Can bad rocker arm adjustment cost me 100rwhp?
my recent dyno after all the headaches with tuning net 387rwhp...
I have heads and cam and that same combo netted on a camaro 484rwhp on an ls1 block... cam is 226/230 113lsa
Any ideas????
afr was from 11.6 to 12.2 at the end
the dyno wb was reading 10.6 to 12.6....
still, tuning will not net 100rwhp.
"All that is needed for the triumph of evil is that good men do nothing..."
Re: Can bad rocker arm adjustment cost me 100rwhp?
Not trying to be a smart aleck...but how bad is "bad" (sound like Bill Clinton?). If your preload is insufficient (hydraulic?) it will definitely be down on power.Originally Posted by The Highlander
Did you degree the cam in?
Several things to consider:
What kind of Dyno? I ask, but because I have seen first hand the inaccuracies of a DynoJet simply based on the position of the ambient air temperature sensor.
Can you post a graph? Bink raises a good point about whether or not the cam was installed correctly. Were there specific ICL directions for the cam? Did it make a torque curve similar to the other car you mention, or is the graph "shifted" to the left or right?
I agree with Bink, "how bad is 'bad'"? If one of your intake valves never opens, then that is a fairly costly error. If each cylinder is producing roughly 60rwhp (or should be based on your expectations), then 1 cylinder down will probably cost at least that much. It is pretty easy to take the valve covers off and check lift with a dial guage.
What lifters, rockers, and pushrods (length)?
Stock rockers, stock lifters...
www.roxanette.com/awfuldyno.jpg
Pushrod length is 7.4 IIRC. This was all sent from cartek.
im down about 70rwtq of what should be expected... honestly i expected 440rwhp here on this dyno etc... still i am 60rwhp DOWN!
if only one cylinder would be off the car would have a heavy miss or imbalance.. the car feels overall w/o the power it should have..
Keep in mind that i did on that same dyno with a headers and intake on a 01 ls6 engine 340rwhp....
You are telling me that with an 04 ls6 block.. ported heads... ported intake... vararam... 226/230 cam i will only gain 47rwhp????? That doesn't sound right.[/url]
"All that is needed for the triumph of evil is that good men do nothing..."
One other thing.. the cam was not degreed... it was installed straight up. besides... that much horsepower on the degreeing of the cam? a degree of the cam can net you 15-20... not 75-100rwhp
"All that is needed for the triumph of evil is that good men do nothing..."
I agree if we're talking about a couple degrees (adv,ret). I'm talking about manufacturing error and/or wrong cam. The only way to know for sure is to degree it and verify lift/duration. 75 - 100 rwhp is a lot left on the bench :( .
How did it sound?? Did it sound tight and healthy?
Cheers,
joel
No, not neccessarily. A miss would be ignition. You will feel a reduction in power if the valves aren't opening/closing fully or are down on a single (or multiple) cylinder(s).
7.4 pr is stock length, right? Which heads are you using LS1 or LS6 ?? Were the heads milled? What's the base circle on the cam?
(LS1 cam has a 19.7mm base circle, 02 and up LS6 cam has a 19mm base circle.)
Cheers,
joel
This is a z06... and it has an 03 engine... but it could be a mistake on the cam now that you say it.. since... they sent me the wrong studs and had to return them... hmm.. interesting...
The engine does sound tight and healthy.. we did beat a 400rwhp 350z with 2 on the vette and he was alone... and him launching first.. so... there is power there.. but... I would have expected to FLY BY!.
The cam was sent from cartek... and... there was no cam card in the box.
Suggestions?
"All that is needed for the triumph of evil is that good men do nothing..."
The more i think of it the more i think you are rightl. probably i have an 01 cam... and i maybe hanging the valves a bit open. In this case what is the solution? change the cam? or use a shorter pushrod?No, not neccessarily. A miss would be ignition. You will feel a reduction in power if the valves aren't opening/closing fully or are down on a single (or multiple) cylinder(s).
7.4 pr is stock length, right? Which heads are you using LS1 or LS6 ?? Were the heads milled? What's the base circle on the cam?
(LS1 cam has a 19.7mm base circle, 02 and up LS6 cam has a 19mm base circle.)
Cheers,
joel
"All that is needed for the triumph of evil is that good men do nothing..."
Shorter pushrods, or in a pinch you can shim the rockers. Make sure you verify geometry -- you want the rocker wiping dead center on the valve stem. Easiest way to check is to pull the rocker, paint the tip of the stem with a Sharpie marker, reassemble, and crank the motor over a few times. Pull the rocker and you'll have a nice shiny stripe
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