1.8 HS rocker pushrod part #
The rockers give you a little more valve lift, a couple of degrees more of effective cam timing, and the roller tip reduces some side load on the valve stem.
The extra valve lift and duration allows a bit more airflow into the cylinders. You end up with about 15 hp more - mostly on the top end.
The extra valve lift and duration allows a bit more airflow into the cylinders. You end up with about 15 hp more - mostly on the top end.
Last edited by TiredGXP; Mar 14, 2008 at 07:00 PM.
Too early in the morning. Dealing with a service center, then my wife, then my job... ABout the only good thing about today is its my B-Day...!!!
TECH Apprentice
Joined: Oct 2006
Posts: 308
Likes: 0
I made a post awhile back that I would like to compair my custom tune to the Vector tune for the guys on this board. To see what changes they make vs my custom tune changes. Its my way of helping out the LS4 family.
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Verdad Gallardo Came across this dyno chart and description while cruising the web this evening. Included a baseline dyno run and then a comparison after upgrading valve springs and installing Crane 1.8 quick lift rockers. Full article is here:
http://www.maxchevy.com/tech/2007/ii_7-rocker-1.html
Dyno Chart (crappy picture, but you can read it) and an excerpt from the article:
"While the flywheel output of the LS4 is rated at 303hp and 323lb-ft, baseline dyno runs (1.7:1 rocker ratio) yielded 255.5hp and 358lb-ft of torque (torque rating enhanced by converter multiplication in Second and Third gear and/or factory rating is on the very low side). As applied to the Impala SS, the Crane 1.8:1 Gold Series rockers increased the output an additional 18.1hp and 16lb-ft of torque at the front wheels. Hey, it’s a start"
http://www.maxchevy.com/tech/2007/ii_7-rocker-1.html
Dyno Chart (crappy picture, but you can read it) and an excerpt from the article:
"While the flywheel output of the LS4 is rated at 303hp and 323lb-ft, baseline dyno runs (1.7:1 rocker ratio) yielded 255.5hp and 358lb-ft of torque (torque rating enhanced by converter multiplication in Second and Third gear and/or factory rating is on the very low side). As applied to the Impala SS, the Crane 1.8:1 Gold Series rockers increased the output an additional 18.1hp and 16lb-ft of torque at the front wheels. Hey, it’s a start"
Staging Lane
Joined: Mar 2008
Posts: 80
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From: Alamogordo NM
How Much? And Where Do I get one? I don't know if you can curse on this site but holy **** if you add that with a CAI, 3" downpipe w/Exhaust and a tune then we'll finally be pushing 300 WHP!!!!!! I think my 'Pala is getting a chubby.
Well. that's probably the highest stock dyno run I've seen (I recall seeing WHP readings from a low of 230 to a high of 255) on one of these cars. Drivetrain loss is usually accepted to be 19%, which would equate to 243WHP. The 230 number would be 24% drivetrain loss, which seems a bit high. The 255 number is about a 15.5% drivetrain loss.
I'd split the difference and use the 243HP as a baseline. Gonna need more than those few mods to hit 300 WHP, unless your dyno operator uses optimistic correction factors.
So lets see how things roll up (using conservative numbers):
Stock ____________ 243whp
Rockers __________ +15 (255)
Exhaust __________ +15 (270)
CAI ______________ +5 (275)
Tune _____________+10 (285) That's about it for easy bolt-ons
Non-bolt ons:
If I can ever get the remaining clearance issues solved for the LS6 intake manifold then add at least 15 HP (hoping for over 20, but 15 is what this swap has dyno'd on LS1 engines). That ought to bump things to 300whp.
There's been a few people start threads for cam changes. No one has ever come back with results to let us know if it was completed or what the engine dyno'd at, so who knows if a cam change has ever actually been done. +40 HP is not unreasonable, but we'll really need headers to take advantage of the better breathing a cam can give.
Head porting, including gasket match to existing intake/exhaust manifold, and a multi angle valve job, maybe another 30 hp.
Headers will have to be a custom fab job, and I don't see us having space (especially at the rear) for anything other than a shorty style header. Maybe 15 hp.
Anyone want to debate assumptions?
**Edit: Or save your pennies for the G8 GXP that GM announced yesterday. It will have the LS3, rated at 402 hp (down from the 430 in the Vette due to more restrictive intake and exhaust), 6 speed auto or manual trans.**
I'd split the difference and use the 243HP as a baseline. Gonna need more than those few mods to hit 300 WHP, unless your dyno operator uses optimistic correction factors.
So lets see how things roll up (using conservative numbers):
Stock ____________ 243whp
Rockers __________ +15 (255)
Exhaust __________ +15 (270)
CAI ______________ +5 (275)
Tune _____________+10 (285) That's about it for easy bolt-ons
Non-bolt ons:
If I can ever get the remaining clearance issues solved for the LS6 intake manifold then add at least 15 HP (hoping for over 20, but 15 is what this swap has dyno'd on LS1 engines). That ought to bump things to 300whp.
