I have hit a wall with my car on spray. I'm new to nitrous so I started with a 150 shot to get used to it and worked my way up to a 250. For every 25hp I went up I gained about 2mph in the 1/8 until the 225 jet. On the 225 I only gained 1mph and the 250 didn't gain anything. My total timing on motor is 26.5* and I'm pulling 2* for every 50hp which looks good on the plugs. On the dyno I only went up to 200 but each jet was about 25hp under advertised on the chart. My motor makes 505/465 to the wheels NA and 673rwhp on the 200 jet. I'm not sure what is holding me back on the bigger jets but I'm thinking cam or maybe headers. Here is my setup.

2000 TA
ls2 402 from TSP
11.5 compression
Prc stage 3 ls6 heads shaved a little to bring up compression
Texas giant cam
Jet Hot 1 3/4 headers
3" catless Y into a muflex 4" catback
Fast ported 92/92
NX nitous kit with 92mm plate, 6an feed with 4an lines from solenoids to plate
running 93 octane with c16 in a stand alone

My converter has the same shift extension on the 200 jet vs the 250 jet so it doesn't seem to be picking up any power over that jet. Let me know what you guys think.

 

I ran into the same issue until I swapped my CAM for a dedicated Nitrous CAM from Martin Smallwood. Night and day difference - went from running low 10s to 9.60s on 300 shot in 3900 llb car. When your CAM isn't optimized for nitrous your tune hits a wall. As well, since your engine can only digest so much nitrous, the extra fuel you are adding makes your tune fat and you actually can end up slower on bigger shot. Just my two cents worth....

 

My guess is that you may have the need to increase ignition energy.

What coil, dwell, gap ?

Those who fit my IGN-1A coil kit report a great power increase and a LOWER Spark Advance setting.

Could that be your wall ?

Lance

 

Stock ls1 coils, NGK br8efs gapped at .030 and stock dwell.

 

Is this a single Fuel/N20 solenoid set up?
If it is a single Fuel/N20 solenoid set up, I am wondering if you are nearing the limit of the -4 line.

Which solenoids are they?

What size jets are in it?

 

Its the nitrous express 90mm plate kit. Lightning solenoids, 6an feed and 4an to the plate. My 250 jets that didn't pick up were 88/56.

This is the exact kit except I have a nitrous outlet 92mm plate.
http://www.nitrousexpress.com/20934-...lb-bottle.html

 

OK, I too agree with the "feed" line area concern.

Now, my "guess" could be confirmed by a Dwell Increase of 1ms.

When you increase coil energy, by raising dwell if possible, the ignition energy increase will be able ignite more fuel with a noted power increase.

What is you current coil dwell value ?

The coil you have has a "stall saver" used to protect the coil from a Dead Short if dwell goes above 5 ms.

Lance

 

My coils are stock ls1 coils and I haven't messed with the stock dwell time. I can try a set of truck coils and raising the dwell time in the Spring . I'm pulling the car apart for the Winter to freshen things up.

 

Can you measure the internal orfice of the n20 solenoid?

 

SURE, I would like to supply your "truck" coils as my version, my manufactured item, has a 10% output increase.
There is the cost factor, when you would compare the cost of the IGN-1A LS coil kit, the difference is only $100.00 in coil cost.

The final solution would be to report the MAX EVER NOS HP requirement ?

Again, I agree there of may be a "feed" problem of NOS.

All here should agree that when HP is increased a GREAT amount, a coil upgrage is ALSO required.

I would like to ADD, "You have a C-16 (dual fuel) wet system".

Many here in SoCal use Propane in the place of race fuel @ $2.85 a gallon.

This fueling style needs NO pump AND has an Octane rating of 130.

Here in my area, we sell/manufacture more of the NOS/Propane systems that "wet" systems

The fuel is COOL when the liquid propane is passed through the orifice then expanded into a gas state.

Lance

 

Lance, I am curious as to know how your coil differs from a factory unit. Is there a change to inductance, DCR, saturation....

 

OK, I have 200 different coils to chose from for your needs.

I will answer, easily, if I know the specific coil you have in your mind ?

Lance

 

What bottle pressure are you running? What exact jets do you have in the plate?

 

Bottle pressure is normally 925-950. Jets are 88/56 for 250 and 82/52 on the 225.

 

Sorry, I should have asked fuel psi as well

 

Fuel pressure is 10-11psi from the stand alone with c16 and 93oct in primary tank. A/F was around 12.0 going down to about 11.3 by the end of the run.

 

I think you've reached the point of starting to tune by spark plug. You're at 16.5 degrees right? I'd like to see a fresh plug with one hit on it to get an idea of where it's at.

 

I was at 16.5 on the 88 jet and 17.5 on the 82. The car is torn apart for the Winter so it will have to wait until Spring. I'm going to try to take out some weight and get 1 7/8 headers with manual cutouts over the winter. I will probably throw on a set of the good truck coils too just in case.

 

I may have found the problem last night. My thrust bearing is taking a **** so I'm tearing down the motor. I found a broken lifter on one of the intake valves that has likely been that way for years. The valve train with this cam is noisy and the car has always ran fine but the cup in the pushrod cup was broken and the metal seal was missing under it. The lifter has probably not been pumping all the way up so that intake valve was probably only opening part of the way. Guess I will find out in the Spring.