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I am building an LS3 with a high-lift Lingenfelter GT11 cam, which recommends stronger dual valve springs. The increased spring pressure suggests a full roller rocker, as do a number of others, in order to avoid side-loading of the valve and premature wear on the guides and stem. All of which I agree with.
The question is, for a daily driver, do I go with a set of Aluminum Yella Terra Ultralite 8.0mm Rockers, Ratio 1.7 YT6667? Or do I go with a set of cast steel PRW PQX Modern Muscle Rocker Arm Systems PRW 0236431? The aluminum set is about $180 more (ignore the Australian dollar pricing), but I like the mini-shaft system between rocker sets and light weight. The steel is cheaper and potentially more durable, though slightly heavier. I considered a set of Comp Cams Ultra Pro Magnums, but they only come in 1.8 ratio, which won't work for what I want with my cam. My concern is, will the aluminum rockers be okay for 100K+ miles in a street car without having to periodically open the valve covers?
Last edited by KCS; 05-07-2016 at 09:26 PM.
Reason: Nonsponsor links removed
high lift and heavy springs do not usually go in the same sentence as daily drivers.
you want near OEM lift with near OEM spring pressures. By keeping pressure and lift minimal you maintain valvetrain reliability, minimal wear and tear. Plenty of 700bhp engines have and will run this way 100k+ miles. Furthermore, if you have an OEM bearing (clearance) you will wish to avoid high rpms (associated with "big cams") anyways, while using a lightweight synthetic oil (since it is a daily).
I am building an LS3 with a high-lift Lingenfelter GT11 cam, which recommends stronger dual valve springs. The increased spring pressure suggests a full roller rocker, as do a number of others, in order to avoid side-loading of the valve and premature wear on the guides and stem. All of which I agree with.
The question is, for a daily driver, do I go with a set of Aluminum Yella Terra Ultralite 8.0mm Rockers, Ratio 1.7 YT6667? Or do I go with a set of cast steel PRW PQX Modern Muscle Rocker Arm Systems PRW 0236431? The aluminum set is about $180 more (ignore the Australian dollar pricing), but I like the mini-shaft system between rocker sets and light weight. The steel is cheaper and potentially more durable, though slightly heavier. I considered a set of Comp Cams Ultra Pro Magnums, but they only come in 1.8 ratio, which won't work for what I want with my cam. My concern is, will the aluminum rockers be okay for 100K+ miles in a street car without having to periodically open the valve covers?
The gt11 cam is actually a fairly mild cam but it does have a lot of lift. May I ask why you're se on that? The ls3 heads arent doing that great .650 lift which is about where that cam is. Now you can use stock rockers on that cam but it will require some attention to detail. The prw stuff I would skip. Normally the cutoff for stock rockers is around.630 lft but people have gone to .650 pretty regularly. If you do want the safety of some roller rockers then I would absolutley do the yella terra pieces and match a good spring with them. The roller rockers will also need some added spring to be able to control the extra MOI. Yella Terra rockers generally dont like any more than 420 open on the springs.
My actual advice here is rethink the cam selection, there are many cams that will perform just as good as the gt11 if not better and will be easier on the valvetrain...My spec would be an EPS 222/234 117+3 it comes in around .600 lift. That cam has very gentle lobes but will still either outperform or at least match the gt11. It can also be used with a good set of beehive springs and stock rockers. So it will save some money and be nicer to the engine.
Originally Posted by kingtal0n
high lift and heavy springs do not usually go in the same sentence as daily drivers.
you want near OEM lift with near OEM spring pressures. By keeping pressure and lift minimal you maintain valvetrain reliability, minimal wear and tear. Plenty of 700bhp engines have and will run this way 100k+ miles. Furthermore, if you have an OEM bearing (clearance) you will wish to avoid high rpms (associated with "big cams") anyways, while using a lightweight synthetic oil (since it is a daily).
