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Thread: port or not port heads

  1. #1
    Senior Member EXPERT BUILDER
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    port or not port heads

    building my first blower engine and confused on what to do with heads.
    eng. specs;
    540ci[4;25 stroke-4.50 bore]
    11.8 to 1 comp
    736 lift rollor cam
    12-71 alcohol blower[25% od]
    enderle "big&ugly" injector hat
    mallory super maglll
    enderle 110 pump


    the heads i have are bordix 2-plus;;should i spend the $1000 or about to have heads flowed or save my money?i'm on a very tight budget but don't want to cut corners either.how much advantage will this $1000 on heads give me..i think i already know answer but would like to hear from experiance blown alcohol engine builders.as i stated--first blower and first alky engine.

  2. #2
    Senior Member RACING JUNKIE
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    Looks Like your just about ready to get serious. LOL

    Nothing better than a blower motor..

    Save your money and buy a nice set of titanium retainers for your heads.

    The Brodix BB2 heads are a great head, These are a CNC head from the factory, so extensive porting isnt neceaasry nor is polishing but,
    In most cases, I just tear down the heads lightly sand down all rough areas in the runners and chambers to a smooth finish, polish the heck out of the runners and chambers, Clean the heads of all debris and reassemble with titanium retainers and check the spring pressures open and closed.

    Whats your engine cubic inch displacement? Your cam seems to have enough lift, but curious as to what your lobe seperation and duration is?

    Is compression ratio calculated including blower boost or are you starting out at 11.8:1?

    If you run too high of compression 16+ or 17:1 on boost you may see better results running high octane race fuel. The highest you can find... Don't get me wrong your motor will run just fine on alcohol, but there are differing levels of fuel for differing levels of compression to maximize optium performance.

    If I am not mistaken these heads flow factory around 340 to 350 but I don't know if they are designed to be ran over 7500 RPM.

    Seems there should be some standard recommendations that come in the box when you purchased the heads.

    Not to be redundent, save your money...

    Have fun doing what your doing.....
    "Can't Means You Don't Want To"

    Haven't You Stomped A Ford,,,,,,,,,,,, Lately?

  3. #3
    Senior Member RACING JUNKIE
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    Are you smoking crack Barry? There is NOTHING better than alky for roots blown, except roots blown alky w/nitro!!!

    Gas and roots /facepalm

    I had a set of GM 990 heads that flowed the same as your Brodix 2+ (350/230 @ .700) on my 505.

    It was an 11.5:1 static motor, similar cam (Ultradyne .723/.725).

    With 18 PSI (about 22% OD on an 8-71) with just hat nozzles, the motor made 1200 HP on the dyno.

    Here's the dyno sheet.

    http://www.onebadgmc.com/gallery/dis...113&fullsize=1

    The small blower held that motor back. You should be able to make some good power with it. Even better if you step up on cam and port flow.
    -WJ Birmingham

    OneBadGMC.com

  4. #4
    Senior Member RACING JUNKIE
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    BB-2

    Those Heads are NOT CNC!
    Unless they are M2 or WP .
    And they are only Good for the Under 500" Motors,Unless they are an EXTRA head,then good for a 565" Motor.
    I was thinking that your motor was in the 572" range,but maybe Not?
    Later
    G 8)

  5. #5
    Senior Member EXPERT BUILDER
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    Quote Originally Posted by ashbros
    Looks Like your just about ready to get serious. LOL

    Nothing better than a blower motor..

    Save your money and buy a nice set of titanium retainers for your heads.

    The Brodix BB2 heads are a great head, These are a CNC head from the factory, so extensive porting isnt neceaasry nor is polishing but,
    In most cases, I just tear down the heads lightly sand down all rough areas in the runners and chambers to a smooth finish, polish the heck out of the runners and chambers, Clean the heads of all debris and reassemble with titanium retainers and check the spring pressures open and closed.

    Whats your engine cubic inch displacement? Your cam seems to have enough lift, but curious as to what your lobe seperation and duration is?

