2002 SS HUGG

So, I've done readings of Aftermarket RockerArms (Harland Sharp & Yella Terra) and both advertise between 10-15 rwhp gains based on reducing friction in the valvetrain. I'm just curious if rwhp is actually a plausible advantage of these rockers, or no? Also, what other advantages could one attain with Aftermarket Rockers? Better Valvetrain Geometry? Reducing weight within the Valvetrain? Quicker Revs? idk...just trying to broaden my knowledge fella's.

vettenuts

iTrader: (4)

The lightest rocker out there is the stock rocker. Here is why I run the YT's on my car. I tried to set up the stock rockers to get the correct geometry but wasn't able to do it. Several rockers didn't even contact the center of the valve stem but were skewed towards the front/back of the valve. The YT's gave me an excellent geometry and a very narrow wipe pattern. I wanted this to minimize the wear on the bronze valve guides that are used in many of the aftermarket heads. As for hp gain, if I got 5 hp I would consider myself lucky. I installed them for a better geometry, not for a hp gain.

PS: The roller tip actually doesn't roll it slides on the valve.

KCS

iTrader: (20)

I agree, the main advantage is better geometry and adjustability. Depending on the rocker system, you can adjust the rocker goemetry easier and even use different pivot lengths. I'm sure you could adjust the height on the stock rockers (mostly), but I haven't tried that yet. For low lift, low spring pressure, streetcar type stuff, an upgraded stock rocker works pretty well.

TurdsOfMayhem

iTrader: (4)

Good post, I've been interested in this as well.

2002 SS HUGG

Yeah, I figured the reality of extra hp was probably out of the question...but figured I would see if anyone actually made hp gains. Now you said, "the main advantage is better geometry and adjustability." With that said, I know you said "the rockers allowed for a very narrow wipe pattern...and they allow you to use various pivot lengths," but what other kinds of valvetrain geometry could one expect out of Aftermarket Rockers? Durability, HP limits, heat treatment...etc. And also, could I expect better valvetrain geometry out of an adjustable rockerarm or would let's say a Harland Sharp 1.7 Non-adjustable be just as good? I know I may have just opened a whole discussion on whether adjustable or non-adjustable rockers are better but I don't care.

vettenuts

iTrader: (4)

The advantage of the adjustable is if you have a lifter with a tight tolerance of preload, such as the Comp R. However, some adjustable rockers have the adjustment at the pushrod cup, which puts it on the moving part of the rocker even though it is on the slower side. Stud mounted adjustables have more flex then those designed with a fixed pivot and adjustment on the pushrod cup.

The downside to aluminum is the fatigue strength is lower than steel generally speaking. From that standpoint, I would expect an aluminum rocker to fail sooner then one made from steel, all things being equal. Aluminum is also 1/3 as stiff as steel so more material is required to obtain the same stiffness (these are generic statements without getting into details of any particular rocker design). Of course it is lighter too so the extra material correctly placed doesn't have to provide a large penalty in rotary inertia. That being said, the stock design is an excellent piece.

The key is understanding the limitations of the design and living within the limitations.

MelScrilla

iTrader: (2)

I've read that a aftermarket roller rocker provides a little more lift than a stock rocker hence a little more hp.

If thats totally incorrect than someone please correct me.

SweetS10V8

iTrader: (4)

Not even concidering geometry.....I would take a sliding follower over a weight adding "roller" wheel any day......

Roller wheels are just added weight IMO. But they make people feel good for some reason...

I like SLPs 1.85 rockers, but I cant handle the extra ratio, or Ill have an LSK type lobe and need new springs. Thats why I run stockers with my CNC LS3 heads.

KCS

iTrader: (20)

By adjustability, I was referring to geometry. Take Comp's Pro Mag's that go back to old school stud mount rocker design. Now the pushrod effects preload/lash and geometry by moving the rocker up and/or down on the stud. You can actually play around with different pushrod lengths, changing the lift profile that the valve sees, and potentially gaining power that way. A LSx rocker would require milling/shimming the stands to move around the rocker. Just about any design is adjustable, it's just some are easier than others.

As for the rollers, there is some pretty knowledgeable experts (more so than I at least) that claim the roller isn't a friction advantage. Supposedly, the "scuff" design of the LSx rocker has a major inherent flex as it "scuffs" back and forth on the valve tip, which alters the pivot length as it stretches and compresses towards and away the trunion axis. The roller stabilizes this point better, which leads to more favorable ratios throughout it's sweep. To take advantage of the MMOI a "scuff" design provides, most teams DLC coat the rocker tip-valve tip interface to reduce that friction/flex. That's $$$.

2002 SS HUGG

This all very knowledgeable information I'm receiving. Thank you guys. However, there are a few things that stand out to me, that I would like clarified.

