1.55 Roller Rocker
- Thread starter Will Flow
- Start date
BRAD_PADGETT
Well-Known Member
I have a set of Scorpions roller rockers. 10 of them have about 1500 miles on them and two are brand new. History- Put them on the new build. Two of the the same exact size split in two. Scorpion admiited they were made wrong- recepticle for pushrod was off. This caused binding resulting the the rocker splitting in half. Scorpion repaced these two rockers. My engine builer found a set of T&D and we put these on instead of waiting on Scorpion. These are 1.55.I can send pics of the set.
I have some for iron heads brand new, 1.55 rollers
big reazon
Member
@moenning1 I may be interested in rockers if op isn’t. Not here to step on toes thought pm me if op passes
TIMINATOR
Well-Known Member
My question: why would anyone want to go to roller rockers without upping the ratio? Depending on the tip radius, many stamped rockers have a varying ratio as a function of lift and geometry.
Many stock rockers have a lower ratio upon initial opening and closing to minimize closing shock on the seat and resultant wear, and still allow more total lift.
Most aftermarket roller rockers are made to have a constant ratio. These can actually have less lift at full opening than the advertised ratio that some stockers do!
Back in the day when some race classes were checked for max lift, some "Cheater" rockers were designed to have higher initial opening and closing ratio rates and stock ratios at max lift. This achieved better cylinder filling and more HP, because the valve lifted quicker off the seat and stayed off the seat higher and longer before closing, but at stock max lift. A LOT of cool Cheater things exist in the real world that are not in the cam catalogue. Being sponsored by a cam company has more benifits than most can imagine!
Most if not all modern roller rockers have quicker opening and closing ratios AND a higher full open ratio too. Altering height of the pivot axle in relation to tip and or pushrod cup height changes this.
A higher rocker ratio changes area under the curve and lengthens duration at all points due to the higher lift gets the valve to the .050 or .200 duration point sooner and later.
Unless your motor is overcammed (rarely) you will always make more power with a higher ratio rocker, or with the same duration roller cam over a flat tappet cam. Same reason, more area under the curve.
For you folks that think; "why go to a higher lift cam or rocker than my heads flow?"
Look at a cam curve, the cams max lift point only occurs for a millisecond at high RPMs. If you go to a higher ratio rocker or a higher lift cam, the port can then be held at its max flow rate for a longer time, thus making more H.P. and I believe that's what we all are after!
P.S. the aforementioned cup, axle, and tip heights are the reason that running the valvetrain geometry for correct pushrod length is as important when changing rocker arm ratios or type, as changing cams.
TIMINATOR
Many stock rockers have a lower ratio upon initial opening and closing to minimize closing shock on the seat and resultant wear, and still allow more total lift.
Most aftermarket roller rockers are made to have a constant ratio. These can actually have less lift at full opening than the advertised ratio that some stockers do!
Back in the day when some race classes were checked for max lift, some "Cheater" rockers were designed to have higher initial opening and closing ratio rates and stock ratios at max lift. This achieved better cylinder filling and more HP, because the valve lifted quicker off the seat and stayed off the seat higher and longer before closing, but at stock max lift. A LOT of cool Cheater things exist in the real world that are not in the cam catalogue. Being sponsored by a cam company has more benifits than most can imagine!
Most if not all modern roller rockers have quicker opening and closing ratios AND a higher full open ratio too. Altering height of the pivot axle in relation to tip and or pushrod cup height changes this.
A higher rocker ratio changes area under the curve and lengthens duration at all points due to the higher lift gets the valve to the .050 or .200 duration point sooner and later.
Unless your motor is overcammed (rarely) you will always make more power with a higher ratio rocker, or with the same duration roller cam over a flat tappet cam. Same reason, more area under the curve.
For you folks that think; "why go to a higher lift cam or rocker than my heads flow?"
Look at a cam curve, the cams max lift point only occurs for a millisecond at high RPMs. If you go to a higher ratio rocker or a higher lift cam, the port can then be held at its max flow rate for a longer time, thus making more H.P. and I believe that's what we all are after!
