heyimrchills

hey my friends had an argument and i just told them ill get an answer from you guys.

is it better for premium/regular gas for a 99 civic ex?
supposedly my friend says on his other car* that some cars arent made for premium and run better on regular..sounds funny right?

what do you guys think?

r22thomas

premium isnt gonna do anything to help. Its not gonna add magic HP. It just ignites at a different point.

Former User

It would be a waste of money and possibly even harmful to run a stock 99 EX on premium gas.

xxstuntin4life

could u give some reasons on this? i beg a differ..

Former User

Main point -- The ignition system of the D16Y8 was designed and optimized to run on regular 87 octane fuel. Running the engine on premium fuel at worst slightly interferes with normal engine performance and at best fails to do more than regular gas.

fryman

Hmm interesting.....I always wondered why cadillacs run horribly on regular octane fuel....I guess that would explain it.

!Ev0$

Would it make a Difference if i use only premium gas on my B16 than regular ?

Former User

The B16 engine is actually designed to run on premium gas.

!Ev0$

is it because of high compression ..so if i run it with regular it would run like shiit?

Former User

The B16 will get the best performance running on premium gas. Avoid using regular gas.

!Ev0$

Will do!

Linked

i believe so based on was ronj says.

running lower octane gas means it will ignite before TDC and compression will be lower = less HP

thumper64

You can run a lower compression engine on high octane, but you won't get as much power. You may see slight gains in fuel economy though... By no means will it damage the motor, but there's little reason to run premium unless you need it.

Most modern cars will adjust for low octane fuel if they're meant for premium, but our Civics aren't quite that advanced. If you have a Type R with 11:1 compression and put 87 in (until it starts knocking and the ECU pulls timing), it will use the same timing and everything else as it would 116 octane C16 and the same as 93 octane Shell Premium. Run what Honda recommends, they know what's best for the car.

boxeocampeon

i actually heard from a mechanic that the d16y8 should be ran on at least 89 octane but 91 would be even better just what i heard tho

Corksil

it makes sense from a technical standpoint - high compression engines want a fuel that doesn't ignite as soon so it can build more compression before the spark. lower compression motors aren't as finicky about this sorta thing.

I'ma run a tank of premium through my b16a3 when I can afford it.

thumper64

It's not a "when you can afford it" thing. If you must run 89, at least don't wind the engine out. Your dynamic compression ratio increases and you will eventually blow your motor, that costs more than the $1-2 difference in splurging for premium.

blkcivic310

alright i found some answers, so... apparently butane, octane, and heptane are all hydrocarbons that explode under different compression. heptane explodes at a lower compression (sooner) than octane. so octane is mixed with heptane so it explodes at an expected compression. 87 grade refers to the percentage of octane in the gas. 87 octane is 87 parts octane, and 13 parts heptane.

the higher your compression ratio of your motor, the higher octane youll want to use. have a high compression motor (like our teggys) and put in 87? your engine will knock because the gas is detonating before the spark plugs fire. not a good thing.

however, that site did not mention anything about higher grade gas being bad for a car that only required 87. so i checked around again. turns out higher grade gas does not hurt an 87 grade motor. but it doesnt help it either. and premium fuel doesnt burn cleaner or prevent buildup of poo inside your engine.

the short of it is to buy whatever your manual says.

Sutterlude

higher octane slower burn better fuel economy

supersize

**** it, i just use the cheapest **** available... times r tight

Dokta

I can confirm a jump in fuel efficiency when using 91 octane in a a 93 DX and in a 93 Si. Gains are about 4 mpg. But I don't think I could discern any performance increase.

supersize

but the extra price over the extra mpg is useless

deegz

10-4 on that note.
But i disagree that a motor designed for a certain level of octane burns all of the fuel, which does leave contaminates.


Higher octane gas requires more compression. If there is not enough compression, not all the fuel is going to be burned. In return this creates carbon build up. Talk to a tuner, and they will confirm this.
There is a reason they have higher level octane gas. If you throw gas on a fire, it ignites instantaneously, if you throw a quart of oil on a fire, it takes longer for it to ignite.
this is direct correlation with gas on octane levels. Diesel runs super high compression along with turbo, the octane is higher, to compensate for the high level of compression. that is why they get more mpg than gasoline trucks.
Higher the octane, the higher the compression you need.
lower octane fuel detonates at a lower level of compression.

Waste of money buying higher octane gas for a car that was designed for a certain level.
read the owners manual and it will confirm this. If the car got better mpg with higher octane gas, and more power, why would they state to run a certain octane........oem stands for lots of r&d.

Whoever says it they gain more poweron higher octane gas with a stock engine, is flat out wrong.
MIILLLLLLIONS of man hours went into research.
With a built motor, its a different story.

supra-n-civic

indeed hahaha

supra-n-civic

not true. generally cars that ar dsigned to run on 92+ fuel are using the fuel because the highr octain fuel fends off detonation. alowing for a more agressive tune

Kidnkorner

Lot's of erroneous information flying in this thread. I like the claims for better fuel economy best! The reason increased fuel economy may be realized is because ther engine is probably all gummed up from cheap gas and getting extra detergent from the premium, and thats a big maybe.

Running premium fuel in a car designed for regular unleaded will not only increase carbon build up but the unburned fuel leftover will wash ring lands scoring cylinder walls, reduce catalytic converter life and create more pollution in the environment.

I don't always use 91+ but when I do I prefer Chevron, top up my friends., lol mMmmM Dos Equis Amber!

It matters where you get gas too. The gasoline itself is generally all the same as most places in the country get it thru a pipeline. It's the detergent and addtives that makes a branded fuel what it is. There is a reason why the generic brand gas station costs less, including your warehouse club gas, these places uses the bare minimum levels of detergent that the government mandates.