Cam and rocker arm?
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Joined: Nov 2001
Posts: 1,151
From: orlando,florida,usa
Re: Cam and rocker arm?
Originally Posted by Kraest
Actually, a stock car can benefit 10-15 rwhp with a dynotune and the Futral line of cams drive near-stock, which would give you MUCH more than a rocker change.
Mike
Mike
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Joined: Oct 1999
Posts: 3,166
From: Inside Uranus
Re: Cam and rocker arm?
Originally Posted by mrr23
didn't say it wouldn't. if you are looking for the most for your money, a cam is the way to go. again, for the reasons, i stated, it is a good choice. most people can do a rocker swap in their driveway versus a cam swap. some people just don't have a dynotune shop nearby. lucky me, i have at least three within 30 minutes of each other. some have to go 8+ hours to get to their local performance shop.
Mike
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Joined: Apr 2003
Posts: 4,507
From: FTW, TX
Re: Cam and rocker arm?
Originally Posted by mrr23
why?? what is the concern??? is it because the valve springs they use???? lifters can't handle it????? piston to valve clearance??????
Yes, most people can do a rocker change in their driveway, but can they also perform the needed spring change to accomodate the higher lift???? If they have the spring compressor and air chuck to keep the valves up they're more than likely quite capable and experienced enough to perform a cam change. Plus as previously pointed out, a tune will further benefit the longer rockers. Saying they won't need a tune is like saying they won;t need a tune with a TR244. No it isn't NEEDED but it'll sure run better and make more power with it.
The VHP/Crane rocker and spring kit is listed on their site for $999. Thats $1000 for all practical purposes, and as stated before with the lift created you're going to wish you have gone with better springs when you break one and drop a valve. Even on a stock cam you'd be well advised to step up to LS6 springs.
You can buy a cam kit for $600. A local shop quoted $500 for an install and all I had to provide was the cam and springs they provided labor, gaskets and fluids. So you're saving $100 so you can bolt on some rockers (Thats a $100 savings IF you already have the spring compressor, air compressor and air chuck) when for $100 more you can have the peace of mind of a professional install. I still fail to see where it becomes financially beneficial. Unless you're willing to risk your entire engine on springs that are designed for les lift than they'll be seeing.
If someone wants to bring up being able to buy them for $400 and used springs, the same can be applied to a cam. I got my cam for under $100.
Last edited by Greed4Speed; Apr 30, 2006 at 12:56 PM.
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Joined: Nov 2001
Posts: 1,151
From: orlando,florida,usa
Re: Cam and rocker arm?
Originally Posted by Kraest
Of course. However, I didn't use bigger rocker arms because of the fact that you'll have PtV problems if you ever go with an aftermarket cam.
Mike
Mike
again, not entirely true. i had the vinci 062 cam in the wife's car. 210/218 .551/.551 with the 1.8 rockers which brought the lift to .589/.589. better to say with some after market cams.
Registered User
Joined: Apr 2003
Posts: 4,507
From: FTW, TX
Re: Cam and rocker arm?
Originally Posted by mrr23
again, not entirely true. i had the vinci 062 cam in the wife's car. 210/218 .551/.551 with the 1.8 rockers which brought the lift to .589/.589. better to say with some after market cams.
Look at the new lobes though. The old school XE lobed Comp ground 224 cam had .563-.566" lift. The new grinds w/XER lobes now have .581" lift and with Futral cams you'll get .588" lift with the same duration.
According to Vinci, w/a .551 you'll actually see .583" lift. This is a minimal difference when compared to modern cam grinds. And for most people who ran smaller cams that have Comp 918 springs you're now on the top end of their abilities. So if you don't change them now, you will before long.
Now where a better aftermarket cam REALLY comes into play is with the ability to change duration and LSA. You can talk increased lift all you want, but you'll see more gains with increased duration and longer ratio rocker aren't going to do much of that for you. A TR224 w/ the .563" lift isn't going to be much slower than a 224R with a .581" lift.
Last edited by Greed4Speed; Apr 30, 2006 at 09:21 PM.
Registered User
Joined: Nov 2001
Posts: 1,151
From: orlando,florida,usa
Re: Cam and rocker arm?
Originally Posted by Greed4Speed
Some OLD tech lobed cams, yes.
