90 octane non-ethanol vs. 110 octane leaded

9192champs

Member
Supporting Member
I have two types of non-ethanol gas available near me:

1) 90 octane non-ethanol
2) 110 octane leaded race fuel

Which would be better to use in my '07 K9?

I have been using the 90 octane and adding a little octane booster, but I was wondering if the 110 leaded race fuel would be ok. (I keep some on-hand for my '69 Corvette anyways.) Just wasn't sure about running leaded fuel in a comparatively much newer bike...


Thanks,
Paul
 

knothead

RIGID4LIFE
Supporting Member
I wouldnt advise it....you going to have alot of carbon deposit because of the leaded fuel which is going to led to alot of top end problems from the carbon deposits....many more side effects to go with it also...it will most likely eat the liner out of your gas tank too....if it was a built race engine it be fine to run it because of the wide open throttle and constant engine coming apart to rebuild it ever so many runs....but the everyday driver it will cause more damage than good.....plus leaded fuel absorbs moisture alot quicker so there would be another problem from it setting for weeks at a time.....just to many cons and not enough pros to use it
 

Sven

Well-Known Member
90 Pro: All around gas without the high maintenance.
Con: Not a good choice for racing purposes.

110 Pro: Higher anti-knock number for high compression engines/turbo/superchargers, etc.
Con: High maintenance is to drain the tank or the octane evaps and the vapor has these $$$ signs out of the gas cap vent.

90 Pro: The 02 is going to live in this environment.
Con: No con here but in compliance.

110 Pro: Who cares, pull it out. This is for racing purposes only so who needs an 02 when a flash feeds the gas/ign.
Con: Solid-liquid-gas goes solid again, and that says an even shorter window for the 02 to survive in.

90 Pro: The cat remember is going to clog with any other octane over 100 [if lead is added], so with 90 no.
Con: No con here but in another chemical compliance running unleaded.

110 Pro: After 100 say, you need lead to up the knock&pre-ign we go higher compression.
Con: This will take out the cat, meaning, the carbon will fill up the honeycomb design and you bog on WOT; no power.

90 Pro: Today's metallurgy has the seat material a little more stable for unleaded.
Con: You can't run unleaded in the classic and antique engines.

110 Pro: You can run leaded in old engines.
Con: Gotta drain and it's back in the steel can or the evap chumps your change.
 
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Mickmorris

mick
Supporting Member
I have been using the 90 ethnol-free from Wawa. Seems to be working just fine. Every now and again depending on where I am when I need fuel I will put in the 93 octane if no ethanol -free is available.
 

heybaylor

Active Member
tiger in your tank ?? octane aint power, it is the burn rate.
lower octane higher burn rate makes more push in lower compression engines.( burns faster, piston at top of stroke)
higher octane lower burn rate makes less power in lower compression engines. ( burns slower, chases piston down the stroke)

lower octane in high compression engine will pre ignite causing "piston damage ( spark knock)
higher octane in high compression engine will burn slower allowing use of higher compression to make more power
 

Sven

Well-Known Member
... it is the burn rate.
Reading comprehension is questionable, but how I understand it is the kinetic wants to light off the gas with a higher compression so the octane is more a pressure valve, a fuse with some time on it. With the race gas, the burn rate is faster so it needs a higher octane to keep it from lighting off under heavy load-low rpm = Knock/Pre-ign... ask me how I know?

lower octane higher burn rate makes more push in lower compression engines.( burns faster, piston at top of stroke)
higher octane lower burn rate makes less power in lower compression engines. ( burns slower, chases piston down the stroke)
From VP Q&A: "As with Q16, so far I have left the timing alone. Run what timing you had with regular methanol. Here’s my thought. The hydrocarbons in the fuel help vaporization, so you SHOULD be able to retard the timing a bit. But the fuel also contains nitroparrifins, which generally need the timing advanced to start the burn earlier. Since they are both in the fuel, they almost seem to cancel each other out, hence the timing will stay the same. Weird huh?"

lower octane in high compression engine will pre ignite causing "piston damage ( spark knock)
Correct. Here is the ask me how I know; was going uphill in a lower rpm with regular gas [87], heard the multi-knock before I had a chance to unload. Pulled a plug and where they have a V in the center of the piston dome for the lathe, the scope saw the moon crater as the V is no longer, but has tiny welded aluminum balls around the crater, and gray dots vaporized into the porcelain nose of the spark plug. So for the plug to catch that dot that close, it would seem knock happens there, or a millisecond before TDC.

