PRW roller rockers?
06-23-2013, 09:22 AM
#1
PRW roller rockers? Anyone know anything about them? Haven't been able to find much on history of the product, where they're made, or any kind of track record. I've been investigating other options for use on my afr heads....I wasn't able to find these on prw's website but found them elsewhere.
http://www.cnc-motorsports.com/rolle...r-rockers.html
Product description
http://www.cnc-motorsports.com/rolle...r-rockers.html
Product description
Designed as the first drop-in aftermarket system for the GM LS Series cylinder heads, these PRW engineered rocker arms utilize the OEM rocker pedestals and will provide a dramatic improvement over the standard rocker arms. Each rocker arm is investment cast from 17-4ph stainless steel with silicone-bronze bushings that incorporates standard OEM oiling. The surface of each rocker is tumbled to reduce stress risers and the toplines and logos are hand-polished for a professional appearance. The system will support high performance valve springs that exceed the limit of hydraulic lifters.
Last edited by ckpitt55; 06-23-2013 at 09:36 AM.
06-23-2013, 09:51 AM
#2
I can only share my experience with them for a 1st gen SBC. I used a PRW aluminum rocker for one season and the bearings started walking back and forth in the housing. I never lost one but replaced with a Scorpion rocker and after a few seasons, the bearings are right where they should be.
06-23-2013, 10:52 AM
#3
I bought a set of their stainless rockers a while back. They are very heavy and I wasn't too impressed with the quality. Some of the roller tips weren't square with the pivot. I contacted PRW and they sent me 3 new ones but they weren't much better so I ended up returning the set.
06-23-2013, 06:21 PM
#5
Roller rockers are a waste on these motors. Just run the stock rockers.
You'll eventually need to replace the valve guides, but I'm not sure how far down the road that would be. Mamo used to run stock rockers on the AFR 205 heads all the time before YT came out with a roller rocker that could actually be bolted on.
You'll eventually need to replace the valve guides, but I'm not sure how far down the road that would be. Mamo used to run stock rockers on the AFR 205 heads all the time before YT came out with a roller rocker that could actually be bolted on.
06-23-2013, 08:03 PM
#6
If I had pm guides I'd be more inclined to agree, but I'm not trying to replace guides every 30k miles. The motor is going into a daily driver, not a weekend cruiser that only sees a few thousand miles a year. 3 years to me is 10 years to someone who doesn't dd the car.
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06-23-2013, 10:13 PM
#8
When an aftermarket rocker breaks its usually in a couple of big pieces and laying in the valve cover area. Its typically very noticeable so its not like you going to put much time on the engine after one breaks.
Stockers losing needle bearings are scarier IMO.....most of the aftermarket stuff has a caged bearing.
Also, you mentioned I ran stock rockers before Yella Terra launched their Ultralite line (which was actually born from an idea I shared with them when new management visited the US back in 05'). Anyway.....thats not true.....prior to that I ran the Crane aluminum roller rockers.....at least when I took apart my Vette's 346 to use it for featuring/debuting the new AFR 205 at the time. It only had stock rockers when it was stock....once I opened it up and installed the aftermarket AFR heads/cam package, it had aftermarket roller rockers right away.
Fact is the stock rockers work well from the perspective of valve control because they are light, but the scrub pattern they produce is horrible and when you start adding RPM and 2X the spring pressure in the mix, not to mention (softer) performance bronze guides, its a real compromised situation with a stock rocker arm (1/3 the expected guide life) and I just wont run them.
Even my CTSV engine project which I just put the finishing touches on with a ported set of LS3 heads I did (that had the PM guides btw), I opted to go with the YT Ultralites. I just prefer a stouter rocker with a roller tip and a narrow contact patch centered across the vale tip....no side loading or scrubbing action to concern yourself with. A stock rocker see-saws across that valve tip placing alot of lateral back and forth stress on the valve and the guide. They may be (and obviously is) OK with no cam lift, PM guides, soft stock cam profiles, and 80 lbs on the seat with 220 open, but that's not what we are really discussing here any more.
