Nitrous Oxide on a late-model sportbike.

O

OB_Brock Davidson

Registered
This is the bottom line..... If you can walk past a bike and SEE the carbs/throttle bodies, WHEN a nitrous backfire does occur the explosion vents towards the atmosphere.

For those of you who do not know: when nitrous oxide is injected into an engine, the system continues to function even when the intake valve closes, during the compression and exhaust cycles. The fuel/nitrous mist has no place to go during this time except backwards. I have photos of my pro-mod bike with a white mist following the carbs at 175 mph !

If the bike is equipped with a down draft/ram air/enclosed type system,(this generally began in the mid 90's) this mist is either trapped in the air box or in the hollow metal cavity underneath the tank.

If, for any reason, this mixture ignites
(bog, hitting the rev-limit, rich condition due to bottle pressure drop or insufficiently filled bottle, poor jet spread selection, weak spark plugs, mechanical failure..... Whatever, etc.etc.
Carbs/ Fuel injection...... It does not matter!)

YOU HAVE A LARGE VOLUME FUEL BOMB, WITH PLENTY OF NITROUS OXIDE AVAILABLE TO ACCELERATE THE EXPLOSION!!

If anyone has a suggestion, aside from not spraying late-model bikes...I'm All Ears!

Brock

ps I have sprayed everything from lawn tractors to motorhomes over the past 15
years......they ALL eventually backfire!

pss. Even Hayabusa.org hero Bob Carpenter got blasted off of his dyno testing a nitrous zx-11. He was nearly killed.
 
Well I'm not a Nitrous expert Brock but what if the Nitrous was injected sequentially?Somehow tie both fuel and nitrous injectors together to fire only when the intake valve is open.
 
Guy's Nitros on a ram air bike is a moot point. What good do you think pushing air through a series of duct work to add pressure and extra fuel to the incoming charge, when the Nitros system can give you more "Air" than you will get at 200 mph with the ram air? Brock's statement on the white mist behind his velocity stacks "aka" FUEL STANDOFF is a normal and spot on of N2O/ or wild cam timing and the problem will NEVER go away. Now as to 1300r's answer, you hit the nail on the head. The timing of the N2'O "vs" intake valve opening has been the problem witn Nitros and ram air bikes so far. :-) Brian
 
Motorhead, I know I'm probably stepping out of bounds here but, I don't think your telling Brock anything he doesn't already know.(rpm limiter switch)

Cause, isn't that what turborick has been doing on his 80hp plus nitrous system?

And, wasn't it Brock that helped T-R get a jump start on his Nitrous system? I'm pretty sure it's the switch part that rick figured out to get his system to work the way it does...
 
yes but how fast is the reaction of the relay?and i never said im god and the only one that knoes this but most dont use the window switch!!!!or use it properly.or with a fast relay.i just want you guys to thik about why this happens on your machines.thats how you fix.find the disease how it effects what and limit its habitat if you cannot eliminate it.if the nitrous is operated at 8000 rpm you will not bog at that rpm below it its shut off. turn it off at 10800 you wont hit limiter melting stuff.i did not invent it took 10 min. to see the benefits after a bog launched our procomp motor years ago.i just wanted you guys to do some solving on your own.not what everyone else does.or you'll be lucky to do almost as good as them at best!!!!!!!!!!case closed so get one.no big deal .
 
nitrous on and off with valves is limited to coil saturation rates and physical size and speed of the solenoids and cannot cycle that fast or we would do it with valves instead of springs and cams.in time!we will!

[This message has been edited by THE MOTORHEAD (edited 05 February 2000).]
 
frank use the window its proven its value no product is better than its operator so keep the activation high8000 or so and use an initial small relay they can operate at 1 or 2 miliseconds the big ones are slow.

[This message has been edited by THE MOTORHEAD (edited 05 February 2000).]
 
if the bike caughs it changes the rpm. if bike boggs it changes rpm. rev limiter is also rpm based. i can limit substancialy the risk of this. without airbox on this type of bike is a death sentence.(see spark leakage and its effects on fuel vapor) {aka bomb}.common denominator rpm.if it bogs so! as long as nitrous does not continue during this slow air ,speed situation it doesent matter.only if nitrous injection overlaps these situations will there be a problem.nitrous should only operate within the powerband of operation(7kto11k)every where else it is unnecessary and dangerous.even on any bike. we lauched a wristpin in columbus in pro comp that way .

[This message has been edited by THE MOTORHEAD (edited 05 February 2000).]
 
The technology to sequentially spray nitrous is in the works. It is complicated and expensive to develop. This will cure a pile of woes!

Until then......band aid cures(window, Hobbs and mercury style switches etc.), will help to lessen the possibility of a nitrous cough. This is especially true with small to moderate doses of juice.

Everyone simply needs to realize that the consequences of a "minor" problem is met with a far more costly result with a late model bike than with the old-style machines. Over the years, I have had numerous nitrous related hiccups and fires...... This is a part of Nitrous Racing that you learn to compensate for. I have never placed the rider (ME!)at such risk until recently. Go to the dragbike.com site and look at the photos of my explosion at Atco. The blast blew the tank off of the bike(cracked my ribs and sternum) and the concussion briefly knocked me out. In the shot shown, I am kicking the bike in an attempt to remove my trapped left leg . I just woke up! I was only traveling at @ 40 mph......Imagine this problem at 175MPH !

My first 2 Bandit passes at Indy this year, I crossed the traps spitting fire(leaned on the bike hard).....no big deal. When I think about this situation on a down-draft machine, it terrifies me !

Brock
www.brockracing.com
 
Brock
Interesting subject this.A few years ago we had a back fire problem with our superstreet bike.It would get to mid track and on the next shift backfire and melt the needles in half luckily the needle half would fall back into the emulsion tube.We changed to titanium needles and solved the problem(bit of a band aid I know).Is it the ignition firing with the valves open? Or lean backfires?
Probably the only way around this problem is to take the fuel away from the mist?I think the FI on the Busa is only sequencial up to a certain rpm then it just runs flat out I'll have to check my notes on this.There are electronic ways of killing the ignition with throwing a spark in when it comes back on line.
Gasabusa
 
gasabusa your kill probably grounds the coils with the kill.this callapses all the coils even the ones on intake stroke.causing them to light the charge whether or not its time.its cheaper to do it this way but whith the juice can be a fine line to walk.the coils triggering wire is actualy the proper way to kill that way it does not fire when its not suppose to.
 
Motorhead, I understand what you are saying here. However, I have to wonder if the residual nitrous could have an effect on backfires once power to the solenoids is interuppted. The gas solenoids are under less pressure so they will flow slightly longer when power is cut, maybe that will help matters with a very temp rich condition ?? Also, do you know a good source for solid state relays? Radioshack has some good mech relays in the commercial catalog but I cannot find any solid state relays.
 
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