    Is compression ratio calculated including blower boost or are you starting out at 11.8:1?

    If you run too high of compression 16+ or 17:1 on boost you may see better results running high octane race fuel. The highest you can find... Don't get me wrong your motor will run just fine on alcohol, but there are differing levels of fuel for differing levels of compression to maximize optium performance.

    If I am not mistaken these heads flow factory around 340 to 350 but I don't know if they are designed to be ran over 7500 RPM.

    Seems there should be some standard recommendations that come in the box when you purchased the heads.

    Not to be redundent, save your money...

    Have fun doing what your doing.....
    11.8 is static comp. before boost.below is cam card specs that came with cam.

  6. #6
    Senior Member RACING JUNKIE
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    Heres a link for brodix bb-2 plus

    http://www.brodix.com/heads/bb2.html

    Here some info I have copied and pasted for ya.

    bbchevy you might be on to something their recommendation for engine size does not exceed 509 cid

    Says they are CNC ported The BRODIX porting design was incorporated into a 100% CNC ported masterpiece that can be mass produced. The CNC ported BB-2 Plus castings are CNC ported to a mirror finish and flow within 1% of each other.

    Cubic Inch Compression Camshaft RPM

    BB-2 PLUS 427 - 509 11.5 Minimum Flat Tappet/Roller 4000-7200

    Also states they flow 344 at 0.700 lift

    Onebad, no cracky cracky today, lol. I spoke out of context. Using fuel with roots application would generate too much heat causing bad fuel atomization and a loss of power, unlike alcohol and nitro.

    As a general rule of thumb, Alcohol is recommended for use between 12.5:1 to 16.5:1 in N/A motors. The key phrase there is "N/A motors"

    [/quote]
    "Can't Means You Don't Want To"

    Haven't You Stomped A Ford,,,,,,,,,,,, Lately?

  7. #7
    Senior Member RACING JUNKIE
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    The heads are a bit small, but they'll work. Boost over comes a LOT of head restriction issues.

    A Dart 360 or 380 would be a better choice, if not a Brodix BB2-Xtra.

    As I've said many times before... You can't put too much cam or head on a blower motor... Only too small.
    -WJ Birmingham

    OneBadGMC.com

  8. #8
    Senior Member RACING JUNKIE
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    Brodix

    Quote Originally Posted by ashbros
    Heres a link for brodix bb-2 plus

    http://www.brodix.com/heads/bb2.html

    Here some info I have copied and pasted for ya.

    bbchevy you might be on to something their recommendation for engine size does not exceed 509 cid

    Says they are CNC ported The BRODIX porting design was incorporated into a 100% CNC ported masterpiece that can be mass produced. The CNC ported BB-2 Plus castings are CNC ported to a mirror finish and flow within 1% of each other.

    Cubic Inch Compression Camshaft RPM

    BB-2 PLUS 427 - 509 11.5 Minimum Flat Tappet/Roller 4000-7200

    Also states they flow 344 at 0.700 lift

    Onebad, no cracky cracky today, lol. I spoke out of context. Using fuel with roots application would generate too much heat causing bad fuel atomization and a loss of power, unlike alcohol and nitro.

    As a general rule of thumb, Alcohol is recommended for use between 12.5:1 to 16.5:1 in N/A motors. The key phrase there is "N/A motors"
    [/quote]

    If He has the CNC BB-2 Plus Version,NOT ALL BB-2 Heads are CNC Ported.
    Later
    G 8)
    Also AGGREE BIGTIME with GMC,that the 360 Dart Head with a S/Charger Is BADDAZZZZ!

  9. #9
    Senior Member EXPERT BUILDER
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    my heads isn't c&ced.still rough casting inside ports.

  10. #10
    Senior Member RACING JUNKIE
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    Quote Originally Posted by hotrodharley
    my heads isn't c&ced.still rough casting inside ports.
    Run it like it is. If you're not happy, rather than spending more money on those heads, which are too small even CNC'd, sell em and get better heads.
    -WJ Birmingham

    OneBadGMC.com


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