I got the car dyno'd for the first time with the cam, I was pretty happy with the #'s it put down:

327.6 rwhp
328.5 rwtq

This was my first time ever on a dyno, it had a wideband o2 and the power seemed good to me but I was a little concerned at the look of the graph. Both lines were even until around 5300 then they started getting wavy the rest of the way. The car had been running great the last couple of weeks since installing the cam and getting PCMforless Hotcam tuning, I had pulled it several times on the road up to 6500 and didn't feel any miss or hesitation. The guy running it said "It seemed like it was looking for fuel up top?" which surprised me. It was raining hard off and on all day and during my runs and temp was in the 50's, could the 100% humidity have caused this stumble over 5300? I really didn't run it over 3000rpm that day on the way there due to the rain so I didn't notice any. I have new plugs, wires, fuel filter and pcv valve and pretty much all the bolt on mods, the one thing that came to mind that could be a problem is my ported and descreened MAF, could that be throwing off the hotcam tune and causing this or could it just have been from the weather that day?

 

starving for fuel up top??
do you have a fuel pressure regulator? Even so, the tuning from pcmforless, that should of fixed that...I wouldn't think the 100% humidity would of played a factor...
aside from that, man those are good HP numbers, I haven't dynoed mine yet, and I don't have tuning but I am aiming for 290'srwhp...

 

My numbers @ 290rwHP and 303torque. Just Hotcam Kit and Borla. (A4)


Nice numbers though. About 330rwHP, but you have the under drive, electric water pump, airfoil, CAI, 160 T-Stat and a M6 so my numbers seem about right.

Just installed some Dynatech Longtubes though

 

Maybe it is from a little knock retard.

 

I don't have an AFPR since I was told it really wasn't necessary, the stock fuel pressure is fine for my mods. Don't get me wrong I'm happy with the #'s it put down, just concerned about the spikes after about 5300. The only thing I can think of is the modded MAF, maybe I'll just put it back to stock.

Paul, those longtubes are going to make a huge difference in power now if you are going from stock manifolds. Do you have any sort of CAI? If not I'd pick one up when you do the LT's it will make a big difference. That cam is likely choking on your stock airbox and manifolds.

 

do you have an LT4 KM??

 

Rob, I don't hear any knocking coming from the motor, but there is more chattering noise of course with the roller rockers now. I do have the LT4km so I thought that would help with any timing retard. Do you think modding the MAF could have anything to do with this, I'm thinking maybe the airflow past the sensors wasn't smooth enough with the screen out and that it could be messing up the PCM tune. Could that be the cause of this?

 

Hell yeah, before the longtubes, man the car use to chug like a 6000 cubic in motor! I kind of liked it, especially when it was multiplied by my borla exhaust. But now that I have the long tubes, It sounds perfect! I couldn't of ask for a better exhaust tone. It's very aggressive now. And who says Borla sounds like crap after a cam? They must've had stock manifolds on like me!

I had Ram Air before I sold my 93-97 SS Hood, I now have nothing but an Autozone airfilter! I'm kinda going in two directions at once, 1. Adding Power and 2. LS1 front end conversion....just need it painted

Now you need some headers! I bet it was loud at your dyno run, mine was!

 

You aren't going to hear knock, even if you have it.... the PCM retards the timing very quickly. You need a scanner to know if you are getting knock retard.

As far as the hacked MAF, what did you tell pcmforless that you were using? I thought tuners didn't like to work with anything other than the stock calibration.

I'd lean toward the knock retard.... retard quickly, put the timing back in slowly, repeat.......

The A/F seems to be right where it should be, so not likely it is running out of fuel.

 

Fred, when I had him program the PCM the first time (before cam) I mentioned the MAF change to him but I didn't mention it again when he added the cam tune. I assume he had that info still on file. Even if that isn't causing this I am going to go back to the stock MAF ends and screen, I have heard many times that tuners don't like working with hacked MAF's too.

I have adjusted the rockers three times now, the last time I went 1/2 turn on each after zero lash using the TDC on #1 & TDC #6 piston method. They seem to be fine except for the normal light chatter and there are also there are no header leaks. What are other possible causes of false knock? Also I have an autoxray scanner, but I havn't checked the timing since installing the cam I've only used it for code checking lately. I'll try that and see.

 

I just realized what may have been causing my knock, if that's what the problem is. I have a new stock single cat I'm using (which I'm removing soon for an ORP) and I have had a problem with the heat shield welds coming loose before and on the way home after the run another weld was broken making a noticible rattle in the exhaust. I fixed it later that day with a pop rivet until I either remove the cat or get it rewelded. Anyway, I think the shield came loose on the dyno because it wasn't doing it on the way there. The car was so loud on the dyno that I didn't even notice if it was rattling (I was standing behind it ) Could that rattle at the cat have caused this knock retard on the top end???