Look at the new lobes though. The old school XE lobed Comp ground 224 cam had .563-.566" lift. The new grinds w/XER lobes now have .581" lift and with Futral cams you'll get .588" lift with the same duration.
According to Vinci, w/a .551 you'll actually see .583" lift. This is a minimal difference when compared to modern cam grinds
Now where a better aftermarket cam REALLY comes into play is with the ability to change duration and LSA. You can talk increased lift all you want, but you'll see more gains with increased duration and longer ratio rocker aren't going to do much of that for you. A TR224 w/ the .563" lift isn't going to be much slower than a 224R with a .581" lift.
Look at the new lobes though. The old school XE lobed Comp ground 224 cam had .563-.566" lift. The new grinds w/XER lobes now have .581" lift and with Futral cams you'll get .588" lift with the same duration.
According to Vinci, w/a .551 you'll actually see .583" lift. This is a minimal difference when compared to modern cam grinds
Now where a better aftermarket cam REALLY comes into play is with the ability to change duration and LSA. You can talk increased lift all you want, but you'll see more gains with increased duration and longer ratio rocker aren't going to do much of that for you. A TR224 w/ the .563" lift isn't going to be much slower than a 224R with a .581" lift.
Originally Posted by VHP website
VALVE TRAIN TIPS
More On Why Our Unique New “Quick-Liftä” Rocker Arm Geometry Makes More HP!
There has been a great deal of dialog on several web forums pertaining to our "QUICK LIFT" camshaft lobes and rocker bodies. To set the record straight, this is what we have always maintained.
Here are a couple of questions about our rockers we would like to address.
Does the varying rocker ratio adversely affect spring harmonics?
Wouldn’t a fixed ratio rocker be easier on the valve train and cause fewer problems?
The first point that needs to be made in answering these questions is that there is no such thing as a constant ratio rocker arm unless you are talking about a very limited range of lift (.150” or less). This is because the pushrod seat end of the rocker and the valve tip end of the rocker are operating through two different distances and their ratio must constantly vary. Traditionally, most rockers have been designed to start the valve off the seat and return it to the seat slowly. (i.e. traditional SBC 1.5 ratio rockers started the valve off the seat at a ratio of 1.4 and did not get to a 1.5 ratio until .350” valve lift). This was because many OE valves were made in two pieces, and quick opening and closing rates could compromise the valve. The use of high quality, one-piece valves has made this a non-issue. Many performance aftermarket companies, including Crane, tried to develop rockers that were as close to constant ratio as possible. For instance, many 1.6 ratio rockers bring the valve off the seat at 1.62; by .250” valve lift, the ratio increases to 1.65 and by .550” valve lift, the ratio comes back to 1.61. Again, the ratio is varying due to the different length of operating arcs of the end of the rocker. Crane’s “Quick-Lift” design causes an “advertised” 1.6 ratio rocker to start the valve off the seat at a ratio of 1.72 and bring the ratio back to 1.60 by .250-.300” net valve lift. This ratio is then maintained through the rest of the lift profile until the valve is within .250-.300” from going back on the seat. It is then returned to the seat at a ratio of 1.72. This geometry is illustrated in this diagram.
Benefits of this geometry include more flow into the cylinder earlier in the cycle, quicker closing of the valve to trap cylinder pressure before combustion, more effective duration at .200” net valve lift while maintaining a relatively short seat-to-seat timing, and less valve spring seat pressure required because of the mechanical advantage of the higher seat ratio.
During development testing and now corroborated by more than two years of field-testing in competition, we have not seen any indication that the “Quick-Lift” geometry contributes to any additional valvetrain problems in any way. In fact, the evidence so far shows that our “Quick-Lift” Polymer Matrix Composite Bearing Shaft Mount Rockers actually seem to reduce harmonic issues in the valve train and extend spring life. At this time, we have no way of telling if this is the bearing construction or the geometry of the body or both! One other important feature of these rockers is the absence of needle bearings, which can break loose under extreme valve spring pressures and cause catastrophic engine problems. On average, we have eliminated 544 needle bearings from an engine with this design!!
