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Need help with nitrous problem...

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Old 07-07-2009, 05:54 PM
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Default Need help with nitrous problem...

First off I've run nitrous on cars before so I'm not COMPLETELY a beginner (posted this in the nitrous section also)...

Anyways, I'll give a short run down of my car quick and then what its doing.

Cam only (MS4 cam) ls1 Camaro w/ th400, regular bolt ons, 2 step, NX EFI nozzle kit with the big solenoids, twin in-tank walbro 255 pumps, TSI convertor (stalls at ~4000 with nitrous)...

So had the car together earlier this year, ran 11.9 on motor but wouldn't hold any sort of a shot before it blew through the convertor (stalled at 4000 on motor then). Pulled that convertor out and sent it back to TSI and had them set it up to stall at ~4000 on the nitrous hit... Took the car back to the track last week, car slowed down to a 12.3 @ 113on motor. Went to make a nitrous pass and the car went 11.6 @ 119 on a 150 shot... Meanwhile my buddy with almost the identical car picked up 12 mph in the 1/4 vs. my 6 mph.... The next pass my car only went 117 on the bottle... BTW I was spraying outta the hole with the car.. The car did not seem to run through the convertor, or outta gear or anything, still had room left on the big end.

I'm running a 62 n20 jet and a 33 fuel jet per NX recommendation... Pulled the nitrous line off the nozzle and I'm getting nitrous, and I know I'm getting fuel. Should be a simple setup that should go 125 or 126 on the 150 gun but obviously is not working.

So my question is does anyone have any suggestions, is it a convertor problem or? (a tight convertor shouldn't lose mph, and I don't know what the problem with the nitrous could be causing a loss of mph).

Any suggestions would be great...
Old 07-07-2009, 06:00 PM
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I would get a new converter builder. but that is just me.

good luck
Old 07-07-2009, 06:25 PM
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You're either knock retarding like MAD, or the converter is junk, or the tranny is slipping like mad.

What are the rpm's thru the traps, have you figured out what the slippage is?

What does the car dyno n/a? Beacuse I would think an auto car with a brake and a cam only motor should be running mid 11's n/a all day long, unless it's really heavy. What is the raceweight?


Something is definately not right, you're not gaining crap for a 150 shot. Hell my sled goes 10.4 on motor and 9.50 with a single 65 jet, and gains 15 mph You have a slip somewhere, or the motor is hurt. I'd get the car on a dyno and see what it does n/a.... I'm guessing you're gonna find out something is hurt.
Old 07-07-2009, 06:43 PM
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the motor runs fine... it does 390 on the motor (with the old 6 speed) with cam only and stock 853 heads... The trans has a fresh rebuild on it... I was kinda leaning toward the convertor as well... thinking I should pull the plugs and check them as well..
Old 07-07-2009, 07:15 PM
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Definately pull the plugs, good chance that if you didn't have the right ones there could be something missing.

Put a fresh set of #7 non projected tip ones in the car, gap them at 35 and if that doesn't get you anywhere, then I'd be looking at the converter.

Look at the trap mph, and rpm also. What were you crossing the traps at, what gearing/tire size are you running? I can give you a rough slippage from the trap mph and the rpm you are crossing at.
Old 07-07-2009, 07:58 PM
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I didn't log the run, but I'm pretty sure the car was at about 67-6800 rpms (not positive but it was in that range...). 28 tire, 3.89 gear,




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