ShiftingGears

Ive been reading and watching about how 928 engines can have improved management software, in the form of new 'chips', to improve efficiency, smooth running and obv. performance. Anyone tried this ? Is this a good idea for the cost?

Fuel efficiency is my number one concern as we pay the highest prices in the world here and I want to be able to drive from here to say the Italian lakes without stressing about gassing up.

As a speed freak performance improvements would be excellent too. It is possible to fill up with 102 octane which can help with both mileage and smooth running. Do chips work or damage or stress the engine internals? Does octane rating make any noticeable difference or improvements?

These engines are old now so whats sensible?

hacker-pschorr

What year 928 do you have? Automatic or manual?

ShiftingGears

1990 GT man.

ShiftingGears

BTW just read alot of stuff here about PorKen chips - what kind of BHP improvements come? and any improvements in fuel efficiency?

And yes the car will be in top maintenance before trying any of these. I agree with that.

Darklands

I don't think you have improvements in fuel efficiency, Old car with no direct injection and no cylinder cut off.

hwyengr

Porsche left room in the programming for safety margins and reducing warranty claims, especially on the pre-EZK cars (earlier than '87) since they didn't have knock sensors. The aftermarket chips carve into those margins. It's all about how comfortable you are with that, for longevity purposes. I haven't heard anything about engines blowing up, but we're also a pretty small group and no independent vendor has the test protocol of a major car manufacturer.

hacker-pschorr

DI engines are having a fun time with valve / intake build-up and cylinder cut off systems destroy engines when lifers fail.

Darklands

I know, there is no free lunch in engine technology! ;-)

Schocki

IMHO a V8 will never be fuel efficient like a four cylinder in-line engine. It was never designed to be top in this category. V8s are about power and torque especially, torque is what makes your drive enjoyable. The best improvement is to have all fuel delivery and ignition components in top condition. New Bosch four hole injectors e. g. are great. Forget about 102 Octane, your engine was designed to use Eurosuper 95 Octane ROZ. 102 Octane helps the fuel companies to fill their pockets, nothing else. Your street legal GT does not benefit at all.
Chips work, especially Ken's EZK-S. It improves the ignition system while you drive the car.

Here are my modifications and yes, they improve gas mileage too:

• Stainless steel X-pipe from Roger with high flow metallic cats. Your engine is an air pump, in order to improve it, you have to make it a more efficient air pump.
• Sharktuner with LH-PEMS module. Took me some time to tune it to the optimum, but it runs great now!
• Two oxgen sensors one for the LH and the wideband to tune the LH-PEMS module.
• Set of four GT cams in my GTS engine, contributes to a better airflow. Higher valve lift, changed duration. Shifts the power curve slightly, runs great, even with my automatic.
• 24 lbs/h Bosch four hole fuel injectors. Only needed if you want to extract beyond 350 BHP.
• New John Speake MAF.
• Ignition system all new, with the standard Bosch copper plugs installed.
• Ken's newest version of his EZK-S. Mapping base is a GT map that was tuned/customized with my EZK-PEMS module before. Ken programmed it into my EZK-S.

What was the best improvement? X-pipe and the EZK-S. With the x-pipe you can really feel that breathing improved. EZK-S takes some driving, but you can feel how power improves after a couple of CEL blinks. I'm using 98 Octane ROZ fuel only here in Spain. Higher octane fuels with the EZK-S don't work well, due to the design of the chip.
Fuel consumption improves a little too. You can't expect wonders, but up to one liter per 100 km is possible, especially on highway driving.

Speedtoys

Your best choice is a well running OE chipped car, in good tune and a tight sealed engine, and properly working fuel system, fresh injectors, O2 sensor, damper/regulators....

Everything else is either just adding fuel "because its good" or optomizing timing and adding fuel (in places)..not that these are BAD things, but..you want to watch fuel, not count HP.

Kevin in Atlanta

I've never owned a GT that when properly maintained needed any improvements. I seriously doubt there is much head room to be gotten.

The Forgotten On

There really isn't. Aside from keeping the engine running in perfect tune, not much can be done to improve MPG.

The only real way to improve it is to modify the trans with either a taller final drive (higher top speed, lower acceleration) or swap the trans to one from a C5 Corvette.

Those are capable of 30 mpg on the highway just from their crazy tall gearing. But with the value of GT's currently that is looked down upon especially if the car is original and nice.

Pagnobito

There's not really any fuel savings to be made apart from not using the throttle much.
Make sure your air mass sensor is properly calibrated and everything else is serviced.
JDSPorsche offer a chip that improves the mid range dip by timing changes and slightly less fuel at the top. All based on many sharktuning sessions, not to be maxed out and cause knocking but improved over base within safe regions.

Kevin in Atlanta

Long before there was Rennlist there was Walt Konecky who swapped in a 2.2 rear end into his GT.

Schocki

I don't know when this event happened, but my GTS drives since 2011 with a S4 2.2 US R&P. https://rennlist.com/forums/928-foru...n-s4-unit.html
I honestly think, that this final drive ratio is more suited. Acceleration up to 160 km/h is marginally slower. To reach 260 km/h is no issue, above you'll need a little patience.
Fuel economy: no difference while in the city.
Different story on the highway: while going at 78 mph, slightly above the limit in Spain (75 mph), I can get 12 l/100 km or 19.6 MPG with no issues. I recently drove to Portugal and was able to go without AC on and for a very long time with the cruise engaged at 70 mph. This way, the GTS achieved an astonishing 10 l/100 km or 23.5 MPG! I couldn't believe it myself, but it is possible with a perfectly tuned and maintained engine.
I think, that our engine is very well-designed and still very "competitive" in comparison to modern V8s used in Porsche SUVs today.