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Thread: Adjustable Cam Gear.. explained!!

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    Adjustable Cam Gear.. explained!!

    On a SOHC engine, an adjustable cam gear will allow you to move the power curve to a specific area in the rpm band. Like moving your peak power on a high-revving Honda to max out at 4000 to 5000 rpm. Typically to improve bottom end power advancing a SOHC engine will do the trick and the converse is true to enhance top end power.


    Basically, the job of the camshaft is to open and close the intake and exhaust valves at the "proper time" relative to engine position (piston travel) - to charge the combustion chamber and expel burnt gasses.

    However, once you've bolted on performance parts, milled the head or installed a lumpy performance cam, you also alter the optimum cam timing that most sport compacts prefer. What can you do?

    By changing the cam timing (retard, advance/overlap), we tune the overall drivability and performance aspect of the car. Even stock engines can benefit by dialing-in cam timing/overlap. These are typical variances in production tolerances that when fine-tuned to your particular engine set-up will easily produce added power.

    Many factory cams operate on the conservative side of performance due to emissions and drivability standards, meaning there's always more power to be gained by learning how-to adjust the intake and exhaust valve timing.

    Just as aftermarket engine management systems manage precise ignition timing, adjustable cam gears allow you to govern the action of the cam, which controls the timing action of the valves to shift peak power points or to tweak timing overlap within the engine cycle. "Overlap" is the point in the cam's cycle where the intake and exhaust valves are open simultaneously. Here's where critical tuning really optimizes performance because you are producing the most efficient charge of air/fuel in and out of the combustion chamber.

    In racing, the ability to dial-in ignition and cam timing/overlap for different track conditions can mean the difference between winning and losing a race. Autocross enthusiasts rely on low to mid-range power for tight turns, whereas drag racers need all the power at the top end. This applies to setting up a car for mostly city or highway driving. In either case, adjustable cam gears will optimize the peak power curve so that maximum performance is adjusted to your style of driving.

    While the aftermarket is ripe with adjustable cam gears, don't assume that all cam gears are the same. Variations in material, design, anodizing, and other engineering deviations can affect quality.

    It's important to note that adjustable cam gears have no direct effect on the duration and lift of the valves, that's the job of the camshaft lobes (profile) as dictated by the cam manufacturer.


    If the intake valves open at 10 degrees before top dead center (TDC) and close at 190 degrees after TDC, the total duration is 200 degrees. The opening and closing times can be shifted with adjustable cam gears to rotate the cam ahead a little as it spins. For example, if we advance the intake cam 5 degrees then the inlet valves would open 5 degrees earlier. The intake open timing would shift to 15 degrees BTDC and the intake valve would also close earlier by the same 5 degrees. In the example above, the valve timing would be IO at 15 degrees BTDC and IC at 185 degrees ABDC. With SOHC engines the cam timing events for intake and exhaust occur together so intake and exhaust events move the same amount. Retarding timing works just the opposite.

    MORE on this here CAM GEAR EXPLAINED
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  2. #2
    Guru of boostage Ben Hewitson is known as a rock round here Ben Hewitson's Avatar
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    very good... we can all read zoom magazine or Automotove engineer too matty... LOL..... i got a few articles an fuel pressure regs too. may post tomorrow.
    Benagiser

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  3. #3
    yeah for sure dood, the more tech stickys we have the better/faster our cars become, or not hehehe
    **CA18DET install from s13** T28bb Turbo, 3inch Mandrel exhaust JunBl Muffler, FMIC, custom piping, HksSSQ, Re-Map ecu, 183kw at wheels@16psi, 1/4 mile 13.1 @ 119mph, Dual stage Electronic Boost controller
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    Guru of boostage Ben Hewitson is known as a rock round here Ben Hewitson's Avatar
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    Quote Originally Posted by mattybaby
    yeah for sure dood, the more tech stickys we have the better/faster our cars become, or not hehehe
    Or we could keep it to ourselves and have the fastest N12 EXA's in SA....

    Benagiser

    I didn't buy an early model Nissan FWD turbo cause i wanted a reliable car now did I...?
    "The smaller the monkey the more it looks like it would kill you at the first given opportunity"





    ,`,,`,,`, <== What is this..? Why do people do this..? Its making me all..ARGH..!

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    The Black Jet TJ20 has disabled reputation TJ20's Avatar
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    LoL at Ben & Matty, both of you arent the only one that can read tech features in a zoom mag or Automotive engineer

  6. #6
    Guru of boostage Ben Hewitson is known as a rock round here Ben Hewitson's Avatar
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    yeah but how many people get automotive engineer and attend their seminars... not many... LOL... i've started making pages for the N12 modifications section. so between us matty adn i should be able to make a decent contribution. especially since i'm about to start on the 1688 stroker motor.... we all gotta work together to get the N12 section up to speed...these N13 boys are leaving us behind.. (on the forum) not on the streets.. ever.. LOL
    Benagiser

    I didn't buy an early model Nissan FWD turbo cause i wanted a reliable car now did I...?
    "The smaller the monkey the more it looks like it would kill you at the first given opportunity"





    ,`,,`,,`, <== What is this..? Why do people do this..? Its making me all..ARGH..!

