Yella Terra Roller Rockers Ratio...

[Frandy]

Hey guys,
Just wondering what would be the best ratio for YT Roller Rockers on a N/A Ecotec V6. All it would have done to it would be a 70mm TB, CAI, 2.5" or twin 2.25" Cat-back Exhaust and Pod Filter.... Any reccomendations?

How much would it set me back, roughly??

CHeers
Francis

[sircruisealotVS]

i have 1.8's on mine, theyre good...i had them on before i did the stroker build when i only had extractors and exhaust, chip and cai into pod..they went really well, had lots of fun till i got used to the power.
from memory i paid almost $1k all up, because at the time i didnt have the time or tools (was moving house) to fit them myself so i got my mechanic to do it.
but the rockers themselves cost around $700-800 (from memory) and are easier enough to bolt on yourself.

[Frandy]

so 1.8 ratio would suit a stock 3.8 fine?? Would a bigger ratio slow the car down?? im not too sure how they work to be honest, just know they are good bang for buck

[sircruisealotVS]

yep, they would be fine...what they do is basically increase the total lift of the valves, and also create less friction in the way they move.
a stock rocker is 1.6 ratio, just so you know.

[Surfwagon]

so 1.8 ratio would suit a stock 3.8 fine?? Would a bigger ratio slow the car down?? im not too sure how they work to be honest, just know they are good bang for buck

If you haven't bought them yet then the biggest ratio would be best because unlike a camshaft change, high lift rockers don't change the timing so you don't get those loss of torque problems like when icreasing opening times and overlap.
I would go for 1.9 Ultralites and not the older Stealth design.
With the stealth the plate that centres the pedestals also spaces up the rocker cover to provide clearence because the Stealths being cast are physically bigger than the Ultralites.
I'm not sure of cost at the moment but there is not a lot of difference between the two different types. There are also 1.95 Ultralites.
I suggest giving Mark (tappethead) or any of the guys at Yelle Terra a ring on 03 9555 5522

[blaze]

yeah wen i get mine im gettin the 1.9s i think v6supercharged.com do a 1.97

[Frandy]

so it doesnt matter how high the ratio is, it wont make the car slower, like wouldnt be overkill?? The bigger the better??

[sixshooter]

so it doesnt matter how high the ratio is, it wont make the car slower, like wouldnt be overkill?? The bigger the better??

Yeah it will be over kill at a point when the valve retainers hit the valve guides or the springs bind up...ending up with bent pushrods, or snapped rockers. You can only lift the valve so far off it's seat...without machining the heads to suit !!!

[Frandy]

so pretty much 1.97:1 wouldnt be overkill?? Would just increase power

[sircruisealotVS]

like surfwagon said, give yella terra a ring or email and ask just to be certain what would be best suited for you. upping the lift too much may cause issues with stock springs, having the neccessary clearances wont be a problem, its just a matter of what ratio stock valve springs will be happy with (which i dont know off the top of my head).

[Surfwagon]

I fitted new slightly heavier valve springs when I rebuilt my engine but prior to the cam bearing failure that cause me to lose oil pressure I had been running 1.9 with no problems with the stock springs.
Only changed them because engine was apart anyway otherwise would not have bothered unless I started to get valve bounce which only happens up near redline anyway which I vary rarely see.

[immortality]

again, talking to YT, they should know exactly the max lift you can achieve with a standard engine. if they offer it, it should fit without a problem.

[Raptorsc]

We fitted FIT 1.97:1 rockers to our car last week, the extractors and exhaust didn't really do anything but the rockers accounted for at least a 16Kw gain and about 4Kw to the extractors and exhaust.

[Surfwagon]

Hey Raptor
Did you dyno the engine with just the extractors and exh or are you just guessing that the 1.97's made 16 of the 20+ rwkw.
Also for choice YT do a 1.95 ratio and granted it doesn't lift as far as the FIT rockers but the YT kit is a couple of hundred $'s cheaper.

[Raptorsc]

Surf

We are guessing the exhaust/extractors made 4kw difference.

Regarding the extractors and pipe we only made .13 of a second (and no change in MPH) improvement at the strip, also to drive the car it felt like there was only the slightest gains, after fitting the rockers at least the difference was very noticeable. Of course until we run again we don't know the strip difference.

Essentially, would anyone like to put an exact figure on the .13sec improvement at the strip in terms of KW for the extractors and pipe upgrade?? We went for 4 kw ........ hence the reason why the rest of the increase is being put with the rockers. A .13 gain could be made with just a tail wind in all probability

[Surfwagon]

I guess if your using extractors and HSV exhaust similar if not the same as XU6 then 4rwkw probably is about right because at the flywheel the difference from the factory was only 9kw (171-180) in the VT-VY's.
If it is the factory HSV system you'd definitely free up some horsepower changing that rear triple direction flow resonator for a straight thru one.