Direct proportion between shot size and A/F points?
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Joined: Jan 2004
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From: Los Angeles, CA
Direct proportion between shot size and A/F points? I'll be setting up a few nitrous systems in the future and would like to know if there is a rule of thumb relating the size of a shot to Air/Fuels. For instance, holding the fuel system as a constant, would a a 50 shot lean off the motor by one A/F point, a 100 shot two points? Just looking for some ideas.
Also, how do most people set up fueling for nitrous? Do you have an alternate fuel program that can be switched to when spraying? I'll be tuning the car from the ECU EPROM so, it'll be complicated to have 2 different tunes that can easily be switched. Do some people just richen up fueling so that spraying is safe, and live with the richness othewise?
Any advice or discussion about your suggestions or your previous NO2 setups is much appreciated.
Also, how do most people set up fueling for nitrous? Do you have an alternate fuel program that can be switched to when spraying? I'll be tuning the car from the ECU EPROM so, it'll be complicated to have 2 different tunes that can easily be switched. Do some people just richen up fueling so that spraying is safe, and live with the richness othewise?
Any advice or discussion about your suggestions or your previous NO2 setups is much appreciated.
Are we talking wet kits or dry kits? With a wet kit if the jet maps are correct your A/F ratio should always be constant as long as your fuel system can keep up, usaully around 11-11.8:1. With a dry kit it relighs on the MAF to add extra fuel and from my experiance with one I had to add fuel to my N/A tune everytime I stepped up the shot. If your going to spray a good sized shot with a dry kit (125+) you will need injectors, fuel pump and more than likley a serperate nitrous tune. With a wet kit you can pull fuel right off the rails and really all you need to do to your tune is pull some timing, you will need to add a fuel pump at about a 150 shot but you will not have to add injectors. 
As far as legality, in CA it's probrably illigal because of the emmisions ***** but in many areas it's illigal to have your bottle hooked up on the street do to the fact that many law makers are ignorant when it comes to the issue (a power adder is a power adder). Then you have areas like mine that the cops think it's cool and want a ride after work. Anyway, hide the bottle in the spare tire compartment and it should never be an issue for you.
BTW: In my first post I said that with the wet kit your A/F ratio should usauly always be costant (in the 11s). I meant that it should always be in the 11s when your only spraying and not N/A. Take my set up for example, N/A my A/F ratio is a steady 12.8-12.9, on the bottle (175 shot) my A/F ratio is 11-11.5. Now with my old dry 125 shot to get that to run 12:1 on the spray I was having to run my N/A tune at about 12.2:1.
BTW: In my first post I said that with the wet kit your A/F ratio should usauly always be costant (in the 11s). I meant that it should always be in the 11s when your only spraying and not N/A. Take my set up for example, N/A my A/F ratio is a steady 12.8-12.9, on the bottle (175 shot) my A/F ratio is 11-11.5. Now with my old dry 125 shot to get that to run 12:1 on the spray I was having to run my N/A tune at about 12.2:1.
Last edited by GM Muscle; Sep 16, 2004 at 05:45 PM.
Thread Starter
TECH Apprentice
Joined: Jan 2004
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From: Los Angeles, CA
I meant that it should always be in the 11s when your only spraying and not N/A. Take my set up for example, N/A my A/F ratio is a steady 12.8-12.9, on the bottle (175 shot) my A/F ratio is 11-11.5. Now with my old dry 125 shot to get that to run 12:1 on the spray I was having to run my N/A tune at about 12.2:1.
There are no "chips" to change in our LS1s. The ECU is reprogramable through the diagnostic port in the car and it pretty much takes two minutes to load a modified tune into the car. I personally use a stand alone handheld unit that is called a Predator. It is kind of like a Hypertech but allows you to adjust fuel and spark along with many other things. So for my current set up I tuned my N/A tune to have an A/F ratio of about 12.8:1 at WOT (I use an LM-1 Wideband to pull A/F ratio readings) and I set my timing to about 25* WOT (normally I would run close to 30* but I pulled 4-5* for the nitrous).
Thread Starter
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Joined: Jan 2004
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From: Los Angeles, CA
I'm not a Predator guy, I use LS1 edit and EPROM mapping software along with an LM-1. And yes (respectfully) every ECU does have a read only memory chip, what do you think you're reprogramming with your predator? I've soldered a socket onto my board for swaps and easy removal. I have actually read my entire Intel flash 800 chip, I know it's a little pointless considering I have LS1 edit. Not a huge fan of the Predator. It applies flat changes to every value in the fuel and/or timing maps which is hardly tuning.
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Ahh, I thought you where asking me how people change their tunes in general. So where you actually changing the Intel chip or you just reflash it? Never really heard of this set up or the EPROM mapping software (liek Autotap?) and I would like to know more about it. My Predator does just fine for me and my set up for now. Hoping the car throws down some good numbers at the track next week.
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TECH Apprentice
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From: Los Angeles, CA
I'd love to hear your numbers. Here's the deal with programming. LS1 edit and others don't actually read the entire chip, they read a segment that contains the engine running parameters. LS1 edit makes it easy by identifiying and describing the maps, as well as scaling the values so you're not modifiying the maps in hexadecimal (a programming language that includes numbers and letters A-F). So theoretically, there's really no reason to do what I did and mess around with the chip (unless you use LS1Edit to find where the maps are in the EPROM's hex code, then you can program as many cars as you want w/o buying the full version of LS1E, I haven't done any car but mine though and my company only does european cars so it was just kind of an exericse. Also the EPROMMING sofware cost my co. over 100K, so you're just running around in circles.) Hope to hear your results.