On Friday, I had my vortech installed on my '05 G35 coupe and tuned by CP Racing and this is what I got on their dyno dynamics:




Then I dyno'd the very next day on a Dynojet and this is what I got:






The a/f readings seem to differ greatly. What do you guys make of this?

Also...I have the zeitronix and have pulled some runs and data logged it but the rpm reading is messed up so I only have a/f as it pertains to boost

Here is a 12 second WOT 1-2-3 pull on an on ramp recorded from my Zeitronix wideband data log....(it has been attatched to this post)

What do you guys think....

 

Pretty lean....scary lean around 4750 rpm's right where the engines torque peak is at its highest. Would be nice to see the a/f drop to around 11.0-11.5 and maintain to redline. I assume CP uses a tail pipe A/F probe.

 

They do...but on my tune...they used it in the front bung, I believe. At the Dyno (the second chart)...they used a tail pipe sniffer

 

I would not want to be running that lean. As the above post stated, get it to somewhere close to 11.5 close to 3500 - 4000 rpms as you can get it and stay at that level at WOT.

 

Thanks for the input...remember though that the second chart (dyno jet) is not a load bearing dyno and the dyno dynamics (first chart) is. Just got off the phone with a local dyno shop and they said that makes a difference right there. I'm probably going to re-tune this thing semi-locally just to be sure.

 

I made an appointment with a good SS Box tuner a few hours away for Friday. Kinda sucks that CP Race's numbers looked good until now. At least they can tighten the belt for me so I wont have to do that.

 

i had my car tuned at cpracing a few weeks ago, car feels great after the tune, they used the tail pipe sensor, i had a bung they could have used, didn't even think of that, what is the difference between using the bung vs the tail pipe. will this cause my air fuel to be more rich/lean ?

 

A note needs to be made that this was done with a sniffer and not a bolt in sensor. Plus didn't your car have cats? My wideband(which is installed on the driver's side, the leanest side) said nothing higher than 12.0 and as the rpm's climbed around 5800 it said it was getting lean. Like 13.0:1.

 

Depends on if you have a catalytic converter installed or not. It doesn't really make much difference if there is no cats, but I think it reads lean if the cats are in and you measure the A/F after the cats.

Someone double check me on that though, not positive...thanks.

 

Why would the driver's side be any leaner than the passenger side? I figured they were the same and thats why it doesn't matter which bank you put your WB02 on.

 

I had Crawford H/F Cats installed prior to the tuning. I think they used the passenger side if I am not mistaken. (I do not know if they used a sniffer or a bolt in sensor)

 

When is full boost reached?.. Cause I think from your Wideband data log and your A/F print out... It seems good since you are getting to the 11's by the end.

Also when tuning where they gradually building up threw the RPM's or just WOT (chances are they built up with the throttle). So you wouldn't need to be in the 11's until WOT. Oh and is your EGT reading in the data log accurate cause if you were too lean you would be raising high temps but you seem fine there too.

But then again IMO.

 

I'm actually running pretty hot...during some onramp runs...i was hitting above 900 C at redline. Most of the time I am between 750 and 850 C during redline.

 

Take a look inside your plenum and lower runners. The #6 cylinder has the most direct flow and has the most volume of air passing by it. In the upper plenum it starts on the passenger side and crosses over in the lower runners to the drivers side. All the cylinders on the passenger side, the air has to make a sharp turn or pass all the way around the plenum for the air to reach them. That is why when people run lean and get missfire codes the first one they'll get is usually #6.

 

Jason,

I'll go ahead and post my 2 graphs from CP Racing. One is hp vs. tq and the other is hp vs. a/f. I took "the king's" instructions on driver and plotted my hp vs tq vs a/f from the 3rd CFL dyno day and you can draw your own conclusions.

A few points:
1. The dyno at CP Racing had the wideband in my drivers side bung.
2. The dyno at Next Level Performance was a tail pipe sniffer.
3. I have crawford cats too.
4. Not sure if I was hitting a full 9lbs of boost on the dynojet dyno run. I seem to be hitting 7.5-8psi. May need to tighten the belt... Will check this once the car cools down.

