84 4+3

Idk. Blown big blocks still scare the **** out of me. And that's after being in a 8 second Z06 (probably faster now that the LS7 took a ****) which was arguably faster on top.... imma just stick with my 300 hp 350 and be happy.

JoeNova

If people spent decades of learning mistakes on the SBC, they would be able to apply them to the SBC.
Yet people are still claiming that 750+ HP requires an aftermarket block, and guys are now taking stock LS aluminum blocks with stock rotating assembly (including stock fasteners in both the rods and mains) down into the mid 4s in the 1/8th mile at over 1500 HP.
Yes, there is a bone stock factory aluminum 5.3 short block running 4.50 in the 1/8th mile.

The block webbing on an LS engine benefits from decades of technology improvements, along with the fact that ALL LS blocks have 6-bolt mains.
The aluminum LS blocks are considerably stronger than the iron gen 1 blocks. Siamese bores in the gen 4 stuff takes this even further.
The weak point in the stock LS stuff is the 4-bolts per cylinder head pattern making it hard to keep the heads down at 1200+ HP, but ARP extended that a few hundred more horsepower with the custom aged 625 studs.

Ever seen the gen 4 connecting rods? They make Gen 1 and 2 rods look like twigs.

Sorry, but the reason they handle so much more isn't because "people learned". Its because the block and rods are literally twice as strong as Gen 1 stuff.

Do I think people underestimate the L98? Absolutely. I don't doubt that it would handle 700 HP for several years under the right conditions on a stock rotating assembly.

But cmon, saying that the LS isn't any stronger is absolutely absurd.

84 4+3

I'd say 700 on an absolutely stock l98 is pushing it. At the very least I'd want main studs... I've seen a lot of caps walk at much lower power... That being said, the rotating assembly itself is capable of it for a while no doubt. I've seen it with my own eyes lol.

JoeNova

Yeah the mains are probably the biggest weak point, especially in the 2 bolt stuff.
If funds were permitting, I'd pick up another C4 and do it differently. I'd do a single turbo setup on the stock L98 and piggyback the stock ECU with a microsquirt.
I could probably get 500-600 at the crank for $1500 bucks or so. Thrash it as hard as I can as often as I can to look for weak points, slowly increasing power.
I think it will take a LOT more than people give it credit for.

If it blows, show how to do a write-up swapping in a craiglist 5.3 or 6.0, reusing the turbo, and retain all stock functionality for another $2000 maximum.

84 4+3

Youd want to shoot for a 113 headed car. Port the crap out of the heads and it'll probably get there. That's the other down side, yes headflow doesn't matter as much under boost but Gen 1 heads are... abysmal compared to even the worst gen 3 head.

If you want, there is a complete l98, harness and all that is for sale for like 500$ near me. Don't have to put it in a car, dyno the bitch and up the pressure until it let's loose. That would be more than adequate for the forum goers to get a kick in the ***. I simply don't have the time to eff around with it anymore. I like turbos, just don't like driving them. Eco tech, EcoBoost, whatever... there is still lag I feel. It ain't bad like the old stuff but I do notice it enough that it annoys me. I've noticed manufacturers keep idle rpms higher to combat it and then cruise rpms are in a range where it keeps some boost present. It's the future no doubt but just mashing the go pedal from a stop... it takes a second.

Way back volvo did a hybrid setup on the boats. Clutched supercharger with a turbo. Super charger engaged for sudden rpm changes and low speeds then disengaged around 1500 when the turbo was spun up. Worked well but was quirky with the tuning at times... clutch lag, overpressure warnings from ramp rates... they dumped it ultimately. But that was sweet because it made it literally the most responsive turbo diesel I've ever driven and really helped hole shots. That was back around 06 or so now.

bjankuski

This is what all factory screw superchargers do. The centrifugal aftermarket blowers work the other way around.

MatthewMiller

IOW, it's not because the end users learned, but mostly because the engineers who designed it learned. It stands completely to reason that a short block originally designed in the early 50s is juuust a little behind behind compared to one designed in the mid-90s.

dizwiz24

fair. You didnt totally discount my statement. Yes we can agree SBC is underestimated. Yes Ill back up and admit the LSx crank is prob stronger.

the LS came out right after people figured out what they were doing.

it benefits from new supercharger, turbocharger, injector/fuel pump technology and internet know-how that wasnt there when the SBC ruled.

i imagine callaway paid someone big bucks to tune the sledgehammer in 1988. Now every caveman can tune a car.

If the LSx didnt exist, I have no doubt people would be achieving similar numbers on SBC’s !

I think for the OPs 700 hp goal, a healthy sbc (hyperteutic pistons/forged rods / cast crank (though forged is preferred) would suffice

TommyFox

Yes like when I'm in the gym and some 25 year old thinks he is strong when he can bench 315 and loses to a 53 year old who can still get 405 for 5 reps. Just messing with you kid but having said that we had a NASCAR engine builder down the road from us for years...yes it's more work especially porting the heads etc. but that was all we had back then. I personally like the big blocks but probably going to do an sbc 427 after I refresh myself with the antiquated L98 fuel management system ...

84 4+3

**** I wish I could throw up 315. would have made throwing the fuel tank back in my truck underneath on my back much easier. I used to throw around 500lb heaters by myself when I was younger... so like 5 years ago... but that got real abusive real quick. Terrible backs run in the family and my lower back is already screwed from that... sucks.

