Roller Rocker Tip weight more results welcome
05-06-2015, 10:13 AM
#21
Roller rockers in general get a bad name because people stick them in there with springs made for stock rockers and lifters made for stock setups and then wonder why the curve looks like ****. If you run RR's you need the rest of the valvetrain to be up to the task plain and simple. You will be rewarded by better geometry and slightly smoother and more power
100% correct.
For most people a stock rocker will serve a great purpose and do everything they need it to. Hell I have stock rockers on my Ultra Street car still!!!
05-06-2015, 10:56 AM
#22
Martin said both are good but the jesels are shaft mounted and will ultimatley have better stability when you get in the serious rpm. Both have the same power potential because they are full rollers on shafts.
Tony recommended the yella terras over the jesels. He said the yella terras and jesels would make the same power and curve but the yella terras will need lighter springs than the jesels. In the end either would work fine I believe. He said he sees no power difference between them, the curves always look good and he has had the jesel float more often.
Roller rockers in general get a bad name because people stick them in there with springs made for stock rockers and lifters made for stock setups and then wonder why the curve looks like ****. If you run RR's you need the rest of the valvetrain to be up to the task plain and simple. You will be rewarded by better geometry and slightly smoother and more power
I would take the YT over the other normal RR's though because the HS scorpion etc are heavier over the nose by a good bit and will take quite a bit more spring to control.
I ended up goin with the YT for mine btw. The cost to keep the jesels was just too high my bad lifter already snowballed into way more money than I wanted and the jesels were adding to that. After selling them I was able to buy an almost new set of YT, used arp head studs and head gaskets and still put money back in my pocket lol. With the research I've done for mild build like mine either works just fine and you won't notice a difference. If you were building a hot hot motor then jesel all the way
Tony recommended the yella terras over the jesels. He said the yella terras and jesels would make the same power and curve but the yella terras will need lighter springs than the jesels. In the end either would work fine I believe. He said he sees no power difference between them, the curves always look good and he has had the jesel float more often.
Roller rockers in general get a bad name because people stick them in there with springs made for stock rockers and lifters made for stock setups and then wonder why the curve looks like ****. If you run RR's you need the rest of the valvetrain to be up to the task plain and simple. You will be rewarded by better geometry and slightly smoother and more power
I would take the YT over the other normal RR's though because the HS scorpion etc are heavier over the nose by a good bit and will take quite a bit more spring to control.
I ended up goin with the YT for mine btw. The cost to keep the jesels was just too high my bad lifter already snowballed into way more money than I wanted and the jesels were adding to that. After selling them I was able to buy an almost new set of YT, used arp head studs and head gaskets and still put money back in my pocket lol. With the research I've done for mild build like mine either works just fine and you won't notice a difference. If you were building a hot hot motor then jesel all the way
05-06-2015, 01:26 PM
#23
Sadly I see more and more of this happening all the time.
05-06-2015, 01:44 PM
#24
Lol the first thing that comes to mind here is Joe the mechanic the puts a 235/243 .6xx cam in his car with 1.75 headers, stock ls1 intake, stock lifters, and a 3" y pipe to a stock catback and then wonders why the car cant get out of the 12's @110mph.
Sadly I see more and more of this happening all the time.
Sadly I see more and more of this happening all the time.
05-06-2015, 05:19 PM
#25
Ok guys so I had a chance to weigh the new generation of yella terras today. The gen 3 is within a few tenths of a gram heavier than the older ones. Now heres when i messed up, I noticed while testing the gen 3 yella terra that the tip weight would vary between 16-18g so either way its still lighter than the jesels. However the angle at which the rocker was at when the tip was placed on the scale had a large effect on the weight. This goes to show that tip weight at 1 instance of valve lift is not necessarily the tip weight at all heights.
Unfortunately I dont have access to the other rockers anymore to make a jig that keeps all the rockers at a set height. However I still dont feel this test is useless. While I cannot say for sure how they all compare at one set height I can still say that the Yellas Terras have the lowest moi. Simply because at every height I measured they still weighed less than the jesels. Also the jesels and other brands as well have a lot of mass in front of the pivot shaft, the YT design is unique in the sense that not only is the front nose hollowed out but also that because the pivot point is so large and further towards the nose the moi is more.
