cgEvan

iTrader: (1)

Could I just upgrade my rockers to 1.6 ratio or 1.7 ratio and gain lift/duration? When I had my 5.0 Mustang, I read a write-up of a magazine doing AFR 185 heads, headers, intake, and 1.7 ratio rockers on the stock cam/bottom end, and making XXXhp (I want to say something high, around 400hp).

Thanks.

JB_97ws6TA

iTrader: (6)

you can gain lift but the duration is ground into the cam, that is not going to change. I am not sure what the factory cam lift numbers are and i doubt that the stock springs would be able to handle the added lift but I am sure someone who has more info on this subject will be able to chime in but to answer your question yes you can add lift by changing rockers but your duration remains the same

gregrob

iTrader: (8)

Yes you will pick up some power from the added lift. You will need new valve springs

97badass

iTrader: (8)

sorry to hijack the thread but... how much do you gain with the stock cam and 1.7 RR?
i think he is also trying to figure this out.

lt1srule

iTrader: (10)

you will need springs .stock springs suck ..

97badass

iTrader: (8)

we know we need new springs as well. with new springs and 1.6's dont you gain like 10-20 hp? so with 1.7 shouldn't you gain like 15-25?

Wooshie

Duration is ground into the cam , but since your valvetrain geometry changes it does affect duration (Like 1-2 degrees)

ss.slp.ls1

iTrader: (36)

I think a conservative number, ~15rwhp, is what I would expect from 1.7rr's and springs.

97badass

iTrader: (8)

ok i just figured with a slightly bigger rocker you would gain more power

JB_97ws6TA

iTrader: (6)

I am not too sure about that, your geometry really isn't changing you just have increased rocker ratio but your lifter rides up and goes back down at the same time as it always would have, your pushrod would still rise and fall as it always had, your rocker would open and close as it always had with the exception of an increased multiplication of lift at the valve but other than that everything remains the same does it not?

kinglt-1

iTrader: (26)

^ Increase in rocker ratio does affect duration. Going from 1.6 to 1.7 will bump it 1-2 degrees.