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Discussion Starter #22
this might be a good idea lol
Let's not get ahead of ourselves. I'm pretty sure this is a bad idea but we'll find out soon enough. Bad decisions make good stories right? Just waiting for things to defrost a bit around here. Could maybe see a vid as early as next week if the weather holds.
 

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Discussion Starter #23
Just a quick update.
Good news = no damage or catastrophic failure.
Bad news = nothing exciting happened.

Went for a little test today and it was WAY rich. Instantly bottomed out my wideband O2 at 10.0:1 so in reality it was much lower than that. I incrementally added timing until I was +2deg ahead of stock, and concurrently took out -5 -10 -15 -20% fuel. Didn't need fancy electronics to tell it was still way off. Surprised I didn't foul a plug today.

Fuel/Nitrous jet ratios are always tricky but I knew this one was going to be some kinda special. Got it home, pulled the datalog, watched the vid's, and tomorrow we will be going with a .019 Nitrous and .009 fuel jet (previously .015 and .009 respectively). See what that gives us.
 

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Discussion Starter #24
So in order to get around the 13.5:1 AFR I kept increasing the nitrous jet size since I'm already using the smallest fuel jet available. I ended up at 0.026 N and 0.009 F which is mathematically adding about 16hp at the crank (Yikes)!

It went surprisingly well and I increased the PWM (valve flutter) until it was taking the full hit. Then it completely lost power and started spewing oil from the breather. Originally I thought I burnt a hole in the piston but after disassembly it turns out it was cracked. Looking at the datalog the AFR was perfect all the way through. Not too hot, just too much power for the little guy (and maybe a bit too much timing, I thought I heard a bit of pinging).

New piston and hardware is ordered and I'm going to max the PWM ramp out at 75% but keep the same jetting. Probably be at -5deg (over stock) timing advance. Was at -3deg at the time of failure. Stupid me I was on 95 octane when I have a jug of race gas right beside it. So it will be at 112 octane leaded next time (no frickin way I can pre det that on a 9.6:1 compression ratio!).

I have LOTS of footage that I'm filtering this weekend so will FOR SURE have a vid on the youtube channel this week (I'll post it here too).

Now I know for sure that the stock engine can handle a minimum of +10hp with a proper wet shot of nos and a very minimal ramp (0.25 seconds).

PS: Has anyone found a forged piston for the stock bore yet? I seriously can't find one.
 

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Discussion Starter #26
Well. I forgot something really really stupid and it took a friend of mine to point it out.

I didn't over gap the rings which explains the weird fracture. More heat = more expansion and the ring ends smack together. When that gap is gone the ring is forced tighter against the cylinder wall, which in turn quickly creates even more heat and more expansion.

Live and learn I guess. Glad I only forgot it here rather than on my ZX10.
 

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Discussion Starter #28
Update on the rebuild.

Have a new piston, rings, wristpin, circlips in there.
Stock ring gap :
0.0059-0.0118 Top
0.0118-0.0177 Second
Current ring gap:
0.014 Top
0.022 Second
Checked the oil control rings (the two that sandwich the wafer portion) and they were 0.017 out of the package so I gapped those to 0.022 as well.

Other changes:
Straight Fury 108 (Leaded)
Cooler plug (went from the stock 6 to a 7)
Indexed plug to the peak of the dome
PWM valve flutter at 75% (37ms closed for 13ms @ 20hz). No ramp.
Retarding timing by 5 degrees

Will try and test it out this week.
 
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