cheap gas in a ultra

deadring · #1 02-19-2005, 07:44 AM

have you guys ever put cheap gas in a PA SC?

i did by accident yesterday.. my god did it hate it.. i couldn't even floor it without getting sputtering and that slight hesitation ...

if you think of putting 87 octan gas, DONT...

Deadring

tman · #2 02-19-2005, 11:19 AM

Deadring, it is indeed a bad idea for the series I SC engine to be run on 87. However, the series II engine got a computer to adjust to changing grades of fuel.

Hansnet · #3 02-20-2005, 02:21 AM

I thought all L67's needed 89 or higher???

kaspr · #4 02-22-2005, 04:48 PM

My '95 P.A. seems to run fine on 87. It accellerates just as well. But I know that it's hard on the engine, even if it's not noticable to the driver, so that's why I never use anything other than premium.

Vincenzo · #5 02-23-2005, 03:51 PM

I'm not sure which series engine I have (or, for that matter, where I can find out), but my '92 PAU runs like a dream on 87 octane and has over 200,000 miles on it.

DioGreer · #6 02-26-2005, 11:05 PM

91 non supercharged has always run wonderfully on the cheap stuff.

ashes2ashes · #7 03-10-2005, 01:08 AM

my question is what's better for a PA SC....92, 93, or 94 octane. I used to put 94 octane into my PA, but think i should start putting 93 octane for 10 cents cheaper a gallon. Is there TRULY a difference??

kaspr · #8 03-10-2005, 04:56 PM

I doubt there's a difference between 94 and 93 octane. The manual says 91 octane is all the engine needs in order to prevent knocking. Of course the computer will retard the timing to adjust to the cheap gas in case of using less than 91 octane, but it's hard on the engine when you race it. So I'd say anything 91 and up will act pretty much the same. I'd go with the cheaper gas.

bolthead · #9 03-15-2005, 12:17 AM

I have a 94 PA SC Ultra that runs great on 87 octane gas. Don't make the mistake of equating octane with power, because it is not necessarily so. Proper octane rating for any engine is determined by one thing and one thing only - the compression ratio of the engine. Very simply put, the higher the compression, the higher the octane needed to cleanly burn and deliver the desired power. However, put high octane gasoline in a low compression engine and you're not only paying a lot more for the gas, you're also hurting your engine. Reason being that a low compression engine can't burn high octane fuel efficiently - it doesn't produce enough heat. So it's actually building up deposits in the cylinders that eventually degrades performance even more.

BOTTOM LINE - use only enough octane to run your engine without knocking and pinging; any more than that is detrimental. This is a classic case of "more ain't necessarily better". If you have a high compression racing engine, that's different. You're going to need high octane gasoline to get the performance you need. Let's face it, folks. How many people on the road today driving stock cars to get from point A to point B are driving cars with high compression engines? VERY FEW!!!

deadring · #10 03-20-2005, 10:36 AM

bolthead:
perhaps what you say it' true.. but in my gauge cluster, it says PREMIUM FUEL ONLY.. the last owner told me to NEVER put cheap stuff in it... and by accident i did.. i can tell you that the car is VERY touchy about that.. with a high flow cone filter and the air restrictor removed at the supercharger inlet, i can tell you that it will sputter like i have a bad spark plug wire... when i put premieum back in at the next fill up it was back to normal... as the powerful 2 ton beast it is

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