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Probably a stupid question, might get flammed for it but here goes. I got my head worked on last month, Full port polish stage (1) n/a camshaft and fidanza lightweight flywheel I have numerous other modifications done on my car but no turbo as of yet. Should i be running a higher grade fuel for my engine? The other day my car threw a P0304 code,( cylinder 4 misfire ) just wondering if that could potentially be my problem. Or should i just add some TKO / Seafoam or any other fuel additive from time to time?

Also i know i should probably get my car dyno tuned, but with the cost is it really worth it? Will i see noticeable gains, if not gains then more reliability?

Thanks alot

 
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it cant hurt to try a higher octane

 
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Sure can when gas is $1.50 a litre here in lovely Ontario Canada... and thats for regular. I think premium is 1.90 ish

 
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dude, i dont know how that traslates to gallons, but its expensive here too

 
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3.8 litres in a gallon so

3.8 x 1.50 we'll say = 5.70 per gallon

 
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ouch, its 4.00 a gallon here for premium

 
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You have to pay to play my friend. You modded your car such that it may need higher octane. Either pay for the gas or pay with a broken engine.

 
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lets all remember the most important thing about it before we ever complain about our gas. no matter how expensive or how bad the gas prices get, we are always ahead of EVERYONE else. be happy we dont drive a v6 or a v8 truck or something....or a 5.0l mustang haha.

 
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Rob got it right. Premium mods = premium gas.

 
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if you get a misfire you should run a higher octane. just remember that if youre goin to run leadd fuel you remove your cat or its going to get clogged. plus leaded fuel smells so yummy

 
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I threw some Premium fuel in my car the other day, and I noticed it had more... prep. Felt like the engine did not have to work as hard to accelerate.

Is it safe to use Premium gas in our Civics?

 
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ya its safe. i run 110 octane LEADED without a cat

 
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I have never put any gas in my car except premium. there was one time i actually put regular after having my car for 2 years using nothing but premium just out of curiousity to see if i would notice a difference...and i did. it was slower to accelerate and it just seemed like an overall loss of power.

i think whether its safe to put premium in our cars or not is totally out of the question. i havent ever used anything else and ive never had any problem of any kind.

 
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post back if the gas doesnt fix your misfire.

 
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got higher compression? if not, higher octane does nothing for you. its something else and i can tell you right now, these cars dont like to be modded. and yeah the car needs tuning, both fuel and cam timing

 
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thats what i was thinking

 
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No the gas didn't help my misfire... It's going into the shop tomorrow to investigate the leaking valve cover.. which is probably why im getting a misfire.

 
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Wow, finally someone with the answer. I was scrolling down....and down.....and down.....waiting for someone to post it. Look in your manual and it'll tell you what kind of gas you should be running in relation to the compression ratio your engine is tuned for. If you put in a higher octane, you'll get a different compression and your timing will be off. This might actually cause a misfire but now I'm getting into areas I'm pretty vague about.
As far as I know, premium + D17 = bad.

 
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i use plus and have switched back to regular several times but i got tired of the lack of acceleration. it was as if something was holding the car back.

 
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did you read that conversion off the top of a urinal, cause thats how i remembered it for school

 
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I have a stock D17A6 that runs a higher compression than a D17A1. The difference between 87 octane and 93 octane unleaded is 20 cents. Do you think I would get 20 cents/gal difference in mpg by running the premium?

I am used to using premium but was told to not run it on my HX; that it wouldn't run as well. (Seemed strange to me, but this is my first D17). My goal is more mpg, not necessarily better "speed or performance". Although more HP/torque usually equates to more mpg if it happens at a low RPM (I don't go above 3000 RPM).

When I run the numbers, I would need to increase my mpg by a little less than 6% to justify the additional cost. ex. 38>40.2 mpg. So do you think I can get an additional 2mpg by running 6 octane points higher?

Also, does someone know of a forum section (on this forum or another) that is dedicated to increasing mpg. Most of the sections here are about increasing HP/torque and that usually comes at a higher RPM range than what I operate at.

Thanks in advance.
Civic Newbie

 
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short answer no^