“Quick-Lift” rocker body geometry causes the rocker arm to be a dynamic component in the opening and closing rate of the valve. Some people who don’t seem to understand this think it is “unnatural” to cause the valve to open faster than the cam lobe dictates, but OHC designs with finger followers have been doing it for years. After all, aren’t we interested in what the valve is doing relative to the piston position? Who cares how we get the valve there at the right time? The point is that “Quick-Lift” rocker geometry will broaden the torque curve (torque x RPM/ 5252 = HP!!!) of any cam you use it with. Our only warning: Super Stockers and others running extremely tight piston-to-valve clearance should check this with “Quick-Lift” rockers. Try ‘em; we know you’ll love ‘em!!
VHP and Crane Cams have been working with each other for many years. Together, we have strived to provide the very best products we can with the latest technology available. We think, we design, we manufacture, we test....then we market the product. It seems that there has been much confusion about Crane/Vinci "Quick-Lift" cam lobes and "Quick-Lift" rocker bodies. We claim that the use of the Quick-Lift lobes with the Quick-Lift rocker bodies results in "effective valve lift" durations @ .200" valve lift equal to most other cam/rocker combinations using cams with 4-8* more duration at .050" cam lift. This is the result of the Quick-Lift Rocker body design. We do not state that our cam lobes (by themselves) give this advantage. The same laws of physics that limit every other cam designer limit our cam lobe designs. We attribute the advantage in valve lift to the "translation" properties of the varying ratio design of our Quick-Lift rocker body design. If you don’t believe us, test any cam lobe (Crane, Comp, Cam Motion, etc.) with stock LS1 rockers. Install a dial indicator on the retainer and a degree wheel on the crank. Plot a lift vs. degrees of rotation curve. Then install the Crane LS1 1.7 rockers (with the pushrods in the Crane kit) and plot the same curve. Measure the duration at .200" net valve lift. The Crane rockers will definitely provide more duration at this checking point. The reason for this is that, contrary to popular belief, the stock LS1 rockers are only 1.7 ratio above .480" valve lift. They actually start the valve off the seat at a 1.54 ratio. What do you think that ratio does to a "super fast" cam lobe? Slows it down quite a bit? The Crane rockers, properly installed, bring the valve off the seat at 1.79. Doesn’t take a math wiz here to see what combination is going to get open quicker and longer!! If you really want to see something interesting, take two lobes that have identical .050" seat-to-seat timing, identical .200" lifter rise timing, but one provides .583" valve lift with 1.7 ratio and the other providing .551 lift with 1.7 ratio. Plot a lift vs. duration curve with any rocker you want (other than Crane) and measure the duration at .200" valve lift. Then do a plot of the .551 cam with 1.8 Crane rockers (this will net out .583 also) and measure the duration difference at .200" valve lift. You will be impressed by how much more this second plot gives over the first. It’s also quicker on the drag strip! We’ve done this. Every person reading these threads can do something like this.
Our point is that the only thing that counts is what happens at the valve and the overall rocker ratio is fundamental to this. Contrary to popular belief, there are no fixed ratio rockers on the market (this is because the valve tip end and pushrod seat end operate on two distinctly different arcs). This is why some rockers add power and some don’t. Crane/Vinci have elected to do extensive development with rockers as a supplement to the lobe. The quickest lobe in the world doesn’t mean diddly if you are using slow acting rockers! Like everything else, it’s the combination that counts. FYI, the higher opening and closing ratios actually allow lower seat pressures because the mechanical advantage of the ratio helps maintain proper lifter preload! Check it out. This isn’t smoke and mirrors; it’s applied geometry and it works!! Roger Vinci
More On Why Our Unique New “Quick-Liftä” Rocker Arm Geometry Makes More HP!
There has been a great deal of dialog on several web forums pertaining to our "QUICK LIFT" camshaft lobes and rocker bodies. To set the record straight, this is what we have always maintained.
Here are a couple of questions about our rockers we would like to address.
Does the varying rocker ratio adversely affect spring harmonics?
Wouldn’t a fixed ratio rocker be easier on the valve train and cause fewer problems?
