some basic bbc math, to get you thinking about your potential dream bbc combos.

Discussion in 'Rotating Assemblies' started by Grumpy, Jun 19, 2018.

  1. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    I recently had a discussion with one of the local guys concerning what heads and rotating assembly he should buy now that he recently purchased a tall deck (10.2") big block chevy block.
    he has a perfectly good 427 forged crank (3.76" stroke) but hes seriously thinking of buying a (4.25" stroke) forged crank.
    the DART blocks got a 4.6" bore.
    ok simple math, displacement= bore diam. x bore diam. x 8(cylinders)x stroke x .7854
    lets assume these are max effort race engines built with 13:1 compression requiring E85 or race octane fuel, and yeah if your going to use e85 Id suggest you slightly increase the intake vport cross sectional area as youll need more air flow for alcohol based fuel.
    [​IMG]

    3.76" stroke x 4.6 bore = 500 inches of displacement
    4.25" stroke x 4.6 bore = 565 cubic inches of displacement

    max piston speed should not exceed about 48,000 inches per minute and that requires high quality forged parts

    3.76" stroke=6380 rpm redline

    4.25" stroke- =5647 rpm redline

    assuming either engine makes about 1.25 ft lbs of torque at close to peak rpm, lets say 500 rpm less
    your looking at about 625 ft lbs on the 500 cubic inch engine.
    close to 725 hp
    it is likely your likely going to want heads with a 4.25 cross sectional area
    Int. Duration is 276 degrees
    Exh Duration is 290 degrees
    LSA is 109 degrees


    http://garage.grumpysperformance.co...onnecting-rod-rod-length-too-stroke-info.510/

    your looking at about 706 ft lbs on the 565 cubic inch engine.
    close to 737 hp is likely
    it is likely your likely going to want heads with a 4.5 cross sectional area
    Int. Duration is 286 degrees
    Exh Duration is 303 degrees
    LSA is 111 degrees

    yes Im fully aware most people don,t bother to read the links and sub-links
    UNTIL they have expensive parts fail.
    but for the few people on the web site that might prefer spending less time and cash replacing expensive failed parts,

    and financing the machine shop owners vacations and paying his mortgage... I post them anyway
    what length connecting rod and what piston pin height are you using, building the 496 BBC?
    yes Im assuming its a tall deck 10.2" block and a 4.25" stroke

    a 4.25" stroke,6.8" rod and 1.270 pin height, for that 10.2 deck height block

    6.8" rod divided by a 4.25" stroke=1.6 ratio

    displacement = bore x bore x stroke x 8 x .7854

    1/2 stroke + rod length+piston pin compression height,
    should roughly equal block deck height ,

    plus or minus a few thousandths,
    minor adjustments in compression,
    due to head gasket thickness and what the piston deck height is are common
    common BB CHEVY piston compression heights are
    1.270"
    1.395"
    1.520"
    1.645"
    1.765"
    remember the blocks deck height, minus the piston pin height minus 1/2 the crank stroke will equal the required connecting rod length
    OR
    the blocks deck height, minus the connecting rod length, minus 1/2 the crank stroke. will equal the required piston pin height

    if you wonder why I suggest using SCAT (H) beam style cap screw connecting rods vs stock or most (I) beam designs this picture should show the increased cam to connecting rod clearance

    After market performance ,big block connecting rods come in several common lengths
    [​IMG]
    6.7-6.8"

    https://www.summitracing.com/parts/esp-67003dl19/overview/make/chevrolet

    https://www.summitracing.com/parts/cpi-u16230/overview/make/chevrolet

    https://www.summitracing.com/parts/sca-6670022a/overview/make/chevrolet

    https://www.summitracing.com/parts/sca-6680022a/overview/make/chevrolet

    https://www.summitracing.com/parts/sca-6680022/overview/make/chevrolet



    [​IMG]
    notice the pin height in the pistons pictured above allow a longer or shorter connecting rod length

    http://garage.grumpysperformance.co...-about-your-potential-dream-bbc-combos.14607/

    http://garage.grumpysperformance.co...od-rod-length-too-stroke-info.510/#post-10311

    http://garage.grumpysperformance.co...onnecting-rod-rod-length-too-stroke-info.510/

    http://garage.grumpysperformance.com/index.php?threads/measuring-rod-and-pin-heights.3760/#post-9968




    blueprint engine blocks
    https://www.jegs.com/v/Blueprint-En...brand&storeId=10001&catalogId=10002&langId=-1

