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So I'm a little apprehensive about this post - I've seen so many cam advice posts that I glance over because I literally have no knowledge on the subject other than I know the difference between a big cam and a small cam. At least I think I do.
I have a gleaming suspicion that my cam I have now is too big for my heads and would work better after a decent CNC porting, either that or a blower. And right now I don't have time for either - just too many projects.
Having said that - What cam would you recommend for my setup?
iron block
Holley Hi-Ram intake Manifold
90mm TB
Stock MAF
4.070" Bore
4.100" stroke
~427ci
Stock LS3 Heads no porting decked to 65cc
10cc dish piston
11.3ish compression
Lunati .660" dual springs
4l80e with HD2 kit "2wd"
Hughes 3000 triple disc but it really stalls at 2200, thinking I need at a minimum 3200rpm for this cam if not 3500
37" tire
5:13 gears Dana 60 HD
Current cam specs
LS1 2131R/2133R HR15
243/251 .653/.660 115 LSA
Feels pretty decent down low - but it struggles off idle, stumbles and pops. Tuner said there was a lot of reversion happening he could see in the MAF.
Other than the off idle performance it feels pretty decent and here's the dyno
3rd gear unlocked the red line shows the split of the gear shift on the last power pull we made - it didn't hold 3rd and kicked down into second.
The changes I am making - #1 going back to the stock intake manifold, ported at home - not like a Radical port job, but pretty close. I also home ported my throttle body and port matched it to the stock L92 intake - it was off by a good 2mm or so.
I plan on getting it back running again with the same cam I have now, I just feel the Lift numbers are a bit on the aggressive side in NA trim.
What I want is Decent drivability down low. Something that wont stumble and kick off the AC compressor which happens now. I'd be willing to loose some top end for that, but not too much - I really thought I'd be closer to the 500whp mark than I am so I'm hesitant to give up too much.
It's an off road truck, driven on the streets primarily, but will be used in Glamis Sand dunes of California with Sand Paddle tires.
Reversion is normal. Seeing it in the MAF at low RPM is also normal, but that's why GM blends the airflow estimation between SD and MAF below a threshold. Did Nic work on it?
Also something I've been noticing is that the LS3 cams seem to have a larger split duration as compared to mine with a tighter LSA as well?? Not sure if that makes for a better cam, but I have read that wide LSA is a dog down low - any truth to that?
He should know better than to pay attention to the MAF at idle lol.
Oh trust me he does - lol This is not a tuning question. I have no doubt he did what he could do. Hell, he nailed my bench tune with my ***** frankenstein list of parts and the fact that I have the odd 2002 Silverado with DBW.
It idles fine - I just can't stab it off the line from idle. That's when I have the problem with the stumble and pop. Also, I can definitely feel the difference between the 1mph idle vs the stopped idle. He said he is commanding all the airflow he can is I think what he said. He said he could goof with some other stuff to make it work, but that would mess other stuff up and didn't want to do that.
06-29-2016, 07:12 PM
Cam advice
