Last post on May 24, 2011 at 7:15 PM
You are in the Honda Civic
What is this discussion about?
Honda Civic, Coupe, Hatchback
#1006 of 1035 Re: Running the Si on regular gas instead of premuium [coupe2]
Jan 02, 2008 (5:56 am)
You don't have to reprogram anything. The knock sensor in the engine will retard ignition to accommodate the lower octane fuel automatically.
However, as shipo has posted, you cannot change the engines compression ratio (unless you plan on rebuilding it yourself), so you would be running your engine with continually retarded ignition. That is going to give you worse gas mileage and will increase your exhaust emissions (if you care about the air you breathe).
So, I too do not see the point. If you really want to run regular gas, you'd have been far better off buying a regular EX sedan instead of an Si.
#1007 of 1035 Re: Running the Si on regular gas instead of premuium [coupe2]
Jan 03, 2008 (12:01 pm)
As was already said, you'll have horrible gas mileage. I have first hand experience with that one. Not in an Si, but another car where premium was only "recommended." I would get a solid 50 miles LESS per tank of gas, and the car ran and felt very anemic. With an 11:1 compression ratio, I'm sure your owners manual states that you should only run regular gas in an emergency situation with just a few gallons of it in the tank and to fill up with premium as soon as possible.
Sure you can run regular in it, but I wouldn't dare trying to run that engine up to 8K RPM with it!! That would be begging for busted pistons and/or bent rods. And there's no way it'd pass an emissions test.
#1008 of 1035 1998 honda cvic help plaese
Jan 11, 2008 (1:46 pm)
ok i have a big problem this honda civic and i dont want to junk it . this is what happened normal drivening for a few miles like 5000 after i got it and the #4 pistons blent on me so i got a head from a junk yard the car was running`good the parts car . so i went home got a new head gasket checked to make sure the head wasn't bent and the block they checked out so i put the head on just like to service manully expained in detail changed the old and antifreez also new plug and wires . ok so to make it somewhat shorter it run but only 1&4 r working so it doesn't run right anyone got any ideas to help me out on this one ??????
#1009 of 1035 Re: 1998 honda cvic help plaese [euroblue]
Apr 07, 2008 (7:19 pm)
ok this may or may not help you but if you message me and give me some more info on the car and what is doing when you start it i may be able to help you some. it could be a timing problem or sparkplugs weren't put in correctly. most likely its your distrubuter is off or cyl 2 and 3 spark plugs are not plugged in correctly. hopefully this may help you i would check all of your connections and COMPLEATLY switch the plugs to see if its just faulty cables. also check the head you pulled and make sure there is no damage to the intake valves that may cause a major problem even if its a chip the size of a large grain of sand.well message me back and ill try to help you my email is terencenayloryahoo.com i am not a pro but im good with cars. if i cant help you ill get u info from one of my friends.
#1010 of 1035 Thinking about an '08 Si
Jun 19, 2008 (4:20 am)
I was wondering what typical MPG you Si folks are seeing? I am coming from a Subaru Forester XT, and I'm probably in the low to mid-20's MPG. I know both cars take premium fuel, but if the Si gets better gas mileage I would consider switching over. My commute (95%) is mostly highway.
Any advice/help would be appreciated.
#1011 of 1035 Re: Thinking about an '08 Si [rock_strongo]
Jun 19, 2008 (1:20 pm)
I average 26-27 mpg, which is mostly suburban and rural secondary roads.
#1012 of 1035 Re: Thinking about an '08 Si [rock_strongo]
Jun 20, 2008 (6:26 am)
There's a whole thread on Civic mileage - check it out: http://townhall-talk.edmunds.com/WebX/.ef7f897/1649
There's also info at 8thcivic.com about it.
Most people seem to average in the mid to high twenties overall, but many people have reported hwy mileage in the 33-34 range. I'm thinking of purchasing one myself, and have a friend with an 07 Si sedan that gets that on the highway, so it can be done; maybe even a bit more if you have everything working in your favor.
#1013 of 1035 Re: Thinking about an '08 Si [motonation]
Jun 20, 2008 (6:31 am)
Very good info. thanks a bunch.
#1014 of 1035 If true, how much really
Jun 22, 2008 (12:12 pm)
For those who have indicated that fuel efficiency will be crushed by using regular, I would like to know by how much, if any. I hear strong definite assertions, but little (actually, no) empirical results, and so must ask.
#1015 of 1035 Re: If true, how much really [unkownuser]
Jun 22, 2008 (11:46 pm)
Unknown. However, it is because the ECU retards spark timing to prevent detonation and keep the motor together on more volatile lower octane fuels.
One thing about using premium, is that most places the differential, no matter what fuel prices rise to, is always going to be $2.60 more for a 13 gallon tank.