The first point that needs to be made in answering these questions is that there is no such thing as a constant ratio rocker arm unless you are talking about a very limited range of lift (.150” or less). This is because the pushrod seat end of the rocker and the valve tip end of the rocker are operating through two different distances and their ratio must constantly vary. Traditionally, most rockers have been designed to start the valve off the seat and return it to the seat slowly. (i.e. traditional SBC 1.5 ratio rockers started the valve off the seat at a ratio of 1.4 and did not get to a 1.5 ratio until .350” valve lift). This was because many OE valves were made in two pieces, and quick opening and closing rates could compromise the valve. The use of high quality, one-piece valves has made this a non-issue. Many performance aftermarket companies, including Crane, tried to develop rockers that were as close to constant ratio as possible. For instance, many 1.6 ratio rockers bring the valve off the seat at 1.62; by .250” valve lift, the ratio increases to 1.65 and by .550” valve lift, the ratio comes back to 1.61. Again, the ratio is varying due to the different length of operating arcs of the end of the rocker. Crane’s “Quick-Lift” design causes an “advertised” 1.6 ratio rocker to start the valve off the seat at a ratio of 1.72 and bring the ratio back to 1.60 by .250-.300” net valve lift. This ratio is then maintained through the rest of the lift profile until the valve is within .250-.300” from going back on the seat. It is then returned to the seat at a ratio of 1.72. This geometry is illustrated in this diagram.
Benefits of this geometry include more flow into the cylinder earlier in the cycle, quicker closing of the valve to trap cylinder pressure before combustion, more effective duration at .200” net valve lift while maintaining a relatively short seat-to-seat timing, and less valve spring seat pressure required because of the mechanical advantage of the higher seat ratio.
During development testing and now corroborated by more than two years of field-testing in competition, we have not seen any indication that the “Quick-Lift” geometry contributes to any additional valvetrain problems in any way. In fact, the evidence so far shows that our “Quick-Lift” Polymer Matrix Composite Bearing Shaft Mount Rockers actually seem to reduce harmonic issues in the valve train and extend spring life. At this time, we have no way of telling if this is the bearing construction or the geometry of the body or both! One other important feature of these rockers is the absence of needle bearings, which can break loose under extreme valve spring pressures and cause catastrophic engine problems. On average, we have eliminated 544 needle bearings from an engine with this design!!
“Quick-Lift” rocker body geometry causes the rocker arm to be a dynamic component in the opening and closing rate of the valve. Some people who don’t seem to understand this think it is “unnatural” to cause the valve to open faster than the cam lobe dictates, but OHC designs with finger followers have been doing it for years. After all, aren’t we interested in what the valve is doing relative to the piston position? Who cares how we get the valve there at the right time? The point is that “Quick-Lift” rocker geometry will broaden the torque curve (torque x RPM/ 5252 = HP!!!) of any cam you use it with. Our only warning: Super Stockers and others running extremely tight piston-to-valve clearance should check this with “Quick-Lift” rockers. Try ‘em; we know you’ll love ‘em!!
VHP and Crane Cams have been working with each other for many years. Together, we have strived to provide the very best products we can with the latest technology available. We think, we design, we manufacture, we test....then we market the product. It seems that there has been much confusion about Crane/Vinci "Quick-Lift" cam lobes and "Quick-Lift" rocker bodies. We claim that the use of the Quick-Lift lobes with the Quick-Lift rocker bodies results in "effective valve lift" durations @ .200" valve lift equal to most other cam/rocker combinations using cams with 4-8* more duration at .050" cam lift. This is the result of the Quick-Lift Rocker body design. We do not state that our cam lobes (by themselves) give this advantage. The same laws of physics that limit every other cam designer limit our cam lobe designs. We attribute the advantage in valve lift to the "translation" properties of the varying ratio design of our Quick-Lift rocker body design. If you don’t believe us, test any cam lobe (Crane, Comp, Cam Motion, etc.) with stock LS1 rockers. Install a dial indicator on the retainer and a degree wheel on the crank. Plot a lift vs. degrees of rotation curve. Then install the Crane LS1 1.7 rockers (with the pushrods in the Crane kit) and plot the same curve. Measure the duration at .200" net valve lift. The Crane rockers will definitely provide more duration at this checking point. The reason for this is that, contrary to popular belief, the stock LS1 rockers are only 1.7 ratio above .480" valve lift. They actually start the valve off the seat at a 1.54 ratio. What do you think that ratio does to a "super fast" cam lobe? Slows it down quite a bit? The Crane rockers, properly installed, bring the valve off the seat at 1.79. Doesn’t take a math wiz here to see what combination is going to get open quicker and longer!! If you really want to see something interesting, take two lobes that have identical .050" seat-to-seat timing, identical .200" lifter rise timing, but one provides .583" valve lift with 1.7 ratio and the other providing .551 lift with 1.7 ratio. Plot a lift vs. duration curve with any rocker you want (other than Crane) and measure the duration at .200" valve lift. Then do a plot of the .551 cam with 1.8 Crane rockers (this will net out .583 also) and measure the duration difference at .200" valve lift. You will be impressed by how much more this second plot gives over the first. It’s also quicker on the drag strip! We’ve done this. Every person reading these threads can do something like this.
