SBC or LS1 and Average Cost of LS Swap?

Discussion in 'Engine Topic' started by sandiego74, Nov 19, 2020.

  1. sandlapper

    sandlapper Veteran Member

    Messages:
    213
    Likes Received:
    57
    Joined:
    Oct 9, 2020
    Location:
    SE CSA
  2. badazz81z28

    badazz81z28 Veteran Member

    Messages:
    19,213
    Likes Received:
    1,091
    Joined:
    May 4, 2001
    Location:
    Alabama
    The heads are the significant reason for power in the LS, but I wouldn’t say that’s the only difference. The hybrid block is a great choice if you want to use lower cost and in some cases more available SBC parts. The block also has improvements in oiling and cooling. At $2500, you’ll have a little invested in the build, but it should last. Unless you want to carb it and run a distributer, mechanical fuel pump...an LQ iron block would be just as good. Gosh it wasn’t too long ago someone was selling LQ crates for $2500.
     
  3. badazz81z28

    badazz81z28 Veteran Member

    Messages:
    19,213
    Likes Received:
    1,091
    Joined:
    May 4, 2001
    Location:
    Alabama
    NA? But the comparable example runs C25 and ridiculous compression? Big horsepower LS NA engines are usually in the 440+ cube arena. However supercharged and turbo engines from 5.3s to the 6.2s commonly produce 1000+ Hp. I don’t know why we keep comparing an ET of a car. That does nothing but compare the overall set-up and the driver. A stock Z06 is a fast car...
     
    1980RS likes this.
  4. 1320feet

    1320feet Veteran Member

    Messages:
    184
    Likes Received:
    50
    Joined:
    Oct 23, 2019
    Location:
    Calgary, Alberta.
    Pretty cool. But seriously, how many dimensions on it are of SBC dimensions? Maybe the bell housing bolt pattern.
     
  5. JMcDonough

    JMcDonough Member

    Messages:
    35
    Likes Received:
    27
    Joined:
    Aug 4, 2018
    Complexity and how much the weight difference matters is somewhat subjective. Again, I advocate adding it all up (parts needed and costs). I did that with a BMW I intended to LS swap, planned and added up all the parts, collected about half, then decided against the swap when the competitive autocross bug hit me.

    GRM article with some additional food for thought:
    https://grassrootsmotorsports.com/articles/addressing-internet-myths-about-ls-swaps/

    On the weight topic, it's really hard to pin down the weight difference for Gen1 SBC vs LS (LS1 or LS3) via google. I found everything from as low as 30 lbs to well north of 100 lbs. This hotrod article is interesting for a couple reasons - 1. The weights (something is clearly wrong with the LS7 weight). 2. The 4 tenth and 3 mph 1/4 mi time delta for ZZ383 vs LS3 (advantage to the LS3). Not sure I'd call that "dominate", but again - LS has other advantages (weight, efficiency, refinement, etc).

    https://www.hotrod.com/articles/hrdp-0810-gm-crate-engine-tests/

    Data point from well-known source (poster and source of into). Don't know if trans was the same or not.
    https://www.pro-touring.com/threads/70591-LS-weight-savings?p=698581#post698581

    A thread with actual gen1 sbc (all iron) and ls1 weights:
    https://ls1tech.com/forums/general-...33920-difinitive-ls1-weight-vs-gen-i-sbc.html

    Let's do some math on the 150lb delta from the TBI engine (iron heads, iron water pump, aluminum intake) to what an more aluminum intensive SBC would weight:
    Using our very handy local database: https://brian-callahan.com/Brians stuff/camaro_database.htm
    - Heads @ ~23lbs/head savings (light GM iron casting vs edelbrock aluminum) = 46lbs
    - Water pump = ~7 lbs
    Those are the obvious ones - I'd expect the LS components that may or may not translate to OP's engine to be lighter also driving the delta (a/c compressor, starter, exhaust manifolds). Let's assume just the starter:
    - LS1 Stock starter weight = 8.5 lbs, TBI starter weight = 19.5 lbs. Using a lightweight SBC mini starter of equivalent ls starter weight = additional 11 lbs

    46+7+11 = 64lbs; 150-64 = 86lbs

    There's probably some other weight to be lost on the TBI engine relative to the LS1 in terms of a OP's install of a prospective carb'd 383). Wiring, intake emissions equipment, smaller/lighter pulleys, etc. Maybe that adds up to ~10lbs. All-in, I'd expect to see something in the neighborhood of a ~76lb difference of a LS1/3 swap vs carb'd 383 as installed. I don't see any obvious components on the LS1 engine that are heavier vs the TBI engine where you'd save vs what is hows in the LS1 tech thread with actual weights. Happy to be wrong on that.

