Compression of our motor and octane

Yes, that is correct. The static ratio is fixed by piston travel.

The intake valve being left open during the compression stroke reduces the overall volume of air. Through this process you get an artificial reduction in compression ratio even though the piston stroke remains unchanged. This reduces the peak pressure in the cylinder.

The benefits of this are adjustable load on every cylinder cycle, cooler chamber temperature, reduced emissions, improved power efficiency and better fuel efficiency.

The lower chamber pressure also allows the use of lower octane fuels.

 

Correct static is fixed but the dynamic compression ratio is changed leaving the valve open.

 

Lower Octane is More Volatile, and can cause premature detonation.
Higher Octane is less Volatile, resulting in a precise ignition and much cooler burn, that is why (2-Stroke) dirt bikes run it.

 

47k miles on my 17 here. I run predominately 93 as my truck flat out runs smoother on it. It's not placebo, it's not a waste of money. On 87 my truck runs like it has a miss and will ping like crazy. No such issues on 93.

I do not buy 93 because I am brainwashed by big oil. I do not buy 93 for more power or better MPG's as I notice no difference. I can tell within miles which fuel I put in my tank. I buy the fuel that makes my truck run best. I've got around 20k miles towing with my truck, it's easy to tell then which fuel is in it then. Easy.

I have taken it to the dealer for this issue, and got told "normal" and "could not replicate"

Still think it's a waste of money to run 93 in my truck? My truck has also had a whining rear diff, a leaking rear diff, whistling a arms, rust in all 4 door sills, an ungodly amount of tranny TSB's, and countless other traits... Has your truck? No? Then maybe your truck isn't just like my truck and maybe my truck runs different than yours and your blanket statement of "higher octane is stoopid" is in fact, stupid.

My truck at light throttle and low RPM will stumble and ping like mad. If yours does, try 93 for a tank or two. If your truck doesn't, i'm insanely jealous.

 

17 Auto here. This is exactly my scenario except different RPMS due to gearing and tranny.

1500 RPM and very light throttle application is my stumble jam.

 

This is my go to fuel for my Camaro !!!

https://vpracingfuels.com/product/c12/

 

My trucks better than your truck...

 

Lol maybe (probably), but there are people here who have had problems I haven't had and hopefully never do.
I come to TW to feel better and worse about my truck simultaneously haha.

 

Not to rub it in but I’m one of those guys that hasn’t had any and I really hope it stays that way. I hope you get your issues worked out brother...

 

Said the Tacoma owner to the other Tacoma owner.
- Every Tacoma owner ever

 

My truck started out good. Then went bad, ugh badly. Now it seems mostly sorted other than the fuel thing of course. I've moved onto the "self inflicted pain" phase of ownership, so any issue I have now came from me making my truck "better".

Lol.

 

I’m able to fit larger wheels and tires when running 93 vs 87, but the sweet spot is 89 as that also allows me to use canola oil at 5k intervals.

 

yeah since I started running premium I’ve been able to fit larger tires...

 

I run 91 because there’s no ethanol in it. The engine runs dam good, no knocking, awesome fricken mileage on the highway and when it’s -30’s c in the winter it starts without plugging in.

 

I've been using mid-grade 89 octane in my vehicles for several years. WHY? Been doing it for years, don't remember exactly why.

Partly because of another similar octane thread/heated discussion on this forum, I filled up with 87 octane before a road trip this past weekend. I did not see ANY difference in performance or MPG on this trip.

I'm going to stick with 87 for a while, just to see how things go.

 

Some days I like it rough I go for 87. Other times I like it smooth I go for the 93.

 

2016 Off Road, 285/70R17, 91,000 miles, steady diet of rocky mountain 85... No complaints, 21mpg by summer, 18.5 by winter. Original motor using Toyota filters...

 

I've had the stumble, hesitation, and overall poor power delivery ever since the beginning with my 2017. I have been able to hear pinging and pre-detonation as well, and have reported it to my dealership without any results. Have always been told it drives/sounds as expected. I had one dealership tech even tell me that they recommend higher octane to customers, despite having no basis for that in the manufacturer documentation.

In the last few thousand miles, I've filled up with 93 and it feels like a different truck. Never stumbles at 1850 RPM like it use to, sounds smoother, and revs easier. It's harder on the wallet but justifiable for me at the moment. I will probably switch back to 87 at some point to prove to myself that it's the octane changing the dynamics.

 

That's impressively high! My commuter is 11.5 and I cant run less than 91.
And my 2ng gen runs in anything that goes in, sounds like the newer motor isn' too picky either

 

IF you are buying fuel at the same station for the 87 try another gas company. Shell, 76, Mobil/Exxon may be better.