Why would you think running 93 octane hurts performance?Still learning and still experimenting but currently a 20p SWS in second hole from lowest (2nd from lowest motor height) as the smaller, 15" diameter seems happier down there.
Fuel Economy is improved with the 20 approx. 10% @ WOT and it turns 52- 5300 loaded and topped out so I'm in an rpm range few people seem to want to run in but the motor seems really happy.
I run nothing but 93 octane which hurts performance slightly but gives me peace of mind and some engine life insurance I feel.
Watersports or a large group onboard would dictate something in the 17 to 19 range and I can make a quick swap to optimize for the weekend but that's a rare occurrence so I'm really happy with my new overdrive!
I hope to update the other thread at the end of this summer.
I have seen that too, alos been in a dyno shop when they were testing 93 vrs 87 and it was a big gain.Because the burn rate is slower and the peak cylinder pressure in the combustion chamber occurs later than optimal, reducing power and fuel efficiency.
Or at least that is what most engine peeps tend to think.
Ahhh...when I saw the post, I knew this would likely to get a bunch of comments. There are multiple reasons why results for various octane ratings are all over the chart. A couple things first. For more than forty years I've run at least one if not two turbocharged cars. Effective compression ratios and cylinder pressures are now part of my DNA. As JDB alluded to, gas octane is not a measure of power, it's a measure of resistance to detonation. Also it depends on how the octane rating is achieved. In the old days that was tetraethyllead (which reduced the BTU's per gallon). In today's era of gas-o-crap, it may mean just increasing the percentage of alcohol ( also decreases the BTU's per gallon). The best, and most costly, way is to start with a better base hydrocarbon and use more sophisticated refining (aka molecule restructuring) for best octane AND high BTU's (read: non-ethanol premium, yeah, it's expensive). And yes, I'm aware that E85 CAN BE a high performance/high octane fuel, but only IF the engine is designed and operated with that in mind. Used in a typical engine the fuel economy, as in MPG, is going to suck, as in a reduction of ~25+% from non-ethanol because that fuel is low BTU content compared to real gasoline.I have seen that too, alos been in a dyno shop when they were testing 93 vrs 87 and it was a big gain.