If I'm missing anything else I can add it later. Sorry for the small pics, as you can tell, I pretty much suck at the internet.

 

888 °C is equal to 1630.4 °F That is kinda hot there.

Your gauge reads in Celcius? And sorry was assuming Fahrenheit

Also results vary clearly by your different results.

 

maybe i'm not seeing something that you all are...

Top pic: The top line is horsepower and the bottom line is your AFR...
2nd pic: the top graph is horsepower and torque and the bottom graph is afr

Both afr curves are almost identical... you're not running lean at all, you're running nice and rich! Perfect for a boosted car!

In the afr world 10:1 is rich and 24:1 is lean... 14.7:1 is stoich (almost all fuel and air gets used in combustion).

 

While AFR looks fine on Dynamics, Dynojet specifically shows lean condition from 4700rpm up to 5900rpm at WOT. If I were tuned the damn thing, 12.0-12.1 would be as lean as I'd allow to be safe.

 

g8tor20
You didnt send me the second dyno . But Ive seen your Z files and the CPR dyno . After looking at all three now , Your CPR dyno A/F looks good , Your Zentroix A/F looked almost exactly the same . But now that you have printed out the Zentronix A/F...it is different than the files you sent me . Are we getting the whole story here ? From the Z file you sent me...your belt is for sure slipping up top ...And was more than likely was slipping more on the second dyno . Throwing your A/F off because you are in a different boost range on your A/F map . You were making over 10psi and now you are only getting 7psi....that will for sure throw off your A/F . Tighten up that belt and it will be ok

 

I'll chime in here to offer a bit of explaination.

The difference in a/f reading are due to a number of reasons:

-Difference in a/f meter design.
DD uses a wideband O2 sensor directly in the exhaust gas flow stream.
DJ uses a remote wand and suction pump to pass exhaust gas over their wideband O2 sensor.

One method is sampling a direct reading, the other is subject to cooling, vaccum leaks, introduction of fresh air etc... Which method do you think more accurate?

-Age of sensor.
DD sensor @ CPR is replaced on a regular interval as a matter of ensuring accurate, repeatable readings. Cheap insurance to ensure an correct readings.

How old was the O2 sensor on the DJ? Has it ever been replaced?

-O2 sensors have a finite life span. They will contiune to work for years and years of use but their accuracy and response time slows thru their lifespan. There are a number of physical factors that can kill or damage a sensor. Soot, oil, water, lead, physical damage from shock.

-Type of dyno
Load vs. inertia
Load bearing dynos are capable of exerting a much more realistic load on a vehicle thru the pull. This translates to an accurate representation of real world conditions. Inertia dyno are capable of exerting 1 loading ramp rate. which may or may not be true to real world conditions. I will not go into the inertia vs. load debate any more here. There are numerous threads of phunk debating w/ peter and myself over the merits.

-How many runs did you make on the DJ?
Lay the a/f from your dj runs over each other. 99% sure if you made 3 runs that day, those 3 a/f graph will not lie over each other.

-Load hold prior to run vs. immediate sampling.
DD dynos allow the operator to hold the vehicle full throttle for a set period of time prior to the run starting. This allows coolant temp to equalize thru the block, cylinder temp & pressures, intake manifold pressure and last but not least exhaust gsa flow to stabilize. This method of sampling is prefered since it allows the engine parameters to start @ the same position run to run.

DJ method has no way to stabilize these parameters before the run. When the vehicle stars a run on the DJ the O2 sensor does not have sufficent flow to produce an accurate reading. Notice EVERY DJ run ever posted starts @ a high a/f ratio and slopes downward for the first couple thousand rpm. All that is happening during that time is the sensor is coming up to temp and reacting to the exhaust gas flow. You are not getting an accurate a/f reading @ that point.

Only load based dyno w/ a holding period before the run start @ a correct a/f reading.

-Lastly.
The timing is very conservitive in your tune. A/F could, not that it is, fluctuate a full point and the tune is very safe. Your car could run 13.5:1 and be fine under it's current tune. The only chance of detonation you have is due to contaminated fuel.

Don't worry about it. Just drive and enjoy.