So the secret to get away with running the lowest octane is to not load the engine at lower rpms. That one knock is fast enough to melt aluminum... remember.

higher octane in high compression engine will burn slower allowing use of higher compression to make more power
Again, not the fastest molecule in the gas, but my understanding is that you need a higher octane, because you want the mix to wait, because it burns faster.

I'm going to explain the current king of the drag strip or don't show up without kind of high performance bike. They found out that running 87 at the strip is better than race gas. So my guess is, you take two of the same bike [all stock] and one runs race, the other runs regular.
The next way to think is see if more air(?) is not it for more HP, but the same 14.7 psi gulp when the intake valve closes. So with the same fuel-to-air is the same, it's a speed(!)event, meaning, who did what faster? Therefore, you can see that the lower octane fired off sooner = Faster is whom? I'll backup the theory about a speed event v. more. Same intake port length and cc is the equal volume. One port has a slight C-curve to it and the other is l-straight. Who drags more around a corner and who is faster if the curve is straight. The friction is who moves faster? Get it, it's not a more-theory, but a 'speed-event' = More HP.

Make sense seeing the difference between saying More v. A Speed Event(s) =Gains 'more' HP?
a. I smoothed the port so the friction makes it flow faster is the same gulp into the chamber.
b. I run a faster fire off to speed up the event is less octane used, same volume of gas pulled from said jet holes.
c. I see said the Alpha number used for BACKUP = 14.7 Pee Yes I am sticking with this theory and you can have your reality... Good luck chasing a trophy... I'd be taking that from you is my reality.

Signed,
NOLTT (Nasty Over Lapper Trophy Taker) I wish. YOu can't take the line out of me or the race face. Make sense? My interpreter will be here if the hand went over the head.
 

TreeGuru

Member
Your daily ride, Todays V-Twin is designed to use Premium gas with 91 to 93 Octane. If you take a trip and stop for gas in a small town where they do have premium gas take a small bottle of additive because the locals don't buy it and it sets in the underground tanks too long. The 87 to 89 Octane and the 100 to 110 will give your daily ride problems.
 

john sachs

Well-Known Member
Your daily ride, Todays V-Twin is designed to use Premium gas with 91 to 93 Octane. If you take a trip and stop for gas in a small town where they do have premium gas take a small bottle of additive because the locals don't buy it and it sets in the underground tanks too long. The 87 to 89 Octane and the 100 to 110 will give your daily ride problems.
All good, except I WOULD NOT recommend additive. If your engine needs additive, or anything more than 93 octane , FIX THE PROBLEM.
John
 

heybaylor

Active Member
quote From Sven


"I'm going to explain the current king of the drag strip or don't show up without kind of high performance bike. They found out that running 87 at the strip is better than race gas. So my guess is, you take two of the same bike [all stock] and one runs race, the other runs regular.
The next way to think is see if more air(?) is not it for more HP, but the same 14.7 psi gulp when the intake valve closes. So with the same fuel-to-air is the same, it's a speed(!)event, meaning, who did what faster? Therefore, you can see that the lower octane fired off sooner = Faster is whom? I'll backup the theory about a speed event v. more. Same intake port length and cc is the equal volume. One port has a slight C-curve to it and the other is l-straight. Who drags more around a corner and who is faster if the curve is straight. The friction is who moves faster? Get it, it's not a more-theory, but a 'speed-event' = More HP."

Used to race two-strokes, ran 87 octane, most two stokes have a very small squish-band that makes compression.
short time frame and relative low "real compression", 87 worked great , "race fuel" was not as good .
to each his own, enjoyed the thread , good folks here ) even Sven (I actually under stand his posts ( most of the time) :cool:
 

Sven

Well-Known Member
I WOULD NOT recommend additive.
I volunteer my time to an old friend who still races. We gather up his track bikes (his, his son, a friend's bike) that I get ready and maintain. We gas up the race cans with the highest test pump gas, then tells me to add whatever ratio to those 5 gallon race cans. Don't recall the brand, but there are a few bottles of it in the race truck that come with us as extras.

