What gas (octane) is best for TCH?
#31
10-29-2006, 06:11 AM
Re: What gas (octane) is best for TCH?
Originally Posted by Big-Foot
I'm not so sure that this is true...
Why you ask?
Because the ECU will advance the timing to the point where the knock sensor picks up detonation and then it backs the timing down a fraction of a degree of rotation until the system is stabil.
With the high static compression (which increases with speed dynamically) - the lower octane fuel will yield less overall resistance to detonation - thereby less timing can be applied. The efficiency of the engine will increase with the longer burn of the fuel (spark advance) to the point of detonation which actually works against the rising piston(s)..
Now in a lower static compression engine, the difference between lower and higher octane is far less as the 87 Octane fuel in a 9:1 compression engine will generally run within 1 degree of timing of the 92 Octane fuel.
I would encourage people with these cars to run their own tests. Obviously you should run the tests in a "somewhat" controlled format so you are comparing apples to apples. Also over 2 or more tanks of fuel to reduce the error factor.
I plan on doing this with my car as soon as I feel the engine / driveline is broken in. Meanwhile - I feel confident that the higher octane will yield a greater efficiency in these engines.
Why you ask?
Because the ECU will advance the timing to the point where the knock sensor picks up detonation and then it backs the timing down a fraction of a degree of rotation until the system is stabil.
With the high static compression (which increases with speed dynamically) - the lower octane fuel will yield less overall resistance to detonation - thereby less timing can be applied. The efficiency of the engine will increase with the longer burn of the fuel (spark advance) to the point of detonation which actually works against the rising piston(s)..
Now in a lower static compression engine, the difference between lower and higher octane is far less as the 87 Octane fuel in a 9:1 compression engine will generally run within 1 degree of timing of the 92 Octane fuel.
I would encourage people with these cars to run their own tests. Obviously you should run the tests in a "somewhat" controlled format so you are comparing apples to apples. Also over 2 or more tanks of fuel to reduce the error factor.
I plan on doing this with my car as soon as I feel the engine / driveline is broken in. Meanwhile - I feel confident that the higher octane will yield a greater efficiency in these engines.
#32
10-29-2006, 07:00 AM
Re: What gas (octane) is best for TCH?
Kluken - Please read post #24 where I get more into the logic and programming behind spark advance and state:
Thank you...
It is possible that the ECU programming limits the maximum values to a greater degree than I have seen. What I have seen in the past is that the ECU can advance the timing from 2 to 3 degrees beyond the value in the spark advance table.
Thank you...
Last edited by Big-Foot; 10-29-2006 at 07:12 AM.
#33
10-29-2006, 07:14 AM
Re: What gas (octane) is best for TCH?
Thanks for the clarification.
I think it would be interesting to see the outcome, but I personally don't ever plan to run anything but 87 in mine. Let me know how it turns out.
I think it would be interesting to see the outcome, but I personally don't ever plan to run anything but 87 in mine. Let me know how it turns out.
#34
10-29-2006, 08:27 AM
Re: What gas (octane) is best for TCH?
My opinion has nothing to do with "staying inside the box" in any way.
I once tried higher octane in my 2004 HCH and saw no benefit. I have also used Acetone in my hybrids with no benefit.
Let me repeat my best point:
There are hundreds of thousands of Priuses on the road, using the same HSD system as the TCH. Don't you think that BY NOW if higher octane was a help for these engines that it would be common knowledge on websites like this one?
Is that not a fact? That shows that there is nothing about higher octane fuel that would benefit the TCH or we would already know about it via the Prius community.
I once tried higher octane in my 2004 HCH and saw no benefit. I have also used Acetone in my hybrids with no benefit.
Let me repeat my best point:
There are hundreds of thousands of Priuses on the road, using the same HSD system as the TCH. Don't you think that BY NOW if higher octane was a help for these engines that it would be common knowledge on websites like this one?
Is that not a fact? That shows that there is nothing about higher octane fuel that would benefit the TCH or we would already know about it via the Prius community.
#35
10-29-2006, 09:05 AM
Re: What gas (octane) is best for TCH?
