Raider89

I have 2008 997.1 Turbo and know book recommends use of 93 octane (I assume regular pump grade). Is slightly higher octane from VP or others better? How much higher would be damaging? This would be for track use only, not street driving. Any recommendations assuming it actually performs better?

LexVan

It would only perform better if it had the proper tune to accommodate the higher octane.

As long as the higher octane fuel is unleaded, the only damage will be to your wallet. In your current state of tune.

stownsen914

Your car has knock/detonation sensors to prevent engine damage from hard use in case fuel quality isn't what it should be. If you track your car using 93 octane, there is a chance you'd be leaving some hp on the table if the knock sensor dials back ignition or boost to keep the engine from self destructing. In such a case, higher octane fuel can give yield some hp by allow the engine to perform with ignition and boost settings on the more aggressive end of normal. Porsches are generally equipped to perform well under hard use, but there's a chance you'd be leaving a little hp on table. I don't know though if this would be the case with your car. Perhaps someone more knowledgeable about your model can chime in on the threshold for the knock sensor kicking in.

Whatever you do, make sure you never put leaded race fuel into your car, or you'll ruin your catalytic converters.

certz

Correct, your car is not tuned to take advantage of higher octane fuel. That said, there is a benefit to higher octane in lower head temperature.

mark kibort

at a cost of less power if not tuned for it.

Raider89

Here is reply from VP Fuels - any comments? Remember, totally stock engine and definitely do not want any damage or negative effects, otherwise will stick with 93 pump gas.


"The most popular option is the VP-101 and typically over pump premium it offers 3 to 5% more power without doing any tuning changes and it's completely safe for your fuel system."

Steve Weiner-Rennsport Systems

The ONLY way you'll know whether you'll benefit from race gas or not is by doing some dyno runs and monitoring knock counts in the DME with a PIWIS (or PST-2). I've seen 50HP disappear when knock counts approached 20+/minute.

If the engine is on the edge of detonation, you can watch the DME pull timing & boost in real time with these factory scan tools.

Der ABT

Correct me if I'm wrong.....technically lower octane had a higher energy potential....so higher octane is technically less power.
But lower octane is not as predictable for ignition. ..aka knock will occur so....with a more predictable fuel even with a lower energy potential ...you can make adjustments elsewhere ex timing to make more power.

A good advantage to higher octane is also a lower running temp. .....

But I'll leave the for sure anwser for others like behe.....

Veloce Raptor

Higher octane has more detonation resistance, which means you can run higher compression and more ignition advance, which can be used to produce more power.

Some cars will slightly adapt to a higher than 91/93 octane and may produce the claimed 3% more power due to more advance. IMO at 3x-5x the price gallon, that is a huge price to pay for an imperceptible power increase.

However in full race conditions a cooler cylinder head in mid summer alone may make it worth it.

Mahler9th

If I had such a car and wanted a definitive answer... all else equal, I'd simply contact the guys at SharkWerks. Of course in my case I'd just stop by on the way to the gym. But I bet they will answer an e-mail or telephone call.

Joe Weinstein

There is a 104-octane unleaded gas only available at one shop very locally, and
they say a lot of Porsche sales folks put it in the turbo Cayennes for sales drives.

When I raced a 996 turbo, I had switchable tunes, and could get 1.5 bar running
the 104-octane gas.

But with a stock tune, any more than about 93 doesn't make a diff.

rhargy

I ran a mildly tuned 996TT for many years and found that the 93 performed great and there was no significant advantage in moving up to 100 for DE's. HOWEVER, I will confess to running the higher octane for races. It seemed to run better over the course of even a sprint and it did run noticeably cooler during the hot weather.
For me it was worth the extra $ during a race weekend, but not so much for DE's.

Olemiss540

The answer is "it depends". On a stock tune turbo, the higher octane fuel will help to prevent pre-detonation and knock, which will prevent you DME from pulling timing to prevent a blown headgasket/motor.

The hotter the ambient air, the more likely for pre-detonation to occur and for power to suffer (as well as engine temps to increase).

Is it a hot day mid summer, I sure would foot for the extra 6 bucks a gallon to ensure a $70K car was running optimally. In the scheme of tracking a 997TT, the cost for extra octane is well worth it.

Fall/Spring? No chance as IAT's are probably well within the realm of optimum operating temps (best bet is to just log you IAT's during your sessions).

If you are tuned? I would run higher octane all of the time as the added boost pressure is going to substantially increase IATs, and unless you are running sufficient intercoolers to account for the added heat, octane is your only bet (or meth).

AudiOn19s

Couple of things - VP101, despite being unleaded, is Oxygenated and without proper tune to account for the extra oxygen content in the fuel you could risk harm to your engine by running this fuel. I would suggest not doing this.

Motorsport 109 or Unleaded Extreme would both work without issue though if you chose to go that route.

997 Turbo will heat soak in a track / DE setting and pull timing. Not a ton but it will. Upgraded intercoolers will help keep intake air temps down to more acceptable levels and help the car avoid pulling timing. On a hot day you'll probably need a combination of upgraded intercoolers plus 100+ octane gas if you want to keep the car optimized at all times. I had champion motorsport intercoolers on our car and they were a nice unit.

As others have stated, in a DE setting I'm not certain any of this is really a requirement. The Porsche DME will keep the motor healthy at all times at the sacrifice of a little power out of the car...it'll still be brutally fast compared to most everything out there.

mark kibort

how is that possible? higher energy potential? if im not knocking today and i dont change the tune, how can I gain near 20hp for the gas alone?