NJ-GT

I'm looking for a tool that I can plug via ODB-II and adjust the rev limiter on the GT3 (or a Cayman).

Is there such product?

For instance, on a fast autocross course I could reach 8,400 rpm in 2nd gear but shifting to 3rd would be a waste, so I would use a 8,600-8,800 rpm rev limiter on that specific course. These are rare occasions where a car hits such spot on an autocross course, and they last 3 secs at most per lap, with just 3 laps done per day on a competitive day.

Then for track sessions (practice sessions), I could run a 7,500 rpm rev limiter, to extend the life of the engine. Then reset to 8,400 rpm for a Time Trial session.

Thanks

ADias

I hope you understand that a manufacturer sets the red limit with specific criteria. It is a regime beyond which bad things happen rather quickly. A 400RPM overrun (even if a brief one) may be very expensive, but... it's your engine.

Nordschleife

you know about beer goggles and pulcritude?

Well this is the automotive equivalent, I won't ask how many.

R+C

Nizer

Rad: Have you tried these guys? I would think they'd know the answer.

http://www.evomsit.com/

997gt3north

Rad,

I'm almost certain (99.999%) the answer is no - to an off the shelf tool that you can purchase to easily do the job - i.e. a Durametric type tool.

I have had a few turbo cars custom tuned for big power upgrades so I'm somewhat familiar with this world.

My suggestion is to call a person I would call a friend Tony - the owner of EPL.

http://eplabs.net/
http://www.facebook.com/EPLabs?sk=wall&filter=12


Tell Tony that Paul O'Neil said you should call him.
Tony has been custom tuning Audis, Porsches for years and is now doing crazy custom work on Turbo 458s, Lambos and R8s.
Tony is very good at what he does, he won't BS you, he has also done Cayman programming.

He is a very good resource.


Paul

911rox

I'm pretty sure that revs up to 9000rpms are only type 1 or 2 in any case... Furthermore, the same engine in a cup car redlines at 9500rpms IIRC... From what I've read of NJ-GTs posts, he really knows his stuff with these cars... Doubt he'd be risking an engine failure...

911SLOW

AFAIK such (specific) product doesn't exist.

You need to work with a tuner that uses the OBD port approach to create for you two different DME programs. One for each rev limiter. Then he can give you a Windows program to run in your laptop on the field together with a correct usb-to-OBD cable.
Each program will have to be uploaded before you can use it.
A process that is time consuming as each time the ECU has to be fully deleted and then all memory banks re-written.
(The rev limiter is not a stand alone setting.)
While doing that you have to have a battery tender so that the battery won't drop below a min value and destroy the expensive ECU.
In addition most of the tuners that use the OBD port for DME upgrades, each time require an internet connection so that they can verify through their program the car's VIN and stop people from buying one DME upgrade and sharing it with their friends.


In a few words, forget about it.

Pick a tuner that knows GT3s and their settings (You might be surprised to know that most have no idea of what they do and just alter a few generic parameters and the throttle sensitivity so that you can "feel" the power..) and discuss with them. Then make one proper DME upgrade. An increased rev limiter (let's say 200-400rpm) is not out of the question for these engines.. as for a lowered one just use your right foot..

997gt3north

Can I guess?

A 7800rpm (or there abouts) 3.8 GT3/RS, lightened to 2800#s, to compete at the absolute max in some autocross series?

If something like this is the idea, purchase a 2nd ECU / MDE from Porsche, have it loaded with a stock program, and then send it to a person like Tony at EPL and have him change the Rev limiter to your exact HP needs. I use to do this with a previous trackcar / street car that I had. My street program was set for maximum HP/TQ power - my track program was designed to work on the track - i.e. a slowly ramping boost program that I could go WOT at the APEX and instead of boost spiking on turbo spool, the boost would slowly climb simulating a NA engine - this is what Tony at EPL programmed for me. I could change the ECU in less than 5 minutes - it was very easy.


Paul

AllanJ

+1

NJ-GT

Thanks all for the feedback.

Yes, I was thinking on a Durametric type of tool where I could set the rev limiter. However, in a brief research, I found out that the Durametric goes through a full ECU re-write, so even in the case where 2 maps are available from a tuner, the risk of getting a ECU damaged after many overwrite attempts is pretty high.

Another option is to have a 2nd ECU, then swap ECUs, but this is just time consuming, albeit safer than overwriting the same ECU multiple times.

The idea of a lowered Redline also helps for certain Time Trial classes where cars are divided by power/weight ratio. So a de-tuned GT3 with lets say 2,800 lbs a 330Hp at 6500 rpm with a redline of 6500 rpm would have a power/weight ratio of 9.015:1 given a 175 lbs driver. The exact same car with a higher redline would produce more power and be assigned to a class where it is barely competitive.

Specifically in NASA Time Trial classes (nice contingency from multiple sponsors), a GT3 can run in TT-S or TT-U. The car is not competitive at National level in TT-U because TT-U includes GT3 Cup cars, F430 Challenge, Viper ACR-X, etc. In TT-S it needs to run too much weight, so I would rather reduce power and reduce weight, than add weight and add power.

997gt3north

Rad,

I can do an ECU swap in 10 minutes - same time it takes to change 2 tires - it is not a big deal at all. You also learn a few tricks as not all screws have to be put back, etc - I would not in any way view this as an issue. I'm assuming for time a trial at 2800#s that you probably aren't doing a cage (likely) and maybe even lose the passenger seat - and that makes it 200% easier and faster.

utkinpol

i think you want racing switchable ECU system with various maps.
like look at revo

http://www.revotechnik.com/index.php?mod=product

and search for multiple program switching

Serge944

Alternatively, you can have a single tune with a higher redline and consciously shift at a lower RPM. That would require self discipline though.

utkinpol

Rad, why don`t you just get yourself a proper cup car? I think you are more than ready to pull this plug finally. All the rest will be half measures, and after your scud it looks to be the only reasonable option.

997gt3north

The one big negative I would see if you had to be a maximum of 6500rpms with the GT3 is that if you needed another gear, you would be dropping down a pretty significant amount of HP in that rpm range - and that may be the killer right there - a turbo car with VV Turbos and a custom tune might work better - or a smaller engined NA or Super Charged car that could be kept higher in the rpm range.