No offense here but this makes very little sense. The ls isnt a gen I SBC from 1968. An oem ls3 cam is 204/211 .551 .522. It is a very mild cam and the springs come in at 90/270 again barely adequate for the stock valvetrain. People easily exceed 230+ duration on an ls3 with .600 lift or more without issue. A normal medium cammed setup on an ls3 would look something like 230/242 113 lsa .620/.610 (just roughed those specs in) along with a set of shimmed beehives or duals packing 130-140 on the seat and 400lbs open. They will then spin that cam to 6800-7k and will daily drive it if they feel the want to do so. I did it at one point and put 40k on the car, lots of other people do too. A healthy cammed ls revving over the factory redline is nothing to be afraid of, please do some research befor making another post like that.
Running Comp ultra gold rollers for 3 years now with no issues whatsoever. Never really understood why so many have problems with after market rockers.
For spring pressure = 1 to 999
if spring pressure * mileage/laps > X then
goto fucked:
else
next pressure
For lift = .500 to .999
if lift * mileage/laps > Y then
goto fucked:
else
next lift
fucked: dropped valve / trashed engine
end
I am trying to show that fucked is function of mileage/laps ("wear and tear") regardless of what engine we are talking about. You can make a better cam/spring/lifter/whatever but there is still some variable X and Y (and Z etc...) for which too many laps is one revolution too much and it will fail.
And the catastrophic result is "new engine" as a dropped valve includes holes in pistons/blocks/bent rods/ruined head and so forth. Not a pretty sight.
So this is where we look at power goals, and ask ourselves if we need the additional lift. If you don't need it, why take the additional risk? Unless you have a pool(population) of a reasonable size (figure 100 people) all of which are running the same exact hardware as you intend, and all of them has 100K+ miles on their engines, and only 1:100 has a valvetrain related failure, then there is no evidence, or reason, to even look twice at such a folly setup, especially in a DD application.
->an OEM spring with an OEM cam, will support 600bhp (forced induction is obvious). This helps keep the RPM down as well.
And kind of stick to that level, for 600-800bhp, upgrade things sure, OEM isn't always best, but do not move far from it if you want to avoid the catastrophic issues associated with "racing parts" on "daily drivers". Again: If you dont need the additional wear, why bother with it?
Its obvious you know very little about how these engines work so again please stop making misinformed posts until you do some more research.
Lots of people on here run the exact sups I mentioned, its all very commons and no ones dropping valves or anything of the sort. Where do you even come up with that?
An oem ls spring is barely enough to keep the stock stuff in control. 600hp on an ls even with fi you better be swapping the stock springs. But you arent getting anywhere close to good power with stock springs. A good spring does a lot more good for the motor than bad.
Lots of people run 400lb of open pressure because its needed with a cam not because they feel like it, and guess what...No one has issues because the springs and everything else in the motor can take it.
Seriously theres so much backwards and inept thinking in your post idk where to even start
For daily driver id keep factory rockers and do trunion upgrade.
Adding heavy after market rockers on med size hyd roller asking for trouble.
Originally Posted by gnx7
Stock rocker arms have been 7's and are some of the lightest available on the market.
Do the trunion bearing upgrade and run them!
That's three votes for stock rocker arms, the first being from my engine tuner. He suggested that if I do experience valve guide wear, it won't be until after 100K mi, so I won't worry about it. He did not like the added nose weight of the Yella Terras (or most any rocker).
So, I will go with a set of Summit trunnion bearing upgrades. Hopefully I won't need to be swapping valve springs every 30K, but we will see how the Trick Flow dual springs hold up. Thanks to all for your advice, it should save me a considerable chunk of change.
As for the GT11, there are quite a few people running this cam on the street, as it is advertised as a street cam with near-stock idle (and all seem happy with it). It makes good numbers by pushing the upper limits of lift (I know), but it keeps LSA and duration near enough to stock, that it will also be possible to SMOG the car here in California, and shouldn't wreck fuel economy either.
That's three votes for stock rocker arms, the first being from my engine tuner. He suggested that if I do experience valve guide wear, it won't be until after 100K mi, so I won't worry about it. He did not like the added nose weight of the Yella Terras (or most any rocker).
So, I will go with a set of Summit trunnion bearing upgrades. Hopefully I won't need to be swapping valve springs every 30K, but we will see how the Trick Flow dual springs hold up. Thanks to all for your advice, it should save me a considerable chunk of change.
