I am running a 20 HP shot on my bike but I have heard of guys using ALOT more what is the biggest shot you have seen go thru a DS and stay together for a decent amout of time and what was the shot when the motor got dusted. Just curiouse what the DS can take.

 

I have ran a 25 shot for years, then a 30 shot for a year, then turned it up to 40. My engine has components to help with the nitrous. In my opinion, a 25 shot is a safe shot with a forged piston. Once you get over that, you will need to start paying extra attention...... Nobody really knows how much is too much, yet.......

 

I've seen a 25 shot hurt a stock motor, there was a RWR CDI on the bike and not only did tthe valves float but the also hit the piston and left nice little indentations.

 

I watched a 40 shot on a 13:1 stock bore make 48 hp on the dyno at 8500 rpm. Power peak on this motor was 10,000 on all motor. We shut down the run early because we were afraid of a lack of load on the dyno.

That same week, we upped it to a 60 shot at the track, saw good gains but it never saw the the dyno with that shot.

We opened the motor to make it a 730 that night and it looked like a perfect motor with perfect burn. We didn't even as much as burn one spark plug that weekend. There are a couple of very important keys to running bigger NOS shots. It starts with the piston..........

Major mentioned something that has burned some people. Don't buy the RWR box with no rev limiter. If you miss a shift or pop out of gear and nail it on the button, you will float your valves and they will contact the piston. Not Good!

 

DSNUT, I've never ran a 60 shot. Whats the fuel and NOS jets?

 

Ive talked to several builders and the Wood box according to them is the best. You just have to be careful. Ive seen the little smiley faces on the top f the piston as well.

 

I think for the everyday racer such as myself, 20shot and below is pretty safe. Anything above that IMO, you should have access to a dyno.

About CDI's.....I believe that a rev limit is bad because the rev limiter cuts the spark, and if you cut the spark under nitrous and fill the cylinder with nitrous and then let off the throttle till the spark comes back with all that nitrous in there.........KABOOM.

I personally have a Vortex CDI, but its been reprogramed with the woods curve, and few other custom curves. But I agree with MrMeaner, that the Woods box is the best.

 

Uh........just because the spark is cut doesn't mean the motor stops turning. Every time the spark is cut on a given engine revolution by the rev limiter, the exhaust valves still open and the nitrous and most of the unburned fuel are still pushed out.

I have never seen a motor on NOS fail due to an accidental bumping of the rev limiter. Has that actually happened to someone?

Wow, I learn something new every day! [img]i/expressions/face-icon-small-smile.gif[/img]


Jeff - I relied on Bo to incrementally increase the NOS shot. He told me we started the day on a 40 shot. Randall made a particularly scary pass down the track (S-curve, lol) and missed his shift to 3rd and still laid down a 4.1. I asked how much NOS we were running, Bo said a 60 shot. I do remember at one point during the day he said he was putting a #26 in each intake side but I don't know what the fuel jets were.

I have the NOS system as it was and won't be shipping that to 4sws until next week. Just out of curiosity I will check the jet sizes before it goes out. [img]i/expressions/face-icon-small-smile.gif[/img]

 

I have been thinking about this question. Nitrous might as well be concentrated liquid oxygen. It allows us to chemically force more air into the combustion chamber. It isn't volitile or explosive. It simply allows you to put more air in than the ports and cams afford on their own, then you add enough extra fuel to keep from running lean and you have instant power adder. It also has a tremendous cooling effect on the intake which helps stave off preignition and it increases air density kind of like intercooling a turbo...........the cooling effect isn't enough though. The fact that you are making so much more power means over all you are making more heat in the combustion chamber. Most people burn down their motor at the 30 shot or more mark. With the really small shots you can get by with the aftermarket CDI and running high octane fuel...........it affords you the flexibility you need to withstand pretty dramatic changes in conditions.....like a 40 degree drop in temperature in less than an hour. If you are running a big shot under those conditions, an aftermarket cdi and the amount of advance it carries, you can't run enough octane to slow the burn enough to save your motor when the temp drops and things go lean. The lean condition won't even get a chance to burn up your motor, the preignition that comes from the elevated temps of the lean condition will burn down your rings or blow your headgasket.

if you can keep the combustion chamber temps cool enough, advance is appropriate and you are aware enough as to what effect your surroundings are having on your O2 levels, you can run a ton of this stuff. (yes, Jed, I have seen the light, lol).

The margin for error gets smaller and smaller the greater amount of oxygen you are forcing through the motor. The reason is if you have a small shot and things get off a few percentage points, you have a small problem. If you run a big shot and things get off the same amount, you have a big problem.

I also think there is a different effect on the motor if it runs lean on carburation while pushing NOS......as compared to the NOS system running lean on its own.......but that will require more thinking before i blab about it. lol

 

I also think there is a different effect on the motor if it runs lean on carburation while pushing NOS......as compared to the NOS system running lean on its own.......but that will require more thinking before i blab about it. lol

How is this ? Have you seen the effects of this ? Does a larger nitrous shot effect the carburator more or less then a small shot ? Does it matter where the nitrous is injected in the intake system ?