So this weekend I decided to play with the Durametric software and log some data from my car. I, like several others here, took advantage of the sale pricing for the FVD tune and thought it would be interesting to see how the tune affected the data.

I’m entirely new to this so I did read up a bit on some of the previous posts on what data to collect, etc. I settled on the following variables:

o Time
o Engine speed
o Engine load
o Boost in psi (a calculated value I created = ((Pressure ahead of throttle plate- Ambient pressure)/1000)*14.5037738. The ambient pressure is actually a variable that changes slightly. Typically between 975 and 990.) It’s a hidden column on my data below.
o MAF (mass air flow)
o IAT (intake air temp) in deg C
o EGT – exhaust gas temp – I believe this is a modeled/calculated value as I don’t think there is a direct measurement from the sensor.
o Ignition angle – same as timing advance I think?
o Injection time – can be used to calculate duty cycle of injectors
o Throttle plate angle – should be at 100 at WOT.
o Vehicle speed (in kph)
o Speed (MPH) - is a calculated value I created = vehicle speed/1.609344
o Lambda banks 1 & 2 -
o Pressure (in millibars)

My car is completely stock, 2007 997TT w/ 35K miles. 93 octane fuel. I did some pulls before flashing the car with the FVD tune. For my pulls, I was in 4th at 60mph when I went WOT. I backed off when I was around 5900rpm at 110 mph. Yes, I realize I should probably have gone to redline but going to redline in 4th is a recipe for jail time as there aren’t many public roads where I could pull this off repeatedly. In hindsight I probably should have done them all in 3rd instead and taken it to redline. Maybe next time.

The data is very interesting to me as an (no longer practicing) engineer..

- I’m not completely sure what engine load is telling me and how it is helpful. Looks like the range is 0-200?
- IAT of 40C seems high to me, but I suppose the more you compress air the higher the temp goes.. At what point does it cause the engine to retard timing or boost?
- EGTs of 800+ when under high boost.. seriously hot temps, at what temp do you start having problems?
- Ignition timing (angle) – Not sure what would be considered “normal”
- Lambda 1 & 2 – I know that 1 is considered stoichiometric.. but here in TX our fuel in a lot of places is 10% ethanol, so it would be considered E90, which changes this a bit?

So here’s the stock data in normal mode. I picked the “average” of the runs, I had one that had a higher boost pressure but used the mid-range one:
(Sorry for the small font.. not sure the easiest way to post a large XLS table..)




Here’s the stock data in sport mode.






I then used the My Genius unit to flash the FVD tune and repeated my runs. The tune runs were done 1 day later when it was a little cooler (by about 6C)

Here’s the FVD tune in normal mode:




Here’s the FVD tune in sport mode:




Clearly you can see that the FVD tune keeps the boost higher for longer. Here’s a graph showing the 4 runs of rpm vs. boost pressure. (Special thanks to member ut_farhan for creating the graph for me!)





I’m curious as to what the camel hump at the first of the tuned curves is caused by.. is this something built into the tune itself? It seems to hit a setpoint and then allow the boost to build even more..

Any comments welcome.. I don’t think I’m going to be doing much more to the car other than possibly an exhaust – the EP is sweet sounding.. I probably won’t venture towards the next stage, e.g. new turbos, intercoolers, injectors, etc..

I have the full data of all my runs in an XML file is anyone is interested..

 

Not an expert but i will try to answer to your Qs, as i know typical values are :

ignition timing - each tuner know how to play with timing, boost, etc... but what i have seen so far from "full boost"-5000 >9-10, 5000-6000 >10 to 20, up on top like low/mid 30s or high 20s
AFR - stock map is lean anyway, but i would run like 0.78-0.82
IAT - yours is growing fasssstttt, maybe meth or better ICs
Do two logs: start at 2500-3000 in second and push till redline, shift to 3rd and redline her; then start 3rd at 2500-3000 and shift to redline; will see also timing up on top and IAT, this will tell a much better story

Hint: give up some parameters like mph, kmh, some mbar values etc to collect more samples/second of what you need. Do injector time on a separate log if you want to calculate IDC

From what I see in the logs, a meth kit would help you a lot with timing, IAT and AFR
Are you sure the gas was really 93 ? looks like very poor gas to me and 10% ethanol isn't so bad in the end

 

Thanks for the logs. A couple of things:

1. Your AFRs with the FVD tune are interesting. If reading the text books, 12.5 AFR (or a lambda of 0.85 which is 12.5 divided 14.70 or thereabouts) is good for maxiumum power on gasoline powered engines. Turbo motors particularly on stock hardware a bit different, IMO. I like to run them richer on torque peak with more timing and then slowly lean out a bit as the rpm rise to make the peak power nice as well. IE, 11.0 under peak torque slowly leaning out to say 11.4 or so. Your car is mid 12s during peak torque and by 6k rpm is already in the 10s AFR wise which isn't good for top end power but is very, very safe.
2. Your IATs (intake air temps) do climb fairly rapidly for what is a short full throttle run (around 6 seconds at full boost judging from your logs.) The DME will start pulling timing in response to those hot air temps above 50 deg C from what I've gathered on these forums. You can bet if you do a second and third gear pull you are getting well above those numbers. A set of GT2RS intercoolers would be a great upgrade while being reasonably priced and OEM parts. Look into it. They will add a lot of consistency to the car as well as smooth the power delivery out.
3. There's always some full throttle wind-up boost overshoot on these cars. I think it has to do with the way the DME calculates load and actuates the VGT vanes. It doesn't appear the VGT setup is as fast reacting as a standard pintle valve wastegate. Also, as you know the 997TTs clutch isn't designed to handle the amount of torque a 3.6L engine at 22 psi of boost can generate. Tuners get around this by limiting the boost in the midrange and ramping it in as RPM climb and the VE of the motor drops which allows the engine to make great top end power, while limiting the torque to levels the stock clutch can hold. Your first "camel hump" is just a slight boost overshoot and the boost rising around 4500 rpm is likely there because they want to preserve your clutch at peak torque while still allowing for more top end power. That's the way I would (and will) tune these cars on stock clutches as well.

