Tacet-Conundrum

Back in the early 90s I remember getting atleast 92 octane in Long Beach ca. Also 93 was possible too. Don't carburatred cars benefit from higher octane. Especially when all the kids use to dump their injectors for carbs in the mid 90s on their hondas?

911rox

Thanx Mooty, will do...

ltc

Octane requirements go up with compression in order to (help) prevent pre-ignition (detonation). That's about it...higher compression ratio, higher octane requirement. Higher octane fuel (in an engine not designed for higher compression ratio, hence higher performance, hence higher output) in a 'regular' engine will NOT yield increased performance.
As a matter of fact, you will begin to see HP actually DROP if a very high octane fuel is used in an engine not designed to use it, since the fuel won't ignite efficiently (cooler burn).

As an engine ages, 2 things can happen:
A. compression ratio goes up (due to carbon build up on the top of the cylinder), which BTW is a common trick in karting and why cc's are measured. This condition would require the use of higher octane fuel.
B. compression ration goes down (due to rings, cylinder, blow by, valves, etc). This conditino would NOT require the use of higher octane fuel.

I don't know exactly how much these ECU's can retard timing, but when (pre)detonation is detected, timing is retarded. Of course the last failsafe is to simply cut the spark (similar to a rev limiter).

daedton

It never surprises me the wealth of information you all know! 91 is the easiest octane to find here in CO, although there's a place selling 93 not to far from Boulder. I'll be running 91 I'm sure as I'll probably blow most of the tank on the way to the track! As one rennlister said, it's December, we're in CO and it will be 50 degrees and Sunny...so off to the track! Now I'm wondering what the stock brake fluid is in the RS? Thanks again!

07 RS
98 C2S
97 C4S
77 911S

TeamDrugMoney

As CJ says, here in New Jersey we have almost 24" of snow and there is a track event going on in Colorado in the 50's. Go Figure!

bob_dallas

I would HIGHLY recommend replacing that brake fluid if you have stock in there. I prefer Motul or SRF. I consider this a minimum requirement to track the car.

Note that you have to replace it all, not just flush because they aren't compatible.

iLLM3

Hahaha, but also didn't Texas and Florida have snow a few weeks ago (parts of those places) but he had 60+ degree weather Craziness indeed... Let's buy some winter awd mobiles, and do the Monticello winter days ... Evo's and Sti's?? LOL, maybe even a GTR hmmmm!

Erik

Funny because on my 996 GT3 I sometimes used 100 octane if it was really hot, figured it could not hurt except for my wallet. Never had an issue. Car did not feel any slower or faster, but since I came out of a 500HP 930S on CIS, I know how expense detonation gets even though all new cars have knock sensors.
The 2 times that I've run 98 in the RS, I got a check engine light. I still get my gas at the track but just the 93, but at the track it is ethanol free. But I've learned my lesson, no more 98 for me since I hate going to the dealer just to check out the CEL.
Goes without saying that I never put leaded in the car.