    DART BLOCKS
    http://dartheads.com/product-category/big-block-chevy/blocks/

    world products blocks
    https://www.billmitchellproducts.com/engine-blocks/

    G.M. performance
    https://www.gmperformancemotor.com/category/LS196.html

    either engine will require a roller lifter cam with a fairly tight 109-111 lsa and about a .700 lift too breath to its potential, both engines would benefit from a tunnel ram intake and dual quads or a stack injection style intake



    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]


    its the attention to details and checking clearance etc. and time and care taken,
    that makes the difference between a barely or average functional ,
    and a rather exceptional engine build, yes the urge to get it running is strong,
    but getting it done correctly is the goal

    [​IMG]
    your fpm is found by multiplying the engine rpms x the stroke x 2
    example
    on a 383 sbc the stroke is 3.75", so 4000fpm on a 383 is reached at 4000rpm x 12"(inches)= 48,000 inches per minute of piston travel
    so 48,000/7.5" of stroke =6400rpm, (7.5" is twice the engines 3.75" stroke)
    exceeding that is a reasonably sure way to over stress the engine or (get into valve control issues ( which is a different can of worms)
    this is a good place to point out that ARP makes much stronger rod bolts and main cap studs,and that the better aftermarket forged 4340 forged connecting rods are far stronger than most OEM connecting rods and that a 7/16" arp rod bolt is on average 200%-250% stronger than a stock 3/8" OEM rod bolt.
    balanced components tend to put significantly lower stress on the engine components
    theres lots of guys that don,t comprehend the stress levels involved in spinning a longer stroke engine up over 7000 rpm,
    as a result theres a lot of guys who as a result get an expensive personal education in that area,of engineering stress management ,
    after their engine "EXPLODED FOR NO REASON" and 90% plus will blame the machine shop ,
    not realizing or refusing to accept, its their own lack of grasping the concepts involved.
    [​IMG]

    ideal port cross section

    [​IMG]
    [​IMG]

    IVE talked to several engineers, all strongly suggested the vertical stack injection manifold pictured below will significantly out flow the horizontal stack version above
    [​IMG]



    [​IMG]
    [​IMG]



    the first few rule's of GRUMPY'S engine assembly

    (1) THINK THINGS THROUGH CAREFULLY ,
    WRITE DOWN A LIST OF COMPONENTS ,

    MAKE DARN SURE THE LIST IS COMPATIBLE WITH,
    and AT LEAST SEMI-REASONABLY PRICED WITHIN YOUR BUDGET.
    FOR WHAT YOU INTEND TO BUILD AND RESEARCH THE RELATED MACHINE WORK,

    RESEARCH CAREFULLY THE COMPONENT INSTALLATION AND INTENDED USE ,
    AND POWER BAND THE PARTS WILL REQUIRE

    AND FIND AN EXPERIENCED MENTOR.

    (2) if in doubt, about how to do anything, on an engine, do some detailed research,
    find and compare at least 3-5 valid trust worthy sources info,
    read the instructions over again, several time's very carefully
    and if available watch several related videos.

    (3) if any component will not easily function as designed or requires a good bit of physical force to install ,
    or your not 100% sure your doing something CORRECTLY

    STOP, FIND OUT EXACTLY HOW THE PARTS SUPPOSED TO FIT AND FUNCTION,& WHY! YOUR HAVING PROBLEMS
    theres a reason, and you better verify your clearances are correct , and your following the instructions before you proceed.

    (4) never assume the parts you purchased can be used without carefully , cleaning them prior too,
    checking the physical condition, verifying clearances and using the correct sealant, lubricants etc.


