For those of you that run engine swaps or modified engines some good news on fuels is here. Sunoco is now offering 94 Octane premium gasoline. IMO, a good idea to run this gasoline in Supercharged, Turbocharged and high compression engines. While all engines may not need it; higher octane in many engines provides insurance against burning a piston. I would guess that if you are running 10 lbs or more boost or over 10:1 compression the 94 octane gasoline would provide somewhat of a safety factor. My Fiero runs 11 psi of boost ( 3.4"pulley on a Gen 5 Supercharger); so this new fuel seems ideal for my engine. There hasn't been a problem with KR's but I use to run Lucas Octane Boost but now its Sunoco 94..

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: For those of you that run engine swaps or modified engines some good news on fuels is here. Sunoco is now offering 94 Octane premium gasoline.

As we all (should) know, Fiero 2.5 and/or 2.8 engines are designed to run on 87 octane regular gas... and yes, I know this thread is aimed at those who are running something other than those engines.

I just wanted to address the higher octane fuels that many of us are forced to use in our boosted (or high compression NA) engines. My '98 JDM Subaru Impreza WRX STi basically requires the highest octane premium gas that's commercially available for its turbocharged 2.0L engine. Here in Vancouver BC, the pump gas with the highest advertised octane level is Chevron 94... so that's what I've been running for years after acquiring my STi.

About a year ago, I became aware of a new fuel available locally... Shell V-Power Nitro+ 93. I didn't pay any attention to it. I figured, what was the point... as it was one octane point less than Chevron 94. However, I stumbled across the following video... and it opened my eyes to the fact that the advertised octane level of a fuel is not the end-all and be-all of how an engine performs.

In the following video, the fella does an exhaustive test comparing power levels attained using various fuels using the same engine. The results may surprise you. I'm not trying to promote any particular gas, but I just wanted to bring to the attention of anyone who may be interested that the highest advertised octane level may not actually be the highest octane level.




If any knowledgeable member here sees any fault with this test, please comment below!

[This message has been edited by Patrick (edited 06-02-2023).]

Good thoughtful post and informative video. I run the 94 octane Sunoco in my 3800SC series III primarily as a safety factor when I run the RPM's up to 5500 at 11 psi of boost. IMO, in a boosted engine more octane is better than less octane as knock under full throttle can blow an engine. KR hasn't been a problem as the engine has an intercooler and I use Lucas Octane booster. Going forward I still feel more comfortable when running 94 Octane gasoline. From now on out I'll not use the Lucas Octane booster because its already destroyed two Oxygen sensors. You remove them, they are coated with an Orange color residue and don't work to spec. .

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Good thoughtful post and informative video.

Thanks Dennis. I'm hoping, if nothing else, that it alerts people to the possibility that there's a better (as in higher octane) gas in their area than what they might currently be running in their high compression NA or boosted engines.

Sunoco High Octane 94 gas isn't available here, but it would've been interesting to have seen how it compares to the fuels tested in that video.

[This message has been edited by Patrick (edited 06-04-2023).]