87 octane vs 93 octane?

[GQ4Life]

Originally Posted by scrming

Here is exactly what you wrote:

"unless car is tuned for 94 over 87 there's is no HP increase unless car is getting knock with 87 there will be no HP increase
Now get car tuned for 93 and get a nice HP bump. "

Ok... let me rephrase things... The car appears to be "tuned" for higher octane right from the factory. The knock sensors however let you run 87 octane. The thing is unless you are monitoring the knock sensors you don't even know your car is "knocking" with 87!

There is no need to get a tune for 93! You can get an HP bump from 93 with the stock tune! You don't need a tune to take advantage of higher octane!

well rule of thumb is 3 degrees of knock or less is ok. Knock sensor automatically pulls timing but yes you are losing power..
Aeroforce Scan Gauge is what I always used to monitor knock..

Thought I never waited long to mod and tune my cars. Last car SRT4 I had for 4 months before first mods.. Camaro I waited 4 to 5 months..

[GretchenGotGrowl]

Originally Posted by GQ4Life

wouldnt be first car I have seen that is actually tune from factory advance a little and knock detector pulls timing couple degrees
SRT4's were this way. Suppose to be tuned for 91 but they got usually about 3 degrees of or so of knock.. run better at 93 and made more HP
The toys were best. Had button that you can put in 100 octane then hit button for a nice 30HP jump

I'm not sure we are talking about the same thing. I suggesting that it isn't specifically tuned for any particular octane, but instead tries to advance until it detects knock. If you put 100 octane it would simple advance more, 110 even more, until it hits the theoretical maximum. Not much coffee yet, so maybe that is exactly what you are saying about the SRT4.

[scrming]

Originally Posted by GretchenGotGrowl

Hey Scrming, do you think it is possible that these things are programmed to advance until they detect knock and then back off a bit? That would be cool, but probably just wishful thinking?

Yes, that appears to be exactly what is happening... seen the same thing with the 2005 Mustangs. One of the magazines even tested it. Ran the car on the dyno with 87, drained the gas WITHOUT removing the car from from dyno and then used premium. Car showed like a 5 RWHP gain simply by running a higher octane on the stock tune!

[GretchenGotGrowl]

Originally Posted by scrming

Yes, that appears to be exactly what is happening... seen the same thing with the 2005 Mustangs. One of the magazines even tested it. Ran the car on the dyno with 87, drained the gas WITHOUT removing the car from from dyno and then used premium. Car showed like a 5 RWHP gain simply by running a higher octane on the stock tune!

Cool. Also may explain why so little gains can be made by tuning these things. The programing is constantly adjusting things within set bounds to achieve a goal at a particular time (fuel economy when tooling around, torque at WOT). Me likey my car more and more every day!

[GQ4Life]

Originally Posted by scrming

Yes, that appears to be exactly what is happening... seen the same thing with the 2005 Mustangs. One of the magazines even tested it. Ran the car on the dyno with 87, drained the gas WITHOUT removing the car from from dyno and then used premium. Car showed like a 5 RWHP gain simply by running a higher octane on the stock tune!

I doubt it just keeps advancing timing. One way check though is put in C16 see what it makes over 93. Car is just tune aggressive like my old car. So run on 93 guys