I would say by the height differences of the jig that at the same height the YT are about 4-5 grams lighter than the Jesels at roughly the same height.
Bottom line is this, the jesels are a full shaft mount system and IF you have a motor that necessitates it the jesels are better rockers for 7500rpm+. If you have a mild build the YT works just fine, no power difference and will have a lower MOI doing it which you coudl argue is better where the added stability of the jesels isnt needed. How much moi is still a little cloudy but it is easily felt when lifting the tip of the rocker in your hand and that does say something.
Also the jesel system weighs roughly 14 lbs and the yt with all the hardware is 7.xx so if you're concerned about weight over the nose on your car thats 7lbs you could lose or save there.
Unfortunately I dont have access to the other rockers anymore to make a jig that keeps all the rockers at a set height. However I still dont feel this test is useless. While I cannot say for sure how they all compare at one set height I can still say that the Yellas Terras have the lowest moi. Simply because at every height I measured they still weighed less than the jesels. Also the jesels and other brands as well have a lot of mass in front of the pivot shaft, the YT design is unique in the sense that not only is the front nose hollowed out but also that because the pivot point is so large and further towards the nose the moi is more.
I would say by the height differences of the jig that at the same height the YT are about 4-5 grams lighter than the Jesels at roughly the same height.
Bottom line is this, the jesels are a full shaft mount system and IF you have a motor that necessitates it the jesels are better rockers for 7500rpm+. If you have a mild build the YT works just fine, no power difference and will have a lower MOI doing it which you coudl argue is better where the added stability of the jesels isnt needed. How much moi is still a little cloudy but it is easily felt when lifting the tip of the rocker in your hand and that does say something.
Also the jesel system weighs roughly 14 lbs and the yt with all the hardware is 7.xx so if you're concerned about weight over the nose on your car thats 7lbs you could lose or save there.
05-06-2015, 06:54 PM
#27
Just curious on opinions here, does anyone think on a mild build there would be a hp difference between the full shaft mount system vs the Yt? Im going to say no simply because as long as you arent spinning crazy rpm and the rocker can stay in control the roller tip is reducing the friction no matter what setup its on
05-07-2015, 03:18 PM
#28
TECH Apprentice
Rocker weight or PMOI Okay, I don’t want to step on anybody's toes here, but the proper way to measure
Polar Moment Of Inertia is with a Trifilar Pendulum.
Most people do not have a scale like this but there is an alternative that is real close.
The next best way is to find out the PMOI of a rocker arm is to weigh the rocker arm but without
the bearing section installed. If it has a bearing cage you would weigh that
part also. But just the parts that rotate back and forth. Next, measure the overall length of the
rocker. Then you take the weight times length times length divided by 10 = PMOI.
For example if you have a rocker that weighs 50grams with a length of 2.8 inches.
Here is how this formula works. First convert inches to CM so 2.8 inches X 2.54 = 7.112cm.
So you take 50g X 7.112 X 7.112 = 2529 divided by 10 = 252 which is the Polar Moment of Inertia.
Whichever rocker has the lowest PMOI will require the least amount of valve spring to maintain control..
Polar Moment Of Inertia is with a Trifilar Pendulum.
Most people do not have a scale like this but there is an alternative that is real close.
The next best way is to find out the PMOI of a rocker arm is to weigh the rocker arm but without
the bearing section installed. If it has a bearing cage you would weigh that
part also. But just the parts that rotate back and forth. Next, measure the overall length of the
rocker. Then you take the weight times length times length divided by 10 = PMOI.
For example if you have a rocker that weighs 50grams with a length of 2.8 inches.
Here is how this formula works. First convert inches to CM so 2.8 inches X 2.54 = 7.112cm.
So you take 50g X 7.112 X 7.112 = 2529 divided by 10 = 252 which is the Polar Moment of Inertia.
