what gas to use...

**oldriceracer** · 10-30-2002, 03:19 PM

does using a higher octane gas increase performance? sorry for the dumb ass question but i asked my dad this and he gave me like a 5 minute explanation of what a higher octane does and when i asked him to speak in english he called me a smartass and walked away. screw that, i was serious, didnt understand a freakin thing he said

**87accordlxph** · 10-30-2002, 03:45 PM

I believe the answer is no, the higher octane is used for higher compression ratio engines to reduce detonation.

I wonder if he said anything about what I just wrote here.

Any other comments are welcome.

-Mike

**Scorpion88LX** · 10-30-2002, 04:04 PM

easy the higher the octane the more it resists ignition under compresion.
just a small expansion of mike's post

**87AccordsterLx** · 10-30-2002, 05:46 PM

...... allthough for some reason it seems like I get better performance out of higher octane gas (93) but I think its just becasue it detonates when its supposed to ... thus making lower octane gas less effecient.....

1988starter · 10-30-2002, 05:54 PM

Higher octain gives me a little better gas mileage for me and resists detionation with advanced timing

**oldriceracer** · 10-30-2002, 06:07 PM

so resisting detonation is a good thing?

**LIL'LXi** · 10-30-2002, 06:43 PM

I also have a 2002 Protege5 and one of the guys on the protege site was running 93 on his new protege and after about 5000 miles his plugs were shot. Aparrently the thing is when you run higher octane on a stock ignition system not set for high octane gas your car can't burn it fast enough, causing your plugs to foul out quicker with high build up of carbon. So basically if your car is all stock it would be best to use what was recomended for your engine. Diffrent octanes burn at diffrent rates and your car is preset to burn that specific rate, usually 87.

**smufguy** · 10-30-2002, 06:58 PM

the only reason newer cars and high performance engines because they usually have high compression . The high octance resists detonation like mentioned above. The lower octance gas detonates after compressed after a limit and the high octane does not detonate. putting a high octane gas in ur car which has no mod but just for fun is not advisable. There is nothing ur gonna get out of it with all stock (if it applies to you) motor and stuff.

It depends on what happens with individuals. LIke every medication says, results vary with individual~cars.

**Neuspeed87lx** · 10-30-2002, 07:51 PM

put 90 in if your worried about it

**Grant2k** · 10-30-2002, 08:26 PM

you are likely to get a pinging with higher octane. but isn't it possible to adjust your timing for the different octane. i really am not too familiar with the subject.

**sanjay** · 10-31-2002, 02:14 AM

Does the higher octane result in a greater fuel efficiency?

Also doesn't the A20A4 engine (a20a3 in america) have a higher compression ratio (9:3:3) than the old. Also, is this compression ratio going to affect the output of power.

**Grant2k** · 10-31-2002, 06:54 AM

Originally posted by sanjay
Does the higher octane result in a greater fuel efficiency?

my understanding is that it would result in lower fuel efficiency because it resits detonation so it is more difficult to burn, so less gas is burned by each firing of the engine.

1988starter · 10-31-2002, 07:12 AM

I should mention that my msd 6al helps the higher octains burn more efficently

**Grant2k** · 10-31-2002, 07:46 AM

i realized that i should have put more to that post. thanks starter for bringing that up. it would burn less effieicntly in our cars, but a car with higher compression or a better ignition system that burns hotter shoudl be able to handle that higher octane, burn all of it, and get more out of it.

**88WhiteLX-i** · 10-31-2002, 04:22 PM

all higher octane gas does is resist detonation. For example 93 octane will resist detonation 93% of the time...

**pmip** · 10-31-2002, 04:24 PM

Yeah, you only need higher octane if you have advanced timing, nitrous, a turbo, etc.

**Grant2k** · 10-31-2002, 06:23 PM

Originally posted by 88WhiteLX-i
all higher octane gas does is resist detonation. For example 93 octane will resist detonation 93% of the time...

but that would mean that 87 octane detonates 87% of the time, which would be resisting definintion more.

**pmip** · 10-31-2002, 06:27 PM

So, if 93 octane resists detonation 93% of the time, how would you explain gas over 100 octane? And Grant2k - you got it backwards, the way he explained it 87 octane RESISTS detonation 87% of the time, it doesn't detonate 87% of the time.

**Grant2k** · 10-31-2002, 06:37 PM

my mistake.

**87AccordsterLx** · 10-31-2002, 07:07 PM

check it out guys... hope this helps....

http://www.howstuffworks.com/gasoline3.htm

**88WhiteLX-i** · 10-31-2002, 08:48 PM

yeah I heard that explaination somewhere, but oh fucking well if its wrong.

**87accordlxph** · 11-01-2002, 09:33 AM

Hah!

I knew I was right all along.
Thanks for the post 87AccordsterLx.

-Mike

**sanjay** · 11-02-2002, 08:25 AM

Has anyone tested the difference though?
LIke filled up full with regular. and filled up full with premium?
and seen the # of km/miles travelled or amount of money cost to fill their tank?

**87AccordsterLx** · 11-02-2002, 09:22 AM

no problem man....

sanjay.... I think the difference would result with too many vairiables to make it worth it... you would need to try it several times and find an average... my uncle who is a very good mechanic says that higher octanes give better gas mileage due to better efficenicy... but if your car has a lower compression ratio then the lower octanes wont detonate causing "pre-detonation" or "knocking" which is harmful for your engine.... so "technically" it doesnt matter if you have a compression ratio such as ours because the fuel wont detonate anyways.... now I still use 93 octane gas becasue I can honestly tell a difference in my cars performance when I use it... It just runs better... thats all I can say about it....

**87AccordsterLx** · 11-02-2002, 09:23 AM

http://static.howstuffworks.com/flash/engine.swf

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