deathsled

Does anyone know if you can tune more aggressively on higher octane? I think you would get the most benefit with race gas if you could advance timing, but are there more gains to be had by leaning out further if you're on 100+ octane?

I guess you would want to monitor EGTs to see how hot you were getting, and of course you would need to be on dyno to see if you were actually making more power or not.

I'm just trying to determine if its worth getting my VAFC2 dyno tuned while on unleaded 100 octane, then adding a switch inline with the power to the VAFC so I can toggle between regular mode and "race" mode

Johnny Sack

on the stock ecu, nope. the stock ecu cant compensate for the increased octane, it can only advance/retard the timing so far.

deathsled

thats not entirely true.

the more you lean out the full throttle a/f ratio with a vafc the more timing you actually get, because the ecu believes there is less airflow or load and increases timing accordingly, this is one of the "side effects" of piggyback tuning (but I like to call it an advantage). So in theory if it was safe to lean out the car to 14.0 or 14.5 on race gas, you might pick up a couple more degrees of timing that you couldn't normally on pump gas. Also, the race gas would help prevent detonation and would almost assuredly keep the ecu from yanking timing unnecessarily.

I wasn't trying to ask if you'd get a performance increase from putting in race gas, it's not that simple of a question. I want to know if anyone has tried pushing the NA tune further on race gas with a leaner AFR and if it has shown any good results.

BlownAP

on a stock ecu, with 100 octane it will keep advancing timing, further and further way beyond what it would do with 91 oct. I believe sideways did a test on this back in the day, on a stock car i think they picked up 16WHP with just 100 octane....

Popeye

Anyone try this ?.......http://www.snowperformance.net/products.php?p_cat=99

deathsled

Im familiar with w/m injection on turbo engine, and I considered it in an NA application. If I were to run some secondary injection it would have to be 100% methanol, because in an NA engine any water volume you inject is taking up valuable space for air and fuel.

the cost benefits are defintely there however.

I guess I could just be a test subject and pick up a kit and try tuning with a 100% meth mix and then on a plain race gas mix, see what kind of gains I can get on the dyno.

One nice thing about injecting 100% methanol would be that your AFRs would decrease, so you could actually lean the stock ECU out a lot, pick up some timing, and still end up with an acceptable AFR of like 13.5

wildcardtrd

The advantage to higher octane gas is that you get to run more timing. W/O full control over your fuel and timing maps though, you won't reap the full benefits of the higher octane gas....plus with the AEM, you can save it as a seperate config file, and just download the appropriate maps for each fuel you use.