rookie1

BTW: Here is a great photo of our two GT3s with the two different Laguna solutions:
http://www.gotbluemilk.com/web160303...s/image38.html

The GT3 in front has Mech33's GPS-valve solution and simple turn-up pipes, the second GT3 has supertrapps (no GPS solution).

MayorAdamWest

I actually have no issue passing sound with Mech33's solution without any turnpipes. I shift around 7000rpm, but even at 9000rpm it's only a little over 92dB.

rookie1

On a 90db day even the 7000rpm shifting might not be enough.

DrJay

Awesome! The many uses of an Arduino!

hoops25

rookie1,
Where did you purchase your turn-ups? I currently have a sharkwerks exhaust but have the stock exhaust in a box...would love to run Laguna.

Any issues with bumper heat/melting?

Did you use a shop in the Bay Area to install? Can you share the cost of the entire setup or point in the right direction?

Thanks,
Chris

MayorAdamWest

I've done about 8 days at different weather conditions doing just that. I am quite sure it works. Not once have I been black flagged.

rookie1

I bought this from SP Motorsports in Hayward. It's custom made, so I suggest give them a call or shoot them a message to ask for a quote. Their website is here: http://www.spmsracing.com/ \
I was really happy with their work, the construction is really high quality and i had no problems with bumper heat. I used the pipes with the stock/OEM exhaust, swapping the factory exhaust tips with these did take ~15 min at the track.


Oh that's good to know, I stand corrected then. Someone told me it wouldn't work so I'm glad to hear that shifting at 7000 RPM is enough to pass on 90db with the GPS-valve solution.

hoops25

Thank you! I'll call them on Monday.

Mech33

*UPDATE*

To try to make the wiring easier to follow, I've created these one-page graphical wiring diagrams for both the 991 GT3 and 997 GT3. Let me know if anything is unclear. Oh, and proceed at your own risk!

sl951

Great diagram Mech33!!

Thanks

Interesting how they changed the polarity between the 991/997.
997 seems to have less risk to 'back driving' the ECU.

Mech33

Thanks, I should have made these in the first place, but I was lazy...

As for "back driving" in the case of a mis-wiring, I think the risk is similar: in one case you might short a 14V output to GND and sink some current from the ECM, and in the other case you might short a GND output to 14V and source some current to the ECM.

I would try and avoid either case and triple-check the wiring. In general I've tried to minimize the risk by using mechanical relays that only apply voltages to the solenoid valve itself and simply disconnect the ECM-side, and then connect the ECM side again but disconnect the GPS system voltage source side.

But as with all mods, do so at your own risk... sometimes you have to pay to play!

sbel

Mech33, is it possible to modify the code in a way that it triggers not only Relay#2 but Relay#1 (for example) at the same time? This way both ECM V+ and ECM V- could be switched for someone who wants to "isolate" ECM completely when the "override" happens. I actually ran 4 wires and currently just disconnect ECM side completely when GPS controller is connected.

I can probably just hardwire one of the relays on board - connect it's coil in parallel to Relay2 but code "fix" could be easier.

Thanks again!

Mech33

Yes it's very possible. This was originally considered but there are a few tradeoffs:

1) you need to run 4 wires through the firewall instead of 2 (this was the main reason the current design was chosen)

2) since both relays will be firing in parallel, there is a race condition and if one is mechanically slower than the other there is a small chance you'll still have the ECU connected or disconnected on one side before the other (likely not a big deal)

3) running two relays doubles the relay board power consumption in the "quiet" state, and the off-the-shelf Arduino board's voltage regulator when powered off of 14V seemed to get a bit toasty when held in that state long periods of time and would sometimes reset itself (thermal shut down). But that was with 4 relays firing in my original testing, so I could try it again with 2.

The firmware would be backward compatible still... so it'd be up to you to either utilize the second switching relay with 4 wires, or not.

The good news is that a 4 wire design would be compatible with all solenoid-based exhaust valve systems (no 991-specific or 997-specific wiring). This was the reason we were considering a 4-wire version more recently with the increased interest from the 981 and 997 folks.

sbel

Mech33, thank you! Good points to consider.

I have 981GTS and it is different from both 991GT3 and 997GT3 where ECM plug polarity is the same and the only difference is whether it's V+ or V- (GND) that's being switched by the ECM in OEM configuration. 981GTS (at least my car) has a reversed polarity for the plug (with ECM V+ being switched), meaning that ECM V+ takes the Green wire on your 991GT3 diagram).

I initially made 991GT3 harness without testing connections with the multi-meter first, got confused, then decided to go 4 wire to make this solution "bulletproof"

Mech33

Hmm that's interesting. Would you mind sketching the diagram for your 981? My impression is the 981 is the same wiring as the 997 (switched V- / GND). It's not obvious how it could be different than both the 991 (switched V+) and 997 (switched V-) unless the solenoid itself is different.