Highest Octane For Stock ECU??

semtex · 09-04-2009, 09:25 AM

Quote:

Originally Posted by wstar

Hmm so this XXX fuel thing is interesting. So the basic idea here, if I'm understanding correctly, is that it's a higher octane fuel which also has added oxygen - and this means the extra oxygen in the fuel is effectively leaning out the mix for more power, and the extra octane is preventing the knock that would otherwise occur if you leaned out the mix that much on pump gas?

That's how I'm interpreting it (not that I'm an expert on fuel by any stretch of the imagination lol). I mean, that's why I find this so intriguing. The idea that you can just pour some of this stuff into your tank and get an immediate 14whp gain -- how can that not catch one's attention? And if I'm understanding the video correctly, they poured it into a tank that already had some regular fuel it, so it was like a 50/50 mix. I'd like to see what would happen if you poured this stuff into an empty tank!

Hi-TecDesigns · 09-04-2009, 10:09 AM

To answer the earlier question about the ECU advancing timing...

Using a semi-closed loop system, The ECU will retard timing as knock appears, and it will advance timing back as knock disappears, slowly but surely until either knock appears or it is back to the default timing. The key here is once the ECU has advanced back to the default value, it will not advance any farther. If there is zero knock on 93 on a sunny day, you are getting the best performance out of the engine possible, and placing a higher octane will not increase power (not getting into the oxygenated argument here). Don't make the mistake that the ECU will continue to advance timing beyond the default until it starts to knock, always giving you the most power possible for each tank of gas... it doesn't work that way.

Modshack · 09-04-2009, 11:08 AM

Quote:

Originally Posted by Hi-TecDesigns

The ECU will retard timing as knock appears, and it will advance timing back as knock disappears, .

Just as an example (from a 2008 Corvette) there are High octane and low octane timing tables that are selected based on knock sensor output. Without tuner intervention, the high octane table is going to give you the most timing advance adjusted for commonly available gas octane, but no more. Tuners can and will build Very high octane tables to take advantage of 100 octane race gas. Usually the only differences with these tunes are the timing adjustments. More octane + more timing = more HP

High:

Low:

09-04-2009, 10:09 AM	#2 (permalink)
Hi-TecDesigns Base Member Join Date: Jul 2009 Location: Glenelg, MD Posts: 146 Drives: 370 Rdstr AT7 BkChry Rep Power: 17	To answer the earlier question about the ECU advancing timing... Using a semi-closed loop system, The ECU will retard timing as knock appears, and it will advance timing back as knock disappears, slowly but surely until either knock appears or it is back to the default timing. The key here is once the ECU has advanced back to the default value, it will not advance any farther. If there is zero knock on 93 on a sunny day, you are getting the best performance out of the engine possible, and placing a higher octane will not increase power (not getting into the oxygenated argument here). Don't make the mistake that the ECU will continue to advance timing beyond the default until it starts to knock, always giving you the most power possible for each tank of gas... it doesn't work that way. __________________ http://hi-tecdesigns.com/images/pict...on%20Small.gif 2000 S2000 Brickyard Red Metallic w/ Romanesque Crimson Kandy, custom everything else

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