sonyman

If you notice any difference in power running 87, and I mean even the smallest difference, you are getting detonation and the engine is retarding timing. You don't have to thrash the car for this to happen either.

jcrome04

I totally agree. I have treated all my vehicles like show cars, and never once has one broken down on me. I mean yeah I've done a timing belt here and there a couple clutches, etc... but I have NEVER ONCE been broken down on the side of the road and needed to call for a tow.

Past Cars In Order of Ownership:
1995 Ford Escort LX (coupe)
1993 Saturn SC2
1991 Lexus LS400
1989 toyota Corolla GT-S
1997 Lexus LS400 Coach Edition (current)

*notice a trend in years?? lol

LS400_Fan

I hope everyone realizes that even at low speed, low rpm, low laod, that timing is rather HIGH and air/fuel ratio is rather LEAN to create efficient burn rates and better gas mileage.

If you insert an octane that can't handle that environment, you will not be happy with how your engine runs.

19psi

while you are completely correct in most of your statement, octane doesn't really matter in a low load situation. i can drive along and monitor knock with a datalogging program i have on my laptop and there is no knock under low load situations. only at high rpm, heavy load would pre ignition become a concern.

jfelbab

My understanding of high compression engine design is that it has needs other than just higher octane. That's why most gasoline manufacturers premium blends have more detergents in them to keep the valves and combustion chamber clean. IMO, while you could probably burn cut rate regular grade gas, you may ultimately wind up with a build-up of carbon deposits or injector clogging by not using fuel with adequate cleaning additives.

Shell, for example, claims they use twice the EPA regulated amount of cleaning agents in their Regular and Plus grades and five times as much in their V-Power premium grade.

Read about the TOP TIER certification here:
http://toptiergas.com/

Surprisingly, not all of the more prominent suppliers meet the TOP TIER certification. Exxon/Mobile and BP/Amoco/ARCO readily stand out in their absence.

See if you are buying from a TOP TIER supplier here:
http://toptiergas.com/retailers.html

19psi

there is something to what you said, but most carbon deposits develop from people taking short trips and not beating on the engine enough. "taking it easy" is not really beneficial to an engine.
that's a whole different topic though...

LS400_Fan

That's incorrect, even if your car is fine in this situation it doens't mean that every car will be. I used to tune high horsepower motors with stand alone EMS' and we've always try to create a lot of timing and a/f ratio in low load/cruising rpm situations to get them to pass emissions and get good gas mileage.

It wasn't very hard to get the timing too high or a/f too lean for it to ping and not only that, but the transition of the fuel/timing map from that low load / high timing situation to even a medium load situation can very easily lead to knock.

19psi

well i don't doubt that is possible. i can do the same thing with my ems on my wrx. however, i let the low load maps stay close to stock to avoid such situations. i don't have to pass emissions and fuel mileage is close to stock.
in a completely stock car like an LS, it's not going to happen though. these things are not fine tuned nor are they trying to make as much hp as possible on teh stock maps.
we're talking about two different goals here. in my post i'm talking about stock cars with normal driving conditions. obviously in a high performance car under different performance maps, we have to play a different game with a/f targets, timing and of course octane will play a part in that.
i don't want to turn this into a debate, since we are comparing apples to watermelons. you are right in what you are talking about in a performance application, just as i'm right in saying that a stock LS won't knock while cruisng on 87.

hobojoe

Agreed buttt its funny i work for a residential elevator company so a huge amount of houses we work in are rich wealthy people and yet you would be amazed at how much the complain about prices of things its kinda funny, yet hmmm there the ones with a brand new lexus ls460L and a aston martin sitting in there garage in there brand new 5 million dollar home.....

DaveGS4

iTrader: (2)

I have deleted several posts that were off topic and insulting to other members. Stuff like this serves no purpose and damages our sense of community.

I'd ask this thread get back on topic and away from personal commentary or it will be closed and folks who continue to insult will have their forum accounts suspended.

turbosix

a bottle of octane booster is going to increase 87 to 87.4 octane. not to mention its going to cost you atleast $3

18 gallons with a 20 cent price difference is $3.60

big deal.

jfelbab

...and you still aren't getting the higher levels of cleaning agents that are present in premium fuel.

19psi

what was said above about octane booster is true. you'd have to buy and dump in about 10 bttles in a 3/4 tank to make it 93 octane. don't waste the money.

mebush

Just some food for thought.......I have a '91 LS with 253,000 miles on it. I have been running 87 or 89 in it the whole time I have owned it which is about 30,000 miles. The previous owner, a friend of mine, bought the car with 150,000 miles on it and ran 87 or 89 in it all the time. I still get 24 mpg on the highway and have never had any preignition problems even driving over mountain passes at 12,000 feet. Point is, when the car was brand spanking show room new and your foot was in the radiator octane probably was something to consider. A car with 100,000 or more miles on it even in pristine condition likely doesn't have the same compression it did new. If your just driving the car (not like your in the Daytona 500) the lower octane is probably just fine.

gdave

WOW i knew most of this to be true but WOW i use 87 octane being on the NE coast im 18, insurance threw the roof, and gas being $3.00 just for regular its a struggle when you have lots of bills, but i might switch with this new knowledge