5 point whoa

ok, I've been wondering for a long time why not to run 93 in an N/A fc. I have been doing it for year, and it runs way better than it ever has, I know no matter what I wont stop running it, but I was wondering why I shouldnt??

JPA

I did the same thing and was told not to, don't know why, but I started using 87 and my car runs better actually, just got 21-22 mpg on a fast trip from Miami to Blue Ridge Mountains (TN) and back.

Also figured out that the slight hesiation at 4,000 rpm is the secondaries kicking in

christi

N/a's like lower octane than higher. They run better.

That's what I've been told. I've always ran 87 octane on the GXL and 'vert. I did, however had 89 in the GXL one day going to a autox event. Didn't make much difference, but what I hear is that n/a's just love to feed on lower octane.

J-Rat

iTrader: (2)

Because your throwing your money away.

The extra octane that is added to the higher octane gas is there to slow pre-ignition in higher combustion motors. All your doing by running high octane in your n/a is causing a cooler flame front, loosing power, and causing premature carbon buildup.

But go ahead, and keep doing it!

Jarrett

J-Rat

iTrader: (2)

More on the subject.

https://www.rx7club.com/forum/showth...ghlight=Octane

SDrotary

Yep a waste of money go with 87

Cory Simpson

J-rat said it all!

tabularasa

Some guy on this forum told me for an s5 vert you should use '91, that the slight increase in octane helps the car.

Anyone have any comments on this?

I would like to use the correct gas for my 91 vert n/a

5 point whoa

well, I could care less, just because someone elses run's better with different kinds of gas. so keep your *** comments to yourselfs, I dont care if yours runs, better with lower, mine runs good with 93, so I thought there was like a big reason thats gunna screw up my car, so dont go getting mad at me, I like my car enough to waste money on it, I dont care if anyone thinks it's stupid!

Liquid Anarchy

iTrader: (2)

Wow... it's great to know the Wilmington people before I get there.

5-point, everyone who posted is right. N/A's prefer the lower octane gas. It's funny to see you throw a bitchfit when people tell you what you're doing is pointless.

If your car is runnig better on 93 Octane, check your timing.

ponykiller

Hey, you asked. Chill out.

RoninAutoBoX

I'm going to have to go in between J-Rat and 5 point whoa. I have always run lower octane gas because the fact is, with our engines having poor thermal efficiency as it is, there is no point in slowing down the flame front, which already has to cover an amazing distance as it is, any further. WE have more combustion chamber area than most big block mountain motor V8s.

AT the same time, better fuel tends to have more detergents and be of a better quality. Lately, I have found myself running 89 just because when I put it in, my fuel economy soars like hell, and my car feels more powerful. It wasn't something I did on purpose. The station I went to was all out of 87, so I put in 89, and rather than getting the similar or inferior performance that I expected, it actually was incredible. I got over 300 miles from that single tank. Usually I am lucky to break 200. The needle barely moved at all on my 110 mile trip from Naples.

So, I guess I'm caught between the technical reasoning, and plain and simple reality. All I know is that 89 works for my car. Perhaps this is a sign that I need to do some fuel system maintinence.

BTW, the best gas I ever threw in my car was 85 octane, yes, eigthy five. I would rather not do that again, but it was some awesome performance.

christi

*** comments? Don't post a help for advice if you're gonna insult. We're just simply putting what IS best for the car, and giving a good-look out to be sure you don't mess it up.. that's all

Cameljoe

Octane rating is the gas ability to resist knock or preignition like J-Rat said or in non-mechanic lingo its resistance to burn. When you compress a gas (any gas) it gets hotter. So when the rotor or piston compress the air/fuel mixture it gets hotter. You can actually get the air/fuel mixture to ignite without a spark if you compress it enough. The only reason you go to a higher octane gas is if you have alot of carbon build up inside the engine which causes the compression to go up slightly which is enough to get the mixture to ignite without a spark. In that case the higher octance gas can be compressed more without igniting.

J-Rat

iTrader: (2)

Who pissed in your Wheaties?

You asked the question, you got the answers. I answered your question, then gave you scientific proof of my statements. What more do you want?

If you want to keep running 93, be my guest. I couldnt care less...

Jarrett

Cory Simpson

I pissed in his wheaties!!!

zinx

iTrader: (3)

I'm not 100% sure on this, but didn't Mazda use 85 octane in all their N/A race cars, including the 787B?

1987RX7guy

iTrader: (3)

^ yes.

RoninAutoBoX

On topof that, some used 2 stroke oil in their gas to reduce octane even further. I used 85 octane and 2 stroke and the car actually ran pretty damn good, but I wasn't sure if this was safe, so I hadn't repeated it.

The first time I put 93 octane in my car, it sputtered, shook, revved uncontrollably, and spit black smoke at idle for a good 5 minutes. Don't know quite what the hell happened there, but I never tried to repeat the same trick again.

christi

Ahh.. you're one of those fellow rx-7 owners who've done the transplant of the OMP and using 2-stroke huh?

Quote:

The first time I put 93 octane in my car, it sputtered, shook, revved uncontrollably, and spit black smoke at idle for a good 5 minutes. Don't know quite what the hell happened there, but I never tried to repeat the same trick again.

LOL.....that doesn't sound too good. Poor car

RylAssassin

LMAO!
WOW why did you join this forum my man, It seems you hate everyone in here!
Listen there giving you advice and you dont have to take it. If you dont agree with it then please have some decency to put it in a normal, intelligent way not "keep your *** comments to yourself" lol
I dont know why but im going to also tell you that what your doing is a waste because a high octane fuel in an engine that has normal compression is a waste. The only possible advantage is that 93 octane is cleaner but with gas prices today why bother. Your car was designed for 87 and higher octane so why use any more than you need?
TII's need high octane due to there high compression. N/A's dont have turbos...

5 point whoa

that explains why they tasted nasty, LOL, I didnt meen to sound mean, I was only talking to j-rat, he said, But sure, Go ahead and keep doing it. it sounded like he was trying to be an *** to me. sorry to everyone else, didnt mean to sound like Cory pissed in my wheaties, even though he did

J-Rat

iTrader: (2)

No, I wasnt trying to be an *** to you. I was stating the facts.

From your original post:

"I know no matter what I wont stop running it, but I was wondering why I shouldnt??"

So after I presented the facts, I ended with the statement "But go ahead, and keep doing it!"

After all, you said you were going to keep doing it anyway. So again I ask, how was this interpreted by you, as me being an ***? You a little jumpy today? Too much caffeine? Get beat up at highschool today and feel like some internet revenge?

Sheesh!

RoninAutoBoX

No, I still have my OMP, since mine is an S5, but it is leaking like a bitch, so I run premix juuuuuuust in case.

I am going to redo my whole fuel system, and change my fuel filter too. I think it may actually be the originalone, explaining some of the problems I have been having.

Wankel7

I agree. I noticed a pronounced difference when running 87 octance in my 86 base model. A good difference.

Somebody posted some where on this forum that most fuels regardless of grade have the same stuff that the higher octanes have. Like, Texaco's Techron is in all grades of its fuel.

In an NA that has not been extremly modded you are throwing away money to no real benifit. So that addage off I like to throw the good stuff in there every month is really incorrect. Seeing how each grade normall has the same stuff in it. The octane being different.

Really, count your self lucky you do not have a turbo and find a need to run the high octane fuel. It is pricey.

James