NOPE. Lean is lean, no matter what the octane is. Lean is BAD!!!! You cannot modify a car and not provide the fuel to support the mods. with the exception of maybe an air filter

 

IMO, it sounds to me that this tune is "on the edge" and is retarding timing and when you add race fuel, it no longer retards timing? It doesn't take much timing retard to significantly reduce power...

 

So here is maybe the better question:

If the car is STOCK, how much octane can be used and still improve power?

In an E39M5 that number is 96 (r+m)/2... the stock DME will advance timing- or more precisely will not retard timing - up to 96...any higher octane results in no change of engine parameters and no higher output.

What is the number for stock K16 and for stock K24 Porsche Programs? Anyone know???

For custom tunes- EPL, UMW, whatever... that question is only answerable by the tuner, they can tell you if they want.

 

No comment, but to avoid further embarrassment, do your self a favor and delete that post before any one else reads it.


What do you consider lean and what do you consider rich .. . whats perfect ratio?

I was talking about modifications like air filter and exhaust ..etc. that dont require a full retune but would benefit from it.

Edit: What engine was in your vette? = ) I have a 69 Stingray

 

Certainly not an expert...but every tuner has their own target A/F. I think that 11.5 is a good middle of the road...higher than that is getting too lean, lower than that is getting too rich, both hurt power, one will destroy your engine in seconds...

 

I'm not kidding though, go over to the forums, talk to Active Autowerke, VF-Engineering, etc. They'll all tell you the DME advances on it's own... I had a Stage 2 AA Supercharged M3 prior to the turbo. I ran race gas in it several times and it was certainly faster - I ran the same cars on pump as I did on race gas and the runs were completely different both times.

I don't see how it's argued against if the dyno's show it? Also, you may not be familiar with the system, but the DME on the E46 M3 is constantly pushing the threshold for knock, so when it gets no knock, it pushes further, and again and again, till it reaches it. My friend who is an EVO tuner explained it to me, he said it works within certain parameters... But the parameters are very large, hence why 109 truly benefits the system unlike most DME's in other cars.

Correct me if i'm wrong. Have you read up on it at all? The only reason I was intrigued by it was cause I owned one, otherwise I could of cared less.

Sounds like one of those to good to be true type of things, but honestly, don't discount it unless you for a fact have talked to an E46 M3 tuner and have been told it's BS... Then i'll believe it; but otherwise I've been told a lot that it's truly the case. Who knows? I don't see how that makes me embarrassed, or naive, the logic makes sense... I'm no tuner, but the E46 M3 DME is supposed to be quite a work of art...

 

The mixture chemically balanced AFR (Air Fuel Ratio) is 14.7 to 1 called the stoichometric mixture.

But 12.5 to 1 has been scientifically proven to burn faster than any other mixture.

 

Actually, 11.5 is on the rich side

Typically we tune for 11.5 to 1 to account for minor variations in the various conditions that might present themselves. Ideal(even on a turbocharged application) is leaner than 11.5. However, running on the richer side will help with a few things.... Safety, Cooling, Cylinder to cylinder variation, Load variation, etc

I will usually set up a street car with about a 10-15% "buffer" that does not interfere with the knock sensors. After that(to an extent), the knock sensors do their thing, followed by a drastic reduction in power. Usually this is only seen in a gross overboost condition.

Depending on the particular setup, some sensors might be much more sensitive than others. To be able to see an actual knock trigger, compare it to the cylinder position and determine if the "noise" was actually knock during a combustion event is key. Engines can get quite noisy at higher rpms...

Although the AKI of the fuel essentially stays consistent, fuel does indeed have a shelf life. Always fuel up at a trusted source that turns over alot of fuel.... this is especially important if you live in a very "wet" environment.

Justin

 

I use to own an AA SC .. the car in the sig is my 682whp E36 M50/S52 GT35R Tec3R standalone.

 

Do you think the V/E of an engine dictates what it wants for an A/F? I've had motors (twin turbo small block V8) that really liked 11.0. My turbo is happy at 12.0.

