Resolved Can I use 89 octane gas in my 97 Eclipse GSX

[jdmfairladyz]

hey guys i have a 97 eclipse gsx with a 14g turbo and i was wondering if i could get away with filling it up with 89 octane gas if i don't run the car hard
thanks

 

[donniekak]

The difference in price would be offset by the loss of efficiency due to the ecu having to constantly pull timing.

 

[Awd-laser]

I would not. I believe the point of the higher octane on the car is to help prevent knock and detonation. I would just stick with 91-93 octane.

 

[boost97gst]

Wait..... yes, you CAN run even 87 oct if you had to. Compression is only around 8.5:1 so if you stay out of boost it should pull no timing or have a noticeable effect. However, this is the big part, you get in to boost even for a second and its going to detonate. Idk about you, but i like no knock in my engines. If you had 10.5:1 pistons in there i would say no to lower octane in any circumstance, but just to clarify, it IS possible on stock compression. Again, cant stress it enough, stay below the "0" on the boost gauge haha. Dont come back and say you melted valves boosting on 89 octane in the summer heat!

 

[fredyvalles1995]

Dont get me wrong but I think is better to be safe than sorry..just get 91 oct

 

[donniekak]

Yes, stock compression is only 8.5:1, but the stock timing maps are built around 91+ octane fuel. Part throttle knock happens all the time. Also, with a small turbo, it's next to impossible to stay out of boost. With an fp red, i see 7-8 psi of boost up hills with the cruise control set to 80mph.

 

[GRAVEDIGGER]

Run the highest you can find... If it's only 91 use that. If you can get 93, use that... Anything with forced induction should be running 91+ octane IMHO.

 

[RamenPride]

So you can save about $5 by filling up with 89 instead of premium?

 

[Twoslow]

It's is in everyone's best interest to run the highest octane available in any and all engines. ICE's are nothing more that heat exchange devices. The higher the octane, the hotter the burn, the hotter the burn, the more power made. Remember PV=nRT!
Also, burning hotter means cleaner. Less build up. I tell people, "I can't afford to run the cheap stuff". Octane also drops over time. Don't kid yourself that the .15 is a savings on a $4 gallon.

 

[boost97gst]

Agreed, im just saying: If you are on E and at a caseys then you CAN run 89. Def not ideal and Donnie you're right, such a small turbo would be very hard to stay out of boost. You'd practically have to disconnect the wg actuator. Why go through the hassle?

FWIW ive never ran less than 91 and im hesitant to put that Pump piss in. In my zx10r i will only use 91 as a last resort

 

[DSM1G90]

The higher the octane, the hotter the burn, the hotter the burn, the more power made. Remember PV=nRT!

On the contrary, the lower the octane creates the hotter burn since there is less junk in the fuel. But, the hotter fuel requires the lower compression.

All the junk does is retards the fuel ignition when then spark plug hits it.

(Course, these new motors with direct injection have over 10.00:1 compression since the 85/87 fuel fires directly into the cylinder when the piston is on the upstroke and is much more of a leaner mix..and you got some good horsepower out of this super hot explosion. If the 4G63 can be modified with direct injection and very high compression, we could be using the NT 4G63 and crank out some serious HP)


Using lower octane will keep the knock sensor happy to retard the timing to reduce knock if one crams on the gas pedal to head into boost.

If you stay mainly out of boost and don't get too crazy, 87/89 would be fine for a DD usage. It's the 02 sensor that tells the ECU what fuel is being used so to map out the correct mixture-that's how these new "flex-fuel" vehicles operate on which fuel being used..be it E-10 or E-85..the O2 sensor makes that decision.
Let the HP people drink up the 91/93 stuff

 

[zkheasley]

DSM1G90 ^^^ knows what he's talking about

 

[DSM1G90]

Thx for the ^^ !

If one really wants to see super hot fuel, find you some "white gas".

"White Gas" is pure gasoline that has no additives in it-it's water clear.

It was used for low compression applications like any flat head ("F"-head) motors that could only read up to 6.0:1 compression. Your Briggs and Statton lawnmower motors are a classic "F-head" motor.

Sad thing in using white gas that the stuff burnt up valve seats since there was no additives to protect valve seats on the exhaust stroke.

Thus, out came leaded fuels to protect the valve seats and it did cause an increase in the octane numbers were it can be used in high compression applications.

EPA changed all that in 1975 with UNL fuels. Thus we came out with hardened valve seats.

Thus, I have a hearty laugh when users think that 91/93 fuels are clean and fresh fuels.
Stuff is so full of junk that if they only saw what was going in their tanks, it might make them shudder some.
But, if one wants serious power, this stuff does the job well-it's the necessary tradeoff in this formula.

Also, if you think that 91/93 fuel usage can get crazy, the Bughatti Veyron 16/4, with the W-16 with the quad turbos require 100 octane street gas for it to hit the 1001HP out of the factory. That stuff is about 10 bucks a gallon and the Veyron, with all four turbos blowing at full peak, can suck fuel at 3miles per gallon.

And I'll confess: I've been using 87 for six years and 40K miles now and never had any problems since I bought the Laser from a kid for cheap that needed money.

Thing was in pretty bad shape, but with some TLC and similar, it's now a great road machine that still can produce when needed...in stock form

I do a lot of town/freeway driving where I hardly go into any serious boost. But, when I do, I still get the response needed from the motor.

-thx DSM