Yet another question about high comp, and octane. We had a pretty god thread about why you can't run pump gas with anything above 12:1 compression pistons. Know I am wondering if it would be better to run a little octane boost additive with the pump fuel, if you are using a 12:1 piston? Any advantages / disadvantages? If so what recommendations as far as brands and how much.

Thanks
Bingenut

if you don't have any knock , you don't have any problem.

so in that case , additives aren't worth doing

.......mixxer

Well run pump gas and see if it pings or knocks. If it doesn't i would go without it. Instead of octain boost i would maybe mix a little race gas with it.

the problem is that if i were going to bother with additives or mixing, i would just go to race fuel and get the massive benefits of true high compression.

walking the fence is no place to be , jump to one side or the other :D

....mixxer

My only trouble with using race gas, is that on the weekends (and in the winter) that I don't race, I go trail riding. Race gas is not available on the trails, but pump gas is. I could always carry a small jug of octane boost in my back pack if I had to. So Mixxer, I will have to remain on the fence until I can afford 2 quads ( since I started racing again, I can't afford one :D ) Now my son is moving up in classes and needs a bigger bike also. (I think I just got another headache))

sorry, i didn't think about the trail ride thing!

what we have done (yes, it's a pain) is do what we call "drop cans"

we drive the truck(s) to th midway points where trails cross roads and hide some cans with a camo blanket a little ways off trail so we can re-fuel at the halfway points

bummer is that you've got to go back and pick them up after the ride

the ONLY true serious high octane additive i have ever found is klotz hi-trate.
but the price ends up the same as buying race fuel
the advantage would be portability into race gas barren land!

........mixxer

I'm soon to be in the same boat. Alot of my rides take me into the mountains but luckily I have friends in that area so I will be keepin 5 gallons at their place. The other solution is running straight race gas and when as soon as you can fill up do it. I can ride into the mountains and cruise around for a while before hitting half a tank. at that point i will hit the fuel station and refill. Not the best solution but i think the benefits will outweigh the drawbacks. one of the guys on this site turned me on to the benefits of a high compression piston. gixxer, trixxer, flixxer ahh hell i can't remember, but i'm sure he's around here somewhere :D :D :wacko: :wacko:

just a quick question, what are you gaining by having a set up that requires you to run race gas/higher octain in the woods for trailriding/being a weekend warrior? wouldnt it make more sense/be more convienent to keep it able to run on pump gas since that is what you are able to get on the trails?

Don't you want to be faster than your friends, :D J/K . Some people, like myself, race most of the summer, but on the off weekends, and in the winter when there are no races, go trail riding when they can.

o ok, i never trail ride and only ride tracks when im not racing. during the winter i usually tear it down. once i spend that much money settign a quad up, no way im taking it in the woods and take a chance of tearing it up. i thought the post was about a trailrider who upped the motor and then was complaining b/c they didnt want to run race gas. sorry miss read :D lol. personally i think a quad that requires race gas for trail riding isnt a good set up, heck i dont even think the adverage trail rider needs a quad like the 450r, yfz or raptor. but thats my warped opinion lol.

it all depend on HOW you ride the trails.

lo if you say so, i still think someone on a z400/400ex could keep up in the tails.

thanks for posting and pinning this dez!!

i'm glad you brought up the tenths of a point thing. it's funny to see a bottle stating octane improvement numbers, but the only reference to the concentration is add this bottle to a "tank" of gas. pretty vague ratio there

you forgot one of my favorite octane boosters: tetraethyl lead


cool about the berrymans'\walmart thing!!! i thought i was the only one who read the bottles :D best deal going, if you're considering a shelf booster

.................mixxer

I find that I use my quad for trails and the sand. Maybe I don't need as much power in the trails, but there are plenty of chances to lay on the throttle and open it up for a bit. Of course, riding at the dunes is a different story and I'll take all the power I can get. The race gas is expensive, but I'm sure it will be worth it.

Dez, that was really good information and is much appreciated.


I am installing a 13:1 JE piston this week and was curious what the minimum octane is that you would run? I've heard that approximately 100 octane is fairly safe. However, several people have mentioned the benefits of the race fuel with the high compression piston. Like Dez said in his article, I don't won't to go overboard, yet I don't want to go under. I want to be using the correct octane that will provide the most HP benefit.

Thanks In advance....

I have the JE/Baldwin 13.5:1 piston with VP U2 fuel which is 101 motor octane and it works great for me

i know i've posted it a bunch of times, but will someone find where i wrote the last episode of "the cams' involvement in dynamic compression" and copy it for me??

you know i'm a slow typist

here's the short version:
cam intake lobe closing \duration + static piston comp rating= dynamic (running) compression.
dynamic compression is the determinant of octane requirements

can't make a call without knowing the cam also

........mixxer

Can you expand on this one. I understand how too high of an octane can hurt the power some, but how can it increase head temps? Is the higher octane fuel burning slower, and thus increasing the exhaust gas temp?

