The Shop Truck

[r3dd0g]

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.

 

[ktmoutfront]

Please remember us little people, now that you are famous.

 

[r3dd0g]

We made it to our hotel. No issues other than being tired, don't have to leave until 11 tomorrow so we can sleep in.

 

[Fastereddie]

I hear you on being n2o gun shy after all you been through.

 

[Babaganoosh]

Don’t send it until the last day if you do, we are all rooting for you to make the drive.

 

[folkenheath]

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?

 

[Wes Harden]

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

 

[r3dd0g]

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.

 

[r3dd0g]

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).

 

[folkenheath]

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).

Yeah I figured that when you started so low.

I went back and looked and found where you were having trouble with melting 7 and 8, was just curious. I only read a couple threads, not much time.

Are you still using these plugs? If so get rid of the pointed tip plugs, they can cause detonation when you are pushing things. Just get a regular tip NGK plug. Maybe even a non projector tip. Call NGK and talk them, if you get the race guy they are really good with that.

We're home, Amber unloaded while I tore the engine down with a friend. There is clearly something else going on with #8, my datalogs for the final run looked better than any of the previous ones, but the damage says something different.

The valve is torched and tuliped, the seat seems OK but it burned out some material from under it, the spark plug was stuck and took the threads with it when I finally worked it back and forth enough to get it out.
I'm hoping it's repairable, but I'm not sure. I'm hoping to find that out tomorrow. The piston looks fine, I need to turn the engine over to look at the cylinder wall, but I'm assuming it will be fine.
The other 7 plugs looked fine after the run, the rest of the valves on that side look fine, when I made the tune for the last run I took an additional 1° of timing out across the board (16°), reduced the target AFR by another .2, added 20% more fuel, pulled 2° more out of #8 (for 6° extra and a total of 22° pulled on #8) and added 15% more fuel to #8. I thought we were being safe, but the picture says something different.

Did you ever figure that out? That looks to me like the valve wasn't sealed correctly and a valve leak with nitrous created that plasma like jet that burned the valve and melted the head. That's probably why the piston was fine.

 

[r3dd0g]