Roller rockers

[Inch]

Hi Holden fans, Dose anyone no kw gain i would get if 1.8:1 roller rockers were used on a 255 kw ls1 motor

[vxchev]

Hi Holden fans, Dose anyone no kw gain i would get if 1.8:1 roller rockers were used on a 255 kw ls1 motor

If you add higher ratio rockers it will change the lift of your cam and will change your power output, very hard to give a guestimate. I guess you know you need to change your springs as the stock one's will let go.

If you know the spec's of your cam to work out the new lift you divide the lift by 1.7 and with the answer you times by new ratio to get the new lift
i.e .559 / 1.7 = ~.329, you then take that lobe lift and multiply it by whatever rocker ratio you want. With SLP 1.85 rockers your new lift specs become .329 X 1.85 = ~ .609

Your cam spec's may be the one below

Manufacturer - Model----------Dur Int-Dur---Exh-Lift-- Int Lift Exh--LSA
GM---body (2001 - 2002)......196......207....0.467.....0.479...........116.0
with 1.80 ratio...........................................0.494......0.507
with 1.85 ratio...........................................0.508....0.521

Your better off changing the stock camshaft to a performance one and not worry about changing the roller rocker ratio.

Here is a link to explain camshafts

[Inch]

Thanks for the info on the cams. Also not much info on 4" maf pipe for ls1,are thay as good as thay make out

[vxchev]

yeh, there is but it's all relative to other changes, best thing to do before buying one is to mod your HSV CAI with a second hole then you will have more air getting into your airbox.

[Inch]

THANKS, I have already put a second hole in and have a after market air filter,MAF pipe would be next ?. Dont no cost to get one to NZ.

[vxchev]

Got to a local HSV dealer and give them the VX GTS Maf pipe part number 06M3990701 I think they around $160-$180AUD if you have no luck may be try the shop on the forum to see if they will separate from the MAF package here
postage from AUS would be cheap the MAF pipe weights not very much at all.
If you have no luck send me a PM and I'll steer you to other places.
Keep away from ported MAF's from my experince the gain was is 5.5rwkws, I took the ported MAF off once I got edit and never looked back.

[Inch]

Thanks for your input