 

No I see you have a big turbo M3, but are you familiar with the E46 M3 DME and tuning setups? That's a sick M3 you have, but those were a bit different than the new M3s and how they're tuned. I can see you're a tuner yourself, but Tec3 Standalones are kind of in a different ball park when compared to an OEM ECU that BMW makes.

I'm just wondering if you've heard anything against the fact that the DME does self adjust the timing. Or are you assuming that it doesn't just because to most tuners it seems too good to be true? I mean why would big companies like AA and VF make such claims of they're false?

I'm willing to be educated on the matter if it's not true, but so far no one has stated it isn't, but rather that it is. I've seen a lot of tuners of other types of cars (non e46 M3 tuners) doubt it, but that doesn't mean it isn't a true fact, you know? I'm curious. I mean there's a good chance BMW make their stuff right, correct?

I'm not claiming it magically tunes itself, but rather it has a wide range of timing that it works within, it's just extremely sensitive in comparison to many other cars out their when comparing their knock sensativity/timing setup.

 

One of the tuners on this forum offers an ECU that reads the octane and adjusts automatically. Not sure which one but for some reason I am thinking it's Promotive.

 

I believe that although the volumetric efficiency CAN affect the target AF ratio, moreso Engine Efficiency is a bigger player in what the AF needs to be. EE is the relation of dynamic compression and how it is being used by the engine at any given time(still a close to stoich cruise AF, and a much richer AF needed for full load).

Justin

 

The main difference in E46 M3 just has the Dual Vanos head like the Euro E36 M where the US E36 M is a single vanos. E46 M3 base hp is 330 .. so 270-280whp stock.

There can be other lurking variables that would effect the dyno results such as.. weather .. dyno used ..

I thought these were numbers claimed just by retuning the stock ECU and higher octane fuel, but reading ur post again I think I read it wrong ..forced induction E46 M3?

AA reflashes the stock ECU for their SC kits .. and the ECU reflashing price can varie by a couple hunderd $$$ depending which sales person answers the phone or how desperate you sound

 

Yes, FI E46 M3s.... That's why I stated I had a supercharged stage 2 M3 from AA.... Dyno numbers and all.

I spent countless hours on the E46 M3 forum in the FI section and read up on it all. If you're telling me you did the same and think that the ECU doesn't auto adjust then please show me where it doesn't - cause there are probably 100+ guys on that board right now that will say otherwise.

I'm confused how the price of the ECU flash has anything to do with it having the ability to pick up on the octane you are running... but anyways, you buy the kit, it's about $12k, so everything comes with it - no haggling with the price, not sure where you heard people have to pay them for flashes, unless it's a custom setup..

I understand their DME's are highly tuned/changed but they note that even the stock e46 M3 DME has the ability to detect the knock threshold and continue to test it till it figures out the flashpoint of the fuel and what degree of timing it can add...

Without beating that dead horse, here's another fact. My car also had their alcohol/water injection kit. With the flip of a switch I could turn the pump on or off in it and I wouldn't have to switch maps like you would if you stopped running the alcohol on an EVO, STi, Supra, Turbo E36 M3, etc... my DME would pick up on the fact that there is no more alcohol being injected into the motor because the knock threshold would drastically change, so it'd pull back timing, then start adjusting from there. And you mean to tell me it magically doesn't do that? Well it does, or else AA would have 100+ blown E46 ME motors

The DME picks up on it all on its own, and as soon as I turn the alcohol injection back ON, the car will soon begin to get much much faster as it begins to advance the timing with the higher knock threshold of the alcohol injection (~100 octane level).

Go figure?

So,
My question that started this thread in the first place, why the hell doesn't the $110k 996 Turbo have such a feature with it's ECU? hahaha Ohwell, i'll live with it. Maybe it's because it's a turbo car, so the variables are just too crazy for it to be able to auto adjust, but still I figured Porsche would of done it too.