CK5
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The Shop Truck

1971 Chevy C20 with a custom flat bed.
Just to be clear I would use a 75 or 100 shot with your boost assuming you:

- take some timing out, normally I prefer fixed timing on the bottle but since you have a supercharger too that won't work so I would probably pull out 1 degree for every 25 HP.
- can add the appropriate fuel with the injectors
- have a strong enough bottom end and ring gap to take it (you should if you are running boost)

I know you already probably know this just being clear for anyone watching.
I understand what you are saying, the engine is built to handle 1700hp, so a 100-200 shot would be fine. I'm a bit gun shy with it though since I melted the head last time.
I got a log today, we're not racing again until Friday, so I have time to review the log and come up with a tune. The next track is also not very good, so I need to take that into consideration.
I'm not sure if you are aware, but this is literally my first drag competition, I've only ever done test and tune.
I'm incredibly pleased with the trucks performance and I will be turning it up, but slowly. During the test session, I was only at 75% duty cycle, so I have some head room, plus I'm only at 45psi base pressure so I could turn that up a bit. I just need to keep an eye on the pressure as I only have a 3.5gpm pump.
 
Watch the plugs, that's where it's at. Especially the one you melted the head in, was that on boost only or N2O as well? What was your timing? The plugs can tell you not only if your A/F but also if your ignition timing is close and if there are any signs of detonation creeping up. The O2 sensors don't tell you all that. If you are worried go with a 50 shot and a 2 degree retard and check the plugs. If all is good then go 75 with 3 degrees, then 100 with 4. Each time you can check the plugs for timing and detonation before you increase it the shot and you can adjust the timing based on your findings. Those are such small increments that you should see it coming before it causes damage. Normally I would start at 100 and then go up in 50 -100 HP increments depending on how it was going, but with two power adders I can understand smaller changes. One time I saw some tiny spots with a magnifier (just a 7x eye cone), so I backed it off 3 jet sizes and they went away, this was with pump gasoline.

Are your injectors flow matched or have you had them flow tested?
 
As for evap freezing, adjust your liw pressure switch to open at 35 psi. Should be an adjustment screw between terminals.

Looks like your having fun and enjoying all that hot hard work
 
The injectors are flow matched, I have EGT probes as well and my tuner did some cyl to cyl adjustments so I should be good there.
It's crazy, but I'm in the running for a trophy in the Nitrous class. 2nd place slowed way down yesterday and our average is only .082 off now, so even 2nd is in range. I was not expecting that on my first go.
1787230156461.png
 
Also, I had already planned on doing what you said, 25hp increments. I'm also going to bump my 2 step from 3000 to 3200 if my torque converter will let me (2500 stall).
 

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