Posts
630
Joined
8/3/2009
Location
Rouse Hill
AU
Edited Date/Time
9/7/2021 11:54am
Two riders have had fuel spray on them in two consecutive races. I don't recall hearing about this before.
Is it the tanks being closer to heat sources? Thinner tank materials? The heat? All the above?
Not the hottest races ever. The perfect storm could occur soon. Someone could be seriously injured or killed at a race.
Whatever it is, something urgent needs to be done to make sure we are not discussing a tragedy real soon.
Is it the tanks being closer to heat sources? Thinner tank materials? The heat? All the above?
Not the hottest races ever. The perfect storm could occur soon. Someone could be seriously injured or killed at a race.
Whatever it is, something urgent needs to be done to make sure we are not discussing a tragedy real soon.
A requirement for low vapour pressure fuel might help and mechanics checking that aftermarket
exhaust pipes are not fuel tank/line/injector heaters.
So sensible mechanical preparation. It gets hot in summer.
The Shop
When it got a hair over 100 in Ogden and SLC, my bike was getting burbles like it was low fuel but still had half a tank.
Only happened once, but still debating it.
Some of the oversize tanks on a couple of my bikes damn near touch the head, I might throw some on just for peace of mind. Last thing I need is gas spaying out while my bike is overheating on some hillside in 100 degree July weather.
The old car guys have figured out how the keep their Model "A"s from vapor locking by adding heavier weight hydrocarbons such as kerosene or stove oil to the fuel.
Edit: Here's a pretty good article on RVP and also distillation curve.
https://www.sunocoracefuels.com/tech-article/rvp-pressure-vapor
I would also point out on VP's website you can see the RVP if you download the spec sheets for the specific fuel.
After doing a little more research, VP has two fuels that is used by the Pro's: MR Pro 6 Reg with a RVP 11.01 and a high temp version which is MR Pro 6 HT that has a RVP of 9.81. So VP has created a better high temp fuel.
MX racing fires are not on anyones (mostly) mind. These two incidents take very little imagination to suggest how bad the next fuel spray might end up. It just needs some awareness and what ever preventative measures can be taken at a level of mechanics looking out fo their rider or the scrutineers doing whatever checks they would need to.
It's worth some effort.
(1) High temperatures. If the air is hot, it is not cooling the radiators down much;
(2) Volatile fuel. VP MR pro 6, the fuel we are using in AMA racing is quite unstable in temps above 95 F;
(3) engine heat - Heat from the motor and exhaust radiate upward into the plastic fuel tank, causing the fuel to boil.
When a couple of those thing occur, then the fuel boils, the tank pressurizes like a pressure cooker under heat, and it can blow the hose right off the fuel cap. It happened yesterday to my rider at Fox raceway, and the hot fuel was squirting him in the face and mouth.
He said it was very hot when it went into his mouth an nose, confirming the boiling.
Pit Row
Let’s say a rider gets sprayed with gas and his gear gets fairly saturated, then he falls down in a corner or goes over the bars and ends up underneath the bike. What if he ends up under the header or mid-pipe with the fuel soaked gear contacting the pipe? Is it combustible? How fast does gear burn? Will it melt into the riders skin? How fast could a fire extinguisher be accessed if it happened?
At first I thought all this was pretty silly, but I don’t want it to become one of those deals where it takes a huge avoidable mistake where someone gets burned before rules are changed. A small amount of proactive preparation could go a long way in keeping riders safe.
1) Fuel tank vent hoses must have a mechanical connection (worm or pinch clamp) where the tube pushes onto the tank breather to prevent disconnection during pressure increase.
2) Every flagger station on the track should have at least one functioning water fire extinguisher and the flagger should be trained in PASS
Larger diameter vent lines leading to a small catch tank baffled with fuel foam, and a vent safely exited behind the rider should be minimum prep for hot days.
The expensive, trick looking gold heat shielding is very helpful for under tank but there are many high tech thin insulation products for turbocharger heat management.
I've done this for years on race cars.
No vapour locks and cooler fuel makes more hp. Crude but effective.
At least if the vent hose blew off it would blow off to the side rather than straight up onto the rider.
If it was a problem with design, half the field would have had the same issue.
Post a reply to: Fuel Spray - fuel overheating. Prevention must start NOW !!