't have much trouble betting money that a 450hp 454BB makes more low end torque then a 450hp 383SB or 406SB.

Well, you ~could~ build a very, very well executed smaller displacement forced induction engine that could do fairly well down low torque wise emulating a bigger displacement engine.

What would make the heads "equal" between a small block and a LS engine? If you picked intake runner cc as the main metric when building a small block to match the power of a LS3 then you'd be using 260cc heads on your small block build. That's a lot of intake runner cc to use on a 383 cu-in 430hp small block build and you likely wouldn't be happy with the result on the street. This is my point. The 2 engine families have enough fundamental design differences that "similar" parts don't just work the same between the two engine families.

As for the rod/stroke ratio. Evaluating rod length based on the rod/stroke ratio it causes is probably the most over-blown part of engine bench racing. The 383 gets way too much attention for having a "poor" rod/stroke ratio. Long stroke big blocks end up with a much worse rod/stroke ratio then a 383 with 5.7" rods yet you don't read much about how those builds are terrible because of it like you do with a 383 small block. It's just accepted to be what it is. You're much better off evaluating rod length based on the piston design (lightest weight yet wrist pin not into the ring pack or compromised strength) and any possible help with clearances it gives you.

 

 

I want to rebuild it with some punch up in power but not wild - targeting 400 gross. So higher compression aluminum heads, decked as needed, a modern cam (the L82 has a good cam for 1980, but machining has come a long way and some better profiles are possible (if I understand things in this area correctly), etc. If I rebuild, then I assume a mild bore to clean up the cylinders and thus I'd need to replace the pistons and maybe rods (I'm not sure). The crank would likely be OK in some fashion. As for heads, I'd go for the better names to ensure the quality including the materials. I live in a business where we use literally thousands of different steel, copper, and aluminum alloys and I have learned you simply cannot trust anything defined as "off-shore", aka China, to be what they say it is.

If I go for a replacement build, then I'm saying build it to the quality of the L82 which is a rock solid engine, again - my understanding. Forged steel crank, not cast iron and certainly not nodular; forged rods, forged pistons, and whatever else provides safety margin both against my abuse (intentional or otherwise) and the possibility that some defect does exist and for the fact that sometimes all the allowed manufacturing tolerances happen to go toward the worst case, though still in spec, direction.

Having spoken with a high school buddy of mine who started a racing engine business pretty much straight out school 40 years ago and is still going strong, he offered me two options on a build, both starting with good used 4 bolt main block. Going with nodular crank, cast pistons and rods, off-shore heads, etc. about $3500. Going with parts of like manufacturing quality of the L82, about $5,500. He stated that he did not have any qualms about building the $3,500 engine since the target hp was 400. So he in no way was trying to scare me into the $5,500 build. I just see the the extra as a reasonable price for the extra peace of mind I'll have.

But, as noted, that's based on one professional builders information, my experience beating the crap out of the L82, and, though not previously mentioned, my brother blowing up his '74 Camaro 350 in '77 (sucked a valve on fuelie heads being pushed with a solid lift cam), and some of the insights (incites? maybe both) in this thread (and others). I am though always happy to get additional input given that there are a lot of far more experienced people than me here.

Thanks,

 

When I built a sbf for my factory five 33 hot rod, I started with a 351 Windsor, bored and stroked it to 408 cu in.
It was recommended and the engine builders I was working with referenced that it was a perfect square with a 4" stroke and 4" bore.
They stated that with that combination they found fewer failures than with 413 or 428 sbf builds.
I was never sure how true it was, but it was a fun motor.
Could the same balance be true for a sbc motor?