That make sense? :P

I know that Howell states in their description of the AFX ECUs that 93 octane is required with these units. Problem: we don't have 93 octane here in AZ. I know a couple gas stations offering 100 (or was it 104?), but I'm not about getting 10gal of 91 here and then driving across town to score a couple more at $4.00/gal unlesss I absolutely have to.

So here's my questions:
1. Besides the telltale ping of internal combustion engine pain and suffering, are there any other warning signs for those who have yet to run an A/F or EGT gauge? (as in engine temps climb first on the OEM temp gauge?)
NOTE: These gauges are being installed before the shootout along with the cams, gears, and SAFC2.
2. The AFX ECUs are marketed as being adaptive to some extent; learning and self-adjusting as they go. Does this mean that it will progressively advance timing to the limits and beyond?
3. Considering the 420A does have its own knock sensor of sorts, wouldn't the AFX detect knock and pull back on the reigns a bit? I know I've read somewhere that the predet event is already passed and did it's damage by the time the ECU recognizes it, but still, the point is there.
4. Is there a particular style of driving that's more prone to predet than others? As in, would driving moderately under 4k be safer than, say, putting the whips to my, uh, whip and redlining her every gear (as in driving 130+ everywhere then)? If so, does keeping a higher rpm level with minimal load contribute to cooling? Or staying lower in the band where the fuel curve is richer?

So that's pretty much it. Daisy is noisy enough that a dump truck could fall from the sky, landing right behind me, and at 3krpm I wouldn't even think to check my mirrors. So I'd like to get some input as to if there are any other ways to be warned of potential predet symptoms or causes. I'm staying under factory redline until I get the ERT head to avoid risking valve trouble (as in dropping one into my <12k bottom end), so I may as well make sure that I'm taking precautions to not low it up, even though a new set of rings are in the plan for the near future.

Thanks for the help guys! This thing is amazing.

87?? your kidding right?
why take the chance? how much did that ecu cost you? how much did that car cost you?

get your octane up. if howell suggests it,then i would consider what they had to say about it not some random guesses as to whats going on in that ecu...

toulene.

91 octane will be fine. Check the neon board for more info on that. Some have had knock in the hot summer with 91octane and some havent. Will the ECU adjust timing if u put in high octane? yes it will. I put 100 octane in my car one time, it took about 3 good 100mph pulls until it recognized it.

I wouldnt use anything less than 91 octane with the AFX\R. I use 93 octane.

If 91 is still giving you some problems you can try running a bottle of Octane booster with every fuel fill-up. Might be just enough to get you over the edge.

Originally posted by CODE4
If 91 is still giving you some problems you can try running a bottle of Octane booster with every fuel fill-up. Might be just enough to get you over the edge.

a bottle of octane booster would take 91 to 91.3

Originally posted by a_miller_76

Originally posted by CODE4 If 91 is still giving you some problems you can try running a bottle of Octane booster with every fuel fill-up. Might be just enough to get you over the edge.

a bottle of octane booster would take 91 to 91.3

After a couple of Jager shots I could spit in the gas tank and have it get a higher octane rating then that off the shelf stuff. LOL

Originally posted by djtrickee
87?? your kidding right? why take the chance? how much did that ecu cost you? how much did that car cost you? get your octane up. if howell suggests it,then i would consider what they had to say about it not some random guesses as to whats going on in that ecu... toulene.

Haha! It's not like I installed it and went to the gas station guys! She's been parked for over 2 weeks. Still has over 3/4 of a tank. (Which is weird because I'm up to over 200 miles on this tank) I don't like the idea of the octane booster because they don't really do anything. One bottle will raise 16gal like 1/10 of an octane point. So like Aaron said, 91 to 91.3 or so. :P

I wonder about water injection? Someday she'll be high comp turbo and with that ECU and some seriously tunable ignition mods, I might stand to benefit. Cheaper in the long run.

And yes. I am thinking about going high comp turbo with teh AFX/R ECU. And not jsut some t25 or 14b or even 16g. When I go turbo, if I'm still on this block (as opposed to 2.4L), I'll be going custom like FP30. Yeah, yeah, yeah. They sai you can't make 200hp NA on stock displacement too. We'll see about that soon enough. What happens if it blows up? You get to buy new parts. Better parts. So :P

EDIT:
Oh yeah, the ECu cost me $250 and a used fender. The car was just under $15k. ;)

He should've been using 91 octane a long time ago if his compression readings were right. ;)

I would suggest looking into using Toluene or Xylene. You can raise it up from 91 to 93 with a gallon of it per tank. I might have to go that route too because my wrx sometimes pings on a stage 1 map. Even without hearing audible pinging, you can get harmful knock.

i would go with propane injection. it makes it like ~110 octane and its pretty cheap. you can make your own kit too. come on at WOT or a constant spray. pretty sure daisy would be raw with the ecu,nasty cams, high cr, an heavy porting with the timing advanced like no other. good luck with traction.

