91 octane all year here in L.A. CA. has the worst gas in the country. I've used 91 in my old 2.7 and in my current 3.0. Our summer blend is for *****, so I've found I either have to pour in a bottle of 104+ or drive out near O.J. Simpson's old house where there's a Unocal with race gas on tap.

I have used 87 on a long trip and gone through a tank of gas and on the way back used the good stuff to compare milage and couldn't believe I had 1/4 tank left so based on that unscientific experiment I don't think it costs any more.I wanted to try this because a mech friend told me the higher end fuel burns better so less waste,I'm thinkin he's right,what do you guys think?

that don't make sense to me unless the 87 caused pinging. Pinging can be very hard to hear on our cars.

as I posted way way above the 91/93 has more additives and less actual gas. Please correct this if I'm wrong

2.7RS w/ ~9:1 CR, mid-grade for street and premium for track.

Jim - PM'd you with a question.

Thanks.

SmileWavy

The owners manual says 87 so that was what I used for the 1st five months I had my '77 2.7. It ran OK so I was happy. Was talking to the PO and mentioned I'd started having a miss around 3200 rpm. She said I should use premium gas so I filled with 94 and it runs like a new car -- no miss and much more and smoother power. Still using it.

YMMV,

The true experts, Steve Weiner, et al, say to use premium as the older 911's don't have knock sensors, and you generally can't hear pinging if it happens. If it is loud enough that you hear it on these engines, you may already have damage. Since I don't drive mine every day the small extra cost is not a big deal. These engines are expensive if detonation does cause a problem.

I monitor detonation during driving. That's why I'm slowly testing lower octane. I really don't want to install a bigger gas tank.

Other than my circumstance it's a iffy thing to use low & mid range gas.

I would like to know how premium could effect an ignition miss.

Never heard this before...what gives? Why would it be so hard to hear since our 911s are not so heavily soudproofed like your average family sedan? I can hear my rockers tapping while I'm driving so why should it be so difficult to hear the slightest ping?

I know the sound of pinging and in the 911 it's unmistakable.

Detonation leads to hot spots that lead to pre-ignition. Pre ignition is ignition miss.

I use 93 for my '86 Carrera and have not tried 87 or 89. ..only in emergencies whenI run out of gas. I have never noticed any predetonation and get 17-28 MPG. On the track I use 94 SONOCO. I have not seen any 91 recently just 93 or 94 at 2.80 to 3.00. I have been able to get 93 at 2.69 so the price is not a real killer...just wait it will go back to 2.15 or 2.30.

I was told that BP had too much ethanol and caused trouble for injectors. I have not noticed any difference but I stick with Shell or SUNOCO. Does anyone know if Ethanol is a problem?

New Mahle RS P&C's on a 7R case. I run mid grade to be safe but suspect I could run 87.

Chevron 92 mixed with 5 gal. of 100 oct. The SC's love it.

Costco 87..........no problemo !!!!