Race fuel

[Gravisman]

Curious who uses it and if anyone knows any good resources for learning about it. I’m particularly curious about what benefits (if any) are to be had in stock engines. I’m coming from a place of zero knowledge, but they were chatting about it on Brap Talk, and that just made me curious to learn about it.

[Butch]

Oh, subscribed.
High octane allows higher compression and making more power. There are tradeoffs. Edit, if I recall, racegas smells great.

At least is what I heard.

Er, so without high compression, race fuel does little? Listening.

[stangmx13]

the main benefits of race fuel ive noticed are:
1. consistent product - theres no risk of water or other contaminants in a fresh pail of race gas. whats on the label is what you get.
2. better throttle response - diff fuel formulas, esp those with extra oxygen, can make the throttle feel crisper.
3. more hp - consistency allows for a better tune, which can increase HP. more oxygen is more HP when tuned properly.

my engine builder said to use race gas, so I use race gas. F&L Xtreme100 is what I use at amateur events. VP MGP is required for MotoAmerica events. both fuels are very close in specific gravity, O2 content, etc. so I dont even bother switching maps. VP MGP is 94 octane, so its not like I need the extra octane in Xtreme100. both are ~$12/gal.

modern motorcycle engines arent like classic big block V8s. you dont need a ton of octane to prevent detonation in huge cylinders with poorly designed heads. VP MR12 is the go-to fuel for making great HP in sportbikes, as it has a ton of oxygen. its only 94 octane. however, it leaves a residue on the head, should not be left in the motorcycle, and will make any trailer or garage smell like death. so there are definite drawbacks.

if someone is serious about racing, they'll build their engine. cut the valve seats, time the cams, get the head gasket thickness perfect, etc. then itll go on the dyno. if they spend all that $$, they should use race gas to protect that investment and for better performance.

would I ever use race gas in a stock engine? nope.

[Biga]

^^THIS^^
Must flush the system every time after the racing weekend.
If you crash and sent to the hospital, make sure a friend knows what to do

[Gravisman]

Cool, good info. Sounds like the takeaway is keep using pump gas until someone builds an engine for you and tells you what gas to use.

[Holeshot]

There's benefits to using MR12 (with mapping) in a stock engine. Gas Station fuel is the bottom of the barrel for power delivery IME given the detergents, etc in it. The throttle on bottom feels sluggish and it isn't crisp at all. It's fine for practice, but for racing even the non oxygenated pump fuel at the tracks is better than Chevron, etc.

[Gravisman]

Originally Posted by Holeshot

There's benefits to using MR12 (with mapping) in a stock engine. Gas Station fuel is the bottom of the barrel for power delivery IME given the detergents, etc in it. The throttle on bottom feels sluggish and it isn't crisp at all. It's fine for practice, but for racing even the non oxygenated pump fuel at the tracks is better than Chevron, etc.

You're referring to the racing fuel at the track (like 100 Octane IIRC at Thill) or the regular 91-ish stuff?

[Holeshot]

At the track fuel. Ideally, you want the lowest octane you can run without having detonation. In a modern stock sport bike, that's 91.

[squidworth]

Interesting that VP says this about MR12:
MR12 is designed to make maximum power in four stroke dirt or street bikes with stock or mild modifications. VP’s best fuel yet for 4-stroke applications that can tolerate lower octane values. MR12 has met fuel rules for AMA Pro/Am, CCS, WERA, NMA, WORCS, SCORE and Best in the Desert as well as club level racing and more. As regulations are ever changing, we recommend checking with tech to be sure.

https://vpracingfuels.com/product/mr12/?c=219

[stangmx13]

MR12 would def help a stock engine make the most possible power. that, a quality flash & tune, and a quality exhaust is probably the most power ull get from any modern sport bike engine without modifying anything internal. most of us dont change much when building an engine, meaning the stock engine is very good.

would MR12 in a stock engine make more power than pump gas in a superstock-ish built engine? I couldn't say, but I bet itd be close. You know what might also be close - the cost of a years worth of MR12 vs. an engine build + less expensive race gas

one thing I wonder about. if you run MR12 in a stock engine, how long before you MUST rebuild? 1 year, 3 years? ill ask my engine builder next time I talk to him.

[squidworth]

completely agree with all your points. I just find it interesting how they position the fuel.

[Holeshot]

I've gone over 3 years on a super sport motor with MR12...then she blew!

[easter bunny]

Originally Posted by Holeshot

I've gone over 3 years on a super sport motor with MR12...then she blew!

What blew? Does it coat the valves and you dropped/ate one? Head gasket from increased compression? Just wondering what the potential cost of a fix is compared to the incremental power.

[stangmx13]

Originally Posted by Holeshot

I've gone over 3 years on a super sport motor with MR12...then she blew!

this makes me think theres no appreciable difference in longevity btw safer race fuel and MR12. it suggests that MR12 is safer than pump gas too.

of course one anecdote isnt much. that motor and that builder def won't apply to everyone else.

[dtrides]

Gravisman, may ask what you are considering putting that race gas in to?
I notice you have a wide variety of bikes listed with your avatar.
I can only assume you might benefit more with some bikes than others with race gas , but I don't know.
And as others have mentioned, the price differential is substantial.
Should one consider putting those funds elsewhere first or is running race gas a no brainer for better lap times?
DT