Author Topic: 110 vs c12 vs oxygenated fuels? what are your experiences/opinions. (Read 8902 times)

JesseA420 · « **on:** August 28, 2014, 01:00:40 PM »

i have been wondering alot about oxygenated fuels. i found this link laying out the specifics of each vp fuel, and it is pretty informational.
http://motocrossactionmag.com/news/racers-guide-to-the-hierarchy-of-motocross-racing-fuels-2

if switching from a sunoco110 or vp110 to a c12, do see some seat of the pants gains? if not, would having a dome cut to the compression ratio to around 15:1 for the c12 show any? the link notes it is optimal up to 15:1. would there need to be any jetting changes going from a vp110 to a c12? what could one expect.

and as far as oxygenated fuels go, would you need to have a head recut to optimize your compression ratio for it? obviously oxygenated fuels would require jetting changes if switching from a non-oxy fuel, but would you need dyno time to fully feel the benefits of the fuel, or would there be significant changes felt just from ballpark jetting and non-fine tuned timing?

all your knowledge and help is appreciated.

udontknowme · « **Reply #1 on:** August 28, 2014, 11:00:29 PM »

recently bought a jug of sunoco supreme. after a few days sitting in the carb its like syrup. frikin engine wont start until you blow air through the pilot jet then runs great until it sits for a few more days and the same shit happens. seems like its not agreeing with the benol. ran the bowl out last weekend so ill see if it fires tomorow without pulling the carb

Burns363R · « **Reply #2 on:** August 29, 2014, 07:22:08 AM »

I run sunoco supreme 112. I bought a 55gal drum of it, and it sits in my shop. I run maxima castor 927 at 28:1 and usually keep 10 gal of premix in the trailer at all times. I have never had it settle out other than in cold weather. Kinda weird yours did it in the carb. I havent seen that.

Burns363R · « **Reply #3 on:** August 29, 2014, 07:30:54 AM »

With any switch in fuels, you may need jetting changes, but it should be minimal if going from say Sunoco 112 to C12. The OXY fuel is defiantly going to run different than standard fuel, but honestly i have no experience with it and dont know which way it would make you go. I would think you would end up going larger on the jets. More fuel/oxygen, more power.

You wouldnt need to cut your head if you go from 110 to 112 octane fuel, but if your compression is already setup for 110, switching to 112 wont gain you anything in terms of power, technically you may loose some due to the slower burning fuel, but that would be negligible if any at all, that is just in theory. To get any more power you would need to recut a head for 15:1 compression which will take advantage of the extra resistance to knock which will be a noticeable gain. Compression is one of the best ways to add power if your willing to buy the fuel.

Unless you have very consistent air most of your riding season, i feel like dyno tuning is a waste. It will get you spot on for the day that you tune. And if your air is consistent then you will be really close all the time. But for me in iowa, with the daily humidity and temperature swings, the jetting goes all over the place. Which is very frustrating. So putting it on a dyno doesnt make sense.

JesseA420 · « **Reply #4 on:** August 29, 2014, 08:05:08 AM »

whoops wrong link in OP, corrected it. also, thanks burns, im not far from you and i know what you mean about the humidity swings.
http://motocrossactionmag.com/news/racers-guide-to-the-hierarchy-of-motocross-racing-fuels-2

udontknowme · « **Reply #5 on:** August 29, 2014, 07:33:46 PM »

Quote from: Burns363R;41905

I run sunoco supreme 112. I bought a 55gal drum of it, and it sits in my shop. I run maxima castor 927 at 28:1 and usually keep 10 gal of premix in the trailer at all times. I have never had it settle out other than in cold weather. Kinda weird yours did it in the carb. I havent seen that.

. im using alittle more oil than 28:1, actually quit a bit more. but i think whats happening maybe is the gas is evaporting possibly. since the high oil content creates a fairly high viscosity mix, it might not take much gas eveaporation to turn it to syrup, considering theres only a ounce or two in the bowl. i should put a measured amount of mix in a container and see after a few days see how much less volume it has. this might tell me whats going on. if theres hardly any decrease in volume then it might be the benol is not doing well for extended periods with this gas for what ever reason. but i found how to avoid it. simply turn the petcock off and run most of it out of the bowl. that way when the engine is fired again later it will be pulling in good mixture rather than trying to suck syrup through the pilot hole

Burns363R · « **Reply #6 on:** August 29, 2014, 08:34:41 PM »

What ratio are you running? I can't imagine using any more. I'd rather run 32:1.

bnau267 · « **Reply #7 on:** August 29, 2014, 09:21:00 PM »

Quote from: Burns363R;41941

What ratio are you running? I can't imagine using any more. I'd rather run 32:1.

Burns, why don't you run 32:1. I ran that in my yz250 for about 5 years and run it in my R. Just curious - not suggesting you switch just wondering why. Bob

Burns363R · « **Reply #8 on:** August 29, 2014, 09:43:14 PM »

I run that because I have been asked to. I used to run 50:1 on the motors my dad used to port and build with sucsess. But honestly I have gotten my new motors really hot a few times and have not melted them down. I belive it's due to the high oil content. If I had ran leaner oil mix. It may not have survived.

bnau267 · « **Reply #9 on:** August 29, 2014, 09:57:03 PM »

That's cool. Nothing wrong with a little extra security.

udontknowme · « **Reply #10 on:** August 30, 2014, 12:02:19 AM »

mentioning ratios just turns into a pissing match so i rather not get into it. if your happy with 50:1 or 28:1 or what ever it is you use then thats all that matters.

anyways ill see if i can get pics of this syrup stuff. i dont recall the regular sunoco doing it. but it appears that either running most of the fuel out of the bowl or draining it out eliminates the issue, so it probly wont be a issue anymore

Burns363R · « **Reply #11 on:** August 30, 2014, 09:13:56 AM »

Don't take it that way. I'm not recommending any changes or anything. Wasn't my intention to come across that way. I appoligize.

mx250r91 · « **Reply #12 on:** September 01, 2014, 11:37:38 AM »

I've always wanted to try VP Q16, the replacement for the old MR2 race fuel used by the pro teams before AMA banned leaded fuel. Leaded, oxygenated, 116 MON, sounds like a good fuel for a high compression 2-stroke. Anyone have any experience with it?

mx250r91 · « **Reply #13 on:** September 01, 2014, 11:38:36 AM »

I've always wanted to try VP Q16, the replacement for the old MR2 race fuel used by the pro teams before AMA banned leaded fuel. Leaded, oxygenated, 116 MON, sounds like a good fuel for a high compression 2-stroke. Anyone have any experience with it?

http://www.vpracingfuels.com/download/Tech-Q16.doc

taft372 · « **Reply #14 on:** September 01, 2014, 02:52:48 PM »

i ran q16 in my 370 and u4.4 they are both oxy fuel