Head tech has come a long way... but some people still think double humps are good. Even the best ported old old school heads are no match for new aftermarket ones. The machine shop I use has been around forever and the owner, in his 6
late 60s now, won't even bother with old heads now unless it's for class specific or restoration purposes. His reasoning is that what you get out is worth just as much as new at the end and it'll still be better because you can clean up the new ones if you wish. Technology is awesome.

Small block 427s are awesome. Needs a good head though.

racer x2

Spencer, the LS has the Efficiency in the combustion chambers and ports, where the power is made. If that is an option go that way and save some weight and fuel. A gen 1 SBC can support the 800 BHP level if properly prepared, $print cars have done that number for decades but it is destructive and co$$tly. Be warned.

MatthewMiller

True, but it's really important to note the issue with the head bolts getting in the way of the ports in the old SBC, as noted above. All the tech in the world can't overcome that barrier to performance that comes from the block design.

What's even more awesome is a 468 LS, which is quite doable with a stock deck height these days. Even more awesome that that is a 480 new-gen LT, which is a thing now, too. Yes, they need some killer heads, and the builders are having trouble finding intakes that flow enough while staying under stock hoods.

JoeNova

That's a big no.

84 4+3

Agreed. I was kind of eluding to that. The best gen 1 heads are where LS heads start. Mainly do to constraints like that.

And no need for a 468 ls. Slap a turbo on a ls7 and be done with it lol. I've noticed on LS builds and I'm not sure if its just me but... as the cubes go up power density doesn't really seem to change. As in horsepower per cube stays more or less equal, which is good. What I have noticed with big blocks is that tends to tick up some as cubes go up but it would seem to me there is more going on there than meets the eye. They're different enough where you can't go apples to apples on things like that but to me it would seem the LS is just optimized well imo.

My next project is a lq4 in an awd escalade so that'll be fun to learn.

Kevova

Money being the equalizer. The LS heads are significantly better than the 23* SBC. That's were the power comes from. 15-18* SBC heads are significantly better than the 23* heads and could change the advantage the LS has. However, a cheap used 18* top end cost as much as 4-5 used 5.3 LS engines.

JoeNova

We were talking strength, not power production.

A note on LS heads -
The worst flowing the LS heads (706/862) are $100/pair throw-aways,
and flow almost identical to the very popular aftermarket Edelbrock Performer heads for the 87-95 small block (Edelbrock 60859, $1600/pair assembled).
Both flow roughly 230/175 CFM.

If you have a 4" bore engine, you can run stock LS3 heads (which go for about $650/pair used),
which flow nearly identical up to .650 lift as the 18-degree Brodix 18 STD X heads (raised intake port, as cast no CNC porting) which are $2200/pair assembled.

Stock LS7 heads flow 350 CFM, and well over 400 CFM with a good CNC port but require a larger bore (4.1xx", I can't remember exactly)

If you're talking aftermarket LS heads, they are every bit as impressive in mostly stock format as the the low-degree, raised port, CNC small block stuff.
Completely custom castings and tons of money make for a fairly level playing field there.

cv67

do a 4 bolt...I have way less than 700 maybe 5-6 I cant hook it Gen 1 no turbo.
Build for what you want....Have smoked a few dyno queens. Those cars dont come alive til 60 plus wgaf then??
I like a license and cheap insurance.

???

JoeNova

You need better tires then. I can hook with 700 on the street with half as much weight out back as you have.

Spencer Ducharme

Well it looks like we had an LS vs SBC debate . Didnt expect that one. Firstly want to thank everyone for all the useful information. But technical specs aside let me share a testimonial here. My generation is much to brazien about their opinions on cars and often misinformed. And one of the biggest things I LOATH about new gen GM fans is that the new camaro, corvette, and sleeper truck guys (speaking of my gen only) have pretty much 0 respect for the SBC and LT-1. And all i ever hear at my local car meets is testosterone wars between that 1 poor guy who just bought an SBC car vs all the c5 and c6 owners, (that and the mustang and LS swapped guys practically holding court against each other...) i feel, with all technical specs aside, that there is a divide between old school and new school GM because of this and I dont feel that should be the case. The Camaro and Corvette represent a heritage of Multiple decades, standing through economy crashes, fuel crisises, and near cancellation by corporate in some cases. And i've done my damndest thusfar to try and get people to understand that if we're gonna pick a fight with anyone. It should be the 302s, 351s, and 5.0's on the strip and track as is the age old rivalry. Not this infighting nonsense. I hope 1 thing we all can agree on in this thread is that GM is GM.

Kevova

At full boost i doubt you are hooking. Turbos allow low power launch an increased power at the 60 ft or 1.5-2.0 seconds later.
with SBC production blocks there is alot of variation in them. 010 which can vary by weight and composition. I have known particularly hard blocks that machine shops never wanted to see again. One the damage in a crash, it's replacement was 20 lbs lighter. It was a big deal for stock car that was now under weight. Supposedly a 010 block with 020 020 behind timing cover and nodular iron 2482 caps was the best block. GM introduced the "bowtie" block in the early 80's because of the lack of QA of production SBC blocks.