According to the Owners Manual (Pg. 94), you can use 87 octane as I have for many years now. It also says you may experience a slight decrease in performance. I myself have not noticed any difference in MPG or HP.
Now here is the question, does anyone have dyno numbers of a B18C1 GSR engine running on 87 vs 91? Thanks.
- Aaron

P.S.
If you are going to whine about how I shouldn't have a GSR if i'm not gonna put premium gas in, please don't post.

 

I feel like my MPG did go down....but not so much of a power loss. It is a 10:1 compression distributor fired car from the 90's though lol. So mine would ping if I accelerated at low RPMs.

After it started pinging and I noticed a MPG drop, I just went back to premium. Used to only be a 20 cent upcharge...so $2 per fill up basically. Too bad premium is like 40-60 cents more per gallon as compared to regular now.

 

I get a difference in MPG for sure. I drive about 100 miles day and have looked into this. For the cost, its generally more effective to use premium. Using premium I'm getting 25MPG (city) with Regular I'm only getting 21.

 

What brand type of fuel are you using chevron ,mobil,76,arco

 

I use whatever is cheapest and have always had the same MPG, about 28-30mpg. That's about 50 or 60% city.
Post some dyno numbers if anyone has em!

 

I have only used 93 from a Shell or Chevron since I purchased my swap. I like to run 93 ethanol free when I can but it is $1/gal more. I get 27 MPG mostly city/80 when on hwy. with out trying but I am in a lighter chassis as well, 94 civic vx. Also have a ITR 4.7 FD transmission.

 

i asked my co worker the same question the other day how he felt about this.
he told me always pumps 87 octane in his 91 civic b16A equipped because its cheaper and admits himself that he feels a bit difference but he doesn't care.

i have a 1997 GSR with a F2B swap and i always pump 91 octane from chevron and nothing else.
i want to take care of my engine and.. me, myself, feel that anything under 91 isn't sufficient.



my uncle always told me while i was growing up,

vtec engines take 91. he always owned GSRs. so i just take his word of advice and never 2nd think it.
but then again, my ECU is tuned for 91 octane.. i just dont want to take the chance.

i get about 30 mpg going 60-65 mph. and make a 50 mile commute to work and back

sometimes i go 70 mph because of flow of traffic or engage in vtec occasionally because im bored or need to pass up a truck, ill get about 27 mpg.. which doesnt bother me much.

 

I pretty much always go 91 from Tom's (independent in buellton, ca) or sometimes from others, don't see much variation. Get 29-30 on my daily 80 mile total commute. I suppose you could save a few pennies, but I sure like to get what I can out of my gsr. She's old enough to vote, just about to turn 200k on original engine, no complaints save paint and some dings. None for mechanical.

 

Drove from Goleta to Lompoc yesterday (about 50miles), about 80-90% Hwy and got around 35+MPG with a passenger in the car including several hills. Average speed was 60MPH. Recently did an oil analysis with Blackstone labs and they said my engine was perfect and that I could have ran my oil to 7,500 miles, highly recommend them.
If anyone ever comes across Dyno numbers, please post them here Thanks

 

I believe what happens when you use 87 in a car with a knock sensor is it will pull the timing if it detects knock, reducing performance

 

that's what I've always believed^^

stock gsr you could probably get away with the middle grade 89 or w/e but once you start pushing 11:1 c/r then I'd rather stay with 91+. I guess altitude plays a role too

 

I believe due to the higher amount of detergents in premium your cat should have a significantly longer life expectancy and your fuel injectors should really never become plugged assuming your fuel filter is replaced at a regular interval.
I always spend a buck and get the good stuff. Same principal as using a quality oil.