• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Question regarding gas



Granted the car will take advantage of the increased timing available.

But that has to be one of the funniest things I've read today. The comment about running premium in all cars is close, but not nearly as bad as this one... Tune your car for the highest octane you will regularly put in it. Note the higher it is, the better it will perform in both efficiency and output.
 
Ok...then explain this since I don't know octane to MPG comparison. If higher octane burns at a higher rate, thus giving your car better performance...how does that INCREASE MPG's too. Since 87 burns slower...how come it gives better MPG's for the most part...I always heard anything with a higher octane rating it lowers fuel economy. If it doesn't then I'd like to know the reasoning. And not one of those...just because it does deals...
 
its because higher octane doesnt burn at a higher rate but resists detonation more which allows for more compression and more timing. That produces more power hence increase in power. Also, if you can increase timing you can increase fuel efficiency.
 


Bio248 said:
could have sworn that the higher octane you have the slower and more complete it burns.
Click to expand...

Thats true as well. In this case, all we seem to be concerned with is knock so thats the #1 thing people notice with increased octane, reduction in knock.
 
It reduces knock yes...but even guys at the track running 7 sec. street cars etc have always told me that higher octane burns faster...you might get better MPG's but everytime I've run a higher octane in a car it'll run through that tank of gas alot faster (eg. 50+ miles) faster than craptastic 87...
 
This is getting about as good as the synthetic oil one was. I just have to throw in my hat here also.:th_nervous:

Gasoline is another mysterious substance, I might be able to shed some light on the mpg side. Let me start off by saying that more chemical energy is released from burning longer chained hydro-carbons than shorter chained ones. Since “gas” is a mixture of hydro-carbons, I’m talking about the average length.

Diesel = very long ~139k BTU/gallon
Regular gas = long ~125k BTU/gallon
Premium gas = shorter ~111k BTU/gallon

This should explain the mpg questions. But also be aware that mixing in ethanol lowers the BTU, so it is possible for premium gas (with out ethanol) to have BTUs close to that of regular 90/10 gas.
 
Last edited:


well, the debate could still go on because im pretty sure with higher timing on premium i could out-mileage my car on lower timing and 87/89.
 
Its not the heat that creates power. Its the expansion and push on the piston which creates power. Higher octane burns slower pushing for longer than the lower octane.

Heat in an engine beyond the point where it brings it up to a stable operating temperature is harmful more than anything else.
 
You must log in or register to reply here.
Back
Top