What if 94 Oct gas makes big differences from Oct 91 gas?
03-25-2012, 07:03 AM
#11
I think 91 octane is the minmum rating that should be used in the S2000 without causing engine damage. Is it the optimum rating for performance? Maybe for high altitude driving, but not lower elevations. I'm sure that some chart is in existence that guestimates optimum octane rating for high compression engines at a given elevation, but I don't have one.
In the Houston area it is not uncommon for fuel delivery traucks to dump leftover 87 octane gas into a 93 octane tank, rather than take it back to the terminal. The gas station owner pays the 87 price, and the customer never knows the difference. A win-win-lose situation IMO. But it happens.
For those of us that have owned our cars for awhile, we're pretty aware of when it runs well...even if it's a gut feeling and nothing else. If your gut tells you the 94 runs better than the 91, then go with your gut feelings.
In the Houston area it is not uncommon for fuel delivery traucks to dump leftover 87 octane gas into a 93 octane tank, rather than take it back to the terminal. The gas station owner pays the 87 price, and the customer never knows the difference. A win-win-lose situation IMO. But it happens.
For those of us that have owned our cars for awhile, we're pretty aware of when it runs well...even if it's a gut feeling and nothing else. If your gut tells you the 94 runs better than the 91, then go with your gut feelings.
I've got two personal tests. A 2000 TL we ran for 100K on regular. No issues. Ran strong. A 05 RL 11:1 compression, has run for the last 60K on regular fuel. What's the major difference? Idle. It sounds a little ruffer. MPG? No affects. I'm able to get epa rating on the 87oc fuel +/- the margin of error.
So in effect, drive with what you want. Less power will be had with 87, stock power will be around 91 and no 'gains' will be had pushing a higher oc rated fuel on a stock block.
Food for thought - octane is probably the least of your concerns. Imagine getting some bad gas in there, maybe with some water and bringing the motor to redline and getting a little bit of 'extra stuff' thrown into the mix. I often wonder how the motor would handle that.
03-26-2012, 07:10 AM
#13
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Well, I just don't want to be told that I am in need of mental exam
but when I switch from 91 to 94, I don't notice any differences so
it explains me why many drivers say it doesn't make differences.
If drivers think it is waste of money to use 94 or higher gas, they won't
use it at all.
However, I still believe ECU recognizes the extra octane from gas
and adapt it to the higher octane gas because if I switch from 94
to 91, it feels little bit different. After one or two full tank
with 91 gas, it seems to be OK, ECU probably adapt to 91 gas after that
I don't know for sure but I wouldn't want to get rid of the chance that
ecu probably recognize higher octane than 91 do something to take advantage of it.
but when I switch from 91 to 94, I don't notice any differences so
it explains me why many drivers say it doesn't make differences.
If drivers think it is waste of money to use 94 or higher gas, they won't
use it at all.
However, I still believe ECU recognizes the extra octane from gas
and adapt it to the higher octane gas because if I switch from 94
to 91, it feels little bit different. After one or two full tank
with 91 gas, it seems to be OK, ECU probably adapt to 91 gas after that
I don't know for sure but I wouldn't want to get rid of the chance that
ecu probably recognize higher octane than 91 do something to take advantage of it.
03-26-2012, 11:56 AM
#14
Honda's ecu maps for S2000's are tuned on 95 octane. Actually all of their high performance cars have an ecu tuned for 95 octane. What happens is there are tables in the ecu that can tell based on the knock levels if you're running lower grade gasoline and automatically retard timing.
In essence, you will gain power all the way up to probably 100 octane fuel.
the knock sensor is there for extreme knock, and the Knock Index level tables are there for fuel differences anywhere from 91-95 octane.
In essence, you will gain power all the way up to probably 100 octane fuel.
the knock sensor is there for extreme knock, and the Knock Index level tables are there for fuel differences anywhere from 91-95 octane.
03-26-2012, 12:13 PM
#15
Really don't know the answer but the OM recs. 91 octane or higher. If 91 is or happens to be mid-grede in your area, try a tankful.
On the other hand, premium is at an average of 10 cents higher per gallon and a tankful would be $1.30/40 over the price of midgrade and about $6 per 1000miles. When viewed in this context, premium becomes an easier purchase. Your call.
On the other hand, premium is at an average of 10 cents higher per gallon and a tankful would be $1.30/40 over the price of midgrade and about $6 per 1000miles. When viewed in this context, premium becomes an easier purchase. Your call.
03-26-2012, 01:47 PM
#16
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IMO you will not gain power with a higher octane fuel, but you will not lose any when the engine - and the air it breaths in - is nice & warm, or at higher altitude.
And thanks for the link
And thanks for the link
03-26-2012, 02:07 PM
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Honda's ecu maps for S2000's are tuned on 95 octane. Actually all of their high performance cars have an ecu tuned for 95 octane. What happens is there are tables in the ecu that can tell based on the knock levels if you're running lower grade gasoline and automatically retard timing.
In essence, you will gain power all the way up to probably 100 octane fuel.
the knock sensor is there for extreme knock, and the Knock Index level tables are there for fuel differences anywhere from 91-95 octane.
In essence, you will gain power all the way up to probably 100 octane fuel.
the knock sensor is there for extreme knock, and the Knock Index level tables are there for fuel differences anywhere from 91-95 octane.
Well, I think it make sense based on my subjective and personal feelings.
Anyway, do you know any articles or references about ecu mapping for 95 octane gas you mentioned above??
04-04-2012, 01:06 PM
#18
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How can one measure the difference between 91 & 94? Can a flashpro do it? If so, how would we know the difference is not due to a margin of error.
Also, fwiw, Chevron 94 up here does not contain any ethanol.
Also, fwiw, Chevron 94 up here does not contain any ethanol.
04-04-2012, 01:16 PM
#19
The engine knows based on knock level. NOT KNOCK COUNTS, but knock level.
04-04-2012, 08:38 PM
#20
i like the 94 in the hot summer months...again as stated above...keeps the car from pulling timing out and the car from falling flat...my 2000 Si is notoriously bad in the 100 degree heat with the A/C on.
darcy
darcy
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