Ok guys i have a 99 z28 that i had a LS3 put in motor build is a ls3 block with WCC Eddelbrock 245 heads in a 72cc with a 243/247/623/623 on a 112 lsa
intake is a ls6 with 36lb injectors tsp 17/8 headers. Ok so here is the issue the car acts like it has a dead cylinder it only made 410 rwhp...We checked the data log it shows bank 2 slightly leaner then bank one.. We changed coil packs no change changed plug wires no changed. We used a reluctor wheel tool and it checks out... The car idles fine and drives ok but is sputters in lower rpm and im about 70 rwhp short of where i should be and im kinda stumped it still pulls hard and i have to use it for LA invasion does any one have any ideas i could try? Also the tune is spot on so its not the tune.

 

2 things. Your intake is WAY to small and run a compression check to see if you have a bad cylinder. Oh one other thing. Is the cam installed correctly?

 

yes and when you work for uncle sam your kinda stuck on how much you make and a fast 102 is not my concern right now a ls6 will work for now
compression is good btw and so is the cam

 

Check your ignition system. Make sure all coils are working, what spark plugs and what gap are you using?

 

intake leaks?

 

swapped the complete coil pack off a other car no diff

 

Mafs? Swap that.

 

speed density tune

 

Double check that you don't have too much lifter preload. If the pushrods are too long it can hold the valves open a bit. I like to have zero lash plus 1/2 turn. Different lifters need different preload though.

Just a thought


DJ

 

thanks every one i think we found it dirty injectors might be the culprit

 

those 36lbs injectors might not be enough in the top end..both my fuel pump and injectors were maxed out on initial tuning of my 416. i now have 50lb/hr injectors and a racetronix fuel pump with wire kit..but haven't gone back for re-tune (injectors obviously not installed yet)

 

I would check injector duty cycle at WOT at high rpms, like SIK02SS said and while you're at it, look into the tune one more time. I would think if it had a dead cylinder you guys would know for sure. Just seems like you need to iron out the wrinkles with that combination.

EDIT: You said "the data log it shows bank 2 slightly leaner then bank one." What did the AFR's look like? What fuel are you using? Can you get us that datalog and dyno sheet?

 

Good tO hear!

Keep me posted!

 

Intake is costing you 30+ horsepower. Might not be all of your problem, but it wont feed those heads, or 416 inches worth a crap.