Fuel Power and the "octane boost" effect (Terry or Molakule?)

[novadude]

Can someone explain this to me?

I thought FP enabled you to use lower octane via reduced CC deposits, and that it did not actually boost octane.

Here is why I ask:

I have been using FP on a regular basis in my Mustang. Cold weather allowed me to drop down to 89 octane gas before I started using FP.

One recent warmer day, I forgot my FP bottle and I filled up with 89 octane. I detected some *slight* audible pinging at WOT. The next day (60 miles later), I filled (topped off) the tank again (89 octane from a different station) but I added FP (3oz for a 15 gallon tank). In the same weather condidtions, the car did not ping with FP in the tank.

Please explain why. Obviously it was not from CC deposits, as the car had been on a steady diet of FP for the past few months. My theory is that maybe I got a full tank of gas that was not 89 octane. Topping off with "real" 89 octane the next day might have raised the overall octane level above the pinging threshold. Is this what happened, or does FP have some kind of octane boosting effect?

 

[jason07-1zzfe]

What year and model Mustang? And what grade does it call for? Just curious. Obiously pre- knock sensor, since you are getting pinging?

They have said FP does not boost octane. There is some other mechanism that may allow use of lower octane. Don't know what that is.

 

[MolaKule]

FP adds more potential energy to the fuel and allows the fuel to burn more evenly when the flame front crosses the CC.

 

[novadude]

quote:

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What year and model Mustang? And what grade does it call for? Just curious. Obiously pre- knock sensor, since you are getting pinging?

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1995 5.0 - no knock sensor. It calls for 87, but the 94/95 cars are known for pinging even with stock timing. I am running 13 deg BTDC for more power (proven 5.0 mod).

FWIW, to the best of my knowledge, even the 2004 GT Mustang does NOT have a knock sensor. I am 99.999% sure this is fact!

 

[novadude]

quote:

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FP adds more potential energy to the fuel and allows the fuel to burn more evenly when the flame front crosses the CC.

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So could the more even burning reduce the tendency to ping?

 

[hannaco]

Yes. The pressure builds up at a slower rate than a sudden increase in cylinder pressure (ping).

 

[Ian Swett]

So in theory Fuel Power works sort of how some of the octane boosters like Torco Mach1 boost octane, but not just by mixing in higher octane fuel? They're some sort of fuel stabilizer which slows the flame front and increases effective octane more than something like toluene would(per unit volume)?

Or is what I'm suggesting impossible?

And if it is possible, why don't gas stations sell '91+', which is 91 with fuel power(or something similar) added, especially in California, where you can't get 93?

-Ian

 

[JTK]

FP completely eliminated the little bit of pinging my 2002 isuzu rodeo 3.2 had when running recommended fuel (87 octane). It took SEVERAL tanks of gas, but now I can even skip a dose of FP every now & then & still no pinging.

Joel

 

[darkdan]

Mustangs (4.6L SOHC) should have gotten knock sensors between 2001 and 2003. I don't recall the year.

Mustangs with DOHC engines already had them.

Doesn't help you with a 5.0 though. =)

 

[rob-the-oil-nut]

quote:

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Originally posted by novadude:

FWIW, to the best of my knowledge, even the 2004 GT Mustang does NOT have a knock sensor. I am 99.999% sure this is fact!

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Wow. What about my '96 Bonneville with a 2001 or 2002 Le Sabre engine? How would one find out? Can a mechanic find it easily? I ask because I hear something like knock sometimes and assumed that couldn't possibly be the case (we still have temps under 32 F and this is not at full operating temp). I also asked the mechanic to up the nominal timing (not done; he didn't have the time) since I was hoping to run a lot of 92 or 94 octane this summer (unless gas hits $3 a gallon)
BTW how long does it take for the ECM / knock sensor to adjust the timing if I fill with Super gas?
Any reason to use less (or more) FP, "MoleKule Mix" or Redline with Super? (Reminder, I use ethanol-blended gasolines)
THANKS!
Rob

 

[darkdan]

According to autozone.com a 2002 Buick LeSabre with the 3.8L V6 does indeed have a knock sensor.

