roller rockers

**tims02** · 05-06-2008, 06:57 PM

What was the problem with the rockers?

**mrr23** · 05-06-2008, 07:16 PM

Originally Posted by tims02

What was the problem with the rockers?

most aftermarket 1.8 rockers only give about 5-7 rwhp. the only rockers that give 15-20 rwhp are the crane rockers. put them on the wife's car with the stock cam. also installed the crane 832 springs to handle the added lift and effective duration change. here's the dyno of before, 500 miles and 8 months later. this was on stock tune as well.

**the_formula** · 05-06-2008, 07:31 PM

ok since ive never been on a dyno....explain that to me..is this dyno sheet in favor of the rockers or against them??

**TACE02** · 05-06-2008, 11:47 PM

now how is it that a 1.8 rocker from any company will give 5-7 RWHP increase, but if you get that same rocker from "crane" it will give 15-20 RWHP gain??? sounds like an advertisement gimmick. I don't know though, guess other companies rockers might weigh more and/or cause more parasitic loss.

**shady milkman** · 05-07-2008, 07:40 AM

Originally Posted by TACE02

now how is it that a 1.8 rocker from any company will give 5-7 RWHP increase, but if you get that same rocker from "crane" it will give 15-20 RWHP gain??? sounds like an advertisement gimmick. I don't know though, guess other companies rockers might weigh more and/or cause more parasitic loss.

i dont know...but i do know one of the gm race car had some aftermarket rockers on it...i think crane...and since there was really no regulation regarding rockers they threw them on and made some really impressive numbers..until the officals found out and banned the rockers ect.

**mrr23** · 05-07-2008, 11:55 AM

Originally Posted by the_formula

ok since ive never been on a dyno....explain that to me..is this dyno sheet in favor of the rockers or against them??

yes, it is in favor.

**mrr23** · 05-07-2008, 12:05 PM

Originally Posted by TACE02

now how is it that a 1.8 rocker from any company will give 5-7 RWHP increase, but if you get that same rocker from "crane" it will give 15-20 RWHP gain??? sounds like an advertisement gimmick. I don't know though, guess other companies rockers might weigh more and/or cause more parasitic loss.

no gimmick. that's my car and i ran the dynos. most aftermarket rockers base their design off of factory. SLP 1.85 for example look just like stock rockers.

here's an explanation on how stock rockers work and the crane rockers work.

VHP and Crane Cams have been working with each other for many years. Together, we have strived to provide the very best products we can with the latest technology available. We think, we design, we manufacture, we test....then we market the product. It seems that there has been much confusion about Crane/Vinci "Quick-Lift" cam lobes and "Quick-Lift" rocker bodies. We claim that the use of the Quick-Lift lobes with the Quick-Lift rocker bodies results in "effective valve lift" durations @ .200" valve lift equal to most other cam/rocker combinations using cams with 4-8* more duration at .050" cam lift. This is the result of the Quick-Lift Rocker body design. We do not state that our cam lobes (by themselves) give this advantage. The same laws of physics that limit every other cam designer limit our cam lobe designs. We attribute the advantage in valve lift to the "translation" properties of the varying ratio design of our Quick-Lift rocker body design. If you don’t believe us, test any cam lobe (Crane, Comp, Cam Motion, etc.) with stock LS1 rockers. Install a dial indicator on the retainer and a degree wheel on the crank. Plot a lift vs. degrees of rotation curve. Then install the Crane LS1 1.7 rockers (with the pushrods in the Crane kit) and plot the same curve. Measure the duration at .200" net valve lift. The Crane rockers will definitely provide more duration at this checking point. The reason for this is that, contrary to popular belief, the stock LS1 rockers are only 1.7 ratio above .480" valve lift. They actually start the valve off the seat at a 1.54 ratio. What do you think that ratio does to a "super fast" cam lobe? Slows it down quite a bit? The Crane rockers, properly installed, bring the valve off the seat at 1.79. Doesn’t take a math wiz here to see what combination is going to get open quicker and longer!! If you really want to see something interesting, take two lobes that have identical .050" seat-to-seat timing, identical .200" lifter rise timing, but one provides .583" valve lift with 1.7 ratio and the other providing .551 lift with 1.7 ratio. Plot a lift vs. duration curve with any rocker you want (other than Crane) and measure the duration at .200" valve lift. Then do a plot of the .551 cam with 1.8 Crane rockers (this will net out .583 also) and measure the duration difference at .200" valve lift. You will be impressed by how much more this second plot gives over the first. It’s also quicker on the drag strip! We’ve done this. Every person reading these threads can do something like this.

**mrr23** · 05-07-2008, 12:14 PM

Originally Posted by shady milkman

i dont know...but i do know one of the gm race car had some aftermarket rockers on it...i think crane...and since there was really no regulation regarding rockers they threw them on and made some really impressive numbers..until the officals found out and banned the rockers ect.

here's what you are refering to

Crane LS1 Gold Race Rockers Too Powerful for Daytona!

here's another one about the engine masters challenge that jeg's has every year

Lennart Bergqvist's Winning Engine Masters Challenge

**nhraformula** · 05-09-2008, 06:55 AM

my arguement against rockers is the fact you can get a cam kit for the same money and make more power.

**the_formula** · 05-09-2008, 07:19 AM

Originally Posted by nhraformula

my arguement against rockers is the fact you can get a cam kit for the same money and make more power.

please show me where i can get the cam kit for less than 200 bucks....ill buy 2 of them

**mrr23** · 05-09-2008, 01:19 PM

Originally Posted by nhraformula

my arguement against rockers is the fact you can get a cam kit for the same money and make more power.

and my retort to that will be is not everyone wants a cam and all that's associated with it. things like headers, better exhaust, a tune, etc.... some want more power without changing how the car sounds, acts, drives, etc..

i will never disagree that it's cheaper to do a cam over the best rocker kit to get (crane).

**Bouvers** · 05-09-2008, 09:11 PM

Originally Posted by mrr23

and my retort to that will be is not everyone wants a cam and all that's associated with it. things like headers, better exhaust, a tune, etc.... some want more power without changing how the car sounds, acts, drives, etc..

i will never disagree that it's cheaper to do a cam over the best rocker kit to get (crane).

yelleterra ultralights, however I don't know if they come 1.8 or not...