Our point is that the only thing that counts is what happens at the valve and the overall rocker ratio is fundamental to this. Contrary to popular belief, there are no fixed ratio rockers on the market (this is because the valve tip end and pushrod seat end operate on two distinctly different arcs). This is why some rockers add power and some don’t. Crane/Vinci have elected to do extensive development with rockers as a supplement to the lobe. The quickest lobe in the world doesn’t mean diddly if you are using slow acting rockers! Like everything else, it’s the combination that counts. FYI, the higher opening and closing ratios actually allow lower seat pressures because the mechanical advantage of the ratio helps maintain proper lifter preload! Check it out. This isn’t smoke and mirrors; it’s applied geometry and it works!! Roger Vinci
Registered User
Joined: Apr 2003
Posts: 4,507
From: FTW, TX
Re: Cam and rocker arm?
READ 4 lines from the bottom of the 2nd to last paragraph.
"(this will net out .583 also)"
Yes, I've read threads about how well they've worked with nice spring harmonics. This was with Crane springs too...
They still aren't cost effective once you factor in the springs and tools to change the springs and the inability to significantly change duration and LSA.
Plus their "quick lift" cam lobes that mirror cams from the early days of the LS1. Smells of propaganda and marketing to get people to pay an extra $600 for rockers when they can do it all with a $350 cam.
Not to mention, why would anyone just blindly believe what a manufacturer says? I can show you all sorts of propaganda from manufacturers that say crossdrilled rotors run cooler....
"(this will net out .583 also)"
Yes, I've read threads about how well they've worked with nice spring harmonics.
This was with Crane springs too...They still aren't cost effective once you factor in the springs and tools to change the springs and the inability to significantly change duration and LSA.
Plus their "quick lift" cam lobes that mirror cams from the early days of the LS1. Smells of propaganda and marketing to get people to pay an extra $600 for rockers when they can do it all with a $350 cam.
Not to mention, why would anyone just blindly believe what a manufacturer says? I can show you all sorts of propaganda from manufacturers that say crossdrilled rotors run cooler....
Last edited by Greed4Speed; Apr 30, 2006 at 09:38 PM.
Registered User
Joined: Nov 2001
Posts: 1,151
From: orlando,florida,usa
Re: Cam and rocker arm?
this is going to be one of those threads that go round and round. again, i can state my points. people that don't want a cam or are looking to extract the most out of what they have. a cam is a cheap way to get what you want. if rockers really didn't work, then why do the other major manufacturers make them? increased sales, maybe. ask comp cams.
i'll have them fix that error on the page. amazing how those spring 'harmonics aren't apparant on my dynos. most don't take the time to figure out why it's there. the tuners and builders blame the rockers and don't want to figure out why.
here's another thing to think about. when you build it into the cam, you throw the lifters, pushrods, and rockers around at those speeds. this, making the spring have to control all of those parts at those speeds. now, slow the cam lobe down. this slows the lifters, pushrods, and lifters down. only moving the valve at the higher ramp speeds. now, the springs have less mass speeds to control.
in the end, do what you want. you want rockers, get them.
i'll have them fix that error on the page. amazing how those spring 'harmonics aren't apparant on my dynos. most don't take the time to figure out why it's there. the tuners and builders blame the rockers and don't want to figure out why.
here's another thing to think about. when you build it into the cam, you throw the lifters, pushrods, and rockers around at those speeds. this, making the spring have to control all of those parts at those speeds. now, slow the cam lobe down. this slows the lifters, pushrods, and lifters down. only moving the valve at the higher ramp speeds. now, the springs have less mass speeds to control.
in the end, do what you want. you want rockers, get them.
Registered User
Joined: Apr 2003
Posts: 4,507
From: FTW, TX
Re: Cam and rocker arm?
