Can someone/anyone....enlighten me on what these things exactly do, cost and how much power is gained.....as you can see, I need a LOT of info :D :cheers:

 

My understanding is that roller rockers provide a little decrease in friction in the valvetrain .. you don't get a big horsepower boost.

 

Actually, they provide a dramatic decrease in friction at the rocking point of the rockers. On an LT1 they show about a 5 HP increase, but more importantly, they showed a decrease on 10 degrees in oil temperature! Free HP!

As long as you are in there performing a swap; be sure to align the rocker tips so that the are evenly centered over the valve stem to minimize valve stem wear. {This means they roll from the inside 1/2 edge of the valve(closed), over the center to the outside 1/2 edge (1/2 open) and back to the inside 1/2 edge (fully open) as the valve is opened by the cam.}

 

I actually would be surprised if the LS1 in the Vette does not come standard with roller rockers - I'm embarrased that I don't know for sure.

What really happens to increase performance is changing the "ratio". Basically, buy changing the fulcrum point, a rocker arm can open the valves more (higher lift). Obviously, there is a practical limit in making sure the valves don't contact the top of the piston - not a good thing.

How much hp this gets you is pretty questionable. Hopefully, Kyle with House of Speed will see this and give his input as he seems to be a fan of this set-up (Hopefully other tuners will chime in as well. I just remember Kyle stating his thoughts on them a while back). I am not near as qualified as the tuners, but this is a start.





[Modified by jschindler, 9:13 AM 3/4/2002]

 

Mark, they dont come as standard. I seriously considered these when the heads were changed. I was told that the difference is very minimal. They are not cheap.

 

Well, I am not Kyle, but maybe I can field this one.... :) :)

The stock LS1 Rockers do have a roller fulcrum point, but not a roller tip. On the LT1, some of the HP gain is actually had by adding the roller fulcrum without changing the ratio. The roller tip generally does not add any HP in and of itself, but can also contribute to lowering oil temps.

You can also get more HP by changing the ratio of the roller rocker or adding mechanical leverage to the fulcrum point. This will increase the lift height of the valve off the seat. It will not increase seat to seat timing, this is mechanically set by the camshaft. You will see a slight duration change at say .300" of lift.
This will all culminate in the increase of HP on your engine.
One of the disadvantages of going with these would be the increase in side load on the valves. This can cause premature wear to the valveguides resulting in needing to "freshen" the heads with either guide liners or new guides and a valve job. There will not necessarily be a HUGE increase in this, but there will be some and you will wear you guides out faster.
You are also putting more stress on the studs holding your rockers to the heads. This is only minimally though.
The price of these for the Crane ones are $699.95 and come with guideplates and pushrods.

I hope this helps.

 

Yea, what Chris said. :yesnod:

FYI, my experience with aftermarket rockers: not worth the headache. They're noisy, require additional maintenance, and just simply don't do that much more than the stock rockers for the $$ or hassle, unless you're building a nice complete motor. Even with a H/C car, I don't think they're too beneficial. Just my opinion though, not gospel. ;) :cheers:

 

Chris' latter comments, side loading and so forth, pertain to increased rocker ratio, roller or not. A full roller in a stock ratio e.g. wouldn't have those issues (any worse than the stock rocker anyway.) Mass of the rocker is another thing to consider.

You could think of the 1.8 Cranes as a poor man's cam swap if it got you more HP and didn't cost so much. :D

 

As Chris said the Crane 1.8 Roller Rockers basically simulate a slightly larger camshaft by giving more duration and lift. If you get stock ratio roller rockers, you really only get the advantages of a slightly smoother valvetrain.