P.S. the aforementioned cup, axle, and tip heights are the reason that running the valvetrain geometry for correct pushrod length is as important when changing rocker arm ratios or type, as changing cams.
TIMINATOR
Sometimes going with a higher ratio rocker ain’t the best either. higher ratio rockers just raise the lift making the cam seem a few degrees bigger, but turbo engines you get all the air you need from the turbo, heads, intake,intercooler, intake manifold. if i was building a N/A engine then I would go with a higher lift rocker depending on the cam I choose. Just my 2cents
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TIMINATOR
Well-Known Member
IMHO: I like to make as much flow and HP off the boost, while making sure the internals will stand up to the boost.
If I can make more HP with less boost:
I will have less back pressure in the exhaust
I will have less pumping pressure (negative HP) pushing on the pistons on the exhaust stroke
I will have more power sooner, as the turbo won't have to spool as high to make the same power (again, less exhaust backpressure too)
I will have better throttle response
I will have a cooler intake charge
With a cooler intake charge, I can run a smaller intercooler, and that gives me less area to have to pressurize before making power, so better throttle response results
I will have lower under hood temps and less heat soak in the intake tract
I can run more timing with less chance of detonation
I will be able to run a lower stall convertor
Less combustion temperatures are easier on plugs, headgaskets, rings, and easier to control detonation
Not my first: rodeo, GN, turbo car, blower car, boat, sandrail, alky, nitrous, intercooler, etc.
"TO EACH, HIS OWN THING....."
TIMINATOR
Just throwing out ideas, do with them as you see fit! Let the shitstorm begin!
If I can make more HP with less boost:
I will have less back pressure in the exhaust
I will have less pumping pressure (negative HP) pushing on the pistons on the exhaust stroke
I will have more power sooner, as the turbo won't have to spool as high to make the same power (again, less exhaust backpressure too)
I will have better throttle response
I will have a cooler intake charge
With a cooler intake charge, I can run a smaller intercooler, and that gives me less area to have to pressurize before making power, so better throttle response results
I will have lower under hood temps and less heat soak in the intake tract
I can run more timing with less chance of detonation
I will be able to run a lower stall convertor
Less combustion temperatures are easier on plugs, headgaskets, rings, and easier to control detonation
Not my first: rodeo, GN, turbo car, blower car, boat, sandrail, alky, nitrous, intercooler, etc.
"TO EACH, HIS OWN THING....."
TIMINATOR
Just throwing out ideas, do with them as you see fit! Let the shitstorm begin!
greeneyegi
Well-Known Member
if installing a roller cam wouldnt it be benficial to run rr to get the best angle/lift ?
Just throwing it out there. Thats why I did mine is why im asking.
thanks for the ideas you have. made me think of a reason
TIMINATOR
Well-Known Member
ALL engines make their power from ALL things: cam duration, lift, ramp rate, valve size and shape, angles, cuts, and radii also, unshrouding, quench, combustion chamber shape, rod ratio, compression(expansion) ratio, rings, end gap, cylinder wall finish, coatings, intake and exhaust tuning, cubic inches, parasitic drag, inertia, polar moment of inertia, windage, cylinder wall rigidity, intake and exhaust restrictions, intake air and water jacket temps, pushrod and rocker stiffness, spring pressure, and dozens of more small things that many folks tend to minimize or ignore the importance of.
The more power make before you add the turbo, the more you will have totally.
If you can't make 50 more HP in one place, make one more in 50 places.
Sure you can just crank up the boost, but you can still get yer ass handed to you by the guy that takes more care of the little things than you do.
I am not anti boost by any means, I am just trying to raise the awareness of a total systems approach to going fast!
TIMINATOR
KNOWLEDGE IS POWER!
The more power make before you add the turbo, the more you will have totally.
If you can't make 50 more HP in one place, make one more in 50 places.
Sure you can just crank up the boost, but you can still get yer ass handed to you by the guy that takes more care of the little things than you do.
I am not anti boost by any means, I am just trying to raise the awareness of a total systems approach to going fast!
TIMINATOR
KNOWLEDGE IS POWER!
