87 vs 93 octane? [Archive]

davidf

07-06-2010, 09:05 AM

So I'm looking at 2 different Celicas for my daughter. A GT and a GT-S. Both nice cars but the GT-S is slightly better equipped and I like that it has rear disc's {GT has drums}. Downside is the GTS requires premium fuel but will never be aggressively driven and has considerable less miles than the GT. Although I'm fairly knowlegable about auto's I wonder how the GTS will run on 87 octane if driven nonaggressively. Any good Toyota techs out there care to chime in. Thanks for any feedback.

Justin

07-06-2010, 09:50 AM

Don't they have the same motor?

Red Alert

07-06-2010, 10:24 AM

Don't they have the same motor?

GTS has something like 11:1 compression. You will be fine running 87 but the ECU will do what it needs to do to keep from damaging the motor so it wont run as good as it could with 93...

tehcodeman

07-06-2010, 10:31 AM

There is the same dilemma/debate for K20 vs R18 motors on the current Civics.

K20 = RSX Type-S and current gen Civic Si which use 93
R18 = Normal Civics (EX, LX, etc.) which use 87

In short, running a lower octane fuel on a high compression motor (which calls for premium) can cause detonation. You might be okay driving conservatively, but it could be damaging in the long run. Running premium may cost you an extra $100/year in fuel. It's cheap insurance to follow manufacturer requirements IMO.

davidf

07-06-2010, 10:41 AM

I do know the GTS motor revs to 7600 whereas the GT not so much. If it'll survive the 87 for daily commuting then thats all she'll need.

Red Alert

07-06-2010, 10:46 AM

Red Alert

07-06-2010, 10:47 AM

I do know the GTS motor revs to 7600 whereas the GT not so much. If it'll survive the 87 for daily commuting then thats all she'll need.

The way she is going to be driving it I wouldn't even worry about it...

tehcodeman

07-06-2010, 10:54 AM

I agree that the ECU can compensate for fuel. I'm just anal about stuff like this I guess.

I like my cars to last as long as they can, so they only see quality part/maintenance. For the same reason I don't cheap out on oil, I don't run RaceTrack/Wal-mart gas in my car. Only Shell for me (or Chevron if a Shell isn't close). Of course, running 93 when it's not needed (Geo Metro for example) is a waste. But if the manual says "Premium Only", then by god put premium in the car. It's not that much more expensive....maybe a couple bucks per fillup on a Celica.

No offense, but I'd trust the recommendations of Toyota/Honda engineers who built the motor rather than asking some dudes on a car forum.

GTS has something like 11:1 compression. You will be fine running 87 but the ECU will do what it needs to do to keep from damaging the motor so it wont run as good as it could with 93...

I agree with this. If it's driven conservatively, I don't think it'll cause any harm. I don't know about Toyota's, but high compression Honda motors bog down at times if you run 87 octane. They just don't run like they're supposed to if you don't use the right fuel.

Red Alert

07-06-2010, 11:00 AM

I agree that the ECU can compensate for fuel. I'm just anal about stuff like this I guess.

I like my cars to last as long as they can, so they only see quality part/maintenance. For the same reason I don't cheap out on oil, I don't run RaceTrack/Wal-mart gas in my car. Only Shell for me (or Chevron if a Shell isn't close). Of course, running 93 when it's not needed (Geo Metro for example) is a waste. But if the manual says "Premium Only", then by god put premium in the car. It's not that much more expensive....maybe a couple bucks per fillup on a Celica.

No offense, but I'd trust the recommendations of Toyota/Honda engineers who built the motor rather than asking some dudes on a car forum.

Not disagreeing with you at all, only a few times have we had to use 87 in the Touareg. 95% of the time I'm using 93 octane(recommended) from Chevron since I really like the techroline they use in all grades of gasoline.

And the difference in price from 87-93 is usually around 20-25 cents and even on a large tank like the Touareg it only comes out to $6-7 more for 93...

IDriveABaseRSX

07-06-2010, 11:10 AM

Well this is my personal experience. On my RSX Type - S for the first 4 years I owned it I ran 87. Then when i boosted it i ran 93. Now that its back to stock im going back to 87. It is not just a 100 dollar difference in gas. Now with this car i took it to the track and daily drove it. Closing in on 100k miles. Just sharing my experience.

