Hello All,
Just thought I'd pop in and say hello and answer a few questions...
The bike I was running at the ACU sanctioned British Land Speed racing bike was the last MTT built 'y2k' from 2006. It runs a 250 series C18 turbine from a Bell Jet 206 helicopter. It produces when new and blueprinted 320shp (shaft horsepower) but 286hp at the rear wheel, at maximum rpm of 6016rpm. I therefore call the bike a MTT 320.
The power curve of a turbine is very steep, so it makes most of its power near the top of the rpm range. To get maximum rpm you have to achieve maximum N1 (combustion/fuel) and N2 (shaft rpm) at the same time. If not you produce far less power. There is no direct physical drive, it connects via an air/torque converter, so you can dial up N1 without moving N2. It takes a bit of getting used to. At maximum N1 you are producing about 300lb ft, so you have to be gentle to prevent snapping the shaft, etc... I have done that before and it can be very dangerous. 54,000rpm makes small things fly very fast!
Lots of mods were done to the chrome bike to make it as safe as possible, after our previous outing at the world wheelie/speed event. The bike is now black. I was pleased as the bike did not suffer any problems, not even an oil drop. All it required was a change of batteries (2 x 12v 680cranking amps!) as the 40 second starting procedure kills batteries if you keep doing it, without resting.
As the bike has no gearbox as such. You have to achieve top speed via changing the front and rear sprockets. I did my calculations accurately but did not factor in the extreme wind resistance at 200mph+ therefore I was down by about 1000rpm from maximum rpm of 6016rpm. This means I was down about 80hp on the rear wheel. I had no other rear sprockets, so best speed I got was 205.87mph on the vbox gps, about 100m shy of the 1.4m trap speed. A new sprocket has been made, that should achieve 6000rpm, that I hope will deliver 215-220mph, I'm not sure until I try.
205.87 mph video over 1 mile
http://youtu.be/3FZddzT8UNAThis is the first 'y2k' that has ever achieved a 'sanctioned' trap/gps speed of 204/205mph. All the other speeds were done by 'radar' guns from a great distance. The radar guns have a well known inaccuracy of about 10%, so I don't know if the real speed is 205mph or 220mph, as until I try, I don't know. MTT have given me a lot of support and help in turbine knowledge to race the bike, without damaging it.
The first ever 'y2k' was bike no.1 and was taken to Bonneville by the owner. The rider did not feel confident to take it beyond a claimed speed of 150/160mph, but after about 3 runs, the inlet sucked up so much salt, it destroyed the turbine by making a hole straight through it - 100mph swirling salt it very abrasive on magnesium!
My C18 turbine is in the process of being stripped and blueprinted, as we think that the turbine is down on power. Anyone that knows about turbines understands that over speeding them (N2 over 6000rpm) or over torquing them (N1 above 104%) or over temping them (EGT over 1550f) will cause internal damage that results in power degradation or catastrophic failure (bang!) When you are going flat out, I need to monitor all of these functions to prevent turbine failure or damage... as the cost to strip and rebuild a turbine truly makes you cry.
When I first took the turbine bike out, stopping was a real problem, as the bike has no engine braking. It has the opposite...it keeps producing power, like a giant turbo with a stuck accelerator. I have to hit neutral button before I can brake, otherwise they don't do anything. Takes a bit getting used to, but I got it mastered now.
The bike will be ready soon for its next outing... with some more safety mods, ready for the next event. I will be most surprised (upset) if the bike does not smash through the previous speed I achieved previously, and yes it is fully road legal and takes basic pump diesel.
Hope this info answers a few questions.
safe racing,
Zef
