Anyone running 87 octane ?

ericem · Post by **ericem** » Thu May 21, 2009 2:42 am

I let my mom use my car and of course she puts a nice tank of 87 octane.... Thanks!! Anyway car seems to drive good still and it has definitely hit the engine by now. Seems smoother if anything. I am confused why would the car knock and ping on 87 octane? Seems quieter if anything haha.

BSOD2600 · Post by **BSOD2600** » Thu May 21, 2009 3:00 am

The ECU should detect the extra knocking and retard the timing more to compensate. If you had a scantool you could verify this.

ericem · Post by **ericem** » Thu May 21, 2009 3:04 am

So what is realistically the risk or not running 91 octane? What if I run 89?

kimokalihi · Post by **kimokalihi** » Thu May 21, 2009 3:37 am

Detonation. Not good for your engine. The high compression can start igniting the fuel before the spark plug fires. That's why it's crucial to run the right octane in high compression motors.

Plus, running higher octane in lower compression engines that call for 87 octane is a waste of money. It will only cause your engine to change the timing advance and thus give you poor performance and less mpg.

ericem · Post by **ericem** » Thu May 21, 2009 3:40 am

Interesting! Ok going to pop in some 91 octane next fill up and keep revs under 4k.... sigh...

kimokalihi · Post by **kimokalihi** » Thu May 21, 2009 3:46 am

WHAT IS DETONATION?
Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

Here's a nice little read about detonation.

http://www.misterfixit.com/deton.htm

I know what you mean though with the lead foot. I drive a metro for the fuel economy. Perhaps you should get a metro for your daily driver? I drive it kind of fast though. I'm only getting 37mpg in a 5spd 3 cylinder hatchback. When I got the car it was getting 42. It's supposed to get 44 on the highway. But something is wrong with the engine and I drive to fast so I'm not getting that good of mileage out of it.

Matt Monson · Post by **Matt Monson** » Thu May 21, 2009 3:58 am

ericem wrote:Interesting! Ok going to pop in some 91 octane next fill up and keep revs under 4k.... sigh...

Don't even wait until you drain the tank. Start topping it off as soon as it drops a quarter tank. Do it again the next quarter tank. And again. Then run it all the way through to near empty, refill it, and reset the ECU.

ericem · Post by **ericem** » Thu May 21, 2009 4:22 am

Honestly a N/A 90-94 legacy sedan LS in good condition meaning little to no rust, and gets 30mpg is fine.

I will put a full tank of 91 tomorrow. I guess next week I will reset the ecu.

kimokalihi · Post by **kimokalihi** » Thu May 21, 2009 4:29 am

I still vote metro for daily driver or 92-95 honda civic 1.5l 4 cylinder. The 92 honda civic with the 1.5l engine gets 35 city 43 highway. Just as good as the metro with more power and more leg room and cargo space.

And keep the legacy for fun. Unless you can't afford it, then I guess an NA subaru would do.

ericem · Post by **ericem** » Thu May 21, 2009 4:38 am

It not really that I can't afford it. It just sucks seeing only like 350km per 50L. vs a N/A which gets around 500+ km. It is also alot more fun if you have been driving the N/A all week, then jump into the turbo

kimokalihi · Post by **kimokalihi** » Thu May 21, 2009 4:44 am

Oh, so you're going to buy an NA sedan and keep the turbo? I thought you were bummed about the mpg and were going to sell the turbo for an NA.

I see that's cool. But just think how cool it would be to get 43mpg on the highway with the civic! Or metro haha.

My Metro. Doesn't look too bad.

kimokalihi · Post by **kimokalihi** » Thu May 21, 2009 4:45 am

I'd love to drop it though and get some bigger swaybars. But I need that money for the subaru so it sits tall and has crazy body roll.

ericem · Post by **ericem** » Thu May 21, 2009 2:34 pm

lol id take a metro over a civic anyday! I still prefer the safety and performance of a sub though. If i really wanted insane fuel economy with awd i could get a 1.8 impeza and put all rs body parts.

n2x4 · Post by **n2x4** » Thu May 21, 2009 3:31 pm

ericem wrote:If i really wanted insane fuel economy with awd i could get a 1.8 impeza and put all rs body parts.

The 1.8 doesn't get as good of mileage as you'd guess. 30 was the best I ever did all highway driving.

I actually ended up swapping a EJ22T into my 1.8 Impreza because the lack of performance was killing me

ericem · Post by **ericem** » Thu May 21, 2009 5:51 pm

wow, oh well I will just stick with my turbo lol. It probably just needs a alignment anyway.

kimokalihi · Post by **kimokalihi** » Thu May 21, 2009 11:07 pm

n2x4 wrote:
ericem wrote:If i really wanted insane fuel economy with awd i could get a 1.8 impeza and put all rs body parts.
The 1.8 doesn't get as good of mileage as you'd guess. 30 was the best I ever did all highway driving.

I actually ended up swapping a EJ22T into my 1.8 Impreza because the lack of performance was killing me

Yeah last time I filled up my 90 NA AWD L wagon I got 27mpg so screw the 1.8.

93forestpearl · Post by **93forestpearl** » Fri May 22, 2009 6:16 am

People with newer LGT's destroy their motors by running 87. Hell, even the Holiday gas around is killing cars. The ECU is reactive, not proactive.

We're talking about the SS, right?

Matt Monson · Post by **Matt Monson** » Fri May 22, 2009 2:20 pm

We were but these guys went so off into left field I've been tempted to lock the thread.

Post by **Legacy777** » Sat May 23, 2009 1:58 am

Yeah....I noticed that too.....once they started talking about the metro I just tuned out and scrolled to the bottom....

asc_up · Post by **asc_up** » Sat May 23, 2009 6:29 am

Just to add my 2 cents, if it ever happens again, I'd recommend doing what Matt said. The only thing I'd personally do different is add a bottle or two of octane booster to the full tank and then top it off with the highest octane gas you can when it gets down to 3/4 of a tank.

ericem · Post by **ericem** » Sat May 23, 2009 4:02 pm

i wasted that slow pos octane back to 91 and i am resetting the ecu as we speak.

555BCTurbo · Post by **555BCTurbo** » Sun May 24, 2009 5:31 am

asc_up wrote:I'd personally do different is add a bottle or two of octane booster

That stuff is basically useless...

A bottle of octane booster effectively raises the octane rating by maybe 1/3 of a point...

If you want a good additive, get some toluene in there.

Impregacy · Post by **Impregacy** » Wed Jun 03, 2009 1:30 am

I always ran 87 in my ej22t. Just with wastegate boost... put 40,000 miles on it that way. I think it's the way to go if you aren't racing, and are careful with the rpms. I doubt the knock sensor was throwing voltage the whole time because I got pretty good mileage >30mpg, so I'm thinking the advance was running at normal levels. I was also worried about my transmission that has 197000 miles on it, so never really beat on the poor car.

Impregacy · Post by **Impregacy** » Sat Jun 06, 2009 6:13 am

BTW it looks like your 98 metro has passenger side A pillar gauge pods--don't tell me it's true.

kimokalihi · Post by **kimokalihi** » Sat Jun 06, 2009 11:43 am

lol no they're not guage pods. They were speaker pods. I made them to house my midranges and tweeters. Ended up not liking the setup and those speakers so I removed them and bought some new A pillar pieces and I'm going to redo them lower and angled differently with different speakers.

They looked pretty good though.

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Anyone running 87 octane ?

Anyone running 87 octane ?