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Discussion Starter #1
Can the stock ECUs take advantage of 100 octane fuel during a track day, or is it a waste of money? The other alternative out here on the West Coast is 91 octane—no 93 available.
 

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Hi there...

In Germany we have the 95 , 98, 100 and 102 octane fuel.

The first 3000km i drove with the recomented 98 Fuel. Was happy. Than after some minor repairs on my 718B i got an 718CS during 2 days as spare. After that my 2.0 feels underpowerd ;)
So i tried 100 Octan but can´t feel a noticable difference. Than i go to "ARAL" filled the gas called 102ultimate and that was a game changer. My Base Boxter feels like he has taken amphitamin...
The 102 gives me wheel spin in corners which i can drive with the pedal on the metal with 98 fuel...

Price is 10 Cent more than regular 98 Fuel but worth the boost.
You realy run with 91? say no please... The change from 95 to 100 should give you a noticable boost. Try it!
 

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If you are running CA 91 then a splash of 100 octane IMHO would be a good addition to bring the overall octane to 93. This may not gain much HP but the motor was designed to run on 93 and will adjust the ECU to account for 91. This would be for track only use as not worth it for the street.

Peter
 

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might try an octane boost
Has anyone in Calif. or other 91-octane region tried octane additive? Please share your observations wrt max. psi on boost gauge...

Per my thread on the topic, I've not been able to coax higher than 11 psi indicated boost on my S (with WOT at low-revs in 2nd gear). However that's at low humidity and moderate temps at sea level. So maybe ambient air pressure, rather than octane, causing the ECU to dial-back on boost?
 

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Has anyone in Calif. or other 91-octane region tried octane additive? Please share your observations wrt max. psi on boost gauge...

Per my thread on the topic, I've not been able to coax higher than 11 psi indicated boost on my S (with WOT at low-revs in 2nd gear). However that's at low humidity and moderate temps at sea level. So maybe ambient air pressure, rather than octane, causing the ECU to dial-back on boost?

I have no experience with any additive at all, but when you read about octane boost the verdict is all over the place.
Also you need alot to go up 3-5 steps.

I have seen 1,1 bar and that was pretty much under the same conditions.


*edit*
Ehresmann dont use any correction when the put a Porsche with turbo on the dyno.
Porsche policy is that you should not do that because the ECU corrects itself and apparently it can handle pretty much all the different conditions a car will ever face.
But what it will do to boost i have no idea, not very much is my guess, there is other stuff going on in a engine that can adjust the power output.
But i am not an expert!
 

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I fill up with RON 98 'cause it's available everywhere here and the 95 is below Porsche's standard.

There is one chain that supplies RON 100 but it's about 10% (or more) alcohol. The decrease in mileage and performance made it (for me) a no-go despite the price advantage of alcohol fuels.

US 91 or 93 would appear to be in the area of "acceptable but not the best" according to my manual. As it is below the standard I'd be very surprised if there wasn't a performance downgrade.

Some of the octane boosters appear to work well--there are a couple of web pages (somewhere) where the actual boost of the treatments were measured. Some did quite well, others were almost useless--and price didn't seem to be an indicator of quality.

Good luck getting good petrol.
 

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Thanks for that--it's really interesting, and clearly indicates the advantages of using a fuel with sufficient octane to take advantage of 'adjustable' timing. The 4% average increase at times went over 10%.

The engine management unit controls boost, and surely the engine would be more accepting of a larger charge of the high octane mix as well as a timing advance. Both of course affect the pressure in the cylinder and hence the power of the engine.

(Warning--I am not an engine engineer!)
 

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Discussion Starter #11
Thanks, @phroenips, for helping clarify the different octane measurement standards at play globally. I should have been more specific that octane in my corner of the world is measured using the (R+M)/2 method, also known as AKI, which translates to 93 octane being Porsche's preferred octane value, with 90 octane being an "alternative fuel." (Gasoline in the US is generally available in 87, 89, and 91 AKI octane grades, with some regions offering 85 and 93.) Also, most gasoline has 10% ethanol in it as well.

So from Porsche's documentation it seems that the 718 engines can take advantage of 93 AKI octane since that's the recommended fuel. So, it would make sense to add some 100 AKI octane to 91 to get closer to 93. But, can they take advantage of even higher octane grades from the factory? Is is wasting money to go higher than 93 AKI?
 

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Hey everyone, I personally have been using Boostane products to get me above 94 octane. I have noticed a difference with my STi Type RA as it is not retarding timing at high boost levels. Not so much with the 718 Cayman though as it works well with the 94 octane we have here in Canada.
Have a look at their website and the videos of it on YouTube.
Cheers
 

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I asked this on rennlist a few months ago in the context of an anticipated first track day. Many learned technical answers, bottom line that there is no benefit and performance is optimized for 93 octane (USA).
 

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If your normal fuel is 91, 2-3 gallons of 100 would help. A full tank would be a waste. Also, if you do this, make doubly and triply sure that any race gas you're putting in is unleaded.

My understanding is the US engine is calibrated for 93 AKI, so going much more above that wouldn't make gains really. It would be nice to see logs on Pump 93 vs Pump 93 mixed with 2-3 gallons of 100UL to see if there's anything to be gained out of that
 
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