NVetro

I am just about ready to start spraying my 383 lt1 nitrous motor...she is at 11:1 compression and runs 93 pump gas...tune is pretty much dead on....I am going to be retarding timing with an MSD digital 6 box...and running a NX wet kit jetted anywhere from 75 to 250 shot...I am also going to have a dedicated fuel cell for the nitrous system. My question was the following, I have disabled my knock sensor as it was going crazy reading false knock more then likley because of my moroso solid motor mounts and/or exhaust being very close to the body. I tried the whole tourlene in the tank to confirm that it wasnt detonating and I had the same result. I had my tuner disable the knock sensor at that point.

My question is, if im running 93 in my tank, what should i run in the nitorus system fuel cell for a shot ranging from a 75 to 250? Should I just keep 116 octane in the cell and 93 in the tank to make sure she doesnt detonate?

Thanks in advance!

Nostang 96z

C16 in the cell and 93 pump gas in the tank. I ran up to a 250 shot and never had any detonation problems. Take out 6-8 degrees for a 150 shot and ~10 for a 200. If you run some C10 in the gas tank with the C16 then you can add more timing (4 degrees retard for 150 shot, 6 for 200 and 8 for 250). If you are running a single fogger with the stock intake I would limit the shot to 200 as anything over will start to melt the back plugs due to distribution problems. BTW-I also had my knock sensor disabled. Make sure you use a wideband and run ~11.4 AFR with the above fuels.

NVetro

Nostang: Thanks for the reply...I think i'll keep 93 in the tank and 116 (c16) in the fuel cell. As for the kit its a NX wet kit with a MAF plate as distribution and the shot will range from 75-250...I should be ok right? Meaning distribution wise, dont want a burn up any plugs or damage anything. Running NGX tr6's gapped at .035.....I am just under 13:1 A/F here is my N/A dyno graph..think ill have any issues?

Ray@NitroDaves

C16 in the dedicated...I also would not go above 200, from the front of the intake, without paying close attention to the distribution.

NVetro

What would be the result of a 250 shot from the front of the intake, what can be damaged? I thought a lot of people spray a 250 via a maf, tb plate, or shark nozzle. Curious.

Nostang 96z

Your A/F Ratio N/A is perfectly fine. You will want to run a little rich on the bottle especially with pump gas. So shoot for 11.4 AFR. You might have to go with a smaller fuel jet to get the AFR correct. Mine started out at 10.0 AFR and I had to lean it out from there. I only tried a 250 shot once and the car only made it to the top of second gear and I felt a small hickup so I let out. I was on my way to a 9.8 pass judging by the 1/8 mile ET /mph but the hickup scared me. Turns out I melted the 2 rear plugs down to nothign that quickly. The Lt1 intakes do not work well with big shots due to the distribution issues. 200 will be plenty scary for you so I wouldn't risk it going with a 250 shot. Just dial it is on the 200 and you will have plenty of hp/tq.

NVetro

As for distribution....my car has a ram air setup not the stock style cold air intake setup...I will be using the MAF distirbution system...isn't this pretty much a direct to the intake manifold? I can understand how if i used a stock style cold air intake this would be a problem with the elbow, but is it still an issue if i'm using ram air with a smooth bellow?

Nostang 96z

The problem is not with the intake tubing in front of the throttle body but with the design of the intake itself. Whenever you are spraying a single/double fogger in the front of the intake opening you are running the risk of distribution problems with the bigger shots. The problem is that the fuel is denser than nitrous and tends to go to the front cylinders first and the back cylinders get more nitrous than fuel (even though the fogger atomized the mixure). The only way around this is to run a direct port for anything over a 200 shot. If you could put an EGT meter on each header tube you would see that the rear cylinders will run very hot compared to the front (even though the AFR could be safe and/or spot on). The problem with wideband 02's is that they only take the average of the cylinders and compute an AFR based on the average without taking into account the cylinder to cylinder variances. That is reason I said to shoot for 11.4-1 AFR. I actually added 10% to my 2 rear cylinders just to help with the distribution issues with the 200 shot but this is only a band aid unless you EGT and fine tune the cylinders. If you are going to get to that level you would be better off going direct port.

NVetro

hmmm....perhaps ill stay at about 200 max then...we will see what happens. A 250 shot every now and then i'm sure is ok though right?

Nostang 96z

Just be very careful if you do spray a 250 hit on it. Check the plugs very closely and if you feel any surge or studder get out of it. Although I have a feeling once you feel a 150 shot you will find that to be plenty..esp with a T56 and your current power level. You will def have trouble hooking up. Just remember, the best forged parts cannot stand up to detonation.

97SS0594

i sprayed a 400 shot through my 355 from the front, did it in 2 200 shot stages, no problems, and the plugs where all equaly worn. intake was bone stock. i sprayed about 300lbs of nitrous through it over 2 years motor was fine. pulled the motor put it in another car and that car ran till an electrical gremlin got hot and the car burned to the ground.