Getting back to my point, his son's ride is some old kawi 650 twin. Built, not stock. It's been there before I showed up hanging out. His personal track bike is a 600 kawi 4cyl. That too is warmed over. Then he decides to start up all his old race bikes. I have each one on video somewhere.

Where do I stand first before he fires them off? Phone aimed right at the exhaust pipe. I kid you not and the vids prove it, I did not see one bellow of smoke. They lived on pure race gas. Injected, remember. They haven't been started since their last race. We are talking in the mid 1990's. With that said, any bike that is lit up before it's loaded in the truck, I'm watching for ring/piston damage via puff.

One puff, leaky guide seals or it's worn. Puffs keep coming, I'm looking at ring fatigue. excess gap. A piston skirt would slap and tap if the material was scored and galled the aluminum off, but they just keep on rolling up the ramp.

If your engine needs additive, or anything more than 93 octane , FIX THE PROBLEM.
John
And you know that shit is going to do jack shit [engine wise] in my opinion. Your engine will never see that kind of abuse, let alone they keep running and have yet to be torn down. Those are injected bikes and that shit sits in the rails, be they plastic or steel. No orings being eaten away are the leaks. No injectors leaking due to chemical etching and sitting with what could not come out.

Again, I'm not the sharpest corner of the page, but a retired engineer neighbor moved, left me with two tech books. One title kind of reads, 'thermodynamic principals' and I started on page one and tried to keep up with the abstract. The math formulas were over my head. But we are taking about zero problems needing fixing, when Heat [kicks in] v. Knock.

I rest my molecule... still there on the piston skirt.

Signed,
Fuel me, Fuel you
 

Th3InfamousI

Admin
Staff member
Supporting Vendor
Supporting Member
I just went through some rural areas on 2400 mile trip and I don't know why I noticed as I have never had any issues running 87 all the way to 93. Whatever was at the pump, some rural areas in this country 87 is it and there isn't a choice and your 100 miles to the next stop or less but who wants to push the bike? So you take what's available. Lots of people look at me funny when I say I'll run 87, but I would be surprised if you notice any difference. I don't do it unless I have to but it hasn't hurt me yet.

Anyways, bike ran fine with any gas, no knocking but I just noticed it seemed to be a bit smoother running 90/91 instead of either 87 or 93.

So I guess my point is dont sweat it too much what pump grade you put in. 110 is too high for a standard street motor

Sent from my Pixel 3a using Tapatalk
 
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knothead

RIGID4LIFE
Supporting Member
I just went through some rural areas on 2400 mile trip and I don't know why I noticed as I have never had any issues running 87 all the way to 93. Whatever was at the pump, some rural areas in this country 87 is it and there isn't a choice and your 100 miles to the next stop or less but who wants to push the bike? So you take what's available. Lots of people look at me funny when I say I'll run 87, but I would be surprised if you notice any difference. I don't do it unless I have to but it hasn't hurt me yet.

Anyways, bike ran fine with any gas, no knocking but I just noticed it seemed to be a bit smoother running 90/91 instead of either 87 or 93.

So I guess my point is dont sweat it too much what pump grade you put in. 110 is too high for a standard street motor

Sent from my Pixel 3a using Tapatalk
I run it to and cant tell a difference....i mean if i got options ofcourse i buy something different but im like you i havent had any issue running 87
 

TreeGuru

Member
Reference my statement above I was just saying our bikes of today are designed for the 91 to 93 Octane and the lower Octane fuel can be a problem. You may not even hear what's going on in your engine. Some people call it Knock, pinging, or detonation. Detonation generally is caused by fuel with a low octane rating. It's the tendency for the fuel to pre-ignite or auto-ignite in an engine's combustion chamber. This early before the spark fires ignition of fuel creates a shock wave throughout the cylinder as the burning and expanding fuel-air mixture collides with the piston that is still traveling towards top dead center. The resulting knock or ping is the sound of the pistons slamming against the cylinder walls. It's like causing damage to your engine from the inside out to other problems. I realize on a trip we got to take what's available just keep off the throttle till you can get a better grade of gas. The consistent use of the lower octane gas doesn't cause acute problems but will develop chronic problems. Problems like engine failure from abrasion, the piston head slowly eroded. mechanical damage, heightened impact cause parts to fracture. Also, effecting piston rings, exhaust or intake valves. Overheating is another serious issue.
It's like a domino effect of problems that lead to more problems.
 
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