TomQ

I've been thinking alot about all these horse power races and how people tune there cars for better "dyno" results.
But have you thought about how "your" cars will perform under real "racing" conditions and not several seconds of dyno runs?
I was told "you have to understand you can tune the PE so the car looks good on a dyno but it will not run as well in street or track. Dyno is only 30 seconds run, real world hours an engine can be running and you do not want is a lot of knock which is piston slap and cause long term damage to pistons and rings. In hot weather like at Sac raceway if you lean it up more, in that heat you will have a lot more knock and I saved you from that but as I said the PCM is tuned to command a 12.5 AFR............"
You can lean your car up to 13.x and get a great numbers on the dyno, but what will happen to you in real life environment?
I was told "As to AFR, a dyno always is 1/2 point richer then on the street thus on street it would be right around a 12.5 AFR which is pefect, add more heat in racing such as day of drags and engine temps would go up and get leaner.
That 1/2 point would not have made much difference to HP on dyno and car does not run like that on the street.
If you leaned it out for dyno then it would even be leaner for real world street and cause knock which would have reduced timing and worse results.
Being the HP and Tq lines in graph were smooth showing there was no knock so best for real world. The cam just as well be the cause as what AFR is but the smart way would have been to have a PCM scanner and record the run for this way I have no data to see how PE was before going to WOT but in any case the real numbers would be higher in track then on a dyno."

See my dyno graphs before tunning and after - please nevermind the mods, see the dyno graphs. For most curious my mods for first dyno graph are:
Stock '03 Z06 with Zip-Tie mod and nothing else.
Second graph is Zip-Tie mod+FLP LTs (off road setup)+TR 224/224/114 Cam. http://www.norcal-ls1.com/multimedia...amp;thecat=500
http://www.norcal-ls1.com/multimedia...amp;thecat=500
http://www.norcal-ls1.com/multimedia...amp;thecat=500

MY PE table is:
RPMS 70C 80C
1600 12.42 12.42
2000 12.70 12.70
2400 12.70 12.70
2800 12.74 12.74
3200 12.74 12.74
3600 12.57 12.57
4000 12.57 12.57
4400 12.57 12.57
4800 12.57 12.57
5200 12.57 12.57
5600 12.57 12.57
6000 12.57 12.57
6400 12.57 12.57
6800 12.57 12.57
7200 12.57 12.57
158F 176F
So, how much are you ready to sacrifice ust for better dyno results?

JeremyF

iTrader: (23)

Anton, I have done a bit of research on this very topic. I have dynoed a vehicle and got a given AFR and then I have tuned the very same vehicle on the street with a WB02. As far as the .5 AFRpoint that is simply the difference of calibrated 02's. I have seen a typical difference of .3 AFR. Any vehicle in the heat will be more likely to ping, therefore I would subtract timing when I see that the Intake air temps or coolant temps are exceeding for example 95F or 35C for IAT and 95C and 200F subtract a .5 deg of timing or so. Me personally I tune on the street first and then go to the dyno and then back to the street to make 100% sure the tune is right. If it pings it is not that much work to fix it. Usually the problems occur @ peak torque 3600-5200 and you will have to retard timing, reason being you have greatly increase cyl head pressure @ a given area and the ignition is just plain too early. I feel a leaner AFR about 13.3 is ideal but it is many times more that too much timing @ peak tq esp. is the problem not being too lean. I have found that there are numerous ways to make the same power in combos of richness and leaness and deg of timing. I do no think you have to sacrfice anything to get better dynos. and as far as dyno AFR and real world the PCM will see the extra incoming air and send the according amount of fuel. NO WORRIES I hope this helps. If you have any other question please give me a call 813.253.0961

Jeremy