Thank you Tripple's.

So i wasn't going crazy, i did read those posts :icon14:

I've highlighted the areas that i think are pertinent here. To me, i personally think that what then happened at CAT, means timing tweaks *ARE* possible and *DID* make a noticeable difference.


Now i'm sorry to say this, but it doesn't take a genius to work out that, once the gains from CAT tuning the spark advance/timing were seen, it would not have been in SZ's interests to then show the loss again on their tune without the spark advance.


I also noticed that the optimal AF ratio was mentioned, but i can see that the comparison AF ration charts from CAT showed a large improvement in the AF.

I'll try to lay this all out so everyone can easily understand this or so I hope. I by NO meas want to make this a this versus that, etc...
I've played with timing tweaks or tried t on the new VHR engines for the last couple of years with no real benefit on an NA car. I was thrown under the bus somewhat in doing the testing for both the OP and Motordyne. I did a true comparison back to back originally when Tony @ Motordyne was at my shop. My job was simple, dyno on the OP's Invidia catback, install the Motordyne E370 catback, dyno the new catback and at the end unrelated to any of the exhaust tweak the tune for the changes the OP made in his mods.

Tony offered the OP a tune at Church as a consolation to the OP's unfavorable review of the exhaust. I personally have nothing to hide from as I have played extensively with the ignition maps and have done lots of talking with Jared @ Uprev about timing tweaks on the VHR. Jared and I spoke today via e-mail unrelated to this situation about knock maps on certain ROMs that have no High Det maps. Jared's response from today: "The newer ECUs do closed loop knock control somewhat differently. They don't use the "high det" map anymore, they just continue to pul timing as long as there is still knock so there's no switchover. The ECU will pull a LOT of timing. They will also advance the timing quite a bit on their own, which is why we're finding it so difficult to make good power gains on these newer Nissans."

How the dyno runs are performed can have an affect on power between runs. Letting the car cool down for longer periods of time, airflow, what gear the run is performed, etc... can all have an effect on the end result.

When I performed the testing on the exhaust systems and lastly the tune differences I did it in the exact same manner allowing for the same time to cool for each run, etc...

At the end of 3 pulls on the Church tune we reflashed to my tune. Here are the results of the runs and the differences in Air\Fuel using my equipment. Again, there are no smoke and mirrors on anything I did. I told the OP when I was reflashing after the 3 pulls we made and brought the laptop into the car at that point.

I will show all the pulls made and differences in AFR. I will also plot the runs in "speed" to show all pulls were made in the same gear as to not affect power. I like to run the mixture leaner at lower engine speeds to help bring up the low end torque. Blue runs were on the Church tune and the red runs are my tune. This was all done on the same day within an hour. The reason I feel that the first two Church tunes were lower across the powerband is because the timing was advanced to far and the ECU was pulling timing and by the 3rd run the ECU adapted to run its optimal timing. This is based upon what Uprev has said and my R&D the last several years.

Run 1
http://www.specialtyz.com/images/seb/run1.jpg

Run 2
http://www.specialtyz.com/images/seb/run2.jpg

Run 3
http://www.specialtyz.com/images/seb/run3.jpg

Run 3 of Church vs a 4th Pull on the SZ Tune to confirm.
http://www.specialtyz.com/images/seb/run4.jpg

I really hope to lay this all to rest and move on. For anyone looking to buy an exhaust the Motordyne is a nice quality piece. Tony put out a great looking system.

Here is an email received from Shawn Church in regards to the delta gain discrepancies from the two dynos.

Is it typical for the AF to change like what Shawn is describing?

These ECUs learn quickly and by the 3rd or 4th pull we would have seen the AFR lean out if that was the case. As you can see on all the pulls the AFRs were nearly identical every time. Come back down if you like and we can again lay this to rest.

Hi Seb,

Just so you know, Shawn at Church Automotive Tuning was not given any details or background on the tune or comparison. The only information he was given is that it was previously tuned and to see if more could be made. No other information was given to him.

Other than the possibility of the ECU changing its short and long term trims, I can't say why they are different but I will vouch for Shawns integrity. He wouldn't fudge results as some have hinted. Not for me, not for anyone. Nor would I.

I'm thinking it is quite possible that both of your results were/are accurate at the time of testing.

----

Jason,

Here is the additional analysis of the 3 best runs of each system. The 3 runs were averaged together to give a clearer picture of the final results.
http://www.motordyneusa.com/media/ku...of%20three.gif

This is the 3 averaged delta plot of best runs with the AF tunes.
http://www.motordyneusa.com/media/ku...of%20Three.gif

At the end of the day, it didn't quite meet your expectation of making 5 more HP, but it was close.

Tony, is that showing the SZ tune i assume? so without the spark advance.

Well i say that because it's comparing the Invidia Vs the MD, which can't be done on the Church/SZ tunes as Church never had the Invidia.

From what I can tell its just the differences between the catbacks is all. No tune differences.

Yeah, reading the titles, there's not tune changes there, just the cat backs and on the SZ tune.

Tony

Thank you for producing those graphs. Those are significant gains I did not expect to see. As a few here have questioned, are those plots representing gains only after a tune from Seb?

Can you make the same plots comparing the two systems without the tuning? This will be based on the first dyno graph you quoted me in. Strictly an exhaust to exhaust comparison.

Also, if we are comparing averages of three pulls, can you produce plots comparing best runs as well. It will be interesting to see how these plots stack up against each other. I'm sure it is very tedious to produce those plots but I and the community will appreciate your efforts.

It is too difficult to extrapolate just based on the one plot posted.

I was reading through this thread and found this. Does anyone know if that's still an ongoing project?