Nut; your correct with your compression idea. At least in the old days. I don't know what the pro's do now days. I "think" I read that Jenkins runs some pretty tight squeeze. But then again those guy's have access to all sorts of weird parts and fuels.

Threads like this is why the DS guy's go so fast. Every one of you people in this thread are on it. I would hate to race any one of you in any motor sport. All of you will go nothing but faster.
Good luck with your racing and building.

 

On the same engine i would expect the acceleration rate to be faster on nitrous. Which is faster a maxed out NA engine like the Albany one or a 60 hp one with a 30 shot of nitrous ?

 

That is a question that someone who can only make 60 hp will want to answer. I will take a motor making power in the high 80's any day because I can run NOS on it to and make that much more power.

Not to long ago there was a discussion about running low compression motors so you can run more NOS. Compression is not the problem. We ran as big of a shot as anyone has claimed so far on 13.5:1 true compression............no detonation or pre-ignition.




I see your point though............and I would love to compare a timed run with each setup on the dyno! [img]i/expressions/face-icon-small-smile.gif[/img] You might be right about what you are getting at......

 

REV LIMITERS are for SISSIES [img]i/expressions/face-icon-small-smile.gif[/img] I am running a Ron Woods CDI and running a NOS wet system I am going to the dunes on New Years now you guys got me worried I am going to miss a gear and blow my motor. I blew my motor last year with a faulty button that stuck my system on and washed my cylinder[img]i/expressions/face-icon-small-mad.gif[/img] I guess I will pray to the sand gods for good luck.
Thanks guys real interesting reading.

 

If you don't remember anything else from this story remember to never trigger a rev limiter while on nitrous. This is a great way to destroy your engine when the rev limiter starts dropping cylinders

http://www.chevyhiperformance.com/te...xide_controls/

One way to keep your nitrous engine safe is to install a MSD RPM Activated Switch. The switch can be adjusted to turn your nitrous off at a selected rpm before the engine hits the rev limiter

http://www.musclemustangfastfords.co...8mmff_nitrous/


http://www.bmnracetech.com/faq.html
Here is one example of a better idea then a rev limiter with nitrous. Lots of companies make the window switches with more or less options to fit your needs.

TP i think you will be fine as the examples above of experienced nitrous users agree your setup is less dangerous then bouncing nitrous off of the rev limiter.

 

Heres what Ive found and Im by no means an expert but I will never rely on NOS. Ive just seen it fail to often. Ive always tried to make my motor fast off NOS and then use it when you need it. And yes it doesnt hit as hard with higher compresion but if your empty you dont miss it as much. I know I could probably go faster but not the route I chose. Ive run the Wood CDI with my Boondockers and I use the button so its a little easier to get off it if something happened. I do run HPR3s and heavy springs and agree with the statement you shouldnt use the Wood CDI without springs for sure

 

Uh...........ok but those are a different kind of rev-limiter. Those limit rpm by cutting power to injectors therefore cutting fuel, not spark. Of course cutting fuel will run the system extremely lean and blow up the motor. The type of rev-limiter that cuts spark is the one that applies to us. These are DS650's that are carburated......not fuel injected V-8's. The following is an excerpt from Nitrous (101):

Ignition RPM limiter-The rev limiter is implemented by cutting the signal to the fuel injectors so the cylinders have no combustion. If you're running a dry system, which depends on the fuel injectors to provide compensating fuel for the nitrous, losing fuel this way is the ultimate disaster. An after market ignition will typically implement the rev limit by cutting off spark rather than fuel, which is a much safer implementation of the rev limit. Typically, you'd get your stock PCM programmed to set the rev limit up higher than you'll ever expect to go (like 7000RPM), and use the setting on the after market ignition as your actual rev limit.

Window Switch-This electrical device provides an open or closed circuit based on the engine being between two RPM values (hence "window") that you chose, so that you'll only flow nitrous in this range. Why would you do that? Well, for two very different reasons.

1) At low RPM, think about what's going on: you're spraying nitrous into the intake at a constant flow. That is, the nitrous bottle and solenoids have no idea what RPM you're at, and they're just pushing it into the intake at a constant volume. Inside the engine, though, the nitrous and fuel combination is being sucked into the cylinders during every stroke. The net result is that at low RPM, you're getting far more of the mixture into the cylinders. At 3000 RPM, for example, you're getting twice the amount as at 6000 RPM. So, you can imagine that running nitrous at, say 1000 RPM, is far more stressful on the motor as at 3000 RPM, and typically causes a "nitrous backfire" - meaning that the nitrous/fuel combination can explode in the intake manifold (rather than the cylinders) - a bad thing. So that's why you don't want the system triggered at low RPM.

2) At high RPM, the situation is easier to explain. Given the discussion of the rev limit above, you may just want the nitrous system to cut off before hitting that rev limit. If you've got a stock ignition, you certainly want a window switch. If your rev limit is implemented by an aftermarket ignition, it's perfectly safe for the motor to run nitrous during the rev limit. It's not particularly easy though, on your transmission or clutch to have all that power during the shift, which may be a reason to keep the window switch set a bit before you shift.



Entire Article

 

2) At high RPM, the situation is easier to explain. Given the discussion of the rev limit above, you may just want the nitrous system to cut off before hitting that rev limit. If you've got a stock ignition, you certainly want a window switch. If your rev limit is implemented by an aftermarket ignition, it's perfectly safe for the motor to run nitrous during the rev limit. It's not particularly easy though, on your transmission or clutch to have all that power during the shift, which may be a reason to keep the window switch set a bit before you shift.

When you shifted you would have nitrous flow in the next higher gear and it would be hard on the clutch and tranny so that reason to run a window switch would not work. How does the brand of ignition you run with a rev limiter on a single cylinder bike make it safe or not safe to use nitrous ? Either it fires the plugs or it doesnt right ? Then you would still have unspent A/F mixture that you hope makes it out the exhaust before it finds a place to ignite. Which aftermarket ignitions is it safe to bump the rev limiter on with nitrous ? Who sells them and where can i get more information on them ?

Doesn't the MSD fire a wasted spark that could ignite this ? If this is true do the others ?

 

Here is what I would do:

I would runa Vortex ignition with a custom curve designed for backing the appropriate amount of timing out for your compression and NOS shot. I would put a good shim-under kit in with heavy duty valve springs and on say a 7500 - 7800 rpm shift point DS which is a moderately built motor, set the rev limiter at 9000 - 9250 rpm still within the limits of your valve springs but high enough to keep you off the limiter in 99% of circumstances.

That will give you reasonable odds on the calculated risks. [img]i/expressions/face-icon-small-smile.gif[/img]

My $0.02

 

So you are saying the Vortex is safe to run nitrous and bump on the rev limiter. Thanks for the info. I just emailed Richard at Vortex's home office so hopefully he responds and explains to us how it works and ill post his response here so we can all learn from it.