There's been a few people start threads for cam changes. No one has ever come back with results to let us know if it was completed or what the engine dyno'd at, so who knows if a cam change has ever actually been done. +40 HP is not unreasonable, but we'll really need headers to take advantage of the better breathing a cam can give.
Head porting, including gasket match to existing intake/exhaust manifold, and a multi angle valve job, maybe another 30 hp.
Headers will have to be a custom fab job, and I don't see us having space (especially at the rear) for anything other than a shorty style header. Maybe 15 hp.
Anyone want to debate assumptions?
**Edit: Or save your pennies for the G8 GXP that GM announced yesterday. It will have the LS3, rated at 402 hp (down from the 430 in the Vette due to more restrictive intake and exhaust), 6 speed auto or manual trans.**
Last edited by TiredGXP; Mar 16, 2008 at 07:32 AM.
You have to remember that parts work with each other
If rockers give you 15hp and you have a CAI, then your only going to get a total of about 20 total hp from those 2 mods together.
Now, if you add a larger downpipe and exhaust, then its really going to be maybe 30+ total.
Its all about what parts and how much they work with each other.
The headers wouldnt be a problem, just need Milzy to make them and they wouldbe be as bad as you think they would be. The right design will set off these cars ALOT...!!!
If rockers give you 15hp and you have a CAI, then your only going to get a total of about 20 total hp from those 2 mods together.
Now, if you add a larger downpipe and exhaust, then its really going to be maybe 30+ total.
Its all about what parts and how much they work with each other.
The headers wouldnt be a problem, just need Milzy to make them and they wouldbe be as bad as you think they would be. The right design will set off these cars ALOT...!!!
Agreed. I see that I didn't really state my assumptions, but this is the most important one.
I've seen the dyno claims on the Magnaflow site. They claim +22 for just the cat-back. I can't seem to find a dyno chart that backs up what difference the Hogan downpipe makes, just "internet babble" to the effect of ~+10. I was figuring that these two exhaust mods would provide a net +15 hp in combination with the other mods listed, not the +32 that these two mods appear to add up to.
We do need a set of headers that can eliminate the problem of how the crossover pipe dumps into the rear exhaust manifold.
At any rate, by the end of May I will have installed:
HS 1.8 rockers (and Comp 918 springs and pushrods)
A homegrown CAI (using ducted air from the FW)
Hogan DP
Magnaflow catback (or maybe a custom 3" like Nacho SS)
LS6 intake, and
Reworked the tune with HPT
My expectation is that these mods, in combination, will dyno +60WHP more than stock. I'll do a baseline run and then use the same dyno after all mods are in so I can see what difference the same dyno shows. If it's +50, I'll still be happy, I don't really expect more than +60.
Since different dyno's provide different numbers (Dynojet higher than Mustang), the maximum power numbers are always going to be "iffy". I want to see how the power and torque curves change from stock - how has the "area under the curve" increased?
We do need a set of headers that can eliminate the problem of how the crossover pipe dumps into the rear exhaust manifold.
At any rate, by the end of May I will have installed:
HS 1.8 rockers (and Comp 918 springs and pushrods)
A homegrown CAI (using ducted air from the FW)
Hogan DP
Magnaflow catback (or maybe a custom 3" like Nacho SS)
LS6 intake, and
Reworked the tune with HPT
My expectation is that these mods, in combination, will dyno +60WHP more than stock. I'll do a baseline run and then use the same dyno after all mods are in so I can see what difference the same dyno shows. If it's +50, I'll still be happy, I don't really expect more than +60.
Since different dyno's provide different numbers (Dynojet higher than Mustang), the maximum power numbers are always going to be "iffy". I want to see how the power and torque curves change from stock - how has the "area under the curve" increased?
Where the hell did they put the dyno chart at on magnaflows website? I Thought it was more like 16 hp and 14lb of tq???
*** well after looking around more, i found the GXP one.
That seems really high. I would guess that number would be more correct if you had a downpipe along with the res removed from that kit.
There will always be a cross over pipe for these cars no matter which company makes headers first. The one company I know of that is working on them, which I cant say at this time will have a cross over just because there is no other way of doing it.
*** well after looking around more, i found the GXP one.
That seems really high. I would guess that number would be more correct if you had a downpipe along with the res removed from that kit. There will always be a cross over pipe for these cars no matter which company makes headers first. The one company I know of that is working on them, which I cant say at this time will have a cross over just because there is no other way of doing it.
Fedex was good to me today and brought the final pieces!! Hope to put it all in in the next few weeks. Maybe with some Drag Radials I can pull off a 12.9 et, that's probaly pushing it though!