Stock is stock and IMO once your building a true performance piece its part of the equation that just needs to be upgraded and improved on. The stress of an aftermarket heads/cam set-up is completely different and the benefits of an aftermarket set-up (the right aftermarket set-up) start paying you significant dividends.
-Tony
06-23-2013, 10:30 PM
#9
I still think for a true daily driver, aluminum rockers aren't a good idea. There are no stainless steel ones that I know of, and I'm not sure why. But that would be ideal in this situation.
I would have recommended to the OP to do ported stock castings and run stock rockers. There's true performance applications and then there is a need to keep stock-like reliability. It sounds like some reliability will be given up in the pursuit of a few HP here. Whether that's a worthwhile trade-off is something we'll see in a couple of years.
However, I think the stock rockers scrubbing and causing issues is way overblown. The needle bearings can be fixed with caged trunions or bronze bushings. In talking to numerous vendors, almost every single one of them steered me away from roller rockers. Tony was the only one who advocated it. Maybe on AFR heads the difference is bad enough to make it worthwhile. But on stock ported castings and TFS and other aftermarket castings, the need just doesn't exist. And I figure if folks are selling Yella Terras and NOT advocating their sale, then there you go.
I will say this though, Tony over-engineers his setups, and they produce great numbers. The attention to detail and use of complementary parts are to be commended. Sometimes though, the budget for that is just too high for most folks and it becomes a "gold-plated" setup. Certainly not for everyone, but for some, it's the ticket.
I would have recommended to the OP to do ported stock castings and run stock rockers. There's true performance applications and then there is a need to keep stock-like reliability. It sounds like some reliability will be given up in the pursuit of a few HP here. Whether that's a worthwhile trade-off is something we'll see in a couple of years.
However, I think the stock rockers scrubbing and causing issues is way overblown. The needle bearings can be fixed with caged trunions or bronze bushings. In talking to numerous vendors, almost every single one of them steered me away from roller rockers. Tony was the only one who advocated it. Maybe on AFR heads the difference is bad enough to make it worthwhile. But on stock ported castings and TFS and other aftermarket castings, the need just doesn't exist. And I figure if folks are selling Yella Terras and NOT advocating their sale, then there you go.
I will say this though, Tony over-engineers his setups, and they produce great numbers. The attention to detail and use of complementary parts are to be commended. Sometimes though, the budget for that is just too high for most folks and it becomes a "gold-plated" setup. Certainly not for everyone, but for some, it's the ticket.
06-24-2013, 12:36 AM
#10
I have afr 215s, hence my concern with roller rockers. If I was running other heads with pm guides I would not care as much. I am also not chasing HP as much as I am chasing components that will allow me to maintain proper valvetrain geometry through travel.
There is a box of rev 3 6645 yella terras sitting here as we speak - given the activity on the forum lately regarding YT and what I know about the material properties inherent to aluminum, I was curious about possible steel alternatives. it seems that there are no other viable options, so I'll be running the yella terras with great attention to setup geometry.
If the man that developed and tested the cylinder heads feels that there is a need to run rollers, I'm going to do so. The stock rockers, while reliable, are still a compromised solution with an aftermarket cam and valvetrain - regardless of what heads you put them on. The arm drags across the valve tip with anything beyond .550" lift, and the wipe pattern itself is pretty wide, this is well documented. Bad for side loading and rocker arm loading. The bottom line is the arms are being used in an application they were not designed for. Call it over-engineering but if I'm putting together an engine the components are going to play together.
There is a box of rev 3 6645 yella terras sitting here as we speak - given the activity on the forum lately regarding YT and what I know about the material properties inherent to aluminum, I was curious about possible steel alternatives. it seems that there are no other viable options, so I'll be running the yella terras with great attention to setup geometry.