Red Alert

07-06-2010, 12:44 PM

mikesrex

07-06-2010, 02:14 PM

it isn't a big cost difference to run the fuel the manufacturer recommends in your car. what are you going to do, run 87 and then let the ECU pull timing after it senses knock?

if you buy the car, just run 93 and be done with it. you are thinking too much.

Matticus

07-06-2010, 02:42 PM

I would think the GTS would get worse gas mileage if you ran 87octane in it. I would run the recommended fuel for the car.

I know my bike gets horrible fuel mileage from certain gas stations ... I've always assumed it is from a lower octane rating than I'm paying for.

pooprajoe

07-06-2010, 02:48 PM

I've only run 93 mainly shell, if not avail chevron, in the past 3-4 cars I've owned, mainly due to if you run less octane, your ecu pulls timing because it senses more knock with the lower grade of fuel. I suggest the 93 always it's a cheap piece of mind in the long run. even for daily use.

iheartJDM

07-06-2010, 04:51 PM

middle grade fuel? lol

SheaAP1

07-06-2010, 04:59 PM

The way she is going to be driving it I wouldn't even worry about it...

What happens when she lets her boyfriend drive it?? lol

I've only run 93 mainly shell, if not avail chevron, in the past 3-4 cars I've owned, mainly due to if you run less octane, your ecu pulls timing because it senses more knock with the lower grade of fuel. I suggest the 93 always it's a cheap piece of mind in the long run. even for daily use.

There is no need to run 93 if your vehicle doesn't require it.

Justin

07-06-2010, 06:57 PM

I say just run 89 then.Compromise.

pooprajoe

07-06-2010, 08:05 PM

What happens when she lets her boyfriend drive it?? lol

There is no need to run 93 if your vehicle doesn't require it.

it's like drinking tap water vs bottle water...

Red Alert

07-06-2010, 08:24 PM

What happens when she lets her boyfriend drive it?? lol

Then if the ECU sees any knock it retards timing to keep things in check... :thumbsup:

mikesrex

07-06-2010, 09:09 PM

it's like drinking tap water vs bottle water...

nothing like that, Phillip

so how many of you have actually tuned a car on different octane fuels?

Red Alert

07-07-2010, 05:48 AM

nothing like that, Phillip

so how many of you have actually tuned a car on different octane fuels?

I don't mess around with tuning much, I leave that up to people who do it for a living... :D

Why do you ask?

Matticus

07-07-2010, 07:01 AM

it's like drinking tap water vs bottle water...
:rotfl:nice try

pooprajoe

07-07-2010, 07:28 AM

:rotfl:nice try
not even going to debate it...

trollin

07-07-2010, 08:14 AM

II would think the GTS would get worse gas mileage if you ran 87octane in it. I would run the recommended fuel for the car.

I know my bike gets horrible fuel mileage from certain gas stations ... I've always assumed it is from a lower octane rating than I'm paying for.
It would if it is tuned for 93 from the factory

Matticus

07-07-2010, 10:47 AM

I
It would if it is tuned for 93 from the factory

I wish I knew of a real cheap and easy way to test the octane ratings of fuel at the pump. I'm sure we would all be pretty surprised at some of the results.

mikesrex

07-07-2010, 10:52 AM

I don't mess around with tuning much, I leave that up to people who do it for a living... :D

Why do you ask?

I was just curious what the difference in timing would be on an 87 vs 93 octane tune. Everyone in here acts like they are experts and shit LOL. I don't have any data on 87 vs 93, but I can show the difference in timing maps for 93 vs racegas.

not even going to debate it...

you can't, Phillip, because you don't know a damned thing about tuning. The only way you might be able to act like you know is if you use google enough. It's dangerous for people like you to act like you know shit you don't. Every now and then someone may actually believe you on a particular topic and end up screwing something up. Instead of being ignorant and talking nonsense, haven't you ever thought about learning something?

mikesrex

07-07-2010, 10:55 AM

I wish I knew of a real cheap and easy way to test the octane ratings of fuel at the pump. I'm sure we would all be pretty surprised at some of the results.

if you have suspicion about a particular pump, I think there is a government entity that may test it for you. I'm not totally sure on this, as this is what one of my professors told me a while back. It's definitely something worth looking into.

