Originally Posted by iolmaster

Finally, someone that understands octane and it's relationship to HP.
Thanks,

Originally Posted by Wilson2000

Not exactly...Jim said "Octane has nothing to do with HP." Then he went on to explain that since the year 2000, knock sensors are utilized to retard the timing in case of knocking. Retarding the timing reduces HP, thus, running lower octane gas reduces HP. We all know what Jim meant, but his blanket statement just isn't true.

Originally Posted by iolmaster

You are correct that the timing does effect the HP. What I said and Jim said is that the octane rating doesn't.

Originally Posted by RRocket

If you're running 87, then floor it...the car will be in full retard to prevent knock because you have a significant load on the engine.

However, your car can run perfectly fine (particularly in cooler weather) on 87 without it pulling timing. BUT that's gently driving the car and preventing any significant load (ie not flooring it, not lugging up hills, etc)

You can even hook up engine diagnostics and see the knock sensor activating.

And, while anecdotal, I had a Supra tuned for 94 octane and 22lbs of boost. 87 would surely cause catastrophic failure if driven hard. But I found myself in the middle of nowhere once, needed gas..and all they had was crap 87. As long as I drove it gently and stayed out of boost...the car was fine. Knock sensor didn't activate once.

I run 91+ on my Lexus car. Mostly because a) it's not prohibitively expensive b) I like not worrying about driving the car "gently".

Originally Posted by rcolan

...I get tired of all these uninformed people who post things like "the manufacturer knows best", "it only costs an extra $12 to fill up with premium",etc. The SC430 is not a high performance sports car, its a Luxury Tourer, and if driven as such it will have no detrimental effect to the engine to run it on regular gas!