In my Ricky Riccardo voice..."Ju got sum splainin' ta do."

Look here.....clicky

Sorry mixxer, je 13:1 piston, hrc cam, sparks pipe, open airbox. Head ported and polish, 3way valve grind

hrc and 13:1 will be fine on a race gas of 100 octane

good pump fuel may also work, but i haven't tried that yet

THANKS !!!!!!!!!!!1

i hate to break the news to you but "the track" isn't the only kind of racing that quads are used for. xc racing is basically trail riding....really really fast.
you need performance for the trails every bit as much as for "da track"

really? ya dont say,
i know about GNCC, but do you ride at the same speed or race any XC? does the adverage rider push their quad the same as someone on the gncc series? usually not.

Alright guys, you're gonna make me look like a big meany and use my outside voice inside here. :glare:

This thread is about octane, and has some very useful information in it. That's why it's pinned. Let's stick to the topic and not make this about who rides fasterest in the woods. B)


Thank you

thats fine, it does have good info, i was hesitant to post init. feel free to delete any of my post.

ok, i've heard rumor that letting pump gas sit lowers the octane rating. like, after a week or 2 the rating starts to go down. is this true? i ran U4 in my stock engine (can't think of the compression ratio at the moment) and it worked well, but not noticeably better than 91 pump, and it sat for a while. what would be the highest compression you could run on 91 octane pump gas? race gas is readily available to me, but i can't afford it. i'm getting ready to mod my engine, but i need to decide what compression i want to run. also, what does it mean when a fuel is "oxynegated"? supposedly U4 is super oxynegated, with an octane rating of about 94, and i could smell it everywhere. the fumes went throughout my entire house, could that be because of the oxynegated thing?

great question

and a big topic to cover....short version:

oxygenated fuels allow you to put more gas in the cylinder (bigger main jet) and all the fuel will be combusted

without the oxygen you are limited to a jet size that only lets in enough fuel to be burned by the amount of air\02 that enters through the back of the carb

you can't take advantage of oxygenated fuels without a dyno and afr to adjust your carb settings....same goes for alcohol, a naturally02 carrying fuel

and yes the lighter hydrocarbons do evaporate and lower your octane rating while gas is being stored

lstly , octane has nothing to do with horsepower. it is a rating of how stable a fuel is. high octane means you have more latitude in your engine setup without fear of the fuel being too ubstable and prone to detonation

...........mixxer

ahhhh, i think i get it. so basically i wasted $50 on 5 gallons of race gas, since i didn't change any carb settings when i used it. lol, nice to know.

if your bike was jetted too rich to begin with, it is possible to get correct jetting by switching to an oxygenated fuel

what about that lucas fuel treatment..

i have ran it in my truck 3 times under a lot of pressure from, engine tuners, and dealerships.

where i live they really push that product.

i dont think it increases octane, but i think it supposed to make it run cooler..

can someone correct me if im wrong, and tell me how that stuff is supposed to work? thanks

:)

While we are talking fuel teatments what do you guys think/know about amsoil fuel treatment?

What's wrong with running Turbo Blue? That's the only "race gas" sold anywhere within 60 miles of my house is the reason I ask...

It was only the avgas he was reffering to.

I use Torco Unleaded Accelerator, Race fuel Concentrate. When added to 93 octane, you can boost octane up to 104. It comes in a metal bottle, and I have the mix ratio figured out by the tank. I still use plastic race jugs for fuel, if it sits for more than a week, it is demoted to my truck tank, the weedwhacker or fire starting fluid.
I do not have alot of motor mods, but find my machine more crisp in throttle response, a cleaner burn, and easier to jet at a constant 100 octane (or close to it.) This stuff has mix ratio's on the can, and it is hard to come by, or afford straight race fuels trackside or above 91 octane at the pump locally.
I also find that regardless of buying premium, the quality control leaves something to be desired as well as station tank conditions from those real hick towns. Just an interesting read: It covers all kinds of fuel additives, pure race as well as avgas specs.
For The Lack of LEAD and OCTANE

so what your saying is i could use this stuff as a alterative to race fuel if need be , just mix it how the bottle says ????

Actually, avgas does not have deicers or Prist added. Most aircraft that run on avgas do not fly high enough to need these additives, so if you want them added they must be added when it is pumped into the tank.

Avgas is essentially "pure" (if there really is such a thing) gasoline with an abundance of TEL (lead) added to give it the desired octane. It has very tightly controlled vapor pressure specs and is very stable. It can be stored well over a year without degrading or causing varnish.

What may be a problem is that lead may not completely vaporize and leave during the combustion process. This is one issue of concern for me as I'm using avgas. However, with the combustion temperatures generated by 13 to 1 C/R most of the lead should be scavanged out the exhaust.

The MON for "100LL" avgas is actually 104 octane.