I have never seen any gains with the 1.8 Cranes on an LS1 that have impressed me. I really think you are best off spending the money on a new camshaft and getting the extra duration and lift the real way, BIGGER CAM :)




[Modified by MattG, 12:00 PM 3/4/2002]

 

thanks for all the info guys...."x'd" off the list, thanks....anyway I'm getting ready to spend WAY too much money on the interior, guess I just wanted to know :D

:cheers:

 

An opposing view :D

Adding them when you do a H/C package can make sense. They are not necessarily noiser than stock lifters, it depends on how well they are adjusted. Also, since the stock rockers are a 1.7 ratio and the Cranes are a 1.8, you will add additional lift to a particular cam swap and gain some additional HP there. In addition, they are significantly lighter and stronger than the stock rockers, again reducing the force to actuate the valves as less mass has to be moved on the fulcrum.

They are not cheap, but do reduce friction and heat in the valve train. Mine went on with my HC package so I don't have comparative numbers to give you.

my .02

 

If you are measuring weight over the valve, I do not think that they are lighter. As a matter of fact, I am pretty sure that these are heavier than stock.
More lift will only increase HP if the heads flow in that range. If your air flow goes turbulent at a certain lift, you will not only not gain power, but you will also loose power. A camshaft really needs to be selected around what the heads air flow characteristics are. With this, the ratio of the rocker needs to be set at that time so the camshaft can be chosen.

Hope this makes sense.
Thanks,

 

i added the 1.8 roller rockers to my car when I installed the LS6 intake, TPIS Longtube Headers, Be Cool Radiator & PS oil cooler. If you do this be sure to have your Valve springs replaced at the same time... If you dont you will get Valve Train Float above 5600 RPM...

vetterdstr :cheers:

 

Another thing to consider is that mass manufactured factory rocker arms are notorious for wide variations in ratio resulting in cylinder to cylinder intake and exhaust inconsistencies.

After market rockers like those from Crane, Competition Cams, Lunati etc. tend to be more uniform.

It's a mod I'm considering next as you don't have get down into the engine for the swap.

Everett

 

I would thing that the tolerance variance is a thing of the past. With the old style stamped rockers the variance was great and aftermarket were almost a necessity. The stock rockers seem to be designed very well with reinforcements where they need to be. I would guess they are lighter than the crane rockers. I guess there is not much to be gained with a roller tip (it only moves fractions of an inch along the valve stem) and increased ratio. The vendors seem to thing the rockers are not a good bang for the buck mod. Has there been any proof of HP of torque increase with just the rockers?

 

I would agree that the cast rocker arms of the LS1 are probably more consistent than the stamped pieces used in the LT1. But, I don't think they're nearly as uniform as the better after market units. Lunati, for example, extrudes theirs then finishes them up on a CNC machine before tumble polishing.

As far as hp/tq increase, there's an article in the April issue of Vette about the effects of rocker arm tuning on engine output. While more is not always better, for a given cam, changing the rocker arm ratio in effect changes the lift and duration of the cam. It also changes the geometry of the valve train slightly which alters the stress and strain on it as well.

Everett



[Modified by EBSDallas, 4:27 AM 3/5/2002]

 

One of the things I did notice after the 1.8 roller rockers were installed was that the top end of the car pulled harder. I dont know if that was helped by the Intake and headers or not... I am not the kind of person who does just one Mod and then takes it to the dyno so I dont know exactly what the Rockers would have dynoed by themselves... IF I had to guess I would say that the rockers were good for 5 rwhp maybe a little more. I know you might tell yourself it is not worth it or the bang for the buck is minimal... I have already installed all the big bang for the small buck mods on my car now... the only thing left is the big $ ones. :)

vetterdstr :cheers:





[Modified by vetterdstr, 4:58 AM 3/5/2002]

 

In my opinion, if you don't mind changing your valve covers, you can't beat the Jesel setup, and the price isn't too bad, around $700 for the 1.7 ratio.

 

I ran into this guy at SpeedWorks that was pushing this
http://www.hotrocker.com/

you decide.

Jeff Nation

 

Interesting concept.

I would hope a professional shop is matching the rocker assembly to the heads, cam, intake, headers etc. when choosing a configuration so as not to lose power/torque by mismatching the components.

Blindly slapping any component onto a car "could" backfire and lose you power/torque.


[Modified by K&B Motorsports, 6:58 AM 3/5/2002]