    What's a 76lb different on the nose of the car mean to autocross performance? If I had to wager a guess on a typical autocross course - maybe a tenth of a second.


    Lightweight wheel comparison on a Miata:
    https://grassrootsmotorsports.com/articles/are-lighter-wheels-really-better/

    Couple aspects to note on those results relative to a 2nd gen Camaro - car is lighter, so % increase is on par (42lbs on a ~2200lb Miata is in the ball park of 76lbs on a ~3400lb Camaro). Heavier wheels are about the worst place to add mass since it not only translates, but also rotates. Also impacts suspension's ability to keep good contact with the surface over bumps. I'd expect delta in the autocross part would be less if the 42lbs was added to the engine vs to the wheels. The Miata in this test is low hp, so the weight is a larger penalty during acceleration than a 400hp, often traction limited Camaro.
     
  6. badazz81z28

    badazz81z28 Veteran Member

    Messages:
    19,213
    Likes Received:
    1,091
    Joined:
    May 4, 2001
    Location:
    Alabama
    Where are the weights in this article? Why do we keep throwing the 1/4 mile ETs out there?? I guess we can make the argument the ZZ427 isn't that much better than the ZZ383....Overall performance is what we are looking at here...put a 383 in a car and put it on the road course, same car with the LS3....The LS3 will dominate....Its almost like comparing peak hp...not a good factor to measure when choosing an engine.
     
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

    Messages:
    22,899
    Likes Received:
    1,467
    Joined:
    Jul 8, 2001
    Location:
    SoCal High Desert
  8. 1980RS

    1980RS Veteran Member

    Messages:
    4,699
    Likes Received:
    1,369
    Joined:
    Jun 17, 2006
    Location:
    MN
    I still think a comparable BBC with a turbo would make 1000hp easily. My friend with a 65 El Camino had a 468 and an F3 Procharger on it made 1450 to rear wheels and run in the low 8's. I am not sure but I think any V8 with a turbo would make good power. The LS platform is a great one to start with, but if one is going to use a junkyard refuge 5.3 with hyper pistons for me you are just waiting for the kaboom with lots of boost on that one.
     
  9. JMcDonough

    JMcDonough Member

    Messages:
    35
    Likes Received:
    27
    Joined:
    Aug 4, 2018
    From the hotrod article (car weight is listed in each engine's section): LS7: 3,420, LS3: 3,334, LS327 (iron block): 3,386, ZZ4: 3,360, ZZ383: 3,360, ZZ427: 3,520, ZZ572: 3,560 LSX454: 3,448

    From some forum posts about the article, there's speculation that the LS7's dry sump system (tank, extra oil (?), lines, pump) resulted in the higher weight vs LS3. They didn't talk about the process used to weigh the car with different engines.

    1/4 mile times and ETs of two engines in the same car, same tires, etc is a good objective measure of real world performance. You can find dyno plots of LS3 and SP383 crate engines to see the difference in area under the curve both with headers (Hot Rod has articles with westech running each). the LS3 looks to make +25-40ftlbs over the SP383 from 3k up to 6k (+25 at 3k, +40 at 6k). No doubt it will be faster on a road course. Again, not sure what your definition of "dominate" is here. In a 2nd gear autocross on street tires (one of the use cases for this thread's OP), I wouldn't expect much of a difference (tenth or two, maybe) due to a 383 likely being traction limited in most places anyway.
     
  10. Fme

    Fme Member

    Messages:
    75
    Likes Received:
    14
    Joined:
    Apr 23, 2013
    Location:
    USA
    After reading through this thread I have to chime in...
    Anybody who is old enough to have experience with Gen I small blocks and young enough to have experience with LS's knows that the LS is superior in every way. Tell me what vintage GEN I out of an average truck from any era that will go to 7000 rpm in stock form and stay together? NONE! ALL LS's are 6 bolt main, rods are light and strong. A GEN IV 6.0L port is bigger than any big block port ever produced, and it comes in a van... For the OP a GEN I, I get it. As for turbo-ing a junk yard 5.3 making a thousand horse power and going Kaboom maybe at Friday Night Test and Tune? By Monday your car is up and running again with another $500 junkyard 5.3. Talk about budget and running 10's all day long cheap.

    If I were the OP, since his engine is up and running currently, I would start collecting parts for the LS swap its worth it...But that's me.
     

Share This Page