How long does it take to adjust to knock? About a stroke give or take.

When you fill up with 93 instead of 87 that day it doesn't adjust the timing to run differently. But if you use some cheap 87 and you're about to knock then it retards the timing so it doesn't knock.

It doesn't sit there adjusting timing all day to produce as much HP as it can.

You sure it's a knock? What does it sound like? Is this the first pushrod engine you've driven?

 

[wtd]

I use FP regularly in my 98 chevy truck with the 5.7L and it still pings on 87 octane gas. I've not tried using a higher octane gas because I want to try to fix the problem, not mask it.

 

[Chris B.]

quote:

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Originally posted by wtd:
I use FP regularly in my 98 chevy truck with the 5.7L and it still pings on 87 octane gas. I've not tried using a higher octane gas because I want to try to fix the problem, not mask it.

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Can you explain how pinging sounds?

 

[hannaco]

The '96 Bonneville with a 2001 or 2002 Le Sabre engine may not have a knock sensor that the ECU understands.

 

[Patman]

quote:

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Originally posted by Chris B.:

quote:

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Originally posted by wtd:
I use FP regularly in my 98 chevy truck with the 5.7L and it still pings on 87 octane gas. I've not tried using a higher octane gas because I want to try to fix the problem, not mask it.

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Can you explain how pinging sounds?

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The best way I can think of to describe it is that it sounds like sparks are going off under your hood under acceleration. Others say it sounds like marbles in a tin can, but I think it sounds more like sparks.

 

[Chris B.]

Thanks Patman! Does this happen only under WOT? And with the engine at high RPM's how do you hear the pinging over the engine roar? I'm going to have to listen for this on my engines.

 

[sbc350gearhead]

You can generally hear it at any rpm that it takes place. You can also feel it. It generally happens at high load, low vacuum conditions. Pinging is bad........but not nearly as bad as its big brother "detonation" (preignition on the compression stroke). No engine can survive detonation for an extended amount of time.......something will break.

 

[rob-the-oil-nut]

quote:

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How long does it take to adjust to knock? About a stroke give or take.

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That's what my #1 mechanic guy said over supper, too

quote:

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When you fill up with 93 instead of 87 that day it doesn't adjust the timing to run differently. But if you use some cheap 87 and you're about to knock then it retards the timing so it doesn't knock. It doesn't sit there adjusting timing all day to produce as much HP as it can.

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He said something similar yet different about that, I'll have to check furthur on that.

quote:

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You sure it's a knock? What does it sound like? Is this the first pushrod engine you've driven?

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I really doubt it's piston slap, it happens above 2000 rpm almost exclusively. And yes, this is my second car, the prior was DOHC.

Regarding Hannaco's "The '96 Bonneville with a 2001 or 2002 Le Sabre engine may not have a knock sensor that the ECU understands." I will bounce that idea off of the applicable mechanic. I want him to take it for a nice test drive, too.
I'm as big on preventive maintenence as my wallet allows

THANKS
Rob

 

[GT Mike]

quote:

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Originally posted by hannaco:
The '96 Bonneville with a 2001 or 2002 Le Sabre engine may not have a knock sensor that the ECU understands.

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The '96 and '01 engines in that car (3800 Series II V6 RPO L36) are identical, and the knock sensors are the same as well. The only differences in these engines was in the design of the throttle body/MAF sensor, and the fuel injectors, but those would have had to be swapped from the original engine, as the wiring harness plugins are totally different.

 

[69 Riv GS]

I believe "pinging" is a word used to describe the noise caused by detonation-the crashing together of two or more flame fronts. The original flame front is broken off usually by; overly advanced ignition timing-sparking the air/fuel mixture before it's compressed enough; Or too much dynamic compression ratio. Also, sharp edges in the combustion chamber can make detonation more likely. It sounds like FP makes the flame front more break resistant.