Originally posted by Uberingram
He should've been using 91 octane a long time ago if his compression readings were right. ;)

Nah 10.5:1 isn't that high that you need 91 for detonation on stock ECU timing. I wouldn't run 87, but 89 is good. I run 89 with my roughly 10.5:1 milled setup.



Exile Racing Technologies: http://www.exileracing.com
una salus victus

Originally posted by Michael_97RS

Originally posted by Uberingram He should've been using 91 octane a long time ago if his compression readings were right. ;)

Nah 10.5:1 isn't that high that you need 91 for detonation on stock ECU timing. I wouldn't run 87, but 89 is good. I run 89 with my roughly 10.5:1 milled setup.

Good point, but he's running the AFX ECU too, that's the problem :)

"predetonation" is a misnomer. It's either detonation or preignition, not both.

my buick skylark had preignition... it was great! gave it a little extra power... the trade off is possible holes in the pistons if you are not careful... luckily that thing has the iron duke in it... 93k and still running strong... it will kick the crap out of those "smoother running" 90 Skylarks with the 2.5 mmm factory defect in MY FAVOR!!!!

i'm done.... back on topic... i'd go to about 91 octane... 89 is cool too, hell, just blow something up and i'll be happy, i like fire and destruction

Thanks guys. I'll be popping for the 91 next tank. Just curious if there were signs other than audible knock to be on the lookout for.

:thumbsup

Originally posted by a_miller_76

Originally posted by Michael_97RS

Originally posted by Uberingram He should've been using 91 octane a long time ago if his compression readings were right. ;)

Nah 10.5:1 isn't that high that you need 91 for detonation on stock ECU timing. I wouldn't run 87, but 89 is good. I run 89 with my roughly 10.5:1 milled setup.

Good point, but he's running the AFX ECU too, that's the problem :)

Until about a week ago he wasn't, and I was referencing Uber's comment that he should have had premium in there with 10.5:1, until not it wasn't neccessary.

Brian knows he needs premium in there now, so all is good. You do know right Brian...



Exile Racing Technologies: http://www.exileracing.com
una salus victus

EW! 87 octane! WHY?!

to get technical...octane is a hydrocarbon with 8 atoms of carbon joined together. if gasoline was made up of 100% octane, it would have a 100% octane rating, we use this percentage because its the actual hydrocarbons in the gasoline that resist pre-ignition and detonation. on the other hand...we have heptane, a hydrocarbon with 7 atoms of carbon joined together, which resist detonationa nd pre-ignition not well at all. it doesnt take much compression at all to get it to randomnly ignite. a fuel made up of 100% heptane's octane rating actual ='s 0.

now, 87 octane means it is made up of 87% octane and 13% heptane...or in other words, KNOCK JUICE. i'd get either 89 or 91 just for the peice of mind.

theres a reason they call knock the 'hammers of hell'

Originally posted by DarkOne
"predetonation" is a misnomer. It's either detonation or preignition, not both.

lol yea i was gunna say somethin too :P

also, brian...detonation kinda sounds like a card is stuck in a bike tire

astas ;)
_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more, but worth it!!!!!!!!!!!!!!!!!!!!!!!!!!!

Originally posted by djtrickee
The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

octane is the rating of the fuels RESISTANCE to ignite.



_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Water/Methanol Injection setup imo:
(sounds safer than propane injection)

www.snowperformance.net

Okay guys. I know what knock is. I also know why higher octane is better on higher CR motors. My question was if there was any signs other than the sound that knock was occurring. Thanks!

:P

Originally posted by DR1665
Okay guys. I know what knock is. I also know why higher octane is better on higher CR motors. My question was if there was any signs other than the sound that knock was occurring. Thanks! :P

Sure, but most of them are visible mainly after the fact.

Detonation has a sound. Preignition does not. Preignition puts holes in piston crowns. Detonation breaks ringlands and flattens rod bearings.

Originally posted by Initial DSM
Water/Methanol Injection setup imo: (sounds safer than propane injection) www.snowperformance.net

i have all 3 ;) heh



_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Originally posted by turbo8u

Originally posted by djtrickee The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

octane is the rating of the fuels RESISTANCE to ignite.

Thats exactly what I said.

Originally posted by djtrickee

Originally posted by turbo8u

Originally posted by djtrickee The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

octane is the rating of the fuels RESISTANCE to ignite.