Originally Posted by Big-Foot
So if I read this right you are saying;
Anyone who claims to get better fuel economy on higher Octane fuel is a LIAR.
and that these people are FOOLS..
and that by putting in a higher than specified octane the fuel economy will be WORSE..
So nice to know that you are so open minded to newly implemented technologies (Atkinson Cycle) and are so openly offering your opinions.
Certainly you must certainly have your own "Atikinson Cycle specific" emperical evidence collected to support your statements...
We look forward to reading and observing this evidence.
Thank you..
Anyone who claims to get better fuel economy on higher Octane fuel is a LIAR.
and that these people are FOOLS..
and that by putting in a higher than specified octane the fuel economy will be WORSE..
So nice to know that you are so open minded to newly implemented technologies (Atkinson Cycle) and are so openly offering your opinions.
Certainly you must certainly have your own "Atikinson Cycle specific" emperical evidence collected to support your statements...
We look forward to reading and observing this evidence.
Thank you..
If all things being equal (same driving pattern, same routes, same techniques, same weather conditions), 2 identical vehicles with a recommended low octane fuel rating. One filled with high octane, one filled with low, the low will do better.
#36
10-29-2006, 09:32 AM
Re: What gas (octane) is best for TCH?
Originally Posted by livvie
Yeup, that's what I'm saying. I don't have time to set people straight on this topic that has been discussed to death. Do your own research and you will see this is the case. Higher octane gas is only needed for higher compression engines, period. There are articles on the net supporting the idea that by using a higher octane gas on a vechile requiring lower octane, the net result is a lowering of mpg.
If all things being equal (same driving pattern, same routes, same techniques, same weather conditions), 2 identical vehicles with a recommended low octane fuel rating. One filled with high octane, one filled with low, the low will do better.
If all things being equal (same driving pattern, same routes, same techniques, same weather conditions), 2 identical vehicles with a recommended low octane fuel rating. One filled with high octane, one filled with low, the low will do better.
BS on you Livvie...Spend the time - tell us how you have amassed all the evidence that is Atkinson Cycle specific.
I've said my peace on the subject.
Thank you for the interaction.
Larry - Your HCH is not an Atkinson Cycle VVT engine. Apples to Apples.
Thank you as well..
#37
10-29-2006, 10:09 AM
Re: What gas (octane) is best for TCH?
Since Big-Foot didn't like the link that lars-ss put up from the Car Talk guys, perhaps this one is better. http://www.cartalk.com/content/colum.../April/08.html
Also, has anyone else besides me noticed the irony of this 'discussion' and Big-Foot's signature...???
Also, someone else commented (sorry I lost who it was) who said the didn't purchase a car because it required premium...it's kinda like not buying some clothing because it requires dry cleaning...a lot of extra expense.
Also, has anyone else besides me noticed the irony of this 'discussion' and Big-Foot's signature...???
Also, someone else commented (sorry I lost who it was) who said the didn't purchase a car because it required premium...it's kinda like not buying some clothing because it requires dry cleaning...a lot of extra expense.
#38
10-29-2006, 02:31 PM
Re: What gas (octane) is best for TCH?
Originally Posted by belbe
....
Also, someone else commented (sorry I lost who it was) who said the didn't purchase a car because it required premium...it's kinda like not buying some clothing because it requires dry cleaning...a lot of extra expense.....
Also, someone else commented (sorry I lost who it was) who said the didn't purchase a car because it required premium...it's kinda like not buying some clothing because it requires dry cleaning...a lot of extra expense.....
Jeff
#40
10-30-2006, 07:28 AM
Re: What gas (octane) is best for TCH?
What I'm hearing is that you guys think by putting higher octane gas on a vehicle that doesn't require it (Let's say my HCH I) will net me higher gas mileage? And at what cost? Anyway, it's a simple test, go and drive your car the same way with higher octane gas in it, and tell me how impressive your mileage is. I'm not convinced and haven't seen or read anything here to support this. The problem with he test is that you will believe that you are getting better mileage and may end up influencing the result. A good test would be to put the gas in for your spouse unbenouced to them and let them drive and you record the mileage. Anyway, good luck.
