I have searched trying to find the answer to this question, but no luck. Can anyone tell me if swapping out my stock rocker arms for roller rockers (same stock ratio), will make a horsepower difference?? I have a stock INTERNAL engine. My mods so far consist of a lid, 85mm MAF, LS6 intake, QTP LT headers, 3" ORY, Corsa cat back, NGK TR55 plugs, 8.5mm wires, HPP 3 (just to adjust shift points and remove top speed limiter) the car is a 99 A4 Trans Am, 18x9.5 ZO6 wheels with 265/35 rubber. Please help any inputs will be appreciated. Also what mods would you recommed??? I do most of the work on my car myself, but I have never cracked into the internals of an engine. Any mods you can suggest, brakes, suspension, or engine. This car is my daily driver and sees the track about twice a year, it also autocrosses about twice a year too. So as you can see daily driving is my main concern with her. Thanks

 

Being a 99, I would do a leakdown test and go from there.
If everything is sound on the block, then perhaps a Stealth cam with valvetrain and THEN new rockers.
You can always send yours to NASTY'S and get them upgraded with clips and new trunions for peace of mind. I think it is like 250>260$$

 

That is the route I'd suggest. No HP to be gained worth speaking of with roller rockers.

 

I just got my roller rockers yesterday from Nasty Performance ! nice piece of material. Give Nate a call he will be able to help you out.

also check here for help www.ls1howto.com

 

waste of money for you performance wise now...the stock rockers may fail eventually..just change them when you do a cam/springs. www.rapidmotorsports.com is the best

 

Thanks for the inputs. Does anyone have any other opinions for the rest of the questions?? ttt

 

i would suggest a mild cam and spring package. something like a 224 or such for a daily driver with a good tune should be a good daily driver
nate

 

I would say that there are a bunch of other things you could get before roller rockers. A nice stealthy cam would be my recommendation - suspension pieces as well. I personally got a set of roller rockers (which still have yet to be put on - but that is another issue) to quiet the valvetrain slightly (after the cam install) and the fact that I destroyed a stock rocker and had to fish out needlebearings. I also got a used set for a pretty decent price.

The rockers have a potential to gain a couple of horses due to flex in the stock rockers but I am pretty sure that would be more of a function of how much lift you have in the cam.

 

A roller rocker also has a ROLLER on the valve stem end to roll across the valve instead
of scrubbing like the stock ones do.A very small amount of friction will be reduced from
this also.Comp cams sells pro magnum rockers for these engines that have these features and allow you to set lifter preload accuratly.Unfortunatly they only come in
1.75 or 1.85 ratio not the stock 1.7.These rockers require you to modify the drivers side valve cover also,if you don't have a 98 car.

 

I was talking with Roger Vinci about this today. He said he and Crane have been working a great deal on this. The problem is that most people ASSUME that the stock 1.7 ratio LS1 rocker is a 1.7 ratio everywhere. It isn't. In fact it's almost impossible for a rocker to have a constant rate since the valve end and the pushrod end operate on two vastly different arcs. (this throws a monkey wrench into a lot of the cam design threads which assume a constant rocker ratio). According to Roger( he set up a pair of dial indicators on an engine, one on the pushrod -with a solid lifter installed- and one on the retainer and put a degree wheel on the crank and ran a whole lift chart and calculated the rocker ratios at each point) the stock rockers start the valve off the seat at a ratio of 1.54:1. The stock rockers do not achieve 1.7 ratio until the lifter is on the nose of the cam. He said many of the other "value" rockers are even worse and start the valve off the seat at an even lower ratio. That's why the Crane accelerated lift rockers provide power where others don't.. They start the valve off the seat at 1.79 and by .250" valve lift come back to 1.72 which they maintain through the rest of the lift cycle until the valve is within .250 of going back on the seat at which time it goes on at a rate of 1.79:1 Since "valve lift" ="cam lift" x "rocker arm ratio", ths results in much greater lift under the valve lift curve and that's how he says the Crane rockers make power when others don't. He said installing a shaft mount system actually raises the pivot point of the rocker and makes this action worse in some cases. All I know is that the Crane rockers made a significant performance increase throughout the whole operating range on my Tahoe.

There are some on this site who have said that this accelerated ratio would be harmful to the engine. According to Roger, many stock OHC cam/rocker combinations used by Honda and Toyota use faster opening and closing rates than what can be achieved with the pushrod engine and they sure don't have any reliability problems! I think Roger might be on to something here!!