2nd stage tuning

[ojh]

John, i have heard that when you go to a second stage the tuneup tends to lean out. Would you learn us a bit on that?
And, i have heard talk of leaning the motor by going to a smaller fuel pill and then raise the fuel pressure. If so wouldn't the result be about the same, that is a smaller jet at higher pressure would equal a larger jet at a lower pressure. There is something in this principle that i don't catch on to, learn us something on that too.
btw, one of the best tech pieces i have ever read is the plug read, esp the motorcycle guy. I've read it a couple times now and still find new stuff in there that i didn't grasp. I will read it again in a couple weeks, we need to give an 'atta boy' to whomever put that together. Thanks for all your help, oj

[John_Heard]

I'm not really sure why when adding stages (or perhaps it's higher volumes of nitrous) tune ups tend to be happier leaner than low volumes. Perhaps it's that the engine is less tolerant of excessive fuel, maybe it's got to do with flow restrictions. I'm not really sure why that is. I do know that if you take this to the extremes, say a 125 shot vs a 700 shot, the 125 shot tuneup isn't all that picky and you're not likely going to hurt something if you're off by a country mile. On the other hand, that 700 shot better be on the money or you're going to hurt something.

The deal with the fuel pressure is at a higher pressure, if your fuel pressure fluctuates, the % of change is going to likely be lower than at a low pressure, which gives you a more stable tuneup. To add to that, regulators like the little holley 12-803 like many use don't really like running down around 4lbs. Personally, I would much rather tweak fuel pressure than yanking jets, especially on a fogger, so running a higher pressure gives me more latitude in making tuneup changes via the regulator.

[ojh]

Just a followup on the second-stage thing, we tried it for the first time last sat. John slept a bit on the tree and hit the second stage along with high gear. It came on for for 1.4 seconds and picked us up from a 4.40/.41 to a sweet 4.30 flat. We're gonna try it at the hit and see if we can"t get a .96 60' - we're low .98's now. This stuff sure is fun.

[John_Heard]

That's awesome - remind me again what class this car runs? 4.30's is a very competitive Outlaw 10.5 car

[ojh]

T/S 116P running as a 'big tire outlaw' or some such name.