Also, I was told they do two tests and average the results. One test uses a GC (can't remember what kind of detector, FID or MS) and determines octane rating with experimental results. The other runs the fuel through an engine and determines the knock threshold with the engine.

Red Alert

07-07-2010, 12:14 PM

I was just curious what the difference in timing would be on an 87 vs 93 octane tune. Everyone in here acts like they are experts and shit LOL. I don't have any data on 87 vs 93, but I can show the difference in timing maps for 93 vs racegas.

I'm relaying my experience with it, and I can tell you that the A4 I had did fine with 87 octane and a very light foot. Guaranteed if I had been heavy on the gas and hit the 19 psi it spikes to it would have started detonating. When we evacuated we were running on fumes and a gas station we pulled into in College Station only had 87 so we took what we could get and it did fine the whole tank.

What race gas do you have data on? I'd be interested in seeing what you have.

mikesrex

07-07-2010, 12:30 PM

I'm relaying my experience with it, and I can tell you that the A4 I had did fine with 87 octane and a very light foot. Guaranteed if I had been heavy on the gas and hit the 19 psi it spikes to it would have started detonating. When we evacuated we were running on fumes and a gas station we pulled into in College Station only had 87 so we took what we could get and it did fine the whole tank.

What race gas do you have data on? I'd be interested in seeing what you have.

from what I have, the ignition maps on racegas (tracktek 111 or 112 can't remember the exact number) were about the same or just a tad bit more timing than on 93. The boost maps are considerably more timing and a tad bit more fuel.

Red Alert

07-07-2010, 12:37 PM

if you have suspicion about a particular pump, I think there is a government entity that may test it for you. I'm not totally sure on this, as this is what one of my professors told me a while back. It's definitely something worth looking into.

Also, I was told they do two tests and average the results. One test uses a GC (can't remember what kind of detector, FID or MS) and determines octane rating with experimental results. The other runs the fuel through an engine and determines the knock threshold with the engine.

I take daily samples to be sent to our lab to determine the octane our unit is sending to tank. I take one tagged motor octane(MON) and research octane(RON) and like you said they are tested different with the motor octane being put under more stress and comes out to being a lower number than the research octane and the average between the two is what you see at the pump.

mikesrex

07-07-2010, 01:18 PM

I'm wondering if I can use any of my stuff in the lab to determine the experimental octane level.

and ROFL at Eric flexing his mod powers by locking a thread that had nobody else posting in!

GODZILLA

07-07-2010, 04:24 PM

I'm wondering if I can use any of my stuff in the lab to determine the experimental octane level.

and ROFL at Eric flexing his mod powers by locking a thread that had nobody else posting in!

:rotfl: i wasnt flexing my mod powers i just thought it was time to move on

mikesrex

07-07-2010, 04:31 PM

:rotfl: i wasnt flexing my mod powers i just thought it was time to move on

as a mod, you will eventually figure out that every now and then it's best to let a thread die of natural causes:rotfl:

FB_RX-Seven

07-07-2010, 06:07 PM

they had a special on the news in houston a while back where they tested octane ratings at different gas stations around houston because alot of ppl were complaining about it. they found out that alot of the gas stations were putting a mixture of the lower 87 octane in the premium tanks because it was cheaper for them and thinking people wouldnt notice the difference. alot of stations got busted. a few of them werent even holding anything over the base 87 octane in the premium tanks. pretty shady. and as far at timing change with different octane goes i tuned my new engine in my boat to run on 93 octane. one of my friends filled it up the other day for me and put 87 octane and it had detonation bad and ran like damnit when i tried to plane out. i had to turn the dizzy back some to make it stop till i got new gas

davidf

07-08-2010, 03:05 PM

Picked up the GTS yesterday in Dallas. Car is immaculate w/67000 miles. I almost want to keep it for myself, LOL. Note: GTS's have zero torque compared to the standard GT but revs like no tomorrow. Nonetheless daughter will be a happy camper. Thank's for everyones input. We'll test the waters on fuel mixture and see where the cars happiest at. Oh well, it's only money....................my money!:(