[n2wheelies]

my winter project for the TL is going to be a very modest dry shot system.

several fellow racers have been bugging me to run their 10 flat bracket and their solution has often been a small dry shot systems, directed at the air temp sensor in the airbox to enrich the mixture via the existing ECU. the torque improvements are v good relative to the size of the shots because of the combination of the airbox cooling and pressuration as a result of vaporization of the N2O

today i bought a purge valve on ebay and im starting to scheme the bottle mounting and electronics provisions.

:devious

 

[tornado]

how much extra hp are you aiming for?

 

[n2wheelies]

maybe a 8 or so hp shot...

 

[fengler]

my winter project for the TL is going to be a very modest dry shot system.

several fellow racers have been bugging me to run their 10 flat bracket and their solution has often been a small dry shot systems, directed at the air temp sensor in the airbox to enrich the mixture via the existing ECU. the torque improvements are v good relative to the size of the shots because of the combination of the airbox cooling and pressuration as a result of vaporization of the N2O

today i bought a purge valve on ebay and im starting to scheme the bottle mounting and electronics provisions.

:devious

use the swingarm as the n2o holder:devious

 

[BikePilot]

Sounds like fun:banana

I always wanted to put a boondockers kit on my CR just for kicks (although it already makes more hp than I can use).

have fun

 

[cyclecamper]

I'm no expert on nitrous, but I'm interested. Tell me more.

So how do you get it to richen up enough?? Make the relay to activate the nitrous solenoid also switch in a resistance on some sensors so the Denso ECU richens? Not a bad idea, assuming the ECU reacts quickly.

The problem with a dry shot is that it can provide enough oxygen to exceed available gas and burn other things, like pistons or valves for instance. How much harder can it be to add another fuel nozzle to give it a wet shot, and be able to either run safer or use more nitrous?

Consider interfacing with two relays, one based on RPM (adapt a Dyna shift light or the shift light option on a PC-3/USB) and another on throttle position (usually just a microswitch), so that you can only turn it on while wide open and above some RPM limit, that way if it's set up properly it will never backfire & burn your airbox etc. Imagine what happens if someone else rides and pushes the button at idle! For that matter, for a "free" but non-adjustable basic "safety" tap the power that was originally for the air solenoid that activated the stock airbox flapper servos; they only activated above some RPM and throttle position (probably need a relay, not much current there). Make it so the nitrous can only work when the stock flapper would have been open.

BTW I doubt there's much real advantage to shooting it in really early upstream, though having the airbox contents cooler does make it act as if the airbox was bigger. But it's a lot more dangerous, can burn your plastic airbox and bike to the ground quickly if the TB backfires. Nitorous fires can be nasty. Also, the "violence" of the injection itself helps stir things up in the intake and atomize the gas, and you'd lose any benefit from that effect if you injected way upstream from the fuel injectors.

 

[BikePilot]

I think the theory is that the cold NOS hitting the IAT will cause the ECU to richen up the mixture

 

[n2wheelies]

I think the theory is that the cold NOS hitting the IAT will cause the ECU to richen up the mixture

josh gets the prize. :thumbup greg, you get the 'back to school nod' :no :laugh nitrous doesnt burn without the presence of fuel and im not planning on spraying any fuel in the airbox. thanks goodness as there would prolly be a lot of hippie casualties from igniting concert balloons :lol

i will have a WOT switch on the tbs for sure. standard setup is to use the starter button for the NOS and a two way switch to go back and forth between starter and NOS mode, the WOT switch also prevents spraying NOS into your airbox when you forget to switch it back before cranking... unless you are one of those guys who likes to start the bike at WOT. :laugh

 

[cyclecamper]

Is that a very common thing to do? I've never heard of that, but my nitrous experience is all with carbs. Doesn't sound like a very good idea to me. Why rely on the slower cooling of the air and sensor when you can just get much quicker, more reliable and more adjustable reaction electrically at the terminals for the same sensor? And if the sensor reacted to just the increased density due to the cold, well it really is that cold and should richen that much just for the cold but should richen even more for the added oxygen. So it would compensate for the cooling due to the expanson and state change etc., correcting for the cold, but not for the fact the oxygen concentration is so much more than air? Sounds like it would make the mix right for air injection, not nitrous injection. And the cold intake is a very good thing, why let it warm up in the airbox or take longer for the cold to get to the TBs? Bad enough that most ECUs take a delayed time-average of the air pressure pulses of a ram-air system, especially in a big-twin with big vacuum pulses, so they take a second to react. But I guess maybe the slight delay with the nitrous coming in so far upstream, maybe the timing for the delayed nitrous and the delayed richening work out OK? Does the hit come on smoother?