Thats exactly what I said.

sort of. you make it sound like compression is the only factor in pre-ignition, which it most certainly is not. higher CR makes for a higher combustion chamber temperature, and this is a mjor factor in pre-ignition, the heat. thats why alcohol engines can run like insane 14:1 compression, the alcohol cools the intake charge enough to help avoid detonation.

brian, if you have a logger ive actually seen a timing change on skrillas car when was running to lean, the car backs way off from the timing retard when the knock sensor is doing its job. so if you were knocking to the point where the knock sensor would pull timing, then you'd feel a difference in the power your car was making.

heres some definitions:

pre-ignition: when the charge ignites before the spark. can happen with or without detonation, but most likely will cause it on a high perf motor. even a glowing hot spark plug tip is a likely culprit of this. pre-ignition acts much like to much ignition timing, except completely uncontrolled

detonation:
when a large amount of the charge burns really fast and controllably, HEAT causes detonation, but not the only cause. pressure plays a big role (high comp like i said ^^^) if heat was the only cause you'd see signs of det near the exhasut valves, usually detonation tkaes place beacuse of to much advance though (and we know the AF/X is a timing advance queen, other wise they wouldnt say to use 93 octane, duh) most of the time, detonation will happen after the combustion has already started



_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Originally posted by turbo8u

Originally posted by djtrickee

Originally posted by turbo8u

Originally posted by djtrickee The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

octane is the rating of the fuels RESISTANCE to ignite.

Thats exactly what I said.

sort of. you make it sound like compression is the only factor in pre-ignition, which it most certainly is not. higher CR makes for a higher combustion chamber temperature, and this is a mjor factor in pre-ignition, the heat. thats why alcohol engines can run like insane 14:1 compression, the alcohol cools the intake charge enough to help avoid detonation. brian, if you have a logger ive actually seen a timing change on skrillas car when was running to lean, the car backs way off from the timing retard when the knock sensor is doing its job. so if you were knocking to the point where the knock sensor would pull timing, then you'd feel a difference in the power your car was making. _________ 96 talon esi-t san clemente, ca as needles of ice are the ill winds' talons the coldest of shadows they seep unto the bone silent souls leave .308 holes

LOL ya it bucked like a rodeo cowboy

Hey Brian, watch out for the:

"What was that sound?" clue

and the:

"WTF just happened to my motor?" mod

Those suck :thumbsup

Me = play it safe imo. I'm not just going to plug this thing in and forget about it. Might see if run4cvr will help me do some data logging this weekend for my birthday. See what she's up to in there.

And thanks for the info guys. It is appreciated. :thumbsup

EDIT:
I do know that I need to use the premium now, but I was wanting some background info just in case thats not enough. I have a thread over at the Neons board to see how this thing plays with others during the summer here in AZ. :P

I dont' know if the 420A is similar to the 4G63, but if you are getting detonation, shouldn't the knock sensor be alerted and give you fuel cut...which you will defintiely feel.

>>>>>click on the link for lots of H20 Injection facts!!<<<

Actualy on Our ecu the way it works (and i beleive it works the same on all modern EFI..) is that after a certain # of knock is acheived, the ECU will compensate by A) Pulling the timing and (think i might be mistaken Enrichening the A/F in some cases to compensate) In both cases you will loose power anyways so just ad octane rating by Propane or Detonation Resistance with Water/Methanol in a 75/25 combo (never ever go over 50% Methanol kk, for the love of your O2)...water will remoove carbon deposits from your combustion chamber which is great...+ water absorbs a lot of heat per volume go to WWW.H20injection.com there Twitch (same name on DSMTuners, great guy btw) can help you out with both propane needs and H20

Originally posted by BlueMoonEclipse
WWW.H20injection.com there Twitch (same name on DSMTuners, great guy btw) can help you out with both propane needs and H20

im actually working with twitch on a new injection system ;) its sick



_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes

Awesome...so another convert to Twitch's gospel bwahahaha

BTW he is one of the ok people on tooners...yup there is some cool people there

I was gona imitate his setup but im going with a 2 boost stage/hobs switch controled Water injection

I bet a lot of you guys would be convinced once you realize it DOES work (and no its not a bandaid fix) really well (specially for us Dry desert air guys)

Originally posted by BlueMoonEclipse
Awesome...so another convert to Twitch's gospel bwahahaha BTW he is one of the ok people on tooners...yup there is some cool people there I was gona imitate his setup but im going with a 2 boost stage/hobs switch controled Water injection I bet a lot of you guys would be convinced once you realize it DOES work (and no its not a bandaid fix) really well (specially for us Dry desert air guys)

you should see my setup man ;) MUHAHAHAHAHA



_________
96 talon esi-t
san clemente, ca


as needles of ice
are the ill winds' talons
the coldest of shadows
they seep unto the bone

silent souls leave .308 holes