Jeff will most likely email you FI maps based on your turbo. I don't know for sure though, I think I heard him mention some kind of subscription service at one point.

Either way; you'll be taken care of by Jeff and it'll be worth every penny.

 

I'm starting a test on stage 1 with 89 octane gas. This tank is a 93/89 octane mix. I doubt I'll have a problem seeing:

a) I hit mid 15's at WOT without pinging on 93 octane
b) use to run my CZ tuned to a bit over 13.0 afr with a bit of ignition advance on 89 octane

But you never know what will happen... i'll keep my ears open and AP watching the knock retard. My car always gets much better fuel mileage on 89 octane for whatever reason so thats why i'm giving it a shot. Perhaps it is the weak ignition system or i'm low on compression which leads the car liking a more easily igniteable fuel... no idea

 

89 is more easily ignitable than 91? what am I missing?

 

yes, that would be why some high performance engines ping with lower octanes. Ping is detonation which means the fuel combusted before it was suppose to because of the temperature in the cylinder. So essentially, the higher the octane the more work the ignition system has to do in some respects.

 

The basic premise of octane.

The higher the octane the more adverse to autoignition and the slower it burns. So you can compress higher octane gas more with less chance of autoignition and it burns slower so you can run more ignition advance.

 

Not slower - just higher initial energy.

 

What do you mean?

 

just a quick question. what AFR's can the stock cat handle?

 

Off topic - but hey.

Flame Speed of Gasoline depends on the chemical makeup of the gasoline itself - and has nothing to do with Octane. Think big nasty chemical equation breaking gasoline compounds and oxygen to form new compounds.

Octane refers to what we call sensitivity in the explosives world; which is the initiation of the chemical reaction all by itself (auto-ignition). Once you have a sensitivity rating / octane - does not refer to the power of the reaction - only the amount of initial energy required to initiate it. So a higher sensitivity/octane means it takes XYZ more energy to start the breakdown. That is why you can advance ignition et al - because the heat from the compression of the mixture is less likely to be high enough to initiate the explosion.

That is why we can run around with military dynamite in a backpack; but you can't do that with civilian dynamite - but they are both the same explosive force.

 

eh????? The cat breaks down from heat; so it would be a combo of ignition timing and AFR.

 

Thanks Kane. Yeah that makes sense. Either way I don't plan on running around with ANY dynamite in my backpack.

 

ok, whats the farthest you could advance the timing and the allowable AFR's

 

Wow - good question; I have no idea; I have the math - but I am not done with it yet; and EVEN then it would be for piston's only (round 1). No theoretical math even exists for the Rotary yet. You don't want to go toooo advanced because the max pressure would occur before 12 Degrees ATDC - which would be a waste of power even if you didn't detonate.

Really lean and really retarded would be the hottest combo for the cat (I think). Short story long; the cat is supposed to be good up to 1600 degrees or more (per Jeff); and boosted I have only seen 1500 (wot; high boost 10 second run uphill).

 

but when you are boosted, some of that heat is lost in spooling the turbo, so it may be hotter for N/A

i know too much advance would be stupid and could be really detremental.

 

If you wanted to be that ragged edge; at this point I would go:

1 - Get spark plugs with pressure sensors built in; log for max pressure as close to 12-15 ATDC.
2 - Get a pyrometer wired - or use the built in cat temp sensor.
3 - Strap it to a dyno and advance ignition as far as you can; then start leaning out the mixture until a) you ping or b) the cat temp exceeds the specs from Mazda.

THAT would be a ragged edge tune.

 

not that hardcore

 

It's hard to read Kane's posts with my left eye, while my right eye watches his signature movie

 

Yep, by reading his posts, I'm learning to controll my eyes like a chamelion.

 

That's an interesting experiment, to get it running efficiently w/ 89. Unless the ignition is retarded to offset the lower octane, it will likely need more fueling to prevent detonation.

If you hit mid 15's at WOT on 93, isn't it dangerous to run that same map on 89? What Fuel Trim do you get at WOT on 93? If the trim is already adding more fuel, it could mean trouble.

I wonder if Cobb's economy mode will safely run 89 octane during summer time.

 

For those of you with NA 8s and an AP. What is your intake air temp? Also at what temprature was it when you took your reading?

I have been seeing between 110 and 120 in 50 degree weather. Not sure if this is good or bad?

 

Got my AP! :D
I got it last night, but Im not able to use it yet.
I dont have the turbo maps for it yet so im waiting on that from Jeff, Im stoked! :D

 

Lower than you with the Racing Beat REVi and Ram Duct it seems...

From around 50 degree F outside, can't really remember

 

it's meaningless to discuss it this way.

the AIT depends on ambient, but also your traffic conditions (how fast you are traveling). Pulling up to a traffic light can make the temps go up to insane numbers.

 

^ Yea, missed that. I was moving on down the highway in my graph, looking at the end of my run, while watching AFR.

 

is Jeff back?