hey guys, I have a I6 300, and also a simple question.

I asked the guys at auto zone if it was safe to use octane booster in my truck, and they said yes. the reason I'm asking is because my friend zack said not to use it unless my engine is rebuilt, and it's not. so, is it safe to use like a half of bottle per tank or what?

thanks,

nathan

 

yes its fine. but for what i ask????????????????????????? most bottle say it will raise octane by 3 points big woop. 3 points is a marketing game. so if you have 87 octane it will turn it into 87.3 octane. people seem to think it will turn 87 into 90. for 5.00 or whatever it costs you could just go buy a few gallons of premium. but even then your engine has no way to take advantage of higher octane. higher octane just burns slower. not a magical horsepower boost.

 

First, I'm sceptical of such products.....snake oil.

Secondly, why not just buy premium fuel? It is a higher octane.

 

higher octane will do you no. good unless the engine was built for it and runs high compression.

 

That's not entirely true. If your engine is computer controlled, it will retard its timing less often because it will be able to advance timing further without experiencing pre-ignition/detonation. On any computer controlled vehicle with a knock sensor,, your computer will keep advancing timing up to the point that the knock sensor detects a spark knock, at which point it will retard the timing a few degrees and then starts the cycle over. So with higher octane fuel, the engine will be retarding itself less often due to the fuel's higher stability.

 

no.

factory systems are not made to do so. the computer will not advance the timing. the advance curve is only for 87 octane.

 

retarding? sorry, I'm still learning all about engines and such.

 

That's 100% false. First of all, more timing does not equal more power. Second of all, the PCM uses a fixed timing curve. It doens't do anything to it unless it detects preignition. It does not advance it until it hears knock and then back it off.

 

That's exactly how it works. It has built in maps and that's what the computer advances to. When it hears a knock, it backs it off. NO,, more timing does not necessarily mean more power,, but when you're spark knocking at the mapped timing value and the engine retards your timing, then you will lose power. And yes,, if your engine's computer sences through all it's instrumentation that the mapped fuel/air ratio and timing is not ideal,, yes it can advance beyond that.

Your engine never runs off of just the built in mapping unless it's in limp-home mode.

 

So please enlighten us all as to how the computer can fire a spark before the pip sensor tells it to. That is the only way it could advance timing beyond the preset value. There is a predetermined value for every combination of sensor inputs that Ford thinks is best. If the pcm hears knock at that value it will retard. It will never arbitrarily advance the timing just because it doesn't hear knock.

 

do the newer (2004/5) vehicles adapt to higher octane? i dont think so but doesnt hurt to ask.

im gunna have to agree with SS here as well.

 

no they don't. factory preset for 85 octane. you can use a tuner to advance the engine to use 93 octane

 

[QUOTE=Silver Streak]That's 100% false. First of all, more timing does not equal more power. Second of all, the PCM uses a fixed timing curve. It doens't do anything to it unless it detects preignition. It does not advance it until it hears knock and then back it off.[/QUOTE


I have to go with the Streak on this one. The timing advance is built into the computer by the software guys and is preset to be determined by load, rpm, engine temp, etc etc, it cant go higher than what the software guys programmed. It can be retarded if the computer picks up some detonation.

This is why some guys go with aftermarket chips because the programming in the chip is set more from a performance aspect than a gas mileage/ regular driver aspect.

Forget the octane booster, run a tank of hitest, if it runs better great, if not go back to regular its that simple, if you want to go faster get a V8 , but for bottom end power , for pulling out tree stumps and pulling around a boat or pulling a house off its foundation stick with the 300.

 

Ok guys,, I'm an engineer specialized in closed loop feedback systems. I'm not blowing smoke up your rears. I've been operating a Haltech E11 v2 engine management system on experimental 5 cylinder engines for a couple of years now. I understand how closed loop ecm's operate. You're all talking open loop operation only. Your saying the engine management system simply reads inputs from the various input sensors and references the built in mapping codes for fuel/air mix and timing, and never checks any type of output. ECM's are capable of learning what works best because they provide inputs, and then check outputs such as O2 sensor, Knock sensor, etc. It uses this information to determine how to alter the preset mapping tables.

For instance, if your engine reads all it's inputs, references the mapping, sets timing/fuel/air accordingly, and then reads that the mixture was much too lean/rich, it will adjust the inputs properly to get the output desired. Again,,, the only time the engine runs strictly off the mapping codes is when it's in open loop.

 

jgetti

Your saying WOT the engine will advance the timing as much as possible...agreed... but in this open loop mode...there is a set timing limit the eec cannot exceed...total timing if you will...in this case the knock sensor is only there if something isn't as it should be...back up, in cases of poor octane, other faulty engine components, owner decided to manually advance the timing or installed an aftermarket chip (less proper octane fuel).

When it comes to closed loop/cruise mode, your making it sound like the total timing advance is limitless and the only time the timing retards is if the knock sensor indicates it should be, and this cycles over and over...but if I understand the ford eec-IV correctly, there is a total timing, pre set in the tables, that the eec cannot exceed even in closed loop. Also my understanding the knock sensor isn't even considered as an input for closed loop/cruise mode, this would only make sense if there was a pre set total timing, as in a cruise situation, the load is low and your advance should be able to reach a reasonable advance limit without ill effect. Surely the ford engineers would have understood that there is a point of diminished returns when it comes to timing, been able to sit down and make reasonable pre set limits, with testing? No? My understanding that the only thing that cycles constantly during closed loop/ cruise mode is the fuel, as the eec tries to increase/decrease as it watches the O2 signal bounce back and forth from lean to rich and vice versa, in order to use as little fuel as possible to maintain a target air/fuel.


Curious, learning, interesting topic for us, non engineers..