1.7 rocker effect

[converted1]

I'm considering adding a set of 1.7 rockers to my build, intake only,its a tman 590 cam, how does the additional lift figure in.
1 will it help make more hp\ if so to the left or right
2 will it help make more torque/if so left or right

[Admiral Akbar]

They will gain about 2-3 degrees of 0.053 equivelent duration and add lift.. Overall you motor can breath a little better.. Typically it increase peak TQ and HP but not do much on the low end unless head flow is limiting..

[HD/Wrench]

OR it will do nothing at all , ( other than lighten your wallet)  Tested that been there and got the tee shirt.. With testing it on your set up there is no way to know and testing means getting the bike on the drum that day up to temp make the base line, pull it down swap the rockers then re tune and test.. At least that is how we did it on a a few different cams. Even easier if you have two extra supports ready to go . Look forward to the results 

[Admiral Akbar]

OR it will do nothing at all , ( other than lighten your wallet)  Tested that been there and got the tee shirt.. With testing it on your set up there is no way to know and testing means getting the bike on the drum that day up to temp make the base line, pull it down swap the rockers then re tune and test.. At least that is how we did it on a a few different cams. Even easier if you have two extra supports ready to go . Look forward to the results 

Absolutely.. At least you got the T shirt... 

[sfmichael]

best results I've seen are where the cam is too small to begin with, not likely with the TMan 590...and as Max stated if the heads are lame the additional lift will help

not knowing what you have for heads is a bit of a wild card - but I'd guess 1-3 hp/tq
I personally have never seen really big gains but can be worthwhile on some builds

Steve/GMR nailed it with his comment 

[HD/Wrench]

OR it will do nothing at all , ( other than lighten your wallet)  Tested that been there and got the tee shirt.. With testing it on your set up there is no way to know and testing means getting the bike on the drum that day up to temp make the base line, pull it down swap the rockers then re tune and test.. At least that is how we did it on a a few different cams. Even easier if you have two extra supports ready to go . Look forward to the results 

Absolutely.. At least you got the T shirt... 

Yep it says " max went to AZ and all I got was this stupid shirt"   HA HA

[pwmorris]

Gain, achieve nothing at all, or lose power. Depending on cam, compression, heads, pipe etc, I have lost torque going to the higher rocker ratio...
As said, gotta test and find out if your combo likes it-or not.
If you can't, don't want to, or don't have access to repeated straight swap, no other changes dyno testing, leave it as is with stock ratio. Some like stock, some like intake only, and some motors like intake and exhaust...

[Matt C]

If the heads are "lame" it won't help at all because "lame heads" won't flow any more
at higher lifts. And the added duration is so negligible, I doubt you'd even be able to
notice it on a dyno. The margin of error is probably greater than any gains you would
get.

Save your money, that's a good cam you have in there.

[NHBagger]

There may be better ways to make more HP or TQ, depending on what you want.  What's the rest of your setup?

[converted1]

107 ci set at 10.8 (est) ccp 205 (est)
massaged on MVA'S
massaged on SE 58MM T/B---5.3 inj
TMAN 590 CAM
RUSH WRATH 2.50

[Admiral Akbar]

 

So what are you trying to accomplish?

[sfmichael]

If the heads are "lame" it won't help at all because "lame heads" won't flow any more
at higher lifts. And the added duration is so negligible, I doubt you'd even be able to
notice it on a dyno. The margin of error is probably greater than any gains you would
get.

Save your money, that's a good cam you have in there.

I know you know it all but I have seen decent gains with stock heads. The valve will be open farther at low/all lifts than it would be normally with stock ratio rockers. They don't only open the valve farther at maximum lift...where the headflow typically flatlines in relation to lift.

[Barrett]

They worked well with my 37's.

[Don D]

I thought TW37s had .510 lift with stock rocker ratio?
This can't be a graph of 37s right?

[BVHOG]

TDC lift and valve to valve clearance will be horrendous with a 590 and high ratio rockers.

[sfmichael]

I thought TW37s had .510 lift with stock rocker ratio?
This can't be a graph of 37s right?

correct

[Matt C]

TDC lift and valve to valve clearance will be horrendous with a 590 and high ratio rockers.

Don't confuse them with facts...

[converted1]

I just happen to have a set lying around,and have seen them added to builds,and was hoping I could use them to get a little more
So I threw the question out here to get the pro's and cons,in this case looks like the cons rule the roost

[Matt C]

I know you know it all but I have seen decent gains with stock heads.

prove it

[Raleigh111]

i do not know the answer to what i am about to say so dont take this the wrong way, asking not stating or telling.

a while back i had a conversation with a guy that makes cams for a living and he said dont bother with those high ratio rocker arms it will rob you of horsepower as it takes more force to lift them. if you want higher lift buy a different cam, gave me some example of a tidder todder at a park? still trying to figure that out in my head. car guys use them all the time and have been for many many years.

i used them anyways and it helped me in my situation?

[Barrett]

I thought TW37s had .510 lift with stock rocker ratio?
This can't be a graph of 37s right?

The graph is from a car guy.. His name is on it.
The TDC would come in at .222

[Barrett]

Here's a test from a car site.. Lifting the valve more than the heads flow didn't make any gains. It did help up to that point.
http://www.hotrod.com/how-to/engine/116-0101-roller-rocker-ratio-test/

[Matt C]

If you need to use high ratio rockers, you have the wrong cam.

[No Cents]

   just curious here...but why did S&S design their new T143 crate engine and use 1.725 rockers arms in that engine?
It seems if the 1.725's didn't help...they would have ran the stock ratio arms.

Ray

[aswracing]

I've carefully tested them multiple times, in various engines, where the change in rocker ratio was the only change I made. I've seen between zero and 2hp improvement, depending on the application.

The rocker arm geometry is a key part of the equation. If it's not right, you may not get even get any measurable additional lift out of them. They're really not a bolt-on mod.