SLOASFK

iTrader: (5)

USDM rotaries have the timing retarded to make them safer to run on lower octane. IDK about E-spec rotaries.

FearNoPiston

iTrader: (17)

Im not sure if this is true but I was told that it is a law that every vehicle is required to be able to run on 87 octane, I'm talking when the car is manufactured and released not a modified one, me personally I will pay the 10 extra cents to have that extra safety of not blowing my engine

SLOASFK

iTrader: (5)

so, how many miles on your engine?

dubulup

where did you hear this?

rynberg

My engine did not blow, the compression was getting on the lower side and one of the coolant seals was starting to fail. I had a couple of thousand track miles on my motor. I don't drive like Grandma on the street. I tore down the engine with 85k miles on it, 54k of which the previous two owners put on. What's your point?

I don't think you're going to find much support around here for running 87 octane in a car that can detonate on 91 octane. Talk about a DUMB way to save a few dollars.

psquare8

Fc had 96k-I beat the car hard-hey I was 25 with a good job and long commute-I was drifting in snow before they had a concept-fc's are great snow cars-traded it when it was failing-bad exhausts-rotors, tires - bushings and suspect apex seals, fd now has 38k - I blew the fd LIM gasket well past 135mph over the summer -car still ran like a tiger - just idled rough- are 350zx's speed limited?- original paper-so I guess I drive slowly. Compression is fine per the shop that did the LIM in November- I asked them to check it in an abundance of caution. Manager said he did it as common practice on any manifold job-perhaps he was not sincere on the "policy" but they did check it or the mechanic was a great actor. I installed my DP two years ago...I could not get the time away from work to do the LIM gasket. Look above - guy with the same set up thinks it runs better with 87. I would add one footnote - I do not put 87 in the winter months as they add something goofy to the gas between Nov 1 and Feb 28 in PA - I do not drive the car a ton in those months but the add stuff for winter was always a concern-never took the chance. I opt for higher octane in winter- my choice-figure 3 tanks around 800 miles. I put premium in it 3 or 4 times a year... and the last time was when the LIM gasket got torched. In 1986 when I purchased my fc I had the chance to meet several Mazda reps - do not buy premium as it will add nothing to your performance. One sales guy pointed me to something in writing he was given as a means to incent the buyer. That was after I purchased the car and on delivery. He drove a 85 fc and had been is 7's for years. So my view is that I put over 125k on two turbo engines using 87 octane about 90% of the time without an issue - NO MAJOR MODS 0 on the fc and 1 DP on the fd. Yes 93 is better and yes Virginia there is a Santa claus....

psquare8

Ummm, actually it is around 20 years and something over 125k in miles on an fc and an fd-see my other post. If you mod it up I have no experience with octane but I do not think you could do a high end proper mod and expect to run 87. I can honestly not remember putting 93 in the fc. I have zero reason to lie or BS the forum - further I agree completely that 93 is better if not best-can you still get 94 in the US. If you have the mods do not chance it. So how many cars have not been moded up or are close to stock on this forum? If your on here chances are you have at least one or two non stock items in you shopping cart. Is this not what this is all about???

kashent

You should do your research before you open your mouth.

Octane rating is the ratio of Octane to Heptane in gasoline, with higher octane gas having more octane (who would have guessed?) However:

Heat of Combustion for heptane: 44.752 MJ/kg
Heat of Combustion for octane: 44.427 MJ/kg

from the wiki: http://en.wikipedia.org/wiki/Heat_of_combustion

So the more Octane you have, the less energy you get when you burn it.

This chemistry lesson brought to you by the letter O.

t-von

iTrader: (8)

Point is you have yet to prove it's unsafe on a completely stock car. Yet your so against it. What's more DUMB? The assumption or the truth? You have done nothing but assume and critisized those for going against what YOU feel is right.

rynberg

What I feel is right? Mazda recommended 91 octane for a reason, and a very good one at that. These motors are easily damaged by detonation...which can be caused by running too much boost for the fuel octane. Why would you risk it just to save a few cents a gallon? That's DUMB, IMO.

Besides, go and look up what EVERY SINGLE MANUFACTURER on the planet recommends for their turbo-charged vehicles. Guess what you'll find. 91 octane. It's not a conspiracy, there's a reason.

Like I said earlier, if you drive around like grandma all the time with only rarely getting on it, I'm sure the motor could last quite a while on 87 octane. But I don't even drive my daily Accord that way.

t-von

iTrader: (8)

That reason is Mazda's and many other manufactuers safety blanket. Nothing else. With a low compression ratio of 9.0 and a super rich A/F mixture under full load, there is more than enough margine of safety to run 87 in a stock Fd. It's DUMB for you to still assume people do it as a cost savings. I do it for performance reasons based of my driving habits. My car is driven at light to mid loads 95% of the time, therefore it makes no since for me to run a slower burning fuel that will build carbon faster. 87 burns faster which will leave less cabon deposits behind. It's perfect for normal driving regardless of what the book says. When was the last time you heard of someone blowing a completely stock Fd due to detonation? Mazda isn't foolish enough to release a vehicle to the market designed and engineered for specifically only one fuel grade. Why do you think the stock 10.1 A/F ratio is so rich? That's how Mazda compensated for people using lower octane. I refer to have the faster buring fuel.



I could easily say it's DUMB to drive any car spirited on public roads. Which is more safe? I think we all know that answer.

alexdimen

iTrader: (13)

You're all wrong, because you're not even on topic!

Buzzardsluck

I could not tell a difference in any aspect between 7psi and 10psi.

BLKTOPTRVL

Not even power? Mine feels a lot slower.

Asterisk

iTrader: (3)

OK, i just saw like 20 of these posts complainig about the same thing, so why thehell not UPGRADE it? put in a renesis knock sensor, or another one that will
work, pair it up with a stadalone, and reprogram the knock mapping so it actualy works. Also, hey if it doesent, why keep it? It's useless then.

Buzzardsluck

I couldnt feel any power difference. IIRC Running the base PFC map I saw 3-4 mph increase in trap speeds.

This was on my old motor BTW minus a few current mods