What are your experiences with aftermarket ECU tune air/fuel ratios on the
987.2 Cayman S
please? What are your aftermarket tunes logging for air/fuel ratios at Wide-Open-Throttle (WOT) from 2500 - 7000 RPM? I'm getting some unexpected data, and wanted to verify with the community whether this is normal or not please.
As much as people discuss dyno and Dragy results, I'd be happy to find a good tune that adds 4ish degrees of ignition advance vs. stock on 92 octane where there's room for it safely, and keeps a normal air/fuel ratio in WOT conditions, good startup, drivability, etc.
On your 987.2s, are you seeing 12.5:1 to 13:1 which has been conventional wisdom on tunes for naturally aspirated gas engines to make good, safe power at WOT from 2500 - 7000 RPM?
Or are you seeing a higher ratio from your aftermarket tune at WOT?
If you have graphs like I've provided as an example, that's great.
Please include your car's config (stock cats, 200-cell cats, no cats; stock intake vs. IPD, etc.), which tuner (
Cobb
,
Cobb
Pro Tune, GIAC, FVD, Softronic, etc.) and environment (street / test track tested vs. dyno cell).
Which brings me to the results I logged below on a
987.2
CS 3.4L driving on a remote test track (not a dyno) for real-world data, using OBD LX running Android's Torque Pro for data logging.
The car is a
987.2
CS with high-flow 200-cell cats, high-flow exhaust, stock airbox with outside vent/sound restrictor removed.
That's it. No IPD plenum, nothing fancy. Focused on reliable, 2000-7000 RPM spirited driving and occasional auto-x, making the power in this range that it has the potential to do.
The blue line is
Porsche
's stock tune - nice, safe 12.8 - 13.2:1 at WOT in RPM range shown.
The other V1, V2, V3 lines are from an aftermarket tune, which seem leaner than I'm comfortable with for WOT in the RPM shown. They're continuing efforts to fix the air/fuel (possibly from my higher-than-normal flowing exhaust), and I'll update later when we know more.
https://cimg0.ibsrv.net/gimg/********.com-vbulletin/1280x720/987_afrs_1c2fa16b708224edcfee3ef9c976c068309e7252.jpg
For context, I've been tuning for decades on laptops with Hondata, AEM, etc. and before that, with jets, air bleeds, distributor springs/weights back to the mid '80s.
Wide-Open-Throttle on naturally aspirated vehicles has been reliable and delivered reasonably safe power in the 12.7:1 target on gasoline (11.8:1 on our 450 WHP S2000 turbo auto-x car).
But since there seems to be no laptop-type access to tune our 987.2 CS, I'm dialing back my expectations to "close enough" on a tune and put my faith in experts who allege they've done hundreds of these tunes.
So from 2500 - 7000 RPM I'd call it good if air/fuel ratios are near 12.8:1 and there's 3-5 degrees more ignition advance than stock/base tune.
The 3 aftermarket tunes I've tried had 1-4 degrees more timing than stock at WOT.
The ones with 3-4 degrees feel more responsive and had slightly better pull. Just wish the air/fuel was closer to what most consider normal 12.8:1ish at WOT, and I'd call it done.
Very pleased with the 200 cell cats, higher-flow exhaust, de-snorked intake restriction, so getting a custom tune seems like overkill since our configuration is very vanilla and likely to "been there, tuned that" by the big firms.
The cylinder head flow / resonances of this engine from 6800 - 7400 RPM aren't worth the wear/tear & "peak" power numbers to me for our use cases.
Bottom line, I'd be set if I had a reliable, safe tune that made use of the improvements in exhaust and intake flow - no interest in IPD plenum complexities. Not looking for magic with the variable valve timing vs. what we did on our S2000s (removed the marketing-hype VTEC kick at 6K by lowering engagement to 4K RPM yielding smooth, linear power curve more conducive to auto-x & track days). Just the finishing touch for what we think this platform is capable of.
Not looking to bash any vendors or incite any holy wars please. Rather, we need to get reasoned, data-driven information on this subject & help people make solid decisions about this important element of the whole combination in our cars.
Thanks in advance for your kindness and wisdom.