If the man that developed and tested the cylinder heads feels that there is a need to run rollers, I'm going to do so. The stock rockers, while reliable, are still a compromised solution with an aftermarket cam and valvetrain - regardless of what heads you put them on. The arm drags across the valve tip with anything beyond .550" lift, and the wipe pattern itself is pretty wide, this is well documented. Bad for side loading and rocker arm loading. The bottom line is the arms are being used in an application they were not designed for. Call it over-engineering but if I'm putting together an engine the components are going to play together.
Last edited by ckpitt55; 06-24-2013 at 01:01 AM.
06-24-2013, 08:32 AM
#14
^This
Came in here to describe the experience I had (which was good) w/PRW's. After seeing that Tony had posted, there's really nothing more to be said. Best of luck on w/the build. Those AFR 215's are GREAT heads.
06-24-2013, 10:46 PM
#16
I feel as though PTV will be snug. Heads are milled for 58.5cc, 2.050" intake valves, block deck height is 9.2335", pistons are 0.0065" out of hole, running 0.040" gaskets. My pistons do have -2cc valve reliefs though.
As for the springs, they're shimmed to within ~0.050" of coil bind at peak lift, and rated for .650" to my knowledge. With a 1.8 rocker on my cam I'd go from .612" to .648" on the intake side. A little hot for my liking - not good for spring life and would further limit me in terms of how hard I could spin the engine.
Could probably be done if I had good reason to but I'd have to revisit my cam selection. I do appreciate the link though, thanks.
Last edited by ckpitt55; 06-25-2013 at 06:47 AM.
06-24-2013, 10:52 PM
#17
Its an eye opening experience....
While alot of guy who pay attention to ideal valve geometry cringe with a wide rectangular patch (more sweep of the roller back and forth), a stock rocker with .600 ish lift literally leaves a square and almost scrubs (not rolls) across the entire length of the tip.
I had a pretty good picture of this and cant find it.....
OK.....looked a little deeper and did find it....it wasnt uploaded to my photobucket yet which was why I was having a hard time tracking it down.
Anyway note in this particular situation the stock rocker hits on only one side of the valve tip....its not perfectly parallel with the valve (at least this one obviously wasn't). Note how far across the tip the red dykem is effected....basically a square contact patch.
Here is an optimized YT set-up with slightly more shim height on this particular engine I built. Its extremely narrow and extremely centered....its literally just pushing the valve straight down...minimal side loading is imparted on the valve stem
I will say this though, Tony over-engineers his setups, and they produce great numbers. The attention to detail and use of complementary parts are to be commended. Sometimes though, the budget for that is just too high for most folks and it becomes a "gold-plated" setup. Certainly not for everyone, but for some, it's the ticket.
And I have to agree with you....I do err on the side of over engineering/optimizing things, but I feel the main reason folks visit this particular site is TECH, and knowledge is power. Stock rockers work....they are reliable, and they actually help valve control because of their light weight....all of these attributes are good, but when your stepping up your game with more spring pressure (double), much more intense lobe profiles, more lift, more RPM, and adding softer bronze alloy guides in the mix (adding insult to injury), a lightweight aftermarket roller rocker becomes a really smart upgrade. They provide all the benefits previously mentioned and will add measurably to your expected guide life (3X), not to mention make more power by imparting more lift/duration at the valve from less deflection.
They are more money and if your on a strict budget I could see taking a pass, but I think if more people realized and better understood all the dynamics involved, they might be willing to drop that $500 extra and feel pretty good about it.....that's my opinion of course but I feel its a pretty good assessment of the situation based on all the people I help and speak to.
BTW, if you do decide to take the plunge (on roller rockers), for the guys looking for the ultimate in rigidity, I sell a 10mm "Pro" version of the YT Ultralite kit for the guys running more RPM and heavy springs. Its a really stout set-up....ran it on my Vader build and have numerous guys out in the field with some "Mamofied" packages that are running it as well. Still a bolt on kit but it requires you to drill and tap the 8mm stock threads to a larger/stouter 10mm thread for the beefier bolt pitch. Its a pretty slick set-up that I was involved with and encouraged them to produce early on much like the entire line of Ultralite rockers themselves.