One, "The advantage of the adjustable (rocker) is if you have a lifter with a tight tolerance of preload, such as the Comp R." Now, I would think a lifter that has a tighter tolerance of preload, let's say between .06 and .08. Hypothetically, wouldn't it be suited best by a non-adjustable rocker, where preload is measured, decided and kept in check by pushrod length and not by the rockers? Or am I totally out in left field?

Secondly, "Supposedly, the "scuff" design of the LSx rocker has a major inherent flex as it "scuffs" back and forth on the valve tip, which alters the pivot length as it stretches and compresses towards and away the trunion axis. The roller stabilizes this point better, which leads to more favorable ratios throughout it's sweep." With this said, could someone go further with this "Scuff" design? I'd like to hear more about this...thanks.

vettenuts

iTrader: (4)

The Comp R (per Comp) preload is 0.002"-0.004". Pretty hard to achieve without some fine adjustability. Having said that, a lot of guys are running them with more preload then Comp recommends.

2002 SS HUGG

Vettenuts, thanks for the info. That's an odd amount of preload to be running on a lifter... a lot like a solid roller...imo. lol

Now, a lot of people recommend staying with the stock rocker arms, because they are suppose to be pretty durable and not prone to breaking. Now, is there anyone here that would recommend using let's say (Harland Sharp or Yella Terra) Rockers, rather than stock? For the added $450 insurance?

melsie68

iTrader: (8)

Be careful of what you read on the internet... If you want to know what a rocker arm does, call T&D or Jesel and have a conversation with an engineer or at least some one who might know something.

For all intensive purposes, the stock rocker arms are very well suited to any hydraulic roller application and are even better with the bearing upgrade from Harlan Sharp. And just for the sake of argument, the latest NASCAR rocker arms are steel and are built with a button tip- in other words NOT a roller tip.

Chrome355z

iTrader: (1)

I'd stick with the stock rockers on your typical "street car" ls1 build. Which would include LS1/7 lifters, hardened pushrods, COMP/PAC springs, and your typical XER lobed camshafts... They can more then handle those applications.

Upgrading to Comp-Rs, aftermarket heads w/ bronze valve guides, etc... then you can start to see benefits from the aftermarket rockers adjustability. But i'm far from an expert.

teke184

iTrader: (5)

for the most part...only if they are designed to increase lift. they do this by increasing the rocker ratio.

stock for the ls1 is 1.7:1, but there are 1.75:1, 1.8:1, 1.85:1 and i think Vinci makes a 1.89:1 version

those will increase lift, which can increase flow, which will proably increase power more than the "reduced friction"

to see what lift will be:

(advertised cam lift)/1.7 = X

(X) x (new rocker ratio) = final lift


example:

cam with .550" lift in standard ls1 application, upgraded to 1.8:1 rockers

.550/1.7 = .3235
.3235 x 1.8 = .582" of lift with 1.8 rockers

Old SStroker

The total moving mass of a stock LS rocker including the upgraded needle bearings is under 100 gm. That's pretty easy to control compared to considerably more massive (heavier) roller rockers, with a greater % or their mass over the valve (the steel ROLLER).

FWIW: You can use nonadjustable rockers with solid lifters. Lash caps and/or closely controlled pushrod lengths work well.

FWIW-2: Lifts over .600 with stock rockers are done regularly without the deadly valveguide wear one hears on the 'net. You have to setup the system correctly...but you should do that with any system.

FWIW-3: AFAIK, Jesel and T&D don't sell non-roller rocker arms to the general public (us), so asking them their opinion on using non-rollers vs. their roller designs is probably a futile endeavor.

FWIW-4: Cup non-roller rocker valve-end tips might be a modified involute shape. And for the cigar: Does anyone know why that might be?


Jon

00 Trans Ram

iTrader: (5)

FYI - I recently built my motor for road racing (actually, Thunder Racing built it). Thread here https://ls1tech.com/forums/dynamomet...tq-411-hp.html

We went with stock rockers, with upgraded trunions.

We did this to minimize overall valvetrain weight, especially where it counts. Aftermarket rockers have more of their weight over the valve. Stock ones are almost perfectly balanced. You can verify this by sitting them on the table next to each other. Try to get the aftermarket one to sit with the long end up in the air - it won't do it. The stock one will.

I've got a smaller cam, but with great springs (925s). We have no qualms about the stocker being able to stand up to this. And, we're talking road racing, where I make a 1/3 mile "pass", two 1/5 mile "passes" plus about ten "squirts" of the throttle. All told, on a single race day, I'm running about 30 minutes (20 minutes constant) at above 3500rpm, and about 25% of that time is at WOT.

02SOMWS6

iTrader: (6)

for factory heads the stock upgraded rockers get my vote. Lighter is better