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Thread: Most Important Vehicle Factors in Selecting a Camshaft

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    Default Most Important Vehicle Factors in Selecting a Camshaft

    Many people frequently ask, “What is the most important factor in making the proper cam selection?” The most important factor is listening to the customer to determine what he/she wants from their vehicle. Next to that, however, comes engine size, final drive ratio, tire size, vehicle weight and transmission type. Engine size (including compression ratio and component types) is obvious, but most people do not appreciate the importance of the other factors in determining proper cam selection. Operating under the assumption that most people want to maximize the performance of their vehicle (as opposed to just operating the engine at as high an RPM as possible), the tire size, combined with the final drive ratio, will determine the engine speed required. For instance, a vehicle with a final drive of 3.42:1 and a tire diameter of 26” will only see about 5400 – 5600 RPM through the lights in high gear in a quarter mile run. Selecting a cam that will make maximum power in the 2500 – 5600 RPM range will provide the best ET. MPH might be higher with a bigger cam, but ET will suffer. This is because MPH is related to peak horsepower, but ET is related to best average torque in the RPM range. Heavier vehicles require a cam with more low end torque than lighter vehicles because it is much more difficult to get a heavier vehicle moving. Automatic transmission vehicles require a camshaft that has idle and low RPM characteristics compatible with the torque converter to be used. Stick shift vehicles must have attention paid to the first gear ratio and the average RPM drop between shifts.

    Many people mistakenly think other engine modifications are more important, but this is false thinking. The camshaft is the “gatemaster” to the flow into and out of the cylinder, but this and all of the other engine components must be matched to putting the power in the RPM range that the drivetrain can use. Once the camshaft is selected, modifications to components on both the intake and exhaust must complement the system. It is no good to have a high flow intake system (large throttle body, high-flow intake manifold and custom cylinder heads) if the exhaust can’t get rid of the combustion products. Proper cam selection takes years of real world experience, which often resulted in as many failures as successes. Let’s face it, you often learn more from your failures than your successes.


    what you see in RED is what i been trying to get through alot of members not only here but elsewhere


    So just remember what comes in must go out!!

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    HPTftw.com Sickx.0's Avatar
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    Good info i dunno if its me but i dont see the RED you mention
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    Quote Originally Posted by skeet View Post
    many people frequently ask, “what is the most important factor in making the proper cam selection?” the most important factor is listening to the customer to determine what he/she wants from their vehicle. Next to that, however, comes engine size, final drive ratio, tire size, vehicle weight and transmission type. Engine size (including compression ratio and component types) is obvious, but most people do not appreciate the importance of the other factors in determining proper cam selection. Operating under the assumption that most people want to maximize the performance of their vehicle (as opposed to just operating the engine at as high an rpm as possible), the tire size, combined with the final drive ratio, will determine the engine speed required. For instance, a vehicle with a final drive of 3.42:1 and a tire diameter of 26” will only see about 5400 – 5600 rpm through the lights in high gear in a quarter mile run. Selecting a cam that will make maximum power in the 2500 – 5600 rpm range will provide the best et. Mph might be higher with a bigger cam, but et will suffer. This is because mph is related to peak horsepower, but et is related to best average torque in the rpm range. Heavier vehicles require a cam with more low end torque than lighter vehicles because it is much more difficult to get a heavier vehicle moving. Automatic transmission vehicles require a camshaft that has idle and low rpm characteristics compatible with the torque converter to be used. Stick shift vehicles must have attention paid to the first gear ratio and the average rpm drop between shifts.

    Many people mistakenly think other engine modifications are more important, but this is false thinking. The camshaft is the “gatemaster” to the flow into and out of the cylinder, but this and all of the other engine components must be matched to putting the power in the rpm range that the drivetrain can use. Once the camshaft is selected, modifications to components on both the intake and exhaust must complement the system. It is no good to have a high flow intake system (large throttle body, high-flow intake manifold and custom cylinder heads) if the exhaust can’t get rid of the combustion products. Proper cam selection takes years of real world experience, which often resulted in as many failures as successes. Let’s face it, you often learn more from your failures than your successes.


    What you see in red is what i been trying to get through alot of members not only here but elsewhere


    so just remember what comes in must go out!!

    good info may put alot of individuals minds at ease
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    Good info

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    Houston Performance Trucks black gmc's Avatar
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    Very good info
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    Houston Performance Trucks la polarbear's Avatar
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    gooooood stuff

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    Good stuff..
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    Houstonperformancetrucks.com Boosted Prime's Avatar
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    Skeet if you dont mind me asking...who do you get your cams through...and have you actually had a performance shop spec a cam based on all those factors especially compression??? Lol i mean i would like to think they do but i was just told wat cam was ordered and i said kool fuck it lets try it out lol
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    Sep. Totm 2010 jr@chapastyle's Avatar
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    yo le pongo un cam bien grandote alkavo me la tunean bien perra!!!!!!! hahahahaha a 262/264 688 691 @ 104
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    Quote Originally Posted by La MaXxImUs PrImE View Post
    Skeet if you dont mind me asking...who do you get your cams through...and have you actually had a performance shop spec a cam based on all those factors especially compression??? Lol i mean i would like to think they do but i was just told wat cam was ordered and i said kool fuck it lets try it out lol
    yes i have and yes all those factors are important, James at rage motorsports did the last cam, also patrick g has spec'd a cam for me along with pete encaudo out of fl. they all asked pretty much the same questions, James was more accurate since he was semi local..

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    Quote Originally Posted by jr@chapastyle View Post
    yo le pongo un cam bien grandote alkavo me la tunean bien perra!!!!!!! Hahahahaha a 262/264 688 691 @ 104
    alv what motor is that cam in thats fukin huge ni los big timers have em that big. Isnt that like overcamed?
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    HPTrucks.com Bolas's Avatar
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    iwish i can go to school to learn about this i reading howto books like Books from SA Designs..they have showed me alot when i couldn't afford school

  13. #13
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    So what do you say is the best for getting rid of the combustion?
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    Houston Performance Trucks runninrich's Avatar
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    U don't want to get rid of the combustion...that produces power lol u do want to get rid of the combustion fumes which u can do with cams that overlap between before the closing of the exhaust valve, by overlapping and openings the intake valve earlier u create an outwash that moves the fumes out much quicker and produces healthier power

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    Default Most Important Vehicle Factors in Selecting a Camshaft


    daymn wish i saw this competition earlier, sounds like fun maybe we could start a thread dedicated to posting out loon necks?? what do people think?

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