Hopefully the pics I provided give you guys a clearer picture of the benefit and aftermarket rocker provides. Its significant IMO but like anything else you have to have it in the budget.
-Tony
06-24-2013, 11:03 PM
#18
BTW, if you do decide to take the plunge (on roller rockers), for the guys looking for the ultimate in rigidity, I sell a 10mm "Pro" version of the YT Ultralite kit for the guys running more RPM and heavy springs. Its a really stout set-up....ran it on my Vader build and have numerous guys out in the field with some "Mamofied" packages that are running it as well. Still a bolt on kit but it requires you to drill and tap the 8mm stock threads to a larger/stouter 10mm thread for the beefier bolt pitch. Its a pretty slick set-up that I was involved with and encouraged them to produce early on much like the entire line of Ultralite rockers themselves.
-Tony
-Tony
06-24-2013, 11:54 PM
#19
Good question
Same lightweight body....different fulcrum/pivot that has a larger hole to accept the beefier 10mm bolt and a larger stanchion for it to fit thru.
My engine has 175 lbs on the seat....440 open....that's getting up there plus I plan to buzz it to 7K on a regular basis so it qualifies.
Cam intensity and lift also...I'm running 1.8 rockers with .660 lift so that makes the need for the beefier stand more worthwhile (less flex in the stand equals more action at the valve).
Reality is being intimately familiar with your set-up its probably overkill but on the other hand can you ever have too rigid a rocker arm? It just wouldn't be worth as much in your set-up as it would be in mine....that's the long and short of it. Most of the guys I have helped with this kit are running Mamofied 230's or Mamofied 245's (obviously more aggressive higher RPM builds)
I wouldn't lose sleep over it....the standard 8mm kit you have is fine but if you were willing to drill/tap your heads and wanted to exchange the ones I sent you, PM me and we can discuss....its a few hundred more for the Pro version though cause its specialized and its a low volume deal at YT in Australia....you always pay more when something isn't manufactured in high volume.
For the other guys reading that might be interested, I have an exclusive on this particular Pro 10mm system because of all my help and involvement in this and the entire "Ultralite" product over the years (as I previously mentioned I was extremely instrumental in the reason it happened and some of the earlier design). Being good friends with the owner now doesn't hurt either.....LOL
-Tony
06-25-2013, 07:48 AM
#20
OP I was in a shop several months back and hoisted one of those. They are SHOCKINGLY heavy. They feel like at least double the weight of a YT and very heavy at the roller.
I apologize in advance for continuing the discussion of stock rockers. Tony have you ever measured the lift change caused by the scrubbing action of the valve? What I mean is, I did a detailed optical inspection of my stock rockers when I pulled for all the recent mods. We have a non-contact optical inspection system at work good to .00001" Anyway by my measurements and what is probably insufficient geometry I get that the OE rockers are ~1.58:1 right off the seat and more like 1.82:1 at peak lift (again for the stock '02 cam). The situation would definitely be exacerbated by a bigger cam with all that scrub.
Just curious if you or anyone had measured actual as-installed lift numbers. I was shocked by the variation that the geometry implied and curious as to how off my math might be.
I apologize in advance for continuing the discussion of stock rockers. Tony have you ever measured the lift change caused by the scrubbing action of the valve? What I mean is, I did a detailed optical inspection of my stock rockers when I pulled for all the recent mods. We have a non-contact optical inspection system at work good to .00001" Anyway by my measurements and what is probably insufficient geometry I get that the OE rockers are ~1.58:1 right off the seat and more like 1.82:1 at peak lift (again for the stock '02 cam). The situation would definitely be exacerbated by a bigger cam with all that scrub.
Just curious if you or anyone had measured actual as-installed lift numbers. I was shocked by the variation that the geometry implied and curious as to how off my math might be.