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in automotive class last week my teacher told us an easy way to put 20 hp on a car engine was to put "roller" style rocker arm since it has less friction you get many benefits. so i was looking in my manual today and saw that there is only a roller on the cam shaft side but there are no rollers on the valve side the just slide across the top of the valve. does any one make a double roller rocker arm? or am i the first to think of this? or is the power gain not enough on the small engine?:thumbsup::eek: also he said that the put double roller rocker arms on the new mustangs and got 31 or 32 horse power i cant remember but it sounds like a good thing to put on my dirt bike.

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in automotive class last week my teacher told us an easy way to put 20 hp on a car engine was to put "roller" style rocker arm since it has less friction you get many benefits. so i was looking in my manual today and saw that there is only a roller on the cam shaft side but there are no rollers on the valve side the just slide across the top of the valve. does any one make a double roller rocker arm? or am i the first to think of this? or is the power gain not enough on the small engine?:thumbsup::eek: also he said that the put double roller rocker arms on the new mustangs and got 31 or 32 horse power i cant remember but it sounds like a good thing to put on my dirt bike.

31 horsepower out of some roller rockers? That smells funny. I put a whole cam and roller system in my old trans am and it was noticeable but not that much of a gain. thats alot of horsepower.

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The crfs have such little spring pressures the roller on the tip is not nessary.the automotive world is actually going to valve springs that are of the conical shape a lot of pepole think that the shape of the spring is the big advantage because of the changes in natural frequency but the real advantage is in the reduction of mass.The smaller coils and smaller retainer reduce mass enough that a considerable amount of spring force can be taken away and still maintain valve controll. As an end result the rocker arm can be made lighter with out flex and not requiring a heavy roller on the tip also futher reduceing mass .on push rod engines the need for heavyer rods is also reduced and flex is reduced causing less stored energy in the push rod that can upset valve control.Roller cams can acheive much faster lobe velocitys than a flat tappet lobe in other words they can have the same durations @ .050" but have much more @ say .200" letting the valve get to and stay @ the higher area of flow and this is where the extra hp would come from.As of last week RHC started work in developing a new lifgter roker arm for the crfs from special steel aloys .I have Lazer digitizing readly avaiable to me as well as cnc capabilities so im hoping to beable to produce some parts @ a reasonable cost. Delwest quoted a price of $1000 each for a rocker arm of this description to some recent customers Of RHC.

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another thing that might be contributing to his large horspower gains is when you put a roller rocker on in some automotive aplications you can intentionally change the rocker arm ratio. Or if you are replacing with the stock ratio rocker arm the stock ones are can be not accurate. example ....an automotive engine lists the rocker arm ratio as 1.5. You could change rocker arms and wind up at 1.6 which makes the valves open further effectively giving your cam more lift than advertised. Also the OEM rockers that list at 1.5 may be around 1.4 or less just from manufacturing errors or tolerances. So when you change to the higher performance rocker arms you now corrected the rocker ration making the cam bigger than it was before giving the engine more power.

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another thing that might be contributing to his large horspower gains is when you put a roller rocker on in some automotive aplications you can intentionally change the rocker arm ratio. Or if you are replacing with the stock ratio rocker arm the stock ones are can be not accurate. example ....an automotive engine lists the rocker arm ratio as 1.5. You could change rocker arms and wind up at 1.6 which makes the valves open further effectively giving your cam more lift than advertised. Also the OEM rockers that list at 1.5 may be around 1.4 or less just from manufacturing errors or tolerances. So when you change to the higher performance rocker arms you now corrected the rocker ration making the cam bigger than it was before giving the engine more power.

More importantly than lift Is the increased valve velocitys gainded by increasing roker arm ratio maximum valve lift is over rated in making more hp .i have had cams made with as much as .050 less lift make a better power curve as well as more hp because of improved profile.

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The crfs have such little spring pressures the roller on the tip is not nessary.the automotive world is actually going to valve springs that are of the conical shape a lot of pepole think that the shape of the spring is the big advantage because of the changes in natural frequency but the real advantage is in the reduction of mass.The smaller coils and smaller retainer reduce mass enough that a considerable amount of spring force can be taken away and still maintain valve controll. As an end result the rocker arm can be made lighter with out flex and not requiring a heavy roller on the tip also futher reduceing mass .on push rod engines the need for heavyer rods is also reduced and flex is reduced causing less stored energy in the push rod that can upset valve control.Roller cams can acheive much faster lobe velocitys than a flat tappet lobe in other words they can have the same durations @ .050" but have much more @ say .200" letting the valve get to and stay @ the higher area of flow and this is where the extra hp would come from.As of last week RHC started work in developing a new lifgter roker arm for the crfs from special steel aloys .I have Lazer digitizing readly avaiable to me as well as cnc capabilities so im hoping to beable to produce some parts @ a reasonable cost. Delwest quoted a price of $1000 each for a rocker arm of this description to some recent customers Of RHC.

When talking about reduction in mass and lighter valve train components is there any improvements to be found by lightening the intake cam followers or buckets? Seems like any way to lessen the burden on the valve springs would be an overall improvement in both performance and longevity.

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ive heard of people puttin YZ250F buckets on the cam side of the crf250's. not that they are any lighter I think the contor makes a smoother lobe to bucket actuation

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The reason for the yamaha lifters was to get more surface area for the cam shafts i was having made .They have less radius machined on them and will take slightl higher lobe velocitys befor running off the edge.years ago i had machined holes through the buckets sides to lighten them this was in the late 70s when the super bikes were still 2 valve and the buckets were heavy.

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