As for the GT11, there are quite a few people running this cam on the street, as it is advertised as a street cam with near-stock idle (and all seem happy with it). It makes good numbers by pushing the upper limits of lift (I know), but it keeps LSA and duration near enough to stock, that it will also be possible to SMOG the car here in California, and shouldn't wreck fuel economy either.
As I stated above theres nothing really wrong with the gt11 but everything you just listed the eps cam will do and more. The lift on the gt11 is just very high for no real good reason.
overlap which is what determines a choppy idle is (intake+exh)/2-(2*lsa) so that gt11 has (215+231)/2-(236)=-8 degrees of overlap which is a very smooth idle. the eps has (222+234)/2-(234)=-6 overlap. They will sound virtually identical and will both pass emissions but the eps will be a lot smoother on the valvetrain. Give geoff at eps a call and tell him what your goals are and mention that grind its very popular for an ls3. But another point to add is most of lope is in the tuning. I can easily make the gt11 chop if I want to or I can make it smooth. I could even make my cam with +3 degrees overlap pretty smooth and then make it rock the car if wanted. So remember that idle smoothness can be manipulated with any cam
Just because the masses use the gt11 doesnt mean its the only great choice. Lingenfelter advertises a lot so that will be reflected in what people use.
As you approach .650 lift with stock rockers the tip of the rocker scrubs the top of the valve and at that high of the lift the rocker geometry begins to go out of whack which isnt good for any components. Its not a deal breaker but something to consider. The eps will be around .600 which means a lot less geometry problems (actually none) and you can use a lighter spring which is better for your valvetrain parts as a whole. There is NO POINT in having .640 lift on stock ls3 heads.
Look at all of the people who recommended that cam and then reread my response and see if anyone is offering information like I just did or are purely recommending the cam because they have it, or like how it sounds.
AThe lift on the gt11 is just very high for no real good reason....
As you approach .650 lift with stock rockers the tip of the rocker scrubs the top of the valve and at that high of the lift the rocker geometry begins to go out of whack which isnt good for any components.....
There is NO POINT in having .640 lift on stock ls3 heads.
Called it "jumping from a cliff without good reason"
Called it "jumping from a cliff without good reason"
In b4 OP tells you to do more research
According to your posts anyone here who runs a cam much larger than stock and couples it with a dual spring like a PAC or BTR is "jumping off a cliff for no reason" and will drop a valve very soon....Of course by that same sentiment you are saying pretty much anyone with a cammed ls is living on the edge, and thats just incorrect and blatantly shows your lack of knowledge.
If the op chooses to go with the gt11 hell likely never have an issue but the info is out there to show that at .650 lift you may not want to use stock rockers. The cam I recommended will do everything hes asked at a safer level than the gt11. Do you have any factual information? Or just more hearsay about people dropping valves with performance cams and springs? Until you can do something of the sort its pretty evident you have no idea how these engines work.
Personally over 630 lift I would recommend roller rockers. Yes the stock steel rockers are a bit lighter over the tip. But the amount of scrubbing vs a properly shimmed and set up roller rocker is night and day. If you're concerned about weight, lighten the valves, keepers, retainer all you want and you can be net lighter than the stock rockers and stock valve train.
When you install an aftermarket cam, you have to look at valve springs as a maintenance item. Higher lift = higher ramp rates = more maintenance. Lots of people forget this and run them. Never check them.
The other very common problem is people fail to beef up the heavy side of the valve train. Running stock lifters and slightly better than stock pushrods under much more severe conditions to save a couple hundred bucks and it costs them the motor.
So, if you're not upgrading lifters and pushrods, don't go too big on the cam. You'll get valve loft or valve float and possibly cause damage. If you're putting in good lifters and 11/32 pushrods or 3/8 pushrods, you've got nothing to fear. But check your springs once a year. Once every six months is preferable.
And I would like to try to convince you to look at cam motion for cams. He will grind you whatever you want but his in house designs have very smooth lobe designs.
