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Need help lost power with bigger shot

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Old Feb 6, 2019 | 11:13 PM
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Default Need help lost power with bigger shot

Hey so my current setup is a lsx 454
I just installed a holley hi ram intake with a direct port setup, my old setup was a mamo ported msd with a direct port setup.
the intake swap picked up power and torque everywhere I will post pics of the graph,
on nitrous I made 870whp on a 200shot through the msd and dropped down to 830whp but with a massive torque gain on a 250 shot.
I will post both graphs,
We started with nitrous express recommended jetting for a 250 shot, 29n 22f at 8-10psi on the fuel side,
it ran crazy rich around 10:1afr, we did another pull dropped fuel pressure to 7 psi, still crazy rich,
we ended up doing 4 pulls on the last pull we were down to 5.5psi on the fuel and still around 10.8:1 afr and continued to lose power,
I have checked all my jets to make sure they are correct, I pulled nitrous solenoids off and checked inlet screen, me and my tuner are not sure where the restriction could be coming from, or are we losing that much power just from the rich condition

let me know if anyone can help, I plan on flowing the system tommorow to ensure I'm getting the proper amount of nitrous through the jets.

thank you

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Old Feb 6, 2019 | 11:15 PM
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Old Feb 7, 2019 | 09:19 AM
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The jets supplied are usually just safe starting points. Normally on a 5-10psi fuel system a 10 jet spread is a good starting point. What sucks with a direct port is that's a lot of jets to by to get all the shots tuned in. Being that rich I'd more than likely try swapping the jets you already have. Example, 250n with 200f jets or 300n and 250f jets. Bump the pressure back to 10psi and start over.
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Old Feb 7, 2019 | 10:34 AM
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What size feed line?
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Old Feb 7, 2019 | 10:48 AM
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Originally Posted by tug686spd
The jets supplied are usually just safe starting points. Normally on a 5-10psi fuel system a 10 jet spread is a good starting point. What sucks with a direct port is that's a lot of jets to by to get all the shots tuned in. Being that rich I'd more than likely try swapping the jets you already have. Example, 250n with 200f jets or 300n and 250f jets. Bump the pressure back to 10psi and start over.
Yes that's what I was going to try today was drop my fuel jet to a 20 or 19 and see how it goes,
Originally Posted by brandon@nitrousoutlet
What size feed line?
I have a -6 feed lines feed line is the same that was used with previous intake as well.

thanks for the replies!
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Old Feb 7, 2019 | 10:59 AM
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For reference, our jet chart calls for 28/22 @ 5psi which would still be rich. A jet change is likely in order.
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Old Feb 7, 2019 | 11:12 AM
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Originally Posted by brandon@nitrousoutlet
For reference, our jet chart calls for 28/22 @ 5psi which would still be rich. A jet change is likely in order.
thanks I have a set of 20f jets I will try to put in now and start out at 10 psi and see if it runs better!
thank you
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Old Feb 7, 2019 | 11:14 AM
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I used a 29 N2O and 19 fuel at 10 psi on my N.O. Direct Port (Ported 102mm Fast) which put A/F around 12.75:1. Ran 9.44 at 145 in my 3800 llb car hitting limiter on both 1-2 and 2-3 as still sorting out shift points....
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Old Feb 7, 2019 | 11:36 AM
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Originally Posted by CanadianEh!
I used a 29 N2O and 19 fuel at 10 psi on my N.O. Direct Port (Ported 102mm Fast) which put A/F around 12.75:1. Ran 9.44 at 145 in my 3800 llb car hitting limiter on both 1-2 and 2-3 as still sorting out shift points....
thanks for the info I just put some 20 jets in the car, I'm going to wait for it to warm up a little outside and go test it out!
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Old Feb 7, 2019 | 03:00 PM
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I'm definitely interested in seeing you afr and hp results with the jet change.
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Old Feb 8, 2019 | 12:20 AM
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Got the jets swapped out and my bottles filled, hopefully it warms up a little tommorow so I can go out and test it. Thanks for the help
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