 

Thanks for the advice - I will do the extra runs and post the results.. I did look thru the rest of my runs and the highest the IAT got was 44 after several tuned sport runs..

I always use 93 octane..what makes you think it might not be? Is it the timing numbers?


Awesome, thanks for the info. I've attached the data from the rest of the runs that day..all after the fvd tune.. IAT maxes at 44 after several sport runs.. I may have to look into better ICs.. ya know that slipery slope and all..

 

That last 4th gear pull in your PDF shows an 8 second run in 4th gear out to 6300 rpm or so. Notice that your IATs go from 21 to 44 deg C in that time period. Substantial increase. IATs are hotter in the higher rpm range where the compressors of the turbos are less efficient. Like I said, a couple 2nd and 3rd gear pulls to redline in succession and I think you'll see IATs well above 50 deg C. At that point, the DME is pulling timing (power) due to excessive heat in the intake charge.

Also, by 6300 rpm your AFRs are extremely rich...in the 9s! I would like to see what they drop to when you rev all the way out to 7k. You have a lot of power left on the table at your current boost levels with air/fuel ratios that rich.

Next time do pulls in third gear out to redline and include timing correction. That gives us an idea of what the DME thinks of the amount of timing it is mapped for with regards to the knock threshold. I'm sure the timing is very, very conservative as well.

 

Awesome stuff, thanks so much. I will do the 4rd gear runs and post the results..by "timing correction" I assume you mean to include the ignition angle data?

I guess I'd rather leave some on the table than risk engine damage..

Thanks again!

 

Can any of you guys put your data in more simple terms?

What have you determined the FVD tune is doing, and how much do you like it?

Rep points for me being honest????

 

I always use 93 octane..what makes you think it might not be? Is it the timing numbers?



Yes timing is very low, dangerously low i would say... that ignition retard is huge and i would check on that, i suppose that over 6000 rpms will reach like low 20 degrees, if so... something is wrong there... your ECU works a lot to keep everything safe and i think this is the only reason you still have a healthy engine, i suppose is the gas quality (try to use some other kind of gas) or the tune (i know your tuner is a good shop, i bought some parts from them in Germany).

IATs- if outside temps were really high, do next logs during the night, you have stock 997.1 ICs right ? If so, 997.2 ICs, aftermarket ICs or meth will improve a lot your IAT, ECU pulls timing a lot at 50C

AFR- to run over 0.85 in a tuned engine is something i wouldn't do, as others said already max power is @ 0.85 for pump, but the loss in power and consumption to run 0.8 lets say is minimal but your engine will run much safer, power comes with a price. Stock map of 997tt is already on the lean side from the factory, but considering the stock boost level, isn't so dangerous... take a look and compare timing and AFR with stock timing...

 

AFAIK, the engine load, is in some way, the bottom line, as it represents torque/power. TTdude went over this a while ago (thanks). By itself, it appears to be a unit-less parameter; but you could use it to compare between cars, and between tunes. I graphed mine and it paralled the torque curve of my engine dyno.

For example, I think (?, pls check) your max is 201 at 4450 rpm, with FVD in sport mode. I'll find my graph and post it later.

 

+1 ... and 200 is alot of corresponding torque... like 800Nm or so, if you are running mafless thats not an actual value tough

 

Great info!

I would like to see the same for 997.2TT: before & after FVD. Anyone got a chance to post the Durametric results?

 

Yes, car is completelyt stock. Im due for a fill-up so I will try to find some quality fuel this time before I take some more data..I think we can get 94 octane around here somehwere..

Thanks for all the insight guys!

 

Ok Gents, I collected some more logs today after I filled up with a fresh tank of 93 from QT. I honestly don’t remember where I got my last tank from, although I *do* always only get 93.<O</O
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Have a look and let me know your thoughts:<O</O
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A few observations:
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- It was cooler this morning when I went out, about 9C when I left the house and 13C when I got back. My IAT never got above 34C.<O</O
- I did the pulls in 3<SUP>rd</SUP> and took them to about redline. There are 2 pulls in sport mode and one in normal mode.<O</O
- I think the timing looks better, at least it’s smoother and doesn’t jump around as much as the last logs.<O</O
- The AFR looks better (?) to me in that it seems to stay in the .81 - .83 range at the upper RPMs and doesn’t go overly rich.<O</O
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Assuming you guys agree these do look better, any idea on what would be the reason? Cooler IATs? Better gas? Both? <O</O
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Looking back again, the IATs were only 10C different in the extremes (34 vs 44) between the two so could that alone be responsible?<O</O
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Thanks for any feedback..<O</O
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