Personally over 630 lift I would recommend roller rockers. Yes the stock steel rockers are a bit lighter over the tip. But the amount of scrubbing vs a properly shimmed and set up roller rocker is night and day. If you're concerned about weight, lighten the valves, keepers, retainer all you want and you can be net lighter than the stock rockers and stock valve train.
When you install an aftermarket cam, you have to look at valve springs as a maintenance item. Higher lift = higher ramp rates = more maintenance. Lots of people forget this and run them. Never check them.
The other very common problem is people fail to beef up the heavy side of the valve train. Running stock lifters and slightly better than stock pushrods under much more severe conditions to save a couple hundred bucks and it costs them the motor.
So, if you're not upgrading lifters and pushrods, don't go too big on the cam. You'll get valve loft or valve float and possibly cause damage. If you're putting in good lifters and 11/32 pushrods or 3/8 pushrods, you've got nothing to fear. But check your springs once a year. Once every six months is preferable.
And I would like to try to convince you to look at cam motion for cams. He will grind you whatever you want but his in house designs have very smooth lobe designs.
Great post.... agree completely. Valve train has to work together.....too mahy upgrade one part, but ignore the rest. When all is matched up and maintained properly, it should cause no problems.
According to your posts anyone here who runs a cam much larger than stock and couples it with a dual spring like a PAC or BTR is "jumping off a cliff for no reason" and will drop a valve very soon....Of course by that same sentiment you are saying pretty much anyone with a cammed ls is living on the edge, and thats just incorrect and blatantly shows your lack of knowledge.
If the op chooses to go with the gt11 hell likely never have an issue but the info is out there to show that at .650 lift you may not want to use stock rockers. The cam I recommended will do everything hes asked at a safer level than the gt11. Do you have any factual information? Or just more hearsay about people dropping valves with performance cams and springs? Until you can do something of the sort its pretty evident you have no idea how these engines work.
Whoa. Everything I own has a "big cam". Cam "size" is in the duration, the length of valve opening, not whether it moves the valve and extra .100 inches or not. If the head can achieve best flow, or even better flow, at low valve lifts (and many do), then any extra lift is pointless.
Alternatively, even if the head DOES flow more at higher lifts, the question remains can the engine UTILIZE that flow effectively.
And lets just say FWIW that an engine does and can utilize/flow more at higher lifts. There is still the nagging question of: Is it worth it, how much do I gain vs lose. There is something to lose when increasing valvetrain weight/resistance to the engine turning. If the gain is 20 horsepower but now I have to change my valvesprings more often (more maintenance = not a daily driver friendly choice), and I lose 2mpg from increased resistance to spin the engine, and my poor bronze guides last half as long, I don't feel that is a very fair trade. It has to really really be worth it, i.e. I need that extra power to win the race, so I can make $$$$$, screw engine longevity/maintenance costs.
All engines work on similar principles. Doesnt matter if its for an aircraft or truck, internal combustion is pretty well known design and there are plenty of improvements to it since the time of these "lsx" versions of affordable V8 tech to learn from and gain advantages by understanding how they all work on those same principles. Valvetrain is just to get the air in and out while timed to piston movements/rate. Everything plays a role, combustion chamber shape, head port design, valve shape/angles, even the geometry of the intake manifold can affect how air moves around the valve and into a chamber and the pressures within the exhaust and intake manifolds. Daily drivers are best with smaller ports than "racing sized ports", just like they are better with smaller cams than "racing sized cams", so when we say daily driver, we are assuming good inlet port velocity, great fuel vaporization and economical use of that fuel, ports which facilitate the increase volumetric efficiency associated with acoustic tuning that complements the style of the exhaust system and... the valvetrain events, which together have more of an effect than anything on a street car when they are timed well within the range of normal driving RPM by ensuring a high Volumetric efficiency whenever the user stabs the pedal at any speed.
Run a lower lift cam in the .600" range and the stock rockers with the trunion upgrade.
