what type of gas grade would supercharger requires?

[bellwilliam]

I chose a Vibe Base instead of GT for 3 reasons:1. I prefer Base's available supercharger over low torque on GT.2. insurance is much less (I assume) with Base, just don't tell the insurance company about the supercharger.3. Base requires only Octane 87, instead of 91, that saves me about 20 cents per gallon. I use about 1000 gallons a year, that's a $200 saving per year.that brings me to my question: what octane fuel grade would supercharer requires?

[andrewmva]

You should ALWAYS run the highest octance you can get... 92 94 whatever....If you are interested in performance, treat your engine rightif you run 87 with the SC good luck...even 87 on a NA engine will destroy it... have a look.... a 20,000 mile engine

[bellwilliam]

according to 2 articles:1. by Consumer Reports, higher octane don't do a thing for your engine, except where the car requires them.2. I believe it is Car and Drivers (or Road and Track) of last year. they tested like 4 different cars. 2 that required premium gas, 2 that don't. for the 2 that required premium, 1 performed the same regardless. for the other 2 that only requires regular 87. 1 car was actually slower with premium. the other wih no difference.I raced cars (in SCCA ITB and ITC for about 4 years) about 5 years ago. we used to run them on dyno. there is always almost no difference in the gas used. except when we were runing an Eclipse Turbo, there was a siginicant HP boost using premium.btw, here in California, we have a whopping 91 octane.

[Faultline]

If you dont want to risk detonation, then use high octane. the only way I have heard of using low octane with SC/turbo, is to set up a water injection system, but that is pretty much a pain to use-always making sure the water tank is full.-----premium performance=premium gas

[Yoda]

quote:according to 2 articles:1. by Consumer Reports, higher octane don't do a thing for your engine, except where the car requires them.2. I believe it is Car and Drivers (or Road and Track) of last year. they tested like 4 different cars. 2 that required premium gas, 2 that don't. for the 2 that required premium, 1 performed the same regardless. for the other 2 that only requires regular 87. 1 car was actually slower with premium. the other wih no difference.I raced cars (in SCCA ITB and ITC for about 4 years) about 5 years ago. we used to run them on dyno. there is always almost no difference in the gas used. except when we were runing an Eclipse Turbo, there was a siginicant HP boost using premium.btw, here in California, we have a whopping 91 octane.Bell,It is possible that your info is a little out of date - your assumption is that the factory fuel injection system is not flexible enough to advance timing to the point where knock would show up. While that may be true for 5 year old cars and some mainstream models that don't play in the horsepower war, today there's very little reason that a manufacturer that builds a car with a knock sensor would limit the spark advance tables in this way. I know I'm probably in the minority here, but what the heck does Consumer Reports know about anything? They repeatedly bash Hyundais, Kia's and echo's with the advice that "you get what you pay for" and steer people into more expensive Corollas, Civics, etc. Thanks a lot there, geniuses ! I didn't read the R&T or C&D article you're talking about, but what were the other variables? Were the cars brand new, recently tuned, was it cold out, were the car's tested at altitude? Was the regular unleaded 87, was the premium 91? You could pretty much repeat my opinion of Consumer's for these magazines - What they basically told you is that for their test, they didn't have a problem with knock with the lower grade gas. So, why not change the test to see where octane does make a difference? Because then there'd be no time left to think up terms like "glued to the tarmac" and such. Andrew was probably just answering your question on what octane to run with a supercharger. Being a skilled driver like you are, you can probably detect heavy knock, but I would not bet on your skills against a $2 knock sensor. It could be retarding spark, fouling up your cats and plugs, dumping extra heat into your system, and robbing you of power when you least expect it. Also this is worst under high load at low RPM, so you might just mistake it for a flat spot or Fuel injection glitch. Fact is FI will increase your engine's appetite for octane, and so will carbon deposits as it gets older. I know this isn't your question at all - but my GT definitely cares whether I give it mid grade 89 octane or premium 93 octane. Heck, I've even convinced myself that it can tell the difference between 10% ethanol and the pure stuff. I used to use 87 octane in my old car for the same reasons you state. When I finally swapped plugs for the second time at 100K, the points were all black with soot and worn back to nothing. If it's just transportation, stay with the 87 - but if it's just transportation, why would you supercharge it ? I'd call that my $0.02, but that appraisal might be a touch too high...

