So assuming you have tried it already , what happens if you put more timing in it while on the Nos?? If your strickly on meth I cant see how it makes any power at 15 degrees timing and thats what it sounds like (down on power) but once it gets out past the 60' its much happier and you can hear the power difference. Does the Nos shut off by a timer or by a hobbs switch sensing boost?? Mike
Sorry Mike. I skipped right over this post. Didn't see it until I read the thread over again.
Yes, I've tried many different timing settings on the nitrous. The problem is this... The nitrous/methanol mix is so cold that you can only get away with a certain shot size. Any larger and the combustion temps are too cold to make additional power. The nitrous and methanol both actually quench the combustion temperatures as they dissociate in preparation for combustion.
There is a sweet spot with the shot size. I kept increasing the shot size until gains stopped, then backed off to the last shot size. The performance level of the shot size that I ended up with was clearly the best shot size judging by 60 foot times. That shot size limit per cylinder, for my engine setup turned out to be between 50 to 60 hp per cylinder. This is according to jet size rating. This is not the net hp produced in the cylinder, which is less due to the chilling affect of the mixture combination on the combustion process. I have come across another person that claimed 50 hp shot per cylinder was the limit he found, also.
I then played with different strategies of timing settings, spool valve operation, and then came the accidental discovery of the nitrous/methanol DT ALS while I was playing around with different timing settings for the nitrous in the garage. The nitrous with the spool valve was worth a tenth off the 60' using more timing on the nitrous. The nitrous/methanol DT ALS was worth two tenths without the spool valve in the picture. When I tried using the spool valve with the ALS, it was back to a one tenth gain. So now, I do not use the spool valve and only use the ALS.
The compromise with using the ALS is this... If I use more timing on the nitrous, it will produce more power,... in the cylinder, but it kills the ALS affect. Resulting boost rise is slow due to less exhaust heat generated.
By retarding the timing while on the nitrous, I make less power, in the cylinder, but increase exhaust temps and light off the portion of the nitrous/methanol mixture that made it past the cylinders unburned. The resulting boost rise is quicker, netting a quicker 60 foot. Since nitrous and methanol both contain their own oxygen supply, there's no need to drop cylinders like the gasoline fellas have to do to get their pop and bang deal. I end up with a smooth and consistent ignition in the exhaust system. You can't even tell it's happening. That's some of the roughness you hear in the exhaust tone during the first 60 feet of the pass. And, you're right. When the nitrous shuts down and the timing comes back in, the engine definitely likes it. But, the bottom line is this,... the ALS strategy nets the best 60' and that's what really counts, isn't it.
I use a timer to shut down the nitrous at 170-180 kPa in preparation for the 1-2 shift where I'm forced to control the boost to 14-15 psi for the shift. Then I let the boost start rising again halfway through the shift. So the boost is rising fast enough with this strategy that I actually have to level it off using a boost controller for the 1-2 shift to keep from overpowering the tires. I also use a pressure switch as a back up that will shut down the nitrous at 200 kPa.
