Z06Vette.com - Corvette Z06 Forum

itchynackers · 05-21-2005, 05:19 PM

I just got my 03 Z dynoed for the first time on a dynojet. Could someone please help me analyze it. I got 358.4 hp, 360 tq with just a vortex & halltech bridge.

The questions I have are... Are these numbers SAE corrected? the CF says 1.01. Does that mean I need to correct it or not? Also, my A/F ratio seems waaay rich. This is the factory tune,no changes. Am I hurting anything with a rich tune? I have never seen a A/F curve go off the chart like this before. What do you think?

Thanks, Adam (hopefully this image works)

RocketSled · 05-21-2005, 05:37 PM

I'd say there's something not right with these.

The peak HP is about the same in each run at about 356 average, but the TQ is radically different, 388 then 409 then 678.

On the far right of the TQ curve, two of the curves show a "spike". Those spikes are bogus, and you don't really have an accurate peak TQ for those two runs since the Dyno reported the amplitude of those spikes as the peak.

I've seen Dynos do this before, but I haven't the slightest idea why. I'm sure someone out there in Forum-land does, though, and they might enlighten us!

Then, there's the AFR. Off the scale at 10. I can't believe you'd make 357HP, which is pretty good assuming you've just got some basic mods maybe, with an AFR that was even close to what the plot says it was.

I suspect the AFR sensor wasn't working right.

itchynackers · 05-21-2005, 08:17 PM

It's obvious about the spikes, thats why I reported 360 tq. I got it directly from the good part of the graph. I saw the A/F sniffers in the tailpipe. Also, no one else reported any problems with the A/F readings on their graphs.

Again, the ONLY performance mods are the Vortex Rammer and the Halltech air bridge. Anyone else care to comment?

Thanks,

BBaxR6 · 05-22-2005, 01:46 PM

Well, with an A/F ratio like that, you should see a "black cloud of death" coming out of the exhaust at WOT. Do you notice a lot of black (fuel) smoke at WOT? Makes me think the wideband on the dyno perhaps wasn't reading correctly. There's definitely 10 or 15hp lurking in a tune if that A/F is correct. Order you some HP tuners or LS1 edit stat!

itchynackers · 05-22-2005, 03:15 PM

I was behind the car the whole time as I wanted to hear the stock exhaust. (I never get to hear it except from inside the car). There was no black smoke at all, none. I had suspected it was running a bit rich though as there is some black "soot" on the lower part of each exhaust tip. I'm a little afraid to do a tune myself. The car goes to Lingenfelters in a month or so, so the tune will get done right then. I did this dyno so I had a baseline to compare the Magnuson to.

Can you tell if the numbers are already SAE corrected or do I multiply the 358 HP times 1.01?

air1kdf · 05-23-2005, 09:44 PM

I would assume that it is time for them to get a new sensor. They do go bad. Actually they get too much carbons inside the sensor itself. Leaded fuels or racing fuels will do this big time, and greatly reduce the usable life of the sensor. The main reason that I think that the sensor is bad, is because you are so close to stock, your numbers are good, the AFR is different in the beginning of all 3 runs, and you see very little black smoke (at 9 or 10:1 AFR you wouldn't be able to breathe).

Also SAE is corrected already. The CF is 1.01 in your case which means that they already multiplied the measured #'s by 1.01 everywhere including the graph.

After you get it back, go to the same place and have them run it again. It's sure to be a good times ahead.

itchynackers · 05-24-2005, 05:55 AM

That could be. Thanks.

COUTO1981 · 05-24-2005, 06:13 AM

It makes no sense to me, why is it so rich but make 358rwhp and 360tq, but the biggest concern, why is it the graph in MPH and not in RPMs ??

is that a real dyno

air1kdf · 05-24-2005, 04:14 PM

Quote:

Originally Posted by COUTO1981

It makes no sense to me, why is it so rich but make 358rwhp and 360tq, but the biggest concern, why is it the graph in MPH and not in RPMs ??

is that a real dyno

Sensor is bad. AFR is bogus. It is a real dyno run, they just opted to graph against the drum. This is actually very common.

Also not to get into a big argument, this type of dyno has the benefit of showing true HP and Torque because it's a drum style dyno. Other style dyno's have other benefits, but at the expense of "real numbers".

RocketSled · 05-24-2005, 05:30 PM

Quote:

Originally Posted by itchynackers

I saw the A/F sniffers in the tailpipe. Also, no one else reported any problems with the A/F readings on their graphs.

Never the less, the AFR data is bad. It's not just inaccurate. With AFRs like that, the engine would have barely run, never mind made decent torque.