Three pattern bbc cams - Page 2
+ Reply to Thread
Page 2 of 2 FirstFirst 12
Results 15 to 23 of 23

Thread:
Three pattern bbc cams

  1. #15
    Senior Member
    Join Date
    Dec 2007
    Location
    Tri-Cities, TN
    Posts
    1,442

    Default

    Custom cams of this nature are not cheap as the grinder has 2 set ups. On the plus side on OEM heads and engines needed every ounce of power they are killer.
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #16
    Senior Member flat screwd's Avatar
    Join Date
    Oct 2008
    Posts
    279

    Default

    Wouldnt a cam profile for every cylinder respective to its own unique flow data yeild a engine thats unpredictible ? In essence confuse the engine ?

  4. #17
    Senior Member
    Join Date
    Dec 2007
    Location
    Tri-Cities, TN
    Posts
    1,442

    Default

    Quote Originally Posted by flat screwd View Post
    Wouldnt a cam profile for every cylinder respective to its own unique flow data yeild a engine thats unpredictible ? In essence confuse the engine ?

    Before symmetrical ports and cnc porting this was done. NHRA pro stock engines had 16 different lobes back in the early 80's
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

  5. #18
    Senior Member
    Join Date
    May 2012
    Posts
    194

    Default

    Quote Originally Posted by flat screwd View Post
    Wouldnt a cam profile for every cylinder respective to its own unique flow data yeild a engine thats unpredictible ? In essence confuse the engine ?
    The idea is to equalize/balance all your cylinders which frees up power buy making smother power instead of having 4 that are stronger than the others


    If each cylinder is not feed the same its allready confused
    Last edited by bowtiebro; 11-04-2012 at 05:18 PM.

  6. #19
    Senior Member jimclauss's Avatar
    Join Date
    Jan 2011
    Location
    Mickleton, New Jersey
    Posts
    1,368

    Default

    Quote Originally Posted by bowtiebro View Post
    Is that engine run on alcohol normally or did it just have a really low compression ratio for that race with out the blower?
    Im just saying if it was blown alcohol it could be a little higher than if it was blown gas and then just switch to gas for the race with out the boost
    I think Bob has to run gas in the GN class.

  7. #20
    gn7
    gn7 is online now
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,782

    Default

    Quote Originally Posted by flat screwd View Post
    Wouldnt a cam profile for every cylinder respective to its own unique flow data yeild a engine thats unpredictible ? In essence confuse the engine ?
    You're looking at this from the wrong angle. Imagine an engine that was made up of 8 individual engines, all with different port flows but all with the same cam profile.
    Ideally you want all the ports to flow the same, and the same cam profile for all the cylinders. But with the OEM BBC heads, that not the case. Even with the newest CNC heads, their is a good port and a bad port. The main reason behind the symetrical port heads.

    In a couple of PM's with bowtiebro, I was pointing out that in the BIG BOY ranks, they have the port flow equalizing down pretty good now, and have moved on to controlled, seperate equalized water flow over the combustion chambers, and the oil pans are compartmentized into paired left-right cylinders with the oil pan acting like 4 oil pans and the windage down to 2 cylinders per compartment.

    The closer they can get the engine to behave like 8 individual, tunable cylinders, the more power they make.
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  8. #21
    Foxwell Motorsports
    Join Date
    Dec 2007
    Location
    N/E Tennessee
    Posts
    12,323

    Default

    Quote Originally Posted by gn7 View Post
    You're looking at this from the wrong angle. Imagine an engine that was made up of 8 individual engines, all with different port flows but all with the same cam profile.
    Ideally you want all the ports to flow the same, and the same cam profile for all the cylinders. But with the OEM BBC heads, that not the case. Even with the newest CNC heads, their is a good port and a bad port. The main reason behind the symetrical port heads.

    In a couple of PM's with bowtiebro, I was pointing out that in the BIG BOY ranks, they have the port flow equalizing down pretty good now, and have moved on to controlled, seperate equalized water flow over the combustion chambers, and the oil pans are compartmentized into paired left-right cylinders with the oil pan acting like 4 oil pans and the windage down to 2 cylinders per compartment.

    The closer they can get the engine to behave like 8 individual, tunable cylinders, the more power they make.
    Just to add:
    The output of an engine is the sum of all the cylinders working together. One cylinder making less power than the rest is not "holding the engine back". They all contribute. Obviously, getting them to all make the same power as the best cylinder is ideal, but that seldom happens. The conventional headed BB Chevy is a perfect example with it's asymmetrical port layout. The left turn ports are inferior to the rigtht turn ports. Even the spread port heads are similar, but not quite as bad. If the difference between the two ports isn't that bad, (as with most aftermarket heads) you usually find an average between the good and bad, and cam accordingly. The lobe won't be "perfect" for either port. -or- depending on how close the ports are, you can maximize either port and let the other fall where it may. A lot of times the cam designer only has "good port" info to work with. However, on OEM heads, the difference between the good port and bad port can be as much as 30cfm in some ranges of valve lift...usually the worst at .500" which can be a very critical lift on some engines. I'll do the very best I can with both ports, not trying to balance them, just trying to get the most I can out of either port. In the end it is what it is and if it's bad enough, as this thread is about, we can put more lobe on the bad port to help make it "work" like the better port. The lobe for the good port is dictated by the parameters of the build.
    Last edited by steelcomp; 11-04-2012 at 06:41 PM.
    FOXWELL MOTORSPORTS
    STRAUB TECHNOLOGIES
    Performance Cylinder Head Specialties
    Custom Cams
    Complete Engines
    Retail/Wholesale Parts sales




    In the madness of this world, know the Peace of God.

  9. #22
    gn7
    gn7 is online now
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,782

    Default

    Agreed, any power from any cylinder is power added, as opposed to a dead hole. Ideally they would all make the same power, but not at the expense of dragging good cylinders down to the level of bad ones. That would be a "socialitic" approach.

    Its one of the reasons for the thinking behind individual timing as well. Don't time the engine to the limits of the detonation prone cylinders, time each one to its maximum output.
    LINK:GN-RACING.COM

    "there are too many pigs for the teats"
    Abraham Lincoln

  10. #23
    Senior Member
    Join Date
    Jan 2009
    Posts
    729

    Default Engine builds

    Quote Originally Posted by gn7 View Post
    Agreed, any power from any cylinder is power added, as opposed to a dead hole. Ideally they would all make the same power, but not at the expense of dragging good cylinders down to the level of bad ones. That would be a "socialitic" approach.

    Its one of the reasons for the thinking behind individual timing as well. Don't time the engine to the limits of the detonation prone cylinders, time each one to its maximum output.
    Wayne Rexwinkle tuned his sbc in my HOMEWRECKER 99-F. He used a compression gague to adjust the valves to get all cylinders close. It was good enough to set the class record in our first run, and be unbeaten for a year.
    HARLAN ORRIN

+ Reply to Thread
Page 2 of 2 FirstFirst 12

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91