i recently changed my nitrous setup to a stand alone fuel system and put in a nitrous outlet plate. i put a 91 jet in the nitrous and a 82 jet in the fuel and set my regulator at 6.5 psi. i put it on the dyno friday nite and on motor it was the same as last year, i did very little tweaking to get the a/f correct and when i sprayed i set up the fjo progressive to start at 50% and end at 75% with a 2 sec ramp. it then made 436 to the tire(this was on a mustang dyno so the numbers will be lower) i thought that seemed a lil low but went ahead and set it to 100% and only increased to 444 ! (and with my old setup with a nitrous works plate and a 175 shot it made 456hp).thats alot less than the 550 i was hoping for. air fuel was 11.2 to 11.7 all the way through except after 6 grand it went to 10.9. i was running from 3000 rpm to 6000 rpm. and the last pull i went to 6200 rpm thats where it went fat, no biggie since i shift at 5900 anyway.

any ideas on why it would be less power with a bigger shot?

 

what was your old fp, was it hooked up to the fuel rail?

 

the old fuel pressure wont matter because the nitrous is on its own fuel system now. No not hooked to rail its stand alone, got its own fuel cell and pump just for the fuel solenoid.

 

What nitrous solenoid are you using?

 

im using the cfn 1803 and 1804 from cold fusion. # 4 line from bottle to solenoid, and #6 from fuel regulator to solenoid. and a #3 from both solenoids to plate

http://www.coldfusionnitrous.com/Sol...x?CategoryID=2

 

Could be your #3 line from the solenoid to the plate. I am using the -4 line from NX, I think is is called the SHO line. Use it on the nitrous solenoid only, costs like $26 bucks, worth a try. You might be flowing to much for the #3 line.

 

I'll throw this out there I have seen engine's with more spray put in them then they could handle. And actually created so much trublance in the intake tract it lost Hp I'm sure this isn't your case With those kind of basline numbers I'd say you've had some head work...

 

yeah the heads have some minor port work. i just dont understand it, maybe the plate wont handle as much as i was told it would.

 

What is the rest of your combo?

 

maybe your are starting to lose some compression.maybe your heads cant support the the air flow for extra spray.i have read that some times that the motors will only use so much spray and then any more wont do any good.

 

You need to play with the tune. I didn't work out the numbers, but I suspect you need more fuel.

Rich

 

388ci stock heads with some minor portwork,intake ported as well.30 lb fms injectors comp 503 cam.1.6 s/s rockers comp.58mm tb. headers, no cats. 3 inch y pipe with a 3 inch bullet and a 4 inch turndown, walbro 255. , no heat or ac, msd opti. and coil.built manual valve body 4l60e trans with a m&m 10inch 3000 converter. 12 bolt with a spool and 3.73's

stand alone 1 gallon cell with a holley blue pump and holley regulator set at 6.5 psi, right now on spray the a/f is averages 11.5 all the way across the board, nitrous outlet plate for a 58mm tb.

 

compression is fine runs the same on motor as it did last year 11.80's, and the same on the 300 shot as it does with the 175 shot

 

Sounds like the heads and cam combo are the restriction.
My 355 made 383rwhp through a th400 and 535rwhp on a 150 shot on a dynojet (I had a 235 242 112lsa cam and GTP stage 2 ported LT4 heads.). I never dynoed it on the 200 shot but I picked up ~4mph in the 1/4. I was using the NX SHO single fogger kit with a custom stand alone fuel system like yours. How much rwhp are you making NA?

 

it made 310 on a mustang dyno n/a last year and this year again made 309