higher ratio rocker arms in turbo application

[thebeewantsboost]

Re: higher ratio rocker arms in turbo application

my post is still on ls1tech. and turbo buick, not much feedback though...
so the stock cam specs are:
how do i figure out what the lift is. with the different ratios
duration 182/190
lift .258 .255
ls 115
ic 111 <---whatever that is.
how do i figure out what the lift is. with the different ratio rockers.

is it like for a 1.9 with stock 1.6 .258 x1.3 = .335
so lift would be .335?


.255 x
1.7 to 1.9 .255 x1.2 = .306
1.8 to 1.9 .255 x1.1 .281

????

[thebeewantsboost]

Re: higher ratio rocker arms in turbo application

not sure if they are 1.7's or .8 they don't say, does anybody know another way to tell?
.335/.306(.281) sounds pretty beefy.

good reading http://www.pontiacstreetperformance....ockerArms.html

[bigbrian442]

Re: higher ratio rocker arms in turbo application

the rocker arms i have are basically an older version of those...
i'm pretty sure it doesn't effect duration... well... it sort of does.... but not really.... the cam doesn't change. so the valve opens at the same time... however.... the vamp rate is much steeper and therefore quicker... so you do have more.. "useable" duration.

Duration is measuered at a given valve lift. Each cam grinder may use a different lift number to chose the advertized duration. Most use 0.006 If your valve is opening at a faster rate, it is getting to the lift the duration is measured at quicker, increasing the duration. This is only a few numbers in most cases.

[bigbrian442]

Re: higher ratio rocker arms in turbo application

my post is still on ls1tech. and turbo buick, not much feedback though...
so the stock cam specs are:
how do i figure out what the lift is. with the different ratios
duration 182/190
lift .258 .255
ls 115
ic 111 <---whatever that is.
how do i figure out what the lift is. with the different ratio rockers.

is it like for a 1.9 with stock 1.6 .258 x1.3 = .335
so lift would be .335?


.255 x
1.7 to 1.9 .255 x1.2 = .306
1.8 to 1.9 .255 x1.1 .281

????

Those numbers look like lobe lift not valve llift. Multiply those numbers by rocker ratio to get valve lift.

[thebeewantsboost]

Re: higher ratio rocker arms in turbo application

gotcha....
i definitely understand why the duration topic is argued. i guess it just matters how you look at it. i see your point though.

you're right.... but thanx i understand the math know.

k lobe lift is (i)255 (e)258

that makes .408/.413 with 1.6 rockers

cam lift
.485/.490 with 1.9
.459/.464 with 1.8
.434/.439 with 1.7
so mine would be .490/.459 or .434. really wish i knew what they were.

[bigbrian442]

Re: higher ratio rocker arms in turbo application

I don't see how 1.9's across the board would hurt anything.

[flamingchicken]

Re: higher ratio rocker arms in turbo application

I don't see how 1.9's across the board would hurt anything.

I agree. With the numbers that you posted you could easily run 1.9's. This considering the GT2 came gives over .507 lift with 1.6 rockers, and is "designed" to run with completely stock heads and valve train. Also the link I posted earlier shows that the 1.9's make higher peak torque, than the ER's and the 1.6 rockers.

[1998silverbird]

Re: higher ratio rocker arms in turbo application

My N2O cam I had in my V6 was a 210/220 duration and 534/547 lifts. That was on 1.6 stock rockers. Think I got my cam used for 150.00 shipped.

[ssms5411]

Re: higher ratio rocker arms in turbo application

The stock rockers are close to 1.66 ratio. You need to have the guides cut down if you are running a cam and 1.9 ratio.

[flamingchicken]

Re: higher ratio rocker arms in turbo application

You need to have the guides cut down if you are running a cam and 1.9 ratio.

Steve is right on that one, the guides where the push rods go will need to be cut to clear the new location of the pushrods.

[thebeewantsboost]

Re: higher ratio rocker arms in turbo application

i got the guides, push rods, springs with keepers and retainer and a hurst short throw alltogether. i'm guessing if the guides are cut, they are cut backwards. from what i want. that will be a problem... idk if i want to run them if they are 1.7's i may contact zzp.
i can't imagine they would be 1.7 if stock is 1.66 but who knows. i would be probably be okay with 1.8 but may try for all 1.9's.
it seems like a big difference inbetween the 2. and i don't see any cams with that much of a difference... ahhhh idk.

[bigbrian442]

Re: higher ratio rocker arms in turbo application

Steve is right on that one, the guides where the push rods go will need to be cut to clear the new location of the pushrods.

The guide is the part of the head that is around the valve stem inside the spring. Just using 1.9 rockers you need to use LS6 retainers or modified stock retainers.

[thebeewantsboost]

Re: higher ratio rocker arms in turbo application

i'm so confused... the valve guides hafta be cut? i thought by guide he meant the cradle that the pushrods ride sit against. don't get why the valve guide would be touched........
and that is only if you are using a cam and rocker arms right?

[flamingchicken]

Re: higher ratio rocker arms in turbo application

The guide is the part of the head that is around the valve stem inside the spring. Just using 1.9 rockers you need to use LS6 retainers or modified stock retainers.

I thought he meant the guides that the pushrods slide into on the rocker pedestal.

I see no reason why the valve guides would need to be cut. I have no issues running the GT2 cam that makes .507 lift with 1.6 rockers. A ton of people run the same cam on stock heads.

[ssms5411]

Re: higher ratio rocker arms in turbo application

Running a cam only is fine for stock heads, its when you want to run more lift adding 1.9 rockers is where your going to need the guides cut. If you have a stock cam then 1.9 rockers is fine.