Roller rockers and turbos
Thread Starter
On The Tree
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Joined: Apr 2006
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From: Columbia, South Carolina
Roller rockers and turbos hey guys, can we discuss how the addition of roller rockers to a turbo setup effects things? It seems for the most part, roller rockers end up being so we can spin the motor harder ... but what about the quicker ramp rate due to the roller, the possible addition of false knock, and the added lift. The increase in hp due to roller rockers is documented for n/a setups, but what about boost setups? Should roller rockers be added purely for high rpm safety reasons, and let a cam take care of increasing the performance? how should a turbo cam be tweaked to take into account the addition of roller rockers? etc...
If you assume that you stay with the same ratio roller rockers as what you are replacing, then really the only gains are due to lowered friction to move them as opposed to a ball/stud rocker or a non-roller shaft mount.
Changing the ratio applies to all rockers, pretty much equally, except as noted above in friction.
The additional mechanical noise that could lead to false knock is a problem in any motor, knock sensor and/or knock sensor module not designed for roller rockers. But I don't hear too much about this problem unless it's with the addition of a solid roller cam and lifters.
Your turbo cam doesn't need tweaking if you add roller rockers of the same ratio. If you switch ratios, you need to ensure the springs and valvetrain can handle it, and perhaps check the valve-to-piston clearance.
Jim
Changing the ratio applies to all rockers, pretty much equally, except as noted above in friction.
The additional mechanical noise that could lead to false knock is a problem in any motor, knock sensor and/or knock sensor module not designed for roller rockers. But I don't hear too much about this problem unless it's with the addition of a solid roller cam and lifters.
Your turbo cam doesn't need tweaking if you add roller rockers of the same ratio. If you switch ratios, you need to ensure the springs and valvetrain can handle it, and perhaps check the valve-to-piston clearance.
Jim
FormerVendor
Joined: Dec 2001
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From: WWW.SPEEDINC.COM
Fwiw we always use stock rocker arms in our turbo builds. Even our shop car that makes 1140rwhp and turns to 7,800rpm.
Any time we've tried using an aftermarket roller rocker or shaft rocker a signifigant loss in rpm capability occured.
Any time we've tried using an aftermarket roller rocker or shaft rocker a signifigant loss in rpm capability occured.
Originally Posted by INTMD8
Fwiw we always use stock rocker arms in our turbo builds. Even our shop car that makes 1140rwhp and turns to 7,800rpm.
Any time we've tried using an aftermarket roller rocker or shaft rocker a signifigant loss in rpm capability occured.
Any time we've tried using an aftermarket roller rocker or shaft rocker a signifigant loss in rpm capability occured.
my setup is essentially a modest street car with only 5 psi of boost. Adding Comp cams pro magnums and their hardened pushrods made the motor rev quicker. In other words, I notice a significant different in how much easier the motor gains rpm. I don't go past 6K, so can't comment on how they affect high rpm.
Thread Starter
On The Tree
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From: Columbia, South Carolina
well, doesn't the size of the roller on the tip effect the rocker ratio. I read something about this the other day when reading about crane cam's quick lift roller rockers. They're still rated at a 1.7 ratio, but they apparently hold this ratio through the entire arc of the rocker whereas stock starts and ends at 1.54 ratio or something, and only peaks at 1.7. It would seem that getting the valve open quicker would be great for boost. Also, with less friction, why would the roller rocker reduce how hard you could spin the motor as mentioned above?
Comp pro magnums have caused valve float and annoying valve adjustment ...so i no longer use them in builds..
The only recommendation for most standard builds is YT ultra-light shaft non-adjustables...or stockers with the HS inner upgrade.
The only recommendation for most standard builds is YT ultra-light shaft non-adjustables...or stockers with the HS inner upgrade.
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9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
I tried to bolt a set to my Edelbrock heads.....
If they are anything to go by, dont expect an easy job. Mine still arent on.
Whether this is due to my head/valve setup, or the fact they dont bolt straight on, I dont know.
And the valve covers will need some work to clear them too.
If they are anything to go by, dont expect an easy job. Mine still arent on.
Whether this is due to my head/valve setup, or the fact they dont bolt straight on, I dont know.
And the valve covers will need some work to clear them too.
Staging Lane
Joined: Aug 2007
Posts: 87
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It does mention this in the instructions.
I bought taller valve covers and am hoping that since the heads are just worked over OEM LS1 heads, they'll drop in without requiring machine work. If they do, I'll just fixture to a mill and clearance myself.