  7. #7
    true! The manual is nearly finished being scaned in, takes sooo bloody long
    **CA18DET install from s13** T28bb Turbo, 3inch Mandrel exhaust JunBl Muffler, FMIC, custom piping, HksSSQ, Re-Map ecu, 183kw at wheels@16psi, 1/4 mile 13.1 @ 119mph, Dual stage Electronic Boost controller
    Extreem HD clutch, Hd King springs lwrd 1-2inch, gabriel shocks, front strut brace, 17inch Chromies.., Re-sprayed Interior Yellow?
    2 Lcd screens, Sony DVD/mp3, custom dash mount, 2 x Alpine type-R subs , 2 x Jaycar amps 1000wrms,Soundstream taran 6.5inch splits.

    A whole AlbumHERE

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    The Black Jet TJ20 has disabled reputation TJ20's Avatar
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    Quote Originally Posted by Ben Hewitson
    yeah but how many people get automotive engineer and attend their seminars... not many... LOL... i've started making pages for the N12 modifications section. so between us matty adn i should be able to make a decent contribution. especially since i'm about to start on the 1688 stroker motor.... we all gotta work together to get the N12 section up to speed...these N13 boys are leaving us behind.. (on the forum) not on the streets.. ever.. LOL
    Yea i agree. Wow a 1688 stroker that be a goer, and as for "these N13 boys are leaving us behind.. (on the forum) not on the streets.. ever.. LOL" Hahaha that's funny

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    Club Member bartman71 has disabled reputation bartman71's Avatar
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    hey matty how do you alter the valve overlap on a SOHC engine with out regrinding?

    just intrested if you have found a way to do this.

  10. #10
    Banned Photoglossy is well respected Photoglossy's Avatar
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    You gotta have a re grind or a new cam thats the only way i see it.... You cant change the shape or placement of the lobe unfortunatly as changing the inlet lobe would also change the position of the exhaust lobe resulting in no change in overlap whatsoever ( stupid SOHCers )


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    Club Member bartman71 has disabled reputation bartman71's Avatar
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    Quote Originally Posted by Photoglossy
    You gotta have a re grind or a new cam thats the only way i see it.... You cant change the shape or placement of the lobe unfortunatly as changing the inlet lobe would also change the position of the exhaust lobe resulting in no change in overlap whatsoever ( stupid SOHCers )
    i was just being a bit sarcastic as the way i read the original post it is like it was writen about DOHC engines

  12. #12
    this is true - you can't adjust overlap on a SOHC engine. Hence why you wont gain as much with cam timing as you do on a DOHC engine. None the less, its something I have always wanted to play with on the e15... Not that I think it could be adjusted very far, ever put the cam belt on a tooth out?
    Sam
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  13. #13
    Club Member bartman71 has disabled reputation bartman71's Avatar
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    it will run like a pig down low or up high. depends if you advance or retard it.

  14. #14
    Regular Wes has disabled reputation
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    A guy here in Perth had a variable cam gear on his white import N12 EXA. Had full Microtech and some other stuff done. Never saw it getting tuned or the end result (the guy worked away and left it at the tuners which was where i saw it about 2 years ago)

    Wouldve been interesting to see how it went

  15. #15
    BQ.05.TD motorsport boostdET is someone we respect boostdET's Avatar
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    does any one have the web site with the adj cam gear for the n12. i have spent the last 40 mint gonig over this years posts but i cant find it. i think it was posted bye do_it_your_self
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    edit: 3/2/07 138.4 kw @16 PSI
    edit: 10/2/07 132.8kw @16PSI
    edit: 2/6/07 142kw @ 13 PSI
    edit: 7/8/07 174kw @15 psi ( new cooler and tune)
    13.7 @108mph 2.24 60ft

  16. #16
    BQ.05.TD motorsport boostdET is someone we respect boostdET's Avatar
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    dw i found it lol

    im having a shocker to nite lol
    microtech lt8 with hand controller, GTR injectors
    550,180,65 cooler with alloy pipe work, walbro 550hp fuel pump
    GT2876R aka GT2540, full custom equal length manifold
    turbo smart duel stage 10-15 psi 3" turbo back

    edit: 3/2/07 138.4 kw @16 PSI
    edit: 10/2/07 132.8kw @16PSI
    edit: 2/6/07 142kw @ 13 PSI
    edit: 7/8/07 174kw @15 psi ( new cooler and tune)
    13.7 @108mph 2.24 60ft

  17. #17
    Regular pulsar38501 has disabled reputation pulsar38501's Avatar
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    Okay - So What's The Address?.....

    So, what is the address for the website where you can get adjustable cam gears for an E16 ?

  18. #18
    DISCO SHOEBOX doityourself is someone we respect doityourself's Avatar
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    Quote Originally Posted by pulsar38501 View Post
    So, what is the address for the website where you can get adjustable cam gears for an E16 ?
    Datrats - adjustable cam gear

    This is no longer available but I'll see if they car send me any technical drawings for making one
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  19. #19
    First Time Poster trapit is very helpful round here
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    this is really cool information.. i found also some useful sites through search engines i will post it once i collect all the important info. thanks

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