93 octane on a 87?

[trendyexr]

Ok, I got my manual to my 1990 exr which is american ex. It has a F22A4 130HP. According to my manual for this model and year, it says it is designed to operate on gasoline with 91 octane rating. I dont see why the other ex's would be on 87 and my a4 ex requires 91. Am I paying more for premium gas for nothing? I personally feel that the car runs and performs better on 91 gas. I have had a FULL tune up very recently (timing belt, plugs, wires, full distributor, many seals, etc..) and the car runs awesome.

Maybe the lx's only need 87 because they have a more retarded timing?

I attached a pic of my manual.

[Cactus]

retarded?

Are you calling my LX retarded? j/k

http://www.streettuners.com/curve/en...cs.html#accord
This link has info about the c/r and other stuff for the stock cb7 engines. Another site,
http://auto.consumerguide.com/auto/u...ex.cfm/id/2047
reports the difference between the a1 and a4 is the exhaust manifold. I don't know if that is the only difference or not, but if it is according the the first link the c/r is the same between the a1 and a4 as well as displacement. If that exhaust manifold is really the only difference, then there should be no difference between the fuel requirements for the two engines.

I can't say why Honda specified 91 for the 90 EX-R's. Perhaps they hadn't fully tested the fuel requirements of the a4 engine and weren't sure how if it would do ok on 86 octane, or perhaps there is something else internal to the engine that requires 91 octane. Anyone else (esp. 90-91 a1, a4, a6's) wanna share what their manuals say?

Until you find out different for sure, though trendyexr, I would just stick with what the manual recommends knowing 91 octane for sure won't cause any problems.

[HondaFan81]

Research Octane Number (RON) is one of two methods of measuring octane on gasoline. Don't you take the RON and the 2nd method (I forget what it's called) and take the average of these two to find the AVG. Octane rating which is what most gas stations here in the U.S. use?

sorry if I've confused the info, but it's something like that.

Here it is:

One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm. The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm. If, for example, a gasoline has an RON of 98 and a MON of 90, then the posted octane number would be the average of the two values or 94.

Source: http://chemistry.about.com/cs/howthi...a070401a_2.htm

[FishyMan]

^^ exactly

(R + M) / 2

ron and mon, ron being regular and mon being harshed condition like for racing and stuff..

[mojo]

OK, I stand corrected. Even though i don't believe any stock F22Ax motor should need anything different than 87, I'd go with whatever your manual says. If it says 86, put 87 in it, if it says 91, put 91 in it. If you've built your motor up, you know what it takes and what it doesn't.

RTFM

[HondaFan81]

Mojo, what do you speak of? We just corrected him, read back a couple threads and check out the info that was obtained.

Also, for you Canadians is the "posted octane number" R+M/2 ?? Or is it just RON or Research Octane Number?

I'm wondering as to why the manual only stated it from one angle...maybe Canada only uses RON for octance rating....?

[trendyexr]

It would be cool if an American Accord owner could look into their manual and see what it says :P. I'm curious to hear what it states in the U.S. but I doubt it's any different. To my understanding so far, my car should run on 91 octane fuel. Why would they state a number in the manual that is totally useless by having to add 2 together and divide. My theory is that, the 1990 EX (for me, exr), needs 91 octane to perform properly because of tuning of the engine. It could be, that in the next couple of years they changed this to 87 octane since it costs less on gas. I really would love to run the cheap stuff on my car, but I just dont feel it runs right.

Aaron

[TMaxxTim]

Guyes...I'm not trying to be a basher or a hater, but we are driving 11-14 year old 4 cylinder cars. They are not high performace engines...the fuel is not going to make a huge difference. And at the age our cars are at, its not going to make a difference for the "life" of the car. These 4cyl engines are not high performance racing engines...fuel does not make them run so much faster or so much better. Its just not going to do much of anything at all...maybe on a car that has its timing electronically controlled, but my guess is most cars have probably have had the timing changed a little bit on our cars.

My point is that I see absolutely no reason to use anything higher than the lowest grade on these cars....thats just my opinion.

[FishyMan]

as far as i think..

an octane rating is just how resistant the gas is to knocking and ping and what not. use what is recommended.. if u notice ping get a tune up or put the next high grade. cars are designed and given an octane rating so that they wont' ping, and yes these cars aren't performance engines where pressure/ temp is that great to make a deal..

and premium doesn't mean it cleans the car better than the low grades.. in fact according to gov regulations (epa?) they said that all grades need to have cleanning additives in them or something.. anyhow..


4 bangers are 4 bangers.

[xplode]

Originally posted by TMaxxTim
Guyes...I'm not trying to be a basher or a hater, but we are driving 11-14 year old 4 cylinder cars. They are not high performace engines...the fuel is not going to make a huge difference. And at the age our cars are at, its not going to make a difference for the "life" of the car. These 4cyl engines are not high performance racing engines...fuel does not make them run so much faster or so much better. Its just not going to do much of anything at all...maybe on a car that has its timing electronically controlled, but my guess is most cars have probably have had the timing changed a little bit on our cars.

My point is that I see absolutely no reason to use anything higher than the lowest grade on these cars....thats just my opinion.

no one ever said we wanted a performance gain.. clearly stated we wanted to try the new fuel for cleaning purposes but you read that rite i guess..

[Alex EX]

i have the f20a dohc motor and i use the 89 since it has a bit more compression. i only use BP, shell, chevron or amoco gas though =)