I bought taller valve covers and am hoping that since the heads are just worked over OEM LS1 heads, they'll drop in without requiring machine work. If they do, I'll just fixture to a mill and clearance myself.
I have seen Mike Brown post about using H/S non-adjustables, but I know a lot of fast turbo guys and if they are hydraulic they are typically running stock rockers.
I had Speed Inc. pull off a set of older YT's off my car, car was not rpm'ing and it seemed to be a valvetrain issue because the springs that were on the car at the time were set up at same spring pressure that most folks run and the springs were not old either.
I had Speed Inc. pull off a set of older YT's off my car, car was not rpm'ing and it seemed to be a valvetrain issue because the springs that were on the car at the time were set up at same spring pressure that most folks run and the springs were not old either.
9 Second Club
Joined: Nov 2003
Posts: 13,616
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From: Norn Iron
Bolting straight to the head....the rocker arms fouled my spring retainers. I think stock style tapered retainers would work fine though.
Mine are parallel dual springs, with a flat retainer.
Then after I clearanced the rockers ( no doubt a bad idea...but I was keen to fit these ), PR length would have ended up at 7.150" to give me 50thou preload.
Yes, these are unmilled heads, and OE deck on the block with GM MLS gaskets. With the current YT's Im on 7.325" PR's which is prob about 60-80thou preload.
So either the rocker platform on my heads is too low, the installed valve heights too long/high, my heads rocker setup is nothing like stock....or Im just very unlucky. Or maybe all of these.
Clearancing the valve covers was the easiest bit !!! At least I could easily see when that was done.
I dont believe the spring platform is wrong, because if I shim this up to the point where the rockers did clear the retainers, it looked like a pushrod would just pop out of the rocker at full lift.
Needless to say I f**king hate LSx valvetrain at the minute !!!!!
Staging Lane
Joined: Aug 2007
Posts: 87
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You using YT or Jesel?
Man, cutting on the rocker arms must have been a tough call. I couldn't do it. I'd have to shim the rocker stands or something. Anything!
My plan is to mock it up, and then adjust either height or PR length.
My short block is all OEM. Heads are CNC ported LS1's from Lingenfelter. Bigger vavles and Comp 921 springs w/titanium retainers.
Good luck on your dilema.
When I get home here in 9 days the fun starts. I'll have a long *** build thread with lots of pictures.
Thanks.
Man, cutting on the rocker arms must have been a tough call. I couldn't do it. I'd have to shim the rocker stands or something. Anything!
My plan is to mock it up, and then adjust either height or PR length.
My short block is all OEM. Heads are CNC ported LS1's from Lingenfelter. Bigger vavles and Comp 921 springs w/titanium retainers.
Good luck on your dilema.
When I get home here in 9 days the fun starts. I'll have a long *** build thread with lots of pictures.
Thanks.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
You using YT or Jesel?
Man, cutting on the rocker arms must have been a tough call. I couldn't do it. I'd have to shim the rocker stands or something. Anything!
My plan is to mock it up, and then adjust either height or PR length.
My short block is all OEM. Heads are CNC ported LS1's from Lingenfelter. Bigger vavles and Comp 921 springs w/titanium retainers.
Good luck on your dilema.
When I get home here in 9 days the fun starts. I'll have a long *** build thread with lots of pictures.
Thanks.
Man, cutting on the rocker arms must have been a tough call. I couldn't do it. I'd have to shim the rocker stands or something. Anything!
My plan is to mock it up, and then adjust either height or PR length.
My short block is all OEM. Heads are CNC ported LS1's from Lingenfelter. Bigger vavles and Comp 921 springs w/titanium retainers.
Good luck on your dilema.
When I get home here in 9 days the fun starts. I'll have a long *** build thread with lots of pictures.
Thanks.
Its a shaft mount setup. If this was shimmed up, as I said, I would be certain a pushrod would pop put of the rocker when the engine is running.
You can only go so far with the installed height of the rockers before getting into trouble. So that was not an option.
TECH Apprentice
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Joined: Nov 2005
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From: Tinker till it blows, then back it off a notch, maybe!!
Using YT's, but wanted to use these Jesels I bought months ago.
Its a shaft mount setup. If this was shimmed up, as I said, I would be certain a pushrod would pop put of the rocker when the engine is running.
You can only go so far with the installed height of the rockers before getting into trouble. So that was not an option.
Its a shaft mount setup. If this was shimmed up, as I said, I would be certain a pushrod would pop put of the rocker when the engine is running.
You can only go so far with the installed height of the rockers before getting into trouble. So that was not an option.
Just a thought......