Whichever rocker has the lowest PMOI will require the least amount of valve spring to maintain control..
05-07-2015, 04:05 PM
#29
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Okay, I don’t want to step on anybody's toes here, but the proper way to measure
Polar Moment Of Inertia is with a Trifilar Pendulum.
Most people do not have a scale like this but there is an alternative that is real close.
The next best way is to find out the PMOI of a rocker arm is to weigh the rocker arm but without
the bearing section installed. If it has a bearing cage you would weigh that
part also. But just the parts that rotate back and forth. Next, measure the overall length of the
rocker. Then you take the weight times length times length divided by 10 = PMOI.
For example if you have a rocker that weighs 50grams with a length of 2.8 inches.
Here is how this formula works. First convert inches to CM so 2.8 inches X 2.54 = 7.112cm.
So you take 50g X 7.112 X 7.112 = 2529 divided by 10 = 252 which is the Polar Moment of Inertia.
Whichever rocker has the lowest PMOI will require the least amount of valve spring to maintain control..
Polar Moment Of Inertia is with a Trifilar Pendulum.
Most people do not have a scale like this but there is an alternative that is real close.
The next best way is to find out the PMOI of a rocker arm is to weigh the rocker arm but without
the bearing section installed. If it has a bearing cage you would weigh that
part also. But just the parts that rotate back and forth. Next, measure the overall length of the
rocker. Then you take the weight times length times length divided by 10 = PMOI.
For example if you have a rocker that weighs 50grams with a length of 2.8 inches.
Here is how this formula works. First convert inches to CM so 2.8 inches X 2.54 = 7.112cm.
So you take 50g X 7.112 X 7.112 = 2529 divided by 10 = 252 which is the Polar Moment of Inertia.
Whichever rocker has the lowest PMOI will require the least amount of valve spring to maintain control..
Thanks' Kip,
I would not be surprised to see some numbers soon here...
Christian
05-07-2015, 04:30 PM
#31
Okay, I don’t want to step on anybody's toes here, but the proper way to measure
Polar Moment Of Inertia is with a Trifilar Pendulum.
Most people do not have a scale like this but there is an alternative that is real close.
The next best way is to find out the PMOI of a rocker arm is to weigh the rocker arm but without
the bearing section installed. If it has a bearing cage you would weigh that
part also. But just the parts that rotate back and forth. Next, measure the overall length of the
rocker. Then you take the weight times length times length divided by 10 = PMOI.
For example if you have a rocker that weighs 50grams with a length of 2.8 inches.
Here is how this formula works. First convert inches to CM so 2.8 inches X 2.54 = 7.112cm.
So you take 50g X 7.112 X 7.112 = 2529 divided by 10 = 252 which is the Polar Moment of Inertia.
Whichever rocker has the lowest PMOI will require the least amount of valve spring to maintain control..
Polar Moment Of Inertia is with a Trifilar Pendulum.
Most people do not have a scale like this but there is an alternative that is real close.
The next best way is to find out the PMOI of a rocker arm is to weigh the rocker arm but without
the bearing section installed. If it has a bearing cage you would weigh that
part also. But just the parts that rotate back and forth. Next, measure the overall length of the
rocker. Then you take the weight times length times length divided by 10 = PMOI.
For example if you have a rocker that weighs 50grams with a length of 2.8 inches.
Here is how this formula works. First convert inches to CM so 2.8 inches X 2.54 = 7.112cm.
So you take 50g X 7.112 X 7.112 = 2529 divided by 10 = 252 which is the Polar Moment of Inertia.
Whichever rocker has the lowest PMOI will require the least amount of valve spring to maintain control..
If thats the case then no question the YT would need much less spring pressure. The yt is a 70-80g body iirc and the jesel and t&d's are around 200g per rocker.
05-07-2015, 05:22 PM
#32
TECH Apprentice
It's not a definition it's a approximation. (J) can sometimes be used in area of moment. This is close as long as both rockers have the same ratio. Its not perfect but OK.