[bellwilliam]

I do agree with you that with cars like Vibe GT that uses Premium fuel, computer will take advantage of it. but for most cars with 87 octane requirement, computer is not designed to take advantage of spark advance. I did a quick search, and here is the car and drivers article, I cut and pasted the last part of the article (nov, 2001), my memory was a bit off, they tested 5 cars total. 3 needed 87 octane, 2 needed 91 octane. the 3 made no difference, 2 needed 92 octane saw significant improvement with 91 octane gas.http://caranddriver.com/xp/Caranddriver ... ine.xml"On arrival, all fuel tanks were drained and filled with 87-octane Mobil regular fuel and driven for two days before track and dyno testing. The tanks were drained again and filled with 91-octane Mobil premium and again driven for two days to allow time for the engine controllers to acclimate to the fuel type and tested again. All dyno and track results were weather-corrected.Our low-tech Ram managed to eke out a few extra dyno ponies on premium fuel, but at the track its performance was virtually identical. The Mustang's knock sensors and EEC-V computer found 2 hp more on the dyno and shaved a more impressive 0.3 second off its quarter-mile time at the track. The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability. This, of course, may also be the case for the gains of similar magnitude realized by the Ram and Mustang.The results were more dramatic with the test cars that require premium fuel. The turbocharged Saab's sophisticated Trionic engine-control system dialed the power back 9.8 percent on regular gas, and performance dropped 10.1 percent at the track. Burning regular in our BMW M3 diminished track performance by 6.6 percent, but neither the BMW nor the Saab suffered any drivability problems while burning regular unleaded fuel. Unfortunately, the M3's sophisticated electronics made it impossible to test the car on the dyno (see caption at top).Our tests confirm that for most cars there is no compelling reason to buy more expensive fuel than the factory recommends, as any performance gain realized will surely be far less than the percentage hike in price. Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump. If the car is sufficiently new and sophisticated, it may not suffer any ill effects, but all such skinflints should be ready to switch back to premium at the first sign of knock or other drivability woes. And finally, if a car calibrated for regular fuel begins to knock on anything less than premium or midgrade, owners should invest in a tuneup, emissions-control-system repair, or detergent additives to solve, rather than bandage, the root problem. Class dismissed. "

[NY Pete]

I seem to remember reading that if you use high octane fuel in a low compression engine you'll end up with carbon buildup in the motor due to unburned hydrocarbons... I'll stick with what the manufacturer recommends unless someone can prove differently!

[DABEAR95]

A car designed for 87 should run 87 octane. I think that the difference is not only ignitability (made my own word ) but flame speed. If you run 110 octane in a regular vibe, the fuel is not igniting as quick as it would normally. This would cause less of the fuel to burn when the piston is in the "sweet spot" thus causing less cylinder pressure to develop, causing less power to be produced. But if you have higher compression and more advanced timing you can offset this loss and gain power. Thus the reason for higher octane fuel.Jason

[andrewmva]

higher octane fuels have less contaminates in them.... simple as that.

[NovaResource]

quote:higher octane fuels have less contaminates in them.... simple as that.That may have been true years ago but not anymore. All fuel grades are required to meet equal levels of cleanliness.

[andrewmva]

quote:higher octane fuels have less contaminates in them.... simple as that.That may have been true years ago but not anymore. All fuel grades are required to meet equal levels of cleanliness. Damn am I that old already??? well.... I never run anything under 91

[Yoda]

As hesitant as I am to present any website as the "difinitive source" on the topic, here are a few good sites:http://www.turborick.com/gsxr1127/gasoline.html http://www.sunocoinc.com/market/transpo ... _fuels.htm Since bellwilliam kindly posted that C&D article, I'll add a mobil link for you :http://www2.exxonmobil.com/Siteflow/Pro ... _Fuels.asp http://www.mobil.com/USA-English/GFM/Pr ... ne_FAQ.asp See, in a half hour, I've already put more thought into this post than Markus put into his whole article. As much of a poindexter as that guy is, I'm surprised that this article is so sloppy. I met him once - he's a pretty smart guy. All those cars were new with one driver in them, he doesn't say temp or sea-level. He admits that there's test to test variation, but never addresses it. Somewhere between 2.6 percent and 6.6 percent is his test variation, if you assume that octane did make a difference in the M3. As you can see from the links above: yes gasoline has to meet certain minimum standards, but in general the higher grades have less sulfur, olefins, and a better detergent package. Shell is probably one exception, since they make such a big deal about all their gasolines getting the same detergent - I'll let you do your own research for that. My point is that there are reasons to buy high octane besides the knock resistance, but if you're going to supercharge your engine, you'll probably want to run premium just for the higher octane.

[Flip-Side]

quote:higher octane fuels have less contaminates in them.... simple as that.That may have been true years ago but not anymore. All fuel grades are required to meet equal levels of cleanliness.Agreed. Now regular gas is required to meet stricter standards. Now...if you use gas with methanol added (Alcohol), you will still get buildup and worse performance from your car. Sunoco, Clark, Speedway, ect. were all known to add methanol. Stay away from the "Bargain" stuff. It's cheaper for a reason.

[DABEAR95]

quote:higher octane fuels have less contaminates in them.... simple as that.Do you have a fuel analysis to prove this? I "think" that the base fuel is actually the same and that the additive package dropped into each tanker determines the octane ratings, detergency, etc. Someone please correct me If I am mis-informed!Jason

[andrewmva]

quote:higher octane fuels have less contaminates in them.... simple as that.Do you have a fuel analysis to prove this? Jason Well I can tell you that I have taken apart TONS of engines....the difference is visable...(see pic above)

[DABEAR95]

Everything adds up as they say