    (5) the quality of a component is generally at least loosely related to the cost to produce it,
    and the amount of detailed research and quality machine work that went into its production.
    if you got a significant reduced price, theres typically a reason.
    it might simply be because a new improved part superseded the one you purchased,
    but it might be a far lower quality imported clone with lower quality materials and machine work.
    its the purchasers responsibility to research quality.

    (6) if you did not do the work personally or at least take the effort to verify it was done correctly and personally verify clearances

    ITS almost a sure thing that it was NOT done , correctly, and yes that mandates you fully understand what your looking at,
    and how the components are supposed to function and have high quality precision measuring tools.

    (7) ITS ALMOST ALWAYS FASTER AND LESS EXPENSIVE , AND PRODUCES BETTER RESULTS IF YOU,
    BUY FEWER HIGH QUALITY PARTS & DO THINGS CORRECTLY THE FIRST TIME

    ID suggest you select from heads from these sources
    Jegs; 800/345-4545; Jegs.com

    Summit Racing; 800/230-3030; SummitRacing.com

    Scoggin-Dickey Parts Center; 800/456-0211; ScogginDickey.com


    TRICKFLOW
    http://www.trickflow.com/egnsearch.asp? ... 4294867081
    http://www.trickflow.com/customerservice
    1-330-630-1555 • 1-888-841-6556

    BRODIX
    http://www.brodix.com/heads/heads.html
    479.394.1075

    DART
    http://www.dartheads.com/products/cylinder-heads
    Dart Machinery; 248/362-1188; DartHeads.com


    AIR FLOW RESEARCH
    http://www.airflowresearch.com/
    toll free: 877-892-8844
    tel: 661-257-8124

    Patriot Performance
    Patriot Performance; 888/462-8276; Patriot-Performance.com


    RHS
    http://www.racingheadservice.com/rhs/cylinder-headshtml
    Toll Free: 877-776-4323
    Local: 901-259-1134

    EDELBROCK
    http://www.edelbrock.com/automotive_new ... main.shtml
    Edelbrock; 310/781-2222; Edelbrock.com

    BMP (world products)
    http://www.theengineshop.com/products/cylinder-heads
    Tel: 631-737-0372
    Fax: 631-737-0467

    BUTLER PERFORMANCE
    http://www.butlerperformance.com/products/cylinder_heads/cylinder_head_labor.html
    866-762-7527

    BLUE PRINT ENGINES
    http://www.blueprintengines.com/ind...sb-chevy-aluminum-cylinder-heads-cnc-machined
    1800-483-4263

    PRO-FILER
    https://www.profilerperformance.com/
    937‐846‐1333

    before you buy components talk to both the vendors and your machine shop of choice , you damn sure don,t want mis-matched components and clearances.
    you need to measure accurately, know what your current block will function correctly with and pay attention to clearances and other details that make or break the engines potential durability and power potential.

    related info
    http://garage.grumpysperformance.com/index.php?threads/calculating-ideal-port-size.624/#post-8692

    http://garage.grumpysperformance.co...od-rod-length-too-stroke-info.510/#post-10311

    http://garage.grumpysperformance.com/index.php?threads/redline.343/#post-15729

    http://garage.grumpysperformance.com/index.php?threads/types-of-crankshaft-steel.204/

    http://garage.grumpysperformance.com/index.php?threads/connecting-rod-strength-h-vs-i-beam.1168/

    http://garage.grumpysperformance.com/index.php?threads/bits-of-427-bbc-build-related-info.15543/

    http://garage.grumpysperformance.com/index.php?threads/427-tall-deck.15267/

    http://garage.grumpysperformance.co...-the-oil-used-and-oil-level-does-mater.15592/

    http://www.wallaceracing.com/cam-spec-calc.php

    http://www.wallaceracing.com/header_length.php

    http://www.wallaceracing.com/runnertorquecalc.php
     
    Last edited: May 12, 2020
  2. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    INFO from a basic phone conversation today......
    and a response I said Id post


    if your looking for a local machine shop,
    in the west palm beach fla area
    be damn sure you get all the details in writing
    dates prices, details on what needs to be done
    delivery dates and take pictures
    these guys generally do decent work




    first choice (use them fairly often to rebuild heads)

