what gas are u guys running in your 2.7 ?
 

i have a 911 s was wondering if i could run 87 ... thought i ask

92 ethanol blend

Chevron 92, but I have a high compression motor.

With my stock motor 89 octane works fine. I've read somewhere that the CIS motors, with their cam timing and injection set-up do not need the highest octane available. I used to run 92 and have not heard any detonation since switching to 89.

OCTANE GRADE
 

All I have ever put into the tank is 87 octane for my 77, 2.7. Have never had a problem that I'm aware of. I would think that much depends on the tuning conditions of your set up.

91-93 octane always. It may not need it but, for the small difference in expense overall, I would rather err to the side of caution.

Yesterday-2.89 for reg. 3.01 for premium. 10 gallons added to tank. Price difference=$1.20. I skipped Starbucks to make up for it.;)

I've always run at least 91 as a preventive issue.

I'm able to monitor detonation with a gauge so I just started to run 50/50 91/89 and so far no prob as the fall comes on. I'd like to work towards full 89 for millage purposes as I'm running carbs that have averaged 16-17 mpg. If the 89 works out I'll further work towards 87. So far I'm optimistic that millage could seriously increase.

Generally how the engine is set up and driving conditions determine what's necessary. 110degF desert heat, Rocky Mt's, etc are all types of factors involved for instance.

I'm using an aggressive timing curve with 10deg initial. So far I may be able to get a 25% increase? Sounds strange to me but it's a hopeful maybe. I was getting 25mpg w/ CIS.

What does your owners manual say?

been running 87 for years in a stock '74..no problems.
ryan

my '77 2.7L ran like junk on 87. i had to buy octane booster to get it back to normal. i haven't tried 89, but 91 works well.

I've had a CIS pinging around 3k in very hot desert if I accelerated heavily when using 91. Fine as long as I know the game.

It never pinged anywhere else on 91 except lugging it on a steep incline. The new cam gives me more chamber psi but the carbs are so rich that the carbs kinda make up any pinging weakness. The flood of gas cools the chamber and Ill stall the engine before it pings.

Anyway I'm gonna check out 89 this season. If it's fine I'll check out 89 during the summer. If ok I'll start the whole deal again with some 87. I don't care about any money. It's about extending the gas millage. And if I don't need any crappy additives "Fine as long as I know the game."

93 on a 74 Carrera high compression motor

98 Shell V-Power with lead additive... just to be safe...

Supposed to be the best around... I don't think 98 is common in the US

There's also a 99 around here, but don't think it will do much for my car... even the 95 would work, but that's no V-Power (which according to Shell marketing is "Adrenaline for your engine" - and don't we all love that).

Navaros911,
Euro 98 is the same as NA 93.

Unless you have modified your engine or your engine is developing carbon deposits anything higher than 87 for standard conditions is stupid. If you insist on wasting your money why dont you send it to me instead? These are pretty low compression engines guys. They really arent all that high performance with the CIS.

OK Paul... could be; I'm no expert on this... but 98 V-Power just sounds good, doesn't it :cool:

Maybe. Then again, maybe you don't know as much as you think you do.

I contend it's called "premium" for more reasons than simply higher octane. I've been told-be it urban legend, myth, or otherwise- that it's a better grade of fuel in addition to having higher octane. Like I said earlier, for the minor difference in cost, I'll err to the side of caution.

If you really need the money though, I'll send you the $1.10.;)

Sure and its "urban myth" that buying SpeedWay type gas will hurt your performance. I've tried it back to back at the track compared to the Marthons and Shell types with NO difference in times. Same octane resulted for me the same performance.

I'm sure there are many local small gas stations that are not equal but premium brand prices over your Speedways and Thortons just didn't pan out in my neck of the woods. I know guys who swear by a brand and that particular brand hurt my times. There are only so many sources for domestic fuels.

I now run VP112, so much for the old pump gas racing days.

I was shocked to see that with a 996 ( I know its computer controlled, but I almost thought that would make it worse with knock sensors) on a chassis dyno there was only 6hp difference between regular and premium fuels back to back. If your car doesn't need the octane your just resisting pre ignition that isn't occuring and has been shown to HURT performance in some applications.

afaik the delivery truck fills from a generally used by all tank and dials in the additives he wants mixed in.

there was a very good hard info thread a few yrs ago on this BBS.

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 !!!!