I'm running what could be considered a "mild" dd setup with the exception of the lobe profile. 225/227 +114 .612"/.614" both with LSL lobes. Passes the sniffer here.(barely) They are NOT a quiet lobe. Johnson 2110 lifters, custom 11/32" manton rods(3/8" won't fit the AFR castings), shimmed YT ultras and hollow manley ss valves with PAC duals. Combined with the Mamo 220's the throttle response is absolutely fantastic. My only regret is the lobes. Should have gone with slower ramp rates. I don't mind the maintenance just the noise. (this is an LS1)
At the end of the day I did not want to have any stability issues. Last setup was just wrong on many levels. I only went with the YT because of the bronze guides. I would have rocked the stock rockers all day long if I had the powdered metal guides.
Sorry I have not been able to get back to this thread earlier, as I have been busy with work. Thank you all for your advice, I do appreciate your guidance.
Originally Posted by redbird555
...overlap which is what determines a choppy idle is (intake+exh)/2-(2*lsa) so that gt11 has (215+231)/2-(236)=-8 degrees of overlap which is a very smooth idle.
I think something may be wrong with the math here. The GT11 lists overlap at -13.0 degrees.
Originally Posted by redbird555
...the eps has (222+234)/2-(234)=-6 overlap. They will sound virtually identical and will both pass emissions but the eps will be a lot smoother on the valvetrain. Give geoff at eps a call and tell him what your goals are and mention that grind its very popular for an ls3.
After doing some thinking, I believe you are right. I had not anticipated that the GT11 would put such high levels of stress on the springs, and that even aftermarket ones would not last. That is not what I want in a daily driver. Thank you for the advice, I will call Geoff at EPS soon.
Originally Posted by redbird555
Just because the masses use the gt11 doesnt mean its the only great choice. Lingenfelter advertises a lot so that will be reflected in what people use.
Look at all of the people who recommended that cam and then reread my response and see if anyone is offering information like I just did or are purely recommending the cam because they have it, or like how it sounds.
Although I have always respected Lingenfelter's brand, the main reason that I wanted to go with this cam is that I could actually see the results in a comparison test with other cams, in addition to SMOG/MPG friendly stock-ness of the events. A custom cam is surely better, but it is harder to predict the outcome.
More specifically, every shop which grinds cams will tell you that they make the best ones (and realistically, what business would tell you that a competitor does it better?), so it is hard to know whom to trust with defining your engine's final personality. I don't plan to buy multiple cams and compare them, and even experienced modders here seldom try more than two or three cams on the same engine, so advice must also be taken with a grain of salt. In absence of comparison numbers, one cam's output may look good, but given all the variables, there is no guaranty that I won't wind up with a car that fails SMOG, or leaves like 5 MPG on the table in an attempt at easy power gains.
It's not that I am distrustful, it's just that it is hard to be a savvy consumer with a product that offers such a custom experience. I suppose I just need to have a little faith, and trust those of you whom have had experience with specific vendors.
Originally Posted by redbird555
As you approach .650 lift with stock rockers the tip of the rocker scrubs the top of the valve and at that high of the lift the rocker geometry begins to go out of whack which isnt good for any components. Its not a deal breaker but something to consider.
Agreed, this is what prompted the OP. The scrubbing and side-loading of the valves is a concern.
Originally Posted by redbird555
The eps will be around .600 which means a lot less geometry problems (actually none) and you can use a lighter spring which is better for your valvetrain parts as a whole. There is NO POINT in having .640 lift on stock ls3 heads.
The engine will not have stock heads. I will be using GM Performance CNC'ed heads. I will also be using a ported stock LS3 intake. I am doing my best to get a lively engine that is willing to change RPM quickly and is responsive to throttle input. Being that it is a daily driver, the times where throttle input and RPM will be at their peak for 500 or so horses will be very few-and-far-between. I feel like this goal will yield a more entertaining experience on the street.
......After doing some thinking, I believe you are right. I had not anticipated that the GT11 would put such high levels of stress on the springs, and that even aftermarket ones would not last.......
Why don't you just spend the very small fee charged and have a cam spec'd to do exactly what you want it too.
I used Pat G. for this service but there are a few guys who are geniouses with this stuff.
I got everything I wanted out of my cam..... just be sure and be specific on your personal goals and wants.
05-07-2016, 07:42 PM
Steel or Alum. Rocker Arms? 
