91 or 87 octane?

87.......

Mac

 

I ditched premium a long time ago. It makes no difference, hell I noticed better MPG with 87 in my FZ1; maybe it's all in my head as I never actually took a chart to notice. No knock, no ping and my bike runs higher compression and is 200ccs up on the VFR.

However, I will note that many sources say that premium gas contains more detergents to clean deposits that can cause detonation and such. Though, unless your bike requires it, I would only think premiums resistance to burning would cause a more incomplete burn per power stroke and may result in more deposits than the increased detergents can compensate for. Besides, I'd rather have more energy-having fuel than detergents.

 

In her '92 the 93 oct give a huge boost in mpg. we tried 91, 89 & 87. the 93 just made it a better bike for mpg and maginal power. It is jetted, two brothers pipe and had a UNI filter if that matters

 

hi,
you will be surprised discovering that, usually, there 's only a refinery that provides gasoline/diesel for ALL BRANCHES. Also, only one type of gasoline (as regards octane ).
So, be sure that all our impressions about 87, 91 etc... are only impressions. The only difference, as someone said, is a clean air filter and good spark plugs.And the different color-additive they add to vary the gasoline color from a branch to another...
Ciao and Lamps !
Carmine

 

The lowest Octane in Australia is Regular @ 91 RON then Premium @ 95 RON then Ultra @ 98 RON.

I'm sure I'm going to get flamed here, but my VFR pulls from 3000rpm alot easier (low end torque) on 98 RON. But shits itself on 91?. I was of the understanding that the 6th gen has electronic advance/retard?. If 98 RON can withstand more compression without pre ignition, wouldn't that mean the piston is squishing the fuel into a smaller space (ie the piston is rising higher in the bore before the sparkplug fires). Same amount of fuel, packed into a smaller space equals a bigger bang?, therefore more HP?.





















r

 

Not sure of the cross reference to Aussies, Europe, etc. for RON, I think its 4 or 5 points higher than ours.

North America uses R+M/2. Octane is measured in 2 laboratory engines one is the Research Octane Number and the second is the Motor Octane Number, the two are averaged.

I used to witness gasoline analysis sometimes for our customers back in the late 80s.

As I recall, they blend the gasoline with Iso-octane (100 octane) and change between the different ratios of sample and sample/iso-octane bowls plotting on a graph the readings from the knock meter as they advance the timing. The two engines run at different RPMs only around 600 & 900. I'll never forget the noise....put-put-put-put-put-put for hours ah!!!!

I do remember asking the technician if high octane gas is better for your engine, he said "if it doesn't ping, it's a waste of money. But the oil companies don't want you to know."

 

Compression remains the same no matter what octane you're running. If your gas is exploding before the spark ignites and it does this regularly and is uncompensated for your motor will be destroyed in short order.

If the engines knock sensor is detecting some bad things happening it will retard the ignition to compensate; in this situation, where lower octane is not sufficient to prevent knock/ping/etc providing the engine with a higher octane WILL increase performance.

RON number is always higher than motor octane, in the US the label on the pump is an average of RON AND MON.

 

I agree with the couple of posts above- compression is a fixed number barring something like massive carbon deposits from major neglect on the pistons that effectively reduce combustion chamber volume- this would have the same effect as an increase in compression ratio.

Ignition advance is an important part of making horsepower. The sooner the ecm can light the fire (to a point) the more pressure is developed as the piston passes TDC and the piston is pushed down with more force developing more power. The downside is excessive ignition advance leads to detonation- this is why knock sensors exist (to detect detonation) and then the ECM can retard the ignition advance to make it stop.

Now knowing this you might be saying to yourself "well if I run premium, it has a higher resistance to detonation so the ECM can run at full advance and make the most power possible" This is good in theory, but in real application the ignition advance curves are set in the ECM to go hand in hand with the fuel mapping based on multiple sensors and just having a higher octane fuel isn't going to coax the ECM to run more ignition advance than it was designed to have. If you have ever heard about people putting a "chip" in their car or truck, usually it is little more than a piggyback ecm that increases ignition advance and possibly richens the fuel mixture slightly. I think Power Commanders are quite similar though I have no real experience with one. With cars there is usually a small increase in horsepower and torque at the cost of having to run premium to keep it from pinging.

 

i'm still not sure what would be better for my '92 vfr750f w/37k miles... 87 or 91?

 

ound::laugh::rofl:

Finally I am seeing many who agree with me.

Simple answer. Burn whatever the owner's manuual said. On the 06, the manual says to burn 87. That is what I burn in my 06. I bought this thing still in the crate. I have turned over 75,000km just the other day (you do the math) other than a couple weeks of higher grade when i first bought it, it has been 87 all the way. No problems...natta, none....zero...zilch.

Capisch? Anything higher that 87 is money out of your pocket that you can be spending on add-on, and into the pockets of those bastardly rich oild companie

 

does anyone have the 90-93 vfr750 manual, wanted to know whats the recommended octane and oil to use?

 

Just to add a little info, having been a tanker driver in my other life. When I'm filling my tanks, all the fuel is the same no matter what the company is. It goes into the cells by octane, but the one difference is there's a clicking sound as the right amount of additives are added to name brand fuels, no name brands no clicks no additives.
The only reason to use a higher octane is if the gas is older and has lost some of the octane spec's(highly unlikely).

 

Ive only had my bike a few weeks and of course in the beginning I thought I should use 91. So for the first 700 miles or so I used 91, then I switched to 89 for a couple tanks, the last 4 or 5 tanks have been 87 with no change. I didn't start tracking mileage until I hit about 1200 on the odometer so I can't comment on a change in mileage, plus the mileage was low in the beginning while I was breaking it in. ANyway, 87 seems to be the way to go.

 

as long as you don't try to run diesel....(yes, someone I rode with pulled up to the wrong pump on her RC51...)

89 is the cheapest around the midewest (corn ethanol) doesn't make a bit of difference between 87, 89, 91 & 93.

 

I would be cautious here. I know for sure that Ford does not recommend using any fuel with Ethanol in their Tauruses. They stipulate that in their manuals and go so far as to say their warranty may be voided for using it. But then again in my Jimmy, there is no such mention so I don't care.

Which I guess brings me back to my forst response. Do what your manual says.

BTW. My usual gas pump ran out of 87 the other day and were selling 93 for the same price. SO that is what I used. I could detect absolutely no difference. But normally 93 is about 10 cents per liter more expensive than 87. That's about 40 cents a gallon. for you fine folk down soth.

 

i use gas and add slick50 to the gas about 2 onces.....

 

At 40 mpg and $17 to $20 a fill, shouldn't we all be using the highest octane, cleanest burning fuel available? I'm just sayin'.....ah, nevermind...too many insights that make sense to me otherwise. I'm gonna throw slag grade in next ...

 

higher octane doesn't equate to cleaner burning

 

So I've been learning! :thumbsup:

 

Name brands give you cleaner burns(with the additives). Off brands may or may not have additives, you'll never know.......