Video shows that octane doesn't make power.

Yes, but that’s more difficult to change

 

Heads much easier to change than a piston...

 

I didn’t know there were aftermarket heads available for the Taco?

 

This video and thread is about an LS. Either way you can still increase or decrease the combustion chamber size easier on a stock head than rebuilding a bottom end.

 

It doesn’t affect static CR, but overlap and timing affects actual cylinder pressure. Overlap, in general, let’s some of the fresh intake charge out the exhaust during the overlap period. Cam timing,duration, and lift affects how much intake charge volume goes into the cylinder to be compressed at whatever ratio the engine was designed around. Some cam grinds require minimal compression ratios to work correctly.
It gets complicated though, because what’s going on in terms of flow in the intake or exhaust tracts changes with rpm. What might be very inefficient and rough at low rpm, might scream on top.

I think what goes on with the Atkinson cycle phase of our engines is the cam timing is altered to blow some of the intake charge back into the tract. I think this is referred as shortening the stroke, which it isn’t, it just delaying when the compression stroke becomes effective.

My point was really, that a number of things affect an engines need for octane. A better test, at least from a construction, or effects standpoint, might have been an iron head small block. However, I suppose from a relevance standpoint, I think most modern engines are now aluminum heads and probably knock sensored.

 

Right, that’s part of the calculation to determine static CR.

 

Higher octane makes a more simultaneous combustion. And that’s a good thing.

 

GM had a lawsuit, over E85, against them dismissed...
GM dealer found the use of E85 to be the cause of the hpfp plunger sticking. The plaintiff alleged GM made the representation E85 could be used 'consistently'. The judge determined GM made no such claim; other than it 'could'.
It was also dismissed in part because the plaintiff did not afford GM adequate opportunity for remedy under warranty.

 

A lot of people have it exactly right on higher octane, and some others have no clue on what happens in the combustion chamber.
Higher octane fuel is more resistant to burn, has better resistance to igniting on hot spots in the combustion chamber, ie pre ignition. Running higher octane doesn’t make any more power at all, but it does let the computer advance the ignition, to take advantage of the fuel it’s detecting.

 

Oh Lawd. Where is your “science” that higher octane “lets” the computer advance the “ignition?”

Hilarious.

Higher octane simply makes the combustion fire precisely. Instead of sporadically popping of like a pop corn popper.

High octane makes Tacomas run fantastic. That 87 Octane is horrible in Tacomas.

 

Like I said, a lot of people have no clue as to what happens in the combustion chamber.
How do you think the computer varies the timing?

 

The Tacoma ECU has multiple ignition timing maps, some of which are dedicated to higher octane. If the ECU sees that it can advance to that higher octane map then it will do so.

Then there are other factors like knock correction, which premium octane will typically yield a higher value than regular octane will.

 

you can see for yourself if you run an OBD scanner. look at the graphs for degrees of timing.

 

Okay?

 

Ya know, I've just got to say something here, it's people like this that make the world suck today, no clue, yet think they know everything, so inept at anything.

PEOPLE SUCK, you, Jack Brewer, suck more then most you idiot.

 

i don't know Jack, where is YOUR science?

increased octane allows for more advanced timing. it's science. VVTI. Variable valve timing w/ intelligence. the ecu is constantly adapting to various conditions.

this isn't the 70s anymore.

 

4 or 5 posts above, I made a remark on how the computer does advance the timing when higher octane is available, and this idiot says this.

 

And I'm correct, PEOPLE SUCK.

 

i feel like you've set the bar too high for an anonymous internet forum...

anyhow i'm running 91 or 93 with a tune. I have no objective way of measuring if it make more HP or not but whatever, still love driving my truck

 

And I like the way mine purrs on 87 without a tune. It used to be tuning was all manual from timing to carburetors. Now you pick the gas and the computer does the rest. As long as it can make the adjustments needed it’s all good. Octane alone might not make more power but it can allow the computer to make timing adjustments that can in some cases increase compression in those engines where timing is used to bleed compression. Boosted engines or those with a wider range of adjustment either require it or at the minimum can take some benefit from it. I’m not a huge fan of blanket statements or especially hyperbole when they clearly don’t apply. There are several taco motors in service not to mention boosted versions and each one is a special case. “Octane doesn’t make power” is misleading at best.