Rocker arm ratio changes net more power?
03-23-2007, 10:02 PM
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Rocker arm ratio changes net more power? I've read alot of threads on the use of 1.8 rockers and just wondered if any of you valvetrain specialists might have an opinion about their use. My car's power curve is just where I need it to be and am curious if these would net me a little more power instead of going to a larger cam. My current cam is 218/221 and .526"/.534". Will it be worth the trouble or do I need to just go bigger cam?
03-23-2007, 10:04 PM
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I wouldnt buy new rockers for a power gain, i would buy them as a stability mod though since a good aftermarket rocker set is a lot better than the stockers.
03-24-2007, 09:31 PM
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Originally Posted by 1hotls1
I've read alot of threads on the use of 1.8 rockers and just wondered if any of you valvetrain specialists might have an opinion about their use. My car's power curve is just where I need it to be and am curious if these would net me a little more power instead of going to a larger cam. My current cam is 218/221 and .526"/.534". Will it be worth the trouble or do I need to just go bigger cam?
yes, using the correct rockers will net you more power.
worth it is up to you. i say yes, as i use the vinci/crane accelerated lift rockers with great success. you end up with more power in the same rpm range that you are in.
here's a dyno comparing stock rockers to the 1.8 accelerated rockers.
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03-26-2007, 09:05 PM
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Any idea how much power you can gain from this swap in a mild cam car? I don't know if I want to do this or just go for the bigger cam. It would definitely be easier to do than a cam swap.
03-27-2007, 12:44 PM
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Don't mean to hijack, but how much more lift and duration with a 1.75 rocker? I have a MTI C2, .224/.224 .581/.581 112 LSA, and am thinking of getting a set before a tune.
03-28-2007, 08:44 AM
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I don't think that they can affect duration but your lift will definitely increase. If your stockers are 1.7, your new lift will be .598 I think. I'm sure someone with more knowledge about these can correct this if I'm wrong. 
03-28-2007, 10:38 AM
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I always thought that if your lift would increase due to the higher ratio, you would also get at least a couple more degrees of duration....maybe someone can chime in and correct me if im wrong.
03-28-2007, 10:40 AM
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Originally Posted by CODE4LS1
I always thought that if your lift would increase due to the higher ratio, you would also get at least a couple more degrees of duration....maybe someone can chime in and correct me if im wrong.
03-28-2007, 05:45 PM
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technically, you don't get any more cam duration as that is ground into the cam. the valve still open and close at the same exact events. cam durations are measured at .004, .050, and .200 lift, most commonly. with a higher ratio, these lift numbers come sooner in the valve events. so, you get an 'effective' increase of duration at the valve. this is called valve duration. and that's what the motor cares about, what happens at the valve.
03-28-2007, 07:35 PM
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Originally Posted by mrr23
technically, you don't get any more cam duration as that is ground into the cam. the valve still open and close at the same exact events. cam durations are measured at .004, .050, and .200 lift, most commonly. with a higher ratio, these lift numbers come sooner in the valve events. so, you get an 'effective' increase of duration at the valve. this is called valve duration. and that's what the motor cares about, what happens at the valve.