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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH99 996.1 gasoline type.
Leading reported evidence
Run ethanol free, top tier premium
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Suggestion
The engine has knock sensors to detect that and it will automatically adjust the spark timing to compensate, but you will lose power and fuel economy in the bargain.
Leading evidence: 'Run ethanol free, top tier premium' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Adjust spark timing' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
The engine has knock sensors to detect that and it will automatically adjust the spark timing to compensate, but you will lose power and fuel economy in the bargain.
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Suggestion · Original poster
I would fill the tank and measure a cuppa octane booster from the gallon can and add it.
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Suggestion
As recommended above, fuels certified with Top Tier compliant detergent packages are the standard bar for "good fuel" in the states.
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Suggestion
tl;dr - don't use octane booster, just use the correct octane fuel to begin with.
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Adjust spark timing
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Suggestion
The engine has knock sensors to detect that and it will automatically adjust the spark timing to compensate, but you will lose power and fuel economy in the bargain.
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Suggestion
If you use an octane rating lower than 93 and nothing changes in the engine, the fuel will detonate in the chamber before the spark plug ignites it and this will cause engine knock.
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11 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T031046Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I ask because the operating manual doesn't match the car year and I saw someone say something about E1 rating for the 99 model.
What does this mean? Currently I am filling it using premium (93) gas. Is this correct? Or can it use regular gas?
Thank you in advance.
I run ethanol free, top tier premium. There is a thread in this forum about Top Tier. The short version is the detergent in Top Tier and ethanol free gas both reduce cylinder wear.
it’s a pita to find both ethanol free and Top Tier in my area. One or the other is easy. If I am road tripping I choose Top Tier if both aren’t available in the same pump.
You Tube
Does anyone use an octane additive to bump it up any. I had to do it for my TR-4. It required 104 octane. I would fill the tank and measure a cuppa octane booster from the gallon can and add it.
Thank you both again.
The octane requirement depends on the compression ratio of the engine. The higher the compression, the higher the required octane rating. Porsche engines are higher compression like most sports car engines. If you use an octane rating lower than 93 and nothing changes in the engine, the fuel will detonate in the chamber before the spark plug ignites it and this will cause engine knock. The engine has knock sensors to detect that and it will automatically adjust the spark timing to compensate, but you will lose power and fuel economy in the bargain. Beyond an octane rating of 95, there is no benefit.
104 octane? even if your'e speaking in RON and not AKI, that's pretty ridiculous. That's race fuel. what on earth did you have done to your TR4?
Octane booster additives
do not
get you there and are an enormous waste of money. All the marketing wankery around them is vague for a reason. They advertise raising by a number, then clarify later that the number is
points
. As in 0.1. Meaning 10 points is 1 octane.. but they don't defined if it's RON, MON, or AKI, which are significantly different. Further, they say it treats "up to" some amount of fuel, and to use "any grade fuel" -- so what, exactly, is being done? It's snake oil. You're better off with a water/meth injection system if you need artificial octane.
tl;dr - don't use octane booster, just use the correct octane fuel to begin with.
The Triumph required a 101 octane value. It would not take ethanol based fuels. Became a big problem when the Sunoco closed.
Not my problem anymore though. My neighbor bought it while I had with the engine torn down. He called me a couple years ago. I forgot to sign the bill of sale.
101 is still absolutely ridiculous, was it a built race engine? it feels like something isn't being understood here, if not. AKI is not equivalent to RON.
regardless, 91AKI E10 fuel is A-OK for your 996. As recommended above, fuels certified with Top Tier compliant detergent packages are the standard bar for "good fuel" in the states. there's no need to blast it with additives or hunt down nonoxy.
Just don't go switching between ethanol free and ethanol enriched, unless you really have to. It can cause phase separation of the water that's held in suspension in the E10 fuels. I've personally experienced this in one of my cars and caused misfires and a CEL. Luckily there was no damage to the engine.
Avoid E15 fuels. Also, in some areas, REC90 is all that is available in ethanol free and shouldn't be an issue to run in your 996, if that's all you have access to.
This makes me rethink going Top Tier if �ethanol free & top tier� isn�t available. Staying ethanol free looks to be the better choice and is easier in my area.
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