    Engine Rebuilders-Palm Beach,
    1722 Donna Rd, West Palm Beach, FL 33409

    second choice (mostly for block line hone & decking)

    Keener's Engine Machine Inc
    2517 N Military Trl, West Palm Beach, FL 33409



    third choice
    these guys get decent reviews but Ive only been there once)

    170 Commerce Rd, Suite 1A
    Boynton Beach Florida 33426
    https://www.mprracingengines.com/
    ok, first step, would be to determine the block and head casting numbers and the current physical condition of the engine,
    and thinking through a realistic budget and time frame.
    you need to know if its a gen IV,V,or V! BIG BLOCK,
    in an older motor home its almost sure to be the basic mark IV 454 engine with a cast crank and oval port heads.
    this is good as theres a wide selection of parts, but again you need to verify what you have and its current condition.
    most of us work on very limited budgets, but unless you know what your starting with as a base you can,t make logical decisions.
    obviously the car you select its weight and the condition of the TH400 transmission ,
    if thats what you choose to use in your project must also be looked at and carefully inspected.
    your budget, a place to work on the car of your choice and the tools and skills you have are also obviously important.
    if you have a couple local car, or hot rodder clubs I would suggest looking into the car shows,
    and clubs as the more contacts you have the easier it tends to be to find parts,
    and gain help from people with skills you might not currently have.
    yeah reading links will at first look intimidating and maybe boring ,
    but youll be amazed at the info and knowledge ,
    youll gain in the process and the questions you did not yet know too ask.
    the basics remain consistent, you want the best flowing heads and intake you can afford,
    some O.E.M. heads can be used with minor port work, some are rather restrictive,
    and yeah we all work on limited budgets that dictate our choices at times,
    at least 9.5:1 compression, a 7-8 quart baffled oil pan,
    and a set of headers and low restriction exhaust,
    a cam will be selected matching the application,
    compression, drive train gearing and intended rpm range and power band.

    [​IMG]
    TRICKFLOW
    http://www.trickflow.com/egnsearch.asp? ... 4294867081
    http://www.trickflow.com/customerservice
    1-330-630-1555 • 1-888-841-6556

    BRODIX
    http://www.brodix.com/heads/heads.html
    479.394.1075

    DART
    http://www.dartheads.com/products/cylinder-heads
    Dart Machinery; 248/362-1188; DartHeads.com


    AIR FLOW RESEARCH
    http://www.airflowresearch.com/
    toll free: 877-892-8844
    tel: 661-257-8124

    Patriot Performance
    Patriot Performance; 888/462-8276; Patriot-Performance.com

    TRJ
    http://trjperformance.com/cylinder-heads-top-end-kits-components/complete-heads/

    RHS
    http://www.racingheadservice.com/rhs/cylinder-headshtml
    Toll Free: 877-776-4323
    Local: 901-259-1134

    EDELBROCK
    http://www.edelbrock.com/automotive_new ... main.shtml
    Edelbrock; 310/781-2222; Edelbrock.com

    BMP (world products)
    http://www.theengineshop.com/products/cylinder-heads
    Tel: 631-737-0372
    Fax: 631-737-0467

    BUTLER PERFORMANCE
    http://www.butlerperformance.com/products/cylinder_heads/cylinder_head_labor.html
    866-762-7527

    BLUE PRINT ENGINES
    http://www.blueprintengines.com/ind...sb-chevy-aluminum-cylinder-heads-cnc-machined
    1800-483-4263

    TRJ
    http://trjperformance.com/cylinder-heads-top-end-kits-components/complete-heads/