If longer ratio rockers really work so well then why don't more people run them?
The point is, its $600 better spent elsewhere. Any way you look at it, you're more than likely going to need a spring change which kills the cost effective DIY Saturday project when you can get a cam change and see much more power gains for the same cash.
The point is, its $600 better spent elsewhere. Any way you look at it, you're more than likely going to need a spring change which kills the cost effective DIY Saturday project when you can get a cam change and see much more power gains for the same cash.
Registered User
Joined: Nov 2001
Posts: 1,151
From: orlando,florida,usa
Re: Cam and rocker arm?
spring change cost is a moot point. you have to do it either way. and people can still do a spring/rocker swap easier than a cam swap. no gaskets need to be bought.
again, i agree you'll get more for the dollar with a cam swap. but, to say it's a waste is something i cannot agree with. some do not want a cam. some have to deal with emissions testing. not saying a cam won't pass. there are numerous reasons as to why someone doesn't want to go the cam route. others, already have the cam they want, just want a little more out of it.
what i will agree with is what you said: for the cost, you can get more out of a cam than with rockers.
here's my dyno with the vinci/crnae 1.8 accelerated lift rockers in the wife's car with the stock 99 cam on stock tune.
http://www.stealthram.com/familypics...andsprings.jpg
here's where the rockers and springs were put on a 5.3L truck.
http://www.stealthram.com/reddogplan.htm
again, i agree you'll get more for the dollar with a cam swap. but, to say it's a waste is something i cannot agree with. some do not want a cam. some have to deal with emissions testing. not saying a cam won't pass. there are numerous reasons as to why someone doesn't want to go the cam route. others, already have the cam they want, just want a little more out of it.
what i will agree with is what you said: for the cost, you can get more out of a cam than with rockers.
here's my dyno with the vinci/crnae 1.8 accelerated lift rockers in the wife's car with the stock 99 cam on stock tune.
http://www.stealthram.com/familypics...andsprings.jpg
here's where the rockers and springs were put on a 5.3L truck.
http://www.stealthram.com/reddogplan.htm
Retired
Joined: Oct 1999
Posts: 3,166
From: Inside Uranus
Re: Cam and rocker arm?
Originally Posted by mrr23
here's my dyno with the vinci/crnae 1.8 accelerated lift rockers in the wife's car with the stock 99 cam on stock tune.
http://www.stealthram.com/familypics...andsprings.jpg
http://www.stealthram.com/familypics...andsprings.jpg
Mike
Registered User
Joined: Nov 2001
Posts: 1,151
From: orlando,florida,usa
Re: Cam and rocker arm?
my only point with the graph is to show they do work and what the expected gains can be from them. would a graph of 481 rwhp from the same car make it any better for you?
to say they are a waste just isn't true. you pick the right rockers and you get the gains. and not all cams will net you 50 rwhp.
to say they are a waste just isn't true. you pick the right rockers and you get the gains. and not all cams will net you 50 rwhp.
Retired
Joined: Oct 1999
Posts: 3,166
From: Inside Uranus
Re: Cam and rocker arm?
Originally Posted by mrr23
again, not entirely true. i had the vinci 062 cam in the wife's car. 210/218 .551/.551 with the 1.8 rockers which brought the lift to .589/.589. better to say with some after market cams.
The newer lines of cams out now that make the most power with stock driveability (Futral's lines for instance) are 230/232 .600 lift for example, that bring over 400 rwhp to the table. With that kind of lift ground into the cam, there's NO reason to upgrade rockers.
Trust me. I had the most powerful N/A stock-bottomed 346ci LS1 Vette on this site before I sold it last week.
Mike
Retired
Joined: Oct 1999
Posts: 3,166
From: Inside Uranus
Re: Cam and rocker arm?
Originally Posted by mrr23
my only point with the graph is to show they do work and what the expected gains can be from them. would a graph of 481 rwhp from the same car make it any better for you?
to say they are a waste just isn't true. you pick the right rockers and you get the gains. and not all cams will net you 50 rwhp.
to say they are a waste just isn't true. you pick the right rockers and you get the gains. and not all cams will net you 50 rwhp.
All the good cams will net you 40-50 rwhp. If you didn't make that, it's not my fault.
Mike