Nitrous Surging and No Gain
Thread Starter
Teching In
Joined: Aug 2010
Posts: 7
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From: Monticello, MS
Nitrous Surging and No Gain Hey guys I recently got my car back on the track after head/lifter swap and am having nitrous issues. I've made many nitrous passes before swapping heads and the car never really picked up a whole lot above 150 tuneup and now it doesn't pick up any ET above 150 shot. I assumed the issue was the 317 heads i had before were choking my motor and figured after swapping to the trickflow 245 cathedral heads with btr nitrous exhaust port it would take the bigger hits but it is much worse. I am running the Nitrous Outlet 102mm wet plate kit. Last trip out the car went 6.4 all three nitrous passes. First pass 150 shot second pass 250 and third pass 300. NOW after looking back through logs the 150 shot averaged 12.0 -12.5 afr, the 250 averaged 10.5 - 11.0 and the 300 shot averaged 10.0 - 10.5 afr. The car made a solid pass on the 150 shot but the 250 and 300 were surging all the way down the track. I assume this is because it is wayyy too fat. I used recommended Nitrous outlet jetting on the 150 and the 250 shot and went down a fuel jet on the 300. 250 jets were 88 nitrous 39 fuel jet. 300 jets were 99 nitrous 41 fuel jet. I was running B8EFS plugs with factory gap and have recently swapped to 10s with .020 gap. Could the extremely rich condition be the cause of the terrible performance/surging and could the rich condition be caused by spark blowout? Also i pulled 2 degrees timing on 150 and 10 on both 250 and 300. Engine Specs below.
414 CI LS
Fast 102 Intake
Trickflow 245 Heads with N20 Port
Comp Short Travel Lifters
LJMS Cam 245 262 .624 .595 113+5 108
Nitrous Outlet 102 Wet Plate Kit
414 CI LS
Fast 102 Intake
Trickflow 245 Heads with N20 Port
Comp Short Travel Lifters
LJMS Cam 245 262 .624 .595 113+5 108
Nitrous Outlet 102 Wet Plate Kit
That's definitely rich and hurting power. What size and length supply line are you running? I've got a vid somewhere of trying to flow a dual stage 4150 plate wide open through a standard 15' 4an supply line. The nitrous pulses non stop from the time you open the noid to the time you shut. Didn't weigh the bottle but I'm guessing 200-220 is all it was moving.
What size headers are you running and details on the rest of the exhaust would help. Nitrous needs to be able to get rid of exhaust to allow it to accept the incoming charge. Bigger is better when it comes to exhaust on nitrous. I run twin 3 inch cut-offs right off the headers... also I run a #10 on the 300 shot and A/F around 13:1. I would aim for the same A/F as N/A.