    PRO-FILER
    https://www.profilerperformance.com/
    937‐846‐1333

    http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/page-5#post-79540

    useful related info,
    Youll rapidly learn that this website has a great deal to offer,
    but its based on you asking questions and reading links and sub links.
    yeah its the links and sub links that hold a great deal of info and tips

    http://garage.grumpysperformance.com/index.php?forums/tbuckets-and-custom-kit-cars.109/

    http://garage.grumpysperformance.com/index.php?threads/casting-numbers-vin.93/#post-9024

    http://garage.grumpysperformance.co...nks-to-casting-numbers-and-info.632/#post-846

    http://garage.grumpysperformance.co...ou-might-want-too-look-over.14682/#post-79254

    http://garage.grumpysperformance.com/index.php?threads/sellecting-cylinder-heads.796/

    http://garage.grumpysperformance.co...ur-very-basic-454-big-block-chevy-build.1211/

    http://garage.grumpysperformance.com/index.php?threads/finding-a-machine-shop.321/#post-3007

    http://garage.grumpysperformance.co...t-intake-on-oval-port-heads.13146/#post-69975

    http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

    http://garage.grumpysperformance.co...mbers-or-a-good-street-combo-your-after.5078/

    http://garage.grumpysperformance.co...no-2000-camshaft-possibilities-for-396.15521/

    http://garage.grumpysperformance.com/index.php?threads/big-block-head-comparison.319/

    http://garage.grumpysperformance.com/index.php?threads/types-of-crankshaft-steel.204/

    http://garage.grumpysperformance.co...n-chamber-big-block-heads-and-casting-s.3960/

    http://garage.grumpysperformance.com/index.php?threads/big-block-pushrod-guide-plates.4596/

    http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/

    http://garage.grumpysperformance.co...at-would-you-build-for-that.11014/#post-48706

    http://garage.grumpysperformance.co...-the-charts-calculators-and-basic-math.10705/

    http://garage.grumpysperformance.co...ng-combustion-chambers.2630/page-3#post-77963

    http://garage.grumpysperformance.com/index.php?threads/finding-matched-valve-spring-required.13774/

    http://garage.grumpysperformance.co...uild-the-engine-to-match-the-cam-specs.11764/
     
    Last edited: Feb 20, 2020
  3. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    http://garage.grumpysperformance.com/index.php?threads/measuring-port-length.15763/

    http://www.wallaceracing.com/piston-speed-velocity.php

    http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/

    http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

    http://garage.grumpysperformance.com/index.php?threads/header-dimension-calculator.15013/

    http://www.wallaceracing.com/runnertorquecalc.php

    http://www.wallaceracing.com/intake-runner-length.php

    http://www.bgsoflex.com/intakeln.html

    https://www.rbracing-rsr.com/runnertorquecalc.html

    http://racehead.com.au/designing-performance/what-size-itb-should-i-use/


    http://garage.grumpysperformance.com/index.php?threads/header-dimension-calculator.15013/

    http://maxracesoftwares.com/softwareproducts.htm
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    and a dial caliper[​IMG]

    ID point out that different cylinder head designs, port sizes and even different cylinder head ports on the same head tend to vary between manufacturers and part numbers for the same engine, and intake manifold runner designs vary even more,


    [​IMG]
    [​IMG]

    [​IMG]
    [​IMG]

    [​IMG]

    [​IMG]


    Id also point out that cam timing matched to the exhaust scavenging has a huge effect on potential intake flow rates. and changes in displacement,cam timing, compression and header design have a very pronounced effect on intake flow rates
    [​IMG]
    [​IMG]
    [​IMG]
    http://garage.grumpysperformance.co...spacers-and-related-intake-modification.1038/



    if you decide to build a serious street/strip performance 496 BBC, taking the effort to do the required math seldom hurts,
    obviously increased cam duration required a matching increase in static compression, if the engines to run at max efficiency.
    youll generally want to be looking at about a 3" to 3.2 square inch cross-sectional area,
    cylinder head intake port, (generally 280cc-325cc ports)
    6.385" connecting rods with 7/16" ARP rod bolts a 4340 forged crank and pistons,
    a cam in the 235-255 intake duration at .050 lift, 2.19-2.30 intake valves and 1.88inch exhaust valves,
    open chamber aluminum heads, and about 10:1-12.5:1 compression,
    and an auto transmission
    converter stall speed in the 3000 rpm-3500 rpm range, an intake with the potential to feed 850 -1000 cfm minimum
    and a low restriction exhaust.
     
    Last edited: May 5, 2020
  4. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

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