ViperC4

Is it ok to run 89 octane fuel with 10% ethanol?

GKK

Yes, 89 octane can be used but, the ECM will retard the timing to prevent engine knock resulting in reduced engine power.

It's stated in the owners manual.








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abdo

Check your owner's manual. It will probably say that 89 octane with no more than 10% ethanol is OK. However, I am able to buy 92 octane with no ethanol and I know that my '86 coupe runs better on it. My mileage is also a little better and the acceleration difference is noticeable.
Others on this forum say they experience no difference.

ViperC4

ok just wanted to make sure i am not worried about a little power loss i have a procharger on the beast.

1bdvet

I used 89 octane ever since I bought mine back in 1991.
Also read the manual it will tell you, that's what you run.

DGXR

The manual says up to 10% ethanol is OK. But I don't see the point putting anything less than 91 in a supercharged V8... just my $0.02

fl_799

You will have to scan the car with tuner pro to know for sure. Look for knock counts and timing retard.

My bone stock '89 will register plenty of knock counts (under heavy acceleration) with anything less then premium fuel.

WW7

My 89 manual says use high test fuel .. It also says, anything less will cause a loss of performance...Why would you put a procharger on the car for more power , then use lower octane fuel to produce less power......WW

hooked073

Mines says the same thing, It says anythingless will spark knock causing the ecm to retard the timing causing less performance

Cliff Harris

I accidentally put 87 octane in my mostly empty tank. I drove it gently and really didn't notice a difference.

gerardvg

You asking for trouble? , turbo/supercharged engines need premium fuel. factory supercharged/ turbocharged vehicles have that in the handbook.

It all depends on the boost you are running, my supercharged/ intercooled vette will ping(knock its head of on standard unleaded . I use the 98 octane stuff that is the only fuel that i have no pinging issues with.

If you are using water/methanol injection that will be different as that will help lower combustion temperatures, that is usually used on blowers without intercoollers.

If using low octane fuel listen out for pinging /knocking, i have gotten away with it on the highway where you just touch the accelerator pedal. just take it easy till your next fill.

Annoyed

Why would you wanna run 89 octane anyways?

You get more power with higher octane, your engine won't ping and it lasts longer as it's a denser fuel.. so it costs you about the same in the end.

hcbph

I don't see where the year and engine were listed. When in doubt, use whatever is listed in the owners manual. I have a 86 L98 and it has 9.5-1 compression and it runs just fine on 87 octane gasohol. I do have access to 89 octane 100% gas which I use prior to putting my vehicles away for the winter, but it does run about $1.00 a gallon more than gasohol.

C4in mesa

Not to high jack this thread but I have a question regarding gas since it is being discussed. At the time of my engine build I asked the builder what about bumping the compression up to 10.5 ? He urged me to just stay at 9.5 and save my money buying 87 octane. My engine runs fine on the cheaper gas. Is there any advatage for 9.5 compression engines to burn 91 or higher gasoline ? I do on occasion thinking it will clean away any unwanted deposits. I see 91 octane selling for $3.80 a gallon so I am saving a few dollars every time I buy 87 octane gas.

ViperC4

honestly i have run 89 octane in everything i have owned and i have never had a problem with any of them. 2008 hayabusa, 2011 hayabusa, 2002 hayabusa, 2012 gmc sierra, 2011 impala, 2012 impala, 1999 porche 911, hell everything gets 89 which has 10% ethanol blend.

For daily driving i would think the ethanol will be fine. If and when i run it on the track i will most surely fill with bp 92 octane.

Paul Workman

Whoa! If you're sporting a Procharger, it raises the anti significantly, far as potential damage when encountering knock. Sure the ECM will retard spark, but if the knock occurs under boost, then the potential for hurting the motor under the higher load when knock occurs...would give pause to running lower octane levels (with a blower especially).

Put another way: the chances for breaking the motor is significantly higher because of the blower in the best of circumstances. If you have to use the lower octane stuff in a pinch, is one thing. But, why increase the possibility?