Hemmings Daily on Octane

jdr3366

jdr3366

Well-Known Member
Let's go through this again.

Hemmings Daily bills itself as "The World's Largest Collector Car Marketplace." Maybe so, but I never heard of them before tonight.

Regardless, they posted an article about octane rating and performance that concludes...

"Although higher octane can cost substantially more per gallon, it does not necessarily mean it is better for your car. Higher octane gas is processed through additional steps that further refine the blend and cause it to burn more slowly than lower octanes. These additional processes are what contribute to the higher pricing, but that does not mean the higher octane will offer any advantage over other blends in many engines. Octane does not offer any better fuel mileage, increase engine horsepower, or make the engine start quicker. Higher octane only reduces the likelihood of engine knock or ping."

The article goes on to discuss high compression engines and the need for higher octane in those vehicles.

You can read the whole thing here.

https://www.hemmings.com/blog/2014/...the-fiction-behind-those-higher-priced-fuels/
 
I think my truck runs better on lower octopus gas. Maybe because that's what it has always had, but when I put mid-grade in it it was harder to start and I had more throttle lag.
 
I don't know why, and I'm not complaining, but gas mileage has gone up by 1.4 mpg or better for the past month. Just shy of 6K on the engine. Using same brand and grade of gas from the same 2 stations. I guess it could be the end of the dreaded 'winter blend'.
 
I've said this before but... if you want to spend the extra bucks to run 91 or 93, ya gotta get a tune to make it worthwhile.
I've been running 91 for about 6 weeks but only because I put a 91 tune in the truck.
 
Interesting reading in that article, especially the mention of knock detectors. You can run almost any engine on regular fuel if you retard the timing enough. Of course, performance and fuel milege also go out the window.
 
Joisey said:
Interesting reading in that article, especially the mention of knock detectors. You can run almost any engine on regular fuel if you retard the timing enough. Of course, performance and fuel milege also go out the window.
Click to expand...
Exactly. Dad's 14:1 Windsor runs up to 38 degrees on the big end but we also put 112 octane in it. Lol
 
Total timing advance is influenced by engine temperature, compression ratio and how fast the combustion chamber is. Most Ford and Chevy have relatively fast chambers (except for the 428 cammer) and can run upwards of 42 degrees of total advance (crank and initial combined). 426 Hemi engines run a buttload of advance because their chambers are 'slow' by design, as hemi shaped chambers are.
 
The Toyota 3.5 V6 should be able to use more timing advance because of the four valves feeding and exhausting the combusion chamber. Smaller valves keep the velocity of the intake charge from dropping as it fills the cylinder. It also allows the valves to direct the intake charge for best charging of the cylinder and evacuation of exhaust gas. By what I see on parts fische, the engine uses a pent roof (hemi) combustion chamber.
 
Joisey said:
The Toyota 3.5 V6 should be able to use more timing advance because of the four valves feeding and exhausting the combusion chamber. Smaller valves keep the velocity of the intake charge from dropping as it fills the cylinder. It also allows the valves to direct the intake charge for best charging of the cylinder and evacuation of exhaust gas. By what I see on parts fische, the engine uses a pent roof (hemi) combustion chamber.
Click to expand...
WHAT!? You mean my Taco has a Hemi?
 
If it would have had a 60's hemi in it it would have been one bad ass truck. Wasn't a slouch the way it was but technology was no friend.
 
Oh, the modern Hemi was a good idea, but it was 'improved' to death. I can't count the people that owned them and told me their modern hemi was EXACTLY like the hemi of the sixties. Gotta laugh sometimes..
 
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