I did a search, but I'm still concerned. I've been having this problem intermittently for about two years.

I made a pass at the track on the bottle and it surged on the top end, right after 3rd gear. The whole pass was logged on my wideband. A/F started out at around 12.2 and dropped to around 11.4 after the pass. Bottle psi was at 1050, but it dropped to 1000 after the pass. This was on a nx 150 wet shot using 62n 31f jets. I leaned the fuel I side a little. No kink in the lines, grounds are tight and clean and the nitrous filter was clean. TR6 plugs gapped at .033. Racetronix hotwire kit. HSW plate. Bypassed the FPSS. Main nitrous line about a year old. Fuel filter changed a few thousand miles ago. MSD pill window switch 3400 on, 6400 off. Timing set at 20* for the bottle with a flip of a switch.

If the car wasn't getting enough fuel, wouldn't it show up on the wideband and lean out? Could a 11.4 A/F be too rich causing a surge? Bigger feed line?

 

The 12.2 to 11.4 is a pretty good drop. Is it a gradual drop or does it spike 12.2 and instantly go to 11.4?

 

whats your AF N/A and does it surge on motor?


can you describe your version of "surging"?

You spraying thru the shifts or have it cutting off before a shift?

 

The A/F gradually drops on nitrous. It runs strong N/A with no surging at all, but I noticed the A/F gradually dropped on my N/A runs also. N/A, it starts out at around 13.2 and it stays there for awhile, but gradually drops to around 12.7 near the 1/4. The surging on the bottle is more like a slight hesitation. Shift points are at around 65-6700 rpms with the window switch cutting it off at 6400. What I did notice only on the bottle passes is that is still shifts hard on 1-2, but it lags on 2-3. Built trans with a shift kit last year.

 

How is the bottle mounted? You say its intermittent, how often does it do it? And does it do it all the time?

Nick

 

Tht bottle is mounted at around a 15* angle (almost flat) with the nitrous fitting and line downward.

The surging occurs about half of the time.

At my power level (400 rwhp n/a), I should gain more than 10 mph on a 150 shot. I was expecting more like 11-13 mph.

 

I had my N20 cutting off 200 rpms before my shifts (6600), and it would surge too... Reason (my reasoning) is you loose that extra HP when the spray turns off and causes the car to shift on N/A so it kind of back pedals.. So, I bumped the N20 cut off to match the shifts and it went away. But, I dont know if I would call it a surge, but more of a bog. Try it and see if it goes away.

And to be safe bump up your REV limiter the same or a little more.

 

I never "felt" it surge on a 1-2 shift, probably due to the shift kit. The kit (stage 2) makes it hit alot harder on a 1-2 for some odd reason. I'll put a 6600 pill in there (basically spraying through shifts) to see if that'll helped.

Anyone else with more suggestions?

 

The RPMS are alot faster from 1st to 2nd so you wont feel the N20 turn off, then shift.... When its getting up top, the RPMS slow down so you will feel it and the spray has time to turn off. Hope it makes since, whats your REV limiter set at? Just asking as you might want to widen the gap a little from the shifts.

I have a Stage V trans, so I know what your talking about.

 

That does make sense. My rev limiter is set at 6900.