Of course the nitrous won't burn (DOH!) but plastic sure will, and the high oxygen content present will make almost anything burn like mad, including the plastic of your airbox. More than one bike has burnt to the ground 'cause of too much nitrous. Thick steel will sustain fire in pure oxygen. I think aluminum will too. Once you start cutting thick steel with an oxy-acetylene torch, you can then turn off the acetylene completely and keep right on cutting with just the oxygen stream, 'cause the steel itself will burn with just the oxygen stream once it gets started. Same thing with your engine parts, too much oxygen and the pistons and valves don't just get burned, they literally will burn up. 'course the nitrous isn't pure oxygen, just has more than air does. I'd think the polypropolene of your airbox might burn in a flash like it was made of paper if it's filled with nitrous instead of air. Sure looked like that to me when a guy hit the button at the wrong time without enough revs or the throttle open enough. Then again, he could have been running a wet shot and spraying fuel & nitrous for all I know.

 

[veetwo tls]

wet is good for CARB (naturaly asperated)
dry is better for EFI

 

[BikePilot]

I think it will work just fine, but I'm no NOS expert. If you were talking about a 50+ hp shot I might be worried, but for a small shot I would think the ECU will add sufficent fuel. You could always map it rich at WOT if needed.

 

[n2wheelies]

tons of folks do this greg. most of the 10 bracket class in fact.

im not just making this stuff up. nitrous isnt going to burn anyones airbox. it takes combustion type pressures and temperatures to ignite and sustain that kind of combustion because you need to dissociate the n2O to o2. as for the response time of the temp sensor, it responds within a few hundred ms which equates to maybe 12 slightly lean cycles per cylinder before the FI catches up from the temp sensor. the airbox pressure also contributes to enrichening and thats instantaneous.

 

[cyclecamper]

I learn something new every day. Just like an old dog.

So the nitrous is nothing at all like adding oxygen...at least not in the airbox? I'd just heard that analogy so often in the context of inside the engine...that the key to making it work safely in the engine was to add the right amount of fuel...and that the nitrous added oxygen that could make pistons and valves literally burn.

Used to see terrible fires from nitrous, but those were all wet systems for carbs, so the nitrous setup would have its own fuel pump that might always be on with a return line, and a lot of crappy homemade hoses for the nitrous and fuel. Things would backfire, belch flames, and then the hoses would burn with the fuel pump pumping and the whole bottle spraying...really awful mess, really hot fire right under the fuel tank, whole bike gone. But if what you say is true, then it must have been the early homemade additional-fuel systems, not the nitrous, that caused the problems.

So if you spray nitrous at STP on say a bonfire (hardly standard temp admittedly), will it contribute oxygen or not?

I'm kinda surprised oil-bath filters and oiled K&Ns and oiled foam, oil-filled TLS airboxes, never catch fire. I guess oil's not that flammable, and a backfire more a shock wave than belching fire?

 

[Guest]

8 hp doesn't sound like much "on paper" but I bet your butt dyno will say otherwise.

 

[n2wheelies]

i dont think spraying NOS on a fire would do much at all.

i could be wrong but i really dont think so. im trying to get a dyno run from the gixxer 1000 guy that is in my recent drag racing videos. he is using a dry shot system and has gone as fast as 9.00s with a :edit 25 shot.

oil is very flammable under pressure. thats the reason for detonation and bottom end failures due to oil in the airbox. art davis will tell you the same thing.

 

[Essex_Andy]

its something like 1300 degrees C to seperate the oxygen from the nitrogen and then the 'free' nitrogen' cools the area where it was released

 

[BikePilot]

The oil thing is true for sure - its a problem on a lot of diesel trucks. The Ford 7.3L motors often warp heads when the CDR valve goes bad and allowes too much crank case mist/oil to get into the rear cylinders.

 

[Guest]

one word: Techlusion. It's the best way to make it work. I've read lot of guys using techlusion box for the fuel enrichment. It boots up very fast. and you can fine tune the fuel mixture for the shot. most common is to fab up a arming button, when you arm the system, the horn button changes to nos button. then just hit that and it activates the techlusion and opens the nos nossles.

 

[deltl1ks]

:hail

 

[billy_tlr]

just been lookin at nos myself dynotune over there in the us have a dry kit fpr efi bikes full set op for like $200 comes with 3 diffrent size jets max bieing 40 hp and the smallest is 15 looks like a nice setup anyone tried it ? link
http://www.dynotunenitrous.com/store/scripts/prodView.asp?idproduct=141
+this caught my eye