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stock l32 spring size dyno issues

rodman

rodman

New member
Well i finally got a chance to jump on the dyno last night...first pull was looking great then at 4500 rmp it fell on its face...played with fuel timing and 2 hrs later we could only get it up to 5000rpm and once again fallls on its face...wondering if im seeing valve float on stock l32 heads idk?Mods are z7 turbo oversized ic er rockers hv3 lt1 maf and 65 mototron injectors...shift points are 6000k and help would be great wondering about stock l32 cam if thats it to or maybe some kind of rev limiter or tc issue making the pcm kill the power????

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The ER's should be 1.85 on the intake and 1.80 on the exhaust valve. They are more for n/a engines. At 10psi on turbo and higher ratio rockers, you should be using #130 springs. Your next step would be to ditch the rockers and go with a turbo cam, #130 springs and a rollmaster double roller timing chain.
 


well if its the springs ..im definately taking out the rockers and and going cam but is 130 really needed?what about 105"s....so your thinking valve float>?
 
The only way to tell if it's valve float for sure is measure seat pressure. What was the air/fuel ratio, and fuel pressure doing. Most of the time when it's valve float the motor will run great then just won't "wrap up" anymore. It's like hitting a brick wall in the power band. My 468cid Big Block makes 540 HP at 6800 RPM and makes 210 at 7000rpm, that's valve float. When it was on the Dyno it sounded sick as hell when the valves started floating when it's in the truck and I float the valve it acts like a rev limiter but I can't hear the sound it made on the dyno.
 
is this the first time its done it? do you have a scan of the run?
If you have hptuners send the file to [email protected] and ill look at it.
You have a electronic throttle body right? there is a table the pcm looks at as a rationality check incase the electronic throttle body screws up. keeps you from accelerating when your foot is off the pedal. if you exceed the airflow values in this table it will trigger a limp mode. might zero this table out for the time being to check things out but dont leave it zeroed out!!!
 
First thing im trying is my plug gap is too big its got al 103's but gapped at .050 and should be at .035....other people have mentioned to disable torque management/ stability control ...i don't have scan my tuner does next time im there ill pic it up if this doesn't work out
 
SO has no 04+ ever been dyno tuned before?someone said remove abs fuse how many wheel sensers does a base 06 have?
 


yeah im sure plenty have been, why would one unplug the abs sensor?(there should be 4 one per wheel.) just turn traction control off should do the same thing. its a most when on a dyno
 
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