What gas for GSR

[NRGie]

The previous owner who did the original swap said he has been using shell 89 for the past 3-4 years and I've done the same so far since i have owned the car, but i got curious today after seeing the octane thread and googled it and i found mixed opinions on whether i should use premium or lower grade octane.

So what do you guys think? Its a 94 GSR motor in a HB civic. Should i keep using 89 or should i switch it to 91?

Thanks

[Sentry]

89 is fine.

[vtec4life]

honda says to use high octane... I do (91). probably does less harm than using 89 if anything.

[sr20s14zenki]

Its not that its going to hurt the engine, but you may get more power as it may be pulling timing due to knock from the 89. That being said, i dont know the compression ratio of your engine, or the particulars about its setup, but i DO know, if a manufacturer says run 91, you run 91, its for a good reason. You can run 89 and get away with it on a ka24de, but they like premium much better...just an example. I do believe they are close to 10:1. Same with my wife's maxima. It specifys 91, we use 91. Its compression ratio is 10:1 as well.

edit: Just looked, b18c1? its atleast 10:1, i would recommend 91.

[TorqueDog]

Wasn't there a thread about this before where it was pointed out that Calgary's elevation means you can effectively drop a petrol grade on most engines?

[Twin_Cam_Turbo]

Does the manual say recommended 91 then minimum 89 or 87? I know with my dads car, it runs 12.5:1 compression ratio and it is recommended 93 minimum 91 octane.

[kvg]

Some cars can run fine on lower octane. I had a 96 maxima ran like a shit and the mpg dropped with out premium gas. Try running a few tanks of premium in the car and see if you can notice a difference. Wouldn't hurt it.

[NRGie]

Yeah I didnt have the original manual for the motor, but ill try using 91 and see if theres a big difference or not

[Cooked Rice]

87 is fine for your daily commutes, especially in colder temps like winter. My 4Runner recommends 91 but I just use 87. In my case there is a slight decrease in performance due to more conservative timing curve with the 87.

[sr20s14zenki]

Still depends on the car and how its tuned from the factory. Do your own research, log your trip KM with regular, and then with premium. on a car with a 10.2:1 compression ratio, i can see why they want 91 in there. Like the poster above said of his maxima, it just would not run well on regular, and its the same with the wife's maxima. We got away with midgrade once....barely haha.

Again, depends on the car, but come on, are you THAT cheap? The price on a FULL tank is around 5$ difference.Always best to do what the manufacturer says.

[gpomp]

Originally posted by Sentry
89 is fine.

[Aleks]

Originally posted by TorqueDog
Wasn't there a thread about this before where it was pointed out that Calgary's elevation means you can effectively drop a petrol grade on most engines?

Yes, most N/A engines don't need 91 octane at our elevation. There isn't enough air. Some cars will run better on 89 and get higher mileage. In some higher states like Colorado regular gas is 85 octane for this reason.