what gas are u guys running in your 2.7 ?

[chhufast]

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

[unclebilly]

92 ethanol blend

[RSBob]

Chevron 92, but I have a high compression motor.

[Cipotifoso]

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.

[michigan]

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.

[SLO-BOB]

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.

[RoninLB]

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.

[stlrj]

What does your owners manual say?

[bigchillcar]

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

[Nikita]

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.

[RoninLB]

Originally posted by Nikita

my '77 2.7L ran like junk on 87.

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."

[Yellowbird RS]

93 on a 74 Carrera high compression motor

[Navaros911]

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).

[Paulporsche]

Navaros911,
Euro 98 is the same as NA 93.

[sketchers356]

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.

[Navaros911]

Originally posted by Paulporsche
Navaros911,
Euro 98 is the same as NA 93.

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

[SLO-BOB]

Originally posted by sketchers356
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.

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.

[Lukesportsman]

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.

[Lukesportsman]

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.

[RoninLB]

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.