octane question

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sathu

New Member
Apr 20, 2005
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The user man recommended 91 octane for the car but I run on 89 from the station. When 91 was at 2$ a gal I use 91 and it does make a different :). It's more responsive to the pedal. The fuel gauge recommend unlead so i guess 87 if good for older car with less mod.
 
shaeff

shaeff

Kurt is FTMFW x2!!!!
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Super Moderator
Mar 30, 2005
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what does unleaded fuel have to do with this? all fuel at gas pumps in north america is unleaded, as far as i know. leaded/unleaded fuel has nothing to do with octane.

-shaeff
 
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chevyeater

wastegate hose is pulled
Mar 30, 2005
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Long Island, NY
There is alot of published information on gasoline and octane ratings. I know this because I did a college paper on gasoline back in the day. Some of it is really worth reading if you are interested in your car and improving its performance.

Here is a good internet source:
http://www.faqs.org/faqs/autos/gasoline-faq/

If your car feels faster on premium, you are doing damage running on regular. Knock sensors can only react to detonation, not prevent it.

I just picked up another load of 117 MON for my mk3. :)
 

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bluemax

The Family Man
Mar 30, 2005
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Orange County, CA
I read somewhere adding leaded fuel into unleaded fuel will raise the octane. But will eventually damage the catalyic converter. Lead raises the octane rating. On the old cars that don't have catalytic converters, you can mix unleaded with leaded to get higher octane rated fuel. But I haven't seen leaded fuel since I started to drive.
 
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rolman

New Member
Apr 13, 2005
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Do a google search on toluene. To increase octane rating for high horepower cars, supposedly this is a very inexpensive and reliable way to increase octane ratings and a lot of racers use it. It costs about 9 bucks a gallon at paint shops, home depot. If i EVER get my Lexus AFM/550 injectors/AFPR installed i may try it.
If i find the link i have at home i will post it, was very good reading.
 
SupraMario

SupraMario

I think it was the google
Mar 30, 2005
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rolman said:
Do a google search on toluene. To increase octane rating for high horepower cars, supposedly this is a very inexpensive and reliable way to increase octane ratings and a lot of racers use it. It costs about 9 bucks a gallon at paint shops, home depot. If i EVER get my Lexus AFM/550 injectors/AFPR installed i may try it.
If i find the link i have at home i will post it, was very good reading.
Click to expand...

yes you can get toluene at almost any art/craft store.
 
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chevyeater

wastegate hose is pulled
Mar 30, 2005
530
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Long Island, NY
Jesus, $9 a gallon for tolulene? C16 is only $10 a gallon, has higher octane and can be run uncut without damaging the fuel system. Leaded, yes. Kills O2 sensors, yes but not really fast. A tank here and there isn't a big deal if you replace the O2 sensor as regular maintenance like you should. Don't bother with lead if you still have a cat on the car though or aren't going to need 117 MON fuel (hint- over 30 psi with good timing).
 
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IJ.

Grumpy Old Man
Mar 30, 2005
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I come from a land down under
Chev: Good point Brian!

All of this octane is useless if you don't really need it as even the best fuel isn't going to "add power".

Where Hi Octane fuels come into their own is resistance to detonation so unless you're running a bunch of Compression or Boost or both it's just costing you $$$
 
esc

esc

WUM WUM!
Mar 30, 2005
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Winston, NC
lol, my prelude says premium only...and yet I always seem to get rod knock in every damn motor.

I can actually tell a difference between 87 and and 93 in our Explorer. Back when I had to drive it daily (Supra was in the shop and the Prelude's original motor spun a bearing) I always ran 93 in it. It ran great, had good acceleration and what-not. But now that we drive it once in a blue moon (like if something needs to be hauled) we only put 87 in it and I can tell a huge difference in the performance.

Never tried to run 87 in anything else I've owned tho
 
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chevyeater

wastegate hose is pulled
Mar 30, 2005
530
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Long Island, NY
Sadly, Toyota thinks people actually read thier owners manual so they shouldn't need to put it on the gas guage. 91 PON is recomended for completely stock vehicles.

If performance improves when using higher octane fuel, ignition timing is bieng retarded due to knock sensor input when using the lower octane. That means that the engine is knocking and damage is bieng done.

I'm beginning to understand why people have head gasket problems with the 7MGTE. 87 octane.
 
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thesupraman

Smirker
May 15, 2005
129
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Frenchtown, NJ
chevyeater said:
Sadly, Toyota thinks people actually read thier owners manual so they shouldn't need to put it on the gas guage. 91 PON is recomended for completely stock vehicles.

If performance improves when using higher octane fuel, ignition timing is bieng retarded due to knock sensor input when using the lower octane. That means that the engine is knocking and damage is bieng done.

I'm beginning to understand why people have head gasket problems with the 7MGTE. 87 octane.
Click to expand...
Oh...didn't know that. My car was not equipped with an owners manual when I got it (weird huh? :icon_roll ). Just assumed it would be on the gauge. Sorry for the mis-info....
 
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