So you want to race a turbo bike? Let's go for a lap.

June 27, 2017

 

 

So, what’s it like to ride a 400hp Turbo Alcohol Drag Bike? It’s a little hard to do without lots of gesticulation, ring ding noises and ‘Tim the Toolman’ grunting, but I’ll give it a crack. To start with, on this bike, you can’t just throw 400 horses at the start line like a boss and expect things to end well. So we use a sophisticated engine management and boost control system to keep things in some semblance of control, ramping boost from 9psi at the startline, through 11psi to 14psi in first gear then increasing with each gear until we hit a maximum of 20psi at the top of the track.

 

2, So, what kind of jigger is it ?

In short, the bike is a standard bore and stroke Suzuki GSXR1000 with stronger internals, using a Mitsubishi TD04 turbo modified with a 20G billet impellor wheel, custom alcohol fuel system and a 7” rear slick.

 

Although not unique, the bike is a little different to other big power sports bike based drag bikes in that it uses a relatively short wheelbase along with a wheelie bar instead of the more common super long swingarms that many others use in order to combat the bike’s tendency to tap the back of the rider’s helmet with the race track.But with a wheelie bar, my bike can’t flip and smash itself into oblivion if I get the clutch or something else wrong. This feature rates fairly highly not only in my book, but my wife, my dog and at least some of my kids would probably agree.

 

3, Warm it up

Before every pass, I warm the motor right up to 100 degrees C in our pit bay so that after spending the usual waiting time in the staging lanes, we’re still close to target temperature when we get the signal to get ready to go. The clutch I use is called a slider and doesn’t operate like normal. So I need to be towed both to the start line, and back from the finish line. With the bike warmed, we clear the data logs, hook the bike up to the tow quad bike and roll around to the staging lanes.Once in the lanes, and after getting the signal to get ready, I’ll fire the bike and let it idle while I gear up. Then my crew guy pushes me to the tunnel where we wait for our lap.

 

4, Right, let’s do it

The official waves us to the water box, I click the bike into third gear and we push the bike through the water and out the other side. On the signal, I grab the front brake, whack the throttle and the motor spins up into the clutch and the bike lights the tyre. With the tyre suitably hazed, I roll out, shut the throttle and paddle the bike the rest of the way to the line. I stop just out of stage and if needed, my crew guy will lift the back of the bike by the wheelie bar and set it down to ensure the bike is pointing straight down the strip.

 

At this point, it’s important to note there is no steering for four gears. So we need to make sure it’s pointed the right way.

 

I select first gear and on the starters signal, roll in and light up the first staging light.We use a boost building function so the bike hits the clutch with about 9psi of boost, or around 280hp. I use a button to activate both this and the launch RPM limiter. I like to bring the revs up to just under the launch limiter rpm of 6000rpm, and wait for the other rider to light up both lights. Then I bring the bike to full throttle. At this point, the engine retards the ignition, dumps extra fuel in and the combustion process moves from happening inside the combustion chamber to partially inside the exhaust manifold and out the turbo dump pipe. The resulting noise and flames spool the turbo and builds boost to our target launch boost level.

 

Then I roll into full stage, the lights count down and I release the launch button.

 

5, Annnnnd Go !

The two step switches off, the engine revs into the slider clutch which digs in and holds the engine at around 9000rpm through the sliding stage. Immediately, the front wheel comes up, the wheelie bar plants itself into the ground and we streak away from the start line with the 7” rear slick howling in protest.The clutch fully locks up and the bike passes the 60 foot marker at around 1.3 seconds. I watch for the shift light. As the light flashes, still at full throttle, I hit the air shift button and the ECU cuts the ignition for 60 milliseconds, just long enough to unload the transmission for the air shifter to ram the bike into second gear.

 

The front wheel touches the ground and jumps back up on the wheelie bar. We drive through second gear and I wait for the shift light again.The light comes on again at 12,000rpm and I hit the shift button a second time, the air ram does its job and slams the bike into third gear. The front wheel touches the ground again and jumps back up into the air.It’s at this point that I start to consider if we’re going straight enough to stay on the gas or if we’re heading towards the centreline or the wall.The shift light comes on again somewhere around 120mph, we hit fourth gear and this time the front wheel stays down….. just. There’s still not enough grip to steer the bike so direction changes at this point are either body language or close the throttle, steer it and get back on the gas. Shift light again and, we hit fifth gear. Now the bike will steer a little if I need it to.

 

We cross the finish line at 160+ mph and around 8.2 to 8.3 seconds if everything goes well. I click sixth gear and start squeezing the brakes and the bike slows down enough so that the clutch disengages and the motor drops to its 1600rpm idle. I blip the throttle as I’m slowing down to ensure it doesn’t stall and eventually roll to a stop and find neutral.

 

I shut the bike down, helmet off and smile very appreciatively at the official who very kindly brings me a much needed drink of cold water while I wait for my crew guy to tow me back to the pits so we can check the logs, refuel, top up the air shift tank and get ready to do it all again. 

 

 

 

 

 

 

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