lean a/f
05-27-2006, 05:15 PM
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Launching!
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lean a/f I've got a 355"95 z with ported afr's,big hydraulic cam, th400,3800 verter,etc,etc.
I went to the dyno yesterday and put close to 400hp to the wheels naturally aspirated. I then added some 100 unleaded fuel. I have a nx dp kit jetted for a 200 shot. The car Na peaks at 6600. I have a dedicated pump for the nitrous. Basically I couldn't get the a/f richer than a 13.5. I had also pulled out 8 degrees of timing from my msd timing control, but the knock sensors still pulled another 4 out. NA timing is at 37 degrees. I believe that the piston in the fuel solenoid is bad, because I had my holley blue flowing almost max at 13 psi, and I started out 9 psi. After increasing pressure 4psi, it only changed my a/f by 1/2 point. It picked up a litle over a hundred horse at 5600 and was pulling 4 degrees of timing out. I've got a new piston on the way for the fuel solenoid. Any idea on how much hp can be gained by richening the a/f down to a 11.5? At 5600 NA the car put 349hp down with a a/f of 13.25.
I went to the dyno yesterday and put close to 400hp to the wheels naturally aspirated. I then added some 100 unleaded fuel. I have a nx dp kit jetted for a 200 shot. The car Na peaks at 6600. I have a dedicated pump for the nitrous. Basically I couldn't get the a/f richer than a 13.5. I had also pulled out 8 degrees of timing from my msd timing control, but the knock sensors still pulled another 4 out. NA timing is at 37 degrees. I believe that the piston in the fuel solenoid is bad, because I had my holley blue flowing almost max at 13 psi, and I started out 9 psi. After increasing pressure 4psi, it only changed my a/f by 1/2 point. It picked up a litle over a hundred horse at 5600 and was pulling 4 degrees of timing out. I've got a new piston on the way for the fuel solenoid. Any idea on how much hp can be gained by richening the a/f down to a 11.5? At 5600 NA the car put 349hp down with a a/f of 13.25.
05-28-2006, 04:25 PM
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Well when you say "bad" talking about the solenoid do you mean completely dead??? cause your a/f ratio would probably be alot worse than 13.5:1 if that solenoid was providing ZERO fuel..... The car would most likely ping like a ************ as sooon as you sprayed it especially on a 200 shot!.... You said power was climbing and you did pick up power although it was only 100hp from what you said.....
Your timing plan is right as I see you're using the 2 degree per 50hp rule which is good.... I might even use 36 degrees as a baseline advance though and see what it does to your NA power.... if you don't lose any i'd keep it at 36 and start pulling timing from there.... You say you have a dedicated pump for your nitrous but how do you have it plumbed???? Same tank, dedicated cell???? Seperate lines??? I'm just trying to get a picture of how you have it setup so i can brainstorm some possible problems....
As far as your power increase depending on your type of kit (you said NX I believe) you should be getting very close at the wheels to the rating of your kit..... I would also check your jetting in your kit again.... I've seen direct port kits where guys have confused the jetting and put the fuel jets in the nitrous nozzles and vice versa.... I know that sounds outrageous but believe me it's something you might want to check just to make sure....
Your timing plan is right as I see you're using the 2 degree per 50hp rule which is good.... I might even use 36 degrees as a baseline advance though and see what it does to your NA power.... if you don't lose any i'd keep it at 36 and start pulling timing from there.... You say you have a dedicated pump for your nitrous but how do you have it plumbed???? Same tank, dedicated cell???? Seperate lines??? I'm just trying to get a picture of how you have it setup so i can brainstorm some possible problems....
As far as your power increase depending on your type of kit (you said NX I believe) you should be getting very close at the wheels to the rating of your kit..... I would also check your jetting in your kit again.... I've seen direct port kits where guys have confused the jetting and put the fuel jets in the nitrous nozzles and vice versa.... I know that sounds outrageous but believe me it's something you might want to check just to make sure....
05-28-2006, 06:29 PM
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Launching!
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no, the psiton I believe is bad in the solenoid. I picked up about 8-10 horse by running 37 degrees instead of 35. I have a sumop coming out of my tank, and all of the lines are seperate from the main pump. The jets are 26 nitrous 20 fuel, which is right for a 200 shot. I'm going to put 24 fuel in though, and just back the pressure off a tad.
05-28-2006, 06:54 PM
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yeah see if the solenoid is bad and try that first.... just keep checking your plugs to make sure you aren't going dangerously lean.... And I would definitely keep using good gas if you're runnin 13.5:1 on a 200 hit.... So you have a sump in the tank with a seperate line feeding the fuel solenoid from your stock tank???? And the engine is fed by the stock lines still????
05-28-2006, 09:23 PM
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there is a sump on the stock tank, and the engine fed by stock lines and 37lb injectors with a 255lph intank. I ran 100 unleaded, but I think next time I'm going to run 112 leaded like I use to.