just want to make sure i am on the right track.

any detonation evidence (silver specs) on the porcelain can be matched roughly to the load it occurs at by the location.

at the top right by the electrode is idle and very low load

around the middle near or just below the base ring is light to moderate load

way down the porcelain by the base is from very high load/wot.

i remember hearing/reading this years back and i want to be sure its valid

also if black spots are carbon, silver i believe to be aluminum, what about white but not shiny spots. coolant? impurities in the gas?

 

That's pretty accurate, but you can't reliably tune a modern engine by the spark plugs, you need some method of knock detection.
White can still be detonation under lean conditions, but it also occurs with impurities and certainly with coolant.

 

certainly no lean conditions i am mid 14s and richer on my motor and the wideband was verified with my other wideband/new sensor. what makes it tough for me is that at wot run/immediate shutdown the plugs are clean so my possible bullshit is taking place under light to moderate load somewhere. i know what you mean about needing knock detection. i got a little something in the mail as we speak. thank you for the reply i just wanted to make sure i wasnt out in left field on this

 

mid 14s at wot?

 

no good lord no. im a ***** when it comes to running an on the edge tune. im like 12.8-13.1 at wot at the moment. anything from 6-7" to about 1" is 13.3-13.6:1. it goes from 13's to 14.0:1 at about 10" and transitions to 15:1 at 20". pretty standard afr if you ask me.


my issue on this motor at the moment is leaky intake valve seals. just did a comp check a few days ago and im 230-240psi and leakdown is 10ish % and under. i dont have the opportunity to replace the guides at the moment, so tomorrow im putting a new set of valve seals in to buy me at least till christmas before they start leaking bad like the current set. in the interim im gonna look for a cheap head and replace the guides in that, with the intent of swapping heads during the week off i have between christmas to new years

 

Even if your collective AFR is stable you may have one cylinder leaner and the other three compensating richer - this is especially common with B series; you may want to try an EGT probe to rule that out. how high is your compression?

 

egt is in the 3rd runner, 2" from the head. if i hammer through 2nd,3rd,4th i see about 700-720c at the top of 4th. highway cruising is usually 650-700c. i do have #3 cyl with a 2 or 3 in the neptune individual cyl compensation. whats the max i should be seeing, and whats considered too much to have to adjust individual cyls

i know with the old rc 310s i had the plugs all had different carbon amount having me change up the cyl trims a good amount. i recent got a set of precision 525cc and the plugs look much more even. side note one of the new injectors dropped part of its o ring into the cylinder while running. i could see part of it melted to the top of the piston lol. i think most of it was in and out though i got lucky i didnt loose much compression or leakdown from it


compression should be right at 12:1 (ls block/crank/rods with p30 pistons and b16 head. head and block have a few thousandths off collectively to true them up). im only using itr cams though so it doesnt bleed much compression out

last week i mixed in 1 gallon of c12 to about 9 gallons of 93. i figure it brought my octane up to around 95-96 and it certainly solved any issue of spots on my plugs. thursday i replaced my leaky intake valve seals so far so good. piston tops are dry again and plugs look clean

 

If you have more than 5% offset per cylinder then you need to rebuild. Forced induction max 10% offset. 2 or 3% is fine, and pretty common. You should compare each cylinder EGT at the same load to determine if one is leaner than the other.
For 12:1 CR on pump gas your high load AFR should be closer to 12.5:1 and mid-range in the low 13's. Unless you change your rod length or quench zone, you might be able to lean out then.
If your head is polished you might want to resurface the ports with a crosshatch pattern instead to keep the fuel off the walls.
Otherwise it may just be your intake manifold causing a flow offset, a low budget IM without proper resonance testing can certainly have delivery issues.

 

Head is stock ports.

As for the intake manifold i was going back and forth between p30 and sk2pro series. i settled on pro series it needed more fuel above 6500 rpm so i assume a bit more hp

i didnt know cruising afr needed to be richer like. high 13s rather than low to mid 14s ill fix that on the way home from work today

 

Yep the skunk2 IM flows much better than the stock P30. shorter runners means more power up top also.
at 12:1 CR you've basically forfeited any option for fuel economy, it needs more fuel in all areas to slow down that volatile combustion.
A longer stroke can combat detonation (and valve contact) since the piston sees less time at TDC. oh and that higher displacement is a nice perk too I guess

 

ill be honest im seeing right about 30mph at the moment mixed city/highway. i must have 4 or 5 good condition 89mm cranks, so it was a no brainer to use. i know i could use cams with bigger primaries to bleed it out a bit, but i have to get it to run and pass obd2 inspection on a stock ecu so i couldnt go too nuts. plus in the winter when i leave for work its often in the single digits or low teens for temperature idk how much a cammed motor would want to run well

i brought all the afr down about half a point or so on the ride home from work. i also got my ghetto knock detection (the listen up hearing aid trick with the mic extended and resoldered so i can get mount it to the block and listen in the cabin.) gonna give it a try tomorrow on the way home from work see if it works. it seems to have some decent feedback from people who have used it as an alternative to det cans or a low cost knock sensor..

thanks for the help. high compression is pretty new territory to me most stuff i do is 10:1 or less forced induction

 

There are OBD2 retrofit ECUs that pass smog inspection, Hondata used to carry them, and I manufacture them. They don't have full communication but that's only a requirement for 04+ vehicles.
I had a 225whp all-motor GSR that passed Colorado emissions on an e85 mix. Just takes some clever tuning. All motor engines can definitely be more challenging to tune IMO, so good luck.

 

thanks man. it sure is a pain since the issues arent at wot. the slight bit of detonation that i was hearing with the listen up was at low rpm like 2000-3000 in the 10" or so range.

heres the timing map im currently settled at.


high cam map has 24-26 degrees total. ignition adjustments are disabled fwiw

 

You should have ignition adjustments enabled. Your idle stability and temp fluctuations are highly dependent on ignition adjustments. Disabling that is more useful for tuning scales and troubleshooting.
A lot of knock happens at higher load in low RPM, especially with the GSR for some reason.
Many times detonation in that area can be due to improper tip-in calibrations, which is often overlooked after upgrading compression.