b.serious

i was just wondering the total timing of a b16 motor NA is approx 25 degrees at 8000 rpms and if we boost it 25 psi and apply the 1 psi per pound of boost retard, that would pull 25 degrees of timing. so one would be running ZERO degree timing.

or is it that there is a lower limit to ignition timing .. like u run 15 degrees for 20 psi and onwards??

i hope ive put my question well...
just for an idea what are u guys running ure ignition timings at say 20 psi.. do mention the engine management used as all of them out there are different with timing values in the tables.

DOHC_16v

I've never tuned a b16, but 1 degree per 1 psi is very conservative on most motors. I usually pull about 1*/2psi and start pulling timing around 3-4psi

b.serious

i get u on that.. for now am running 1 bar of boost and my timing value in the tables is 15.5 degrees for 14.4 psi .. which is about 0.6* per pound of boost retard. no knock and the color change on the spark plugs is right at the apex of the 90* turn on the ground strap..

now the total timing the engine sees is not what the figures are in the tables in crome pro. there is a base ignition table which adds on top of the timing tables. so according to that my total timing is 15.50 + 8.95 = 24.45 degrees in total at 8000 rpms.

the 1 degree per pound of boost was an example. i know its too conservative but what if we apply that rule and run 25 psi.. that wud pull 25 degrees and the timing in the tables would be ZERO..
how can an engine run with zero timing.. that is what am confused about. there has to be a lower limit. which is?????

FactionR

keep in mind that you may be talking about 1*/psi on pump. 25psi is not going to want pump, your going to run higher octane that will allow higher levels of advance.

b.serious

am running 97 RON.
again 1 psi per pound is just an example...
25 psi means 25 degrees
and a stock NA b16 runs total 25 degrees of timing in the crome(romeditor) table B10
so that is 25-25 = 0 degrees in the table..
does it make sense now... ???

rorik

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b.serious &raquo;</TD></TR><TR><TD CLASS="quote">how can an engine run with zero timing.. that is what am confused about. there has to be a lower limit. which is?????</TD></TR></TABLE>

I don't think anyone will be able to give an exact number there. Part of the oem map even has negative timing values.

DOHC_16v

There is no lower limit, but too little timing will actually increase the EGTs and can even cause detonation.
If you're running pump gas and are still getting detonation below 10-15*, lower the boost or compression, or install water/meth injection.
On race gas you may be able to run more timing than the engine runs stock @ high boost without any detonation

rorik

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHC_16v &raquo;</TD></TR><TR><TD CLASS="quote">There is no lower limit, but too little timing can even cause detonation.
</TD></TR></TABLE>
Can you cite this? Like by example, source, explanation, or reference? Doesn't make any sense to me..

JDogg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik &raquo;</TD></TR><TR><TD CLASS="quote">
Can you cite this? Like by example, source, explanation, or reference? Doesn't make any sense to me..</TD></TR></TABLE>

too little timing = really hot exhaust valves = preignition

blaze the chemi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b.serious &raquo;</TD></TR><TR><TD CLASS="quote">how can an engine run with zero timing.. that is what am confused about. there has to be a lower limit. which is?????</TD></TR></TABLE>
Not a honda, but my 92 Chevy S10 4.3L has a 0 degree timing. It even states this on the hood sticker for emissions.

Doesn't the VE at the high rpms help the fact that you can run timing closer to 0*? The cylinder pressure is lower since it is after the max tq? Just trying to apply the research I have accumilated over the years.

rorik

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">

too little timing = really hot exhaust valves = preignition</TD></TR></TABLE>

Damn. I should have thought of that. How many degrees behind mbt would be enough to cause this, any rough idea?

JDogg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik &raquo;</TD></TR><TR><TD CLASS="quote">

Damn. I should have thought of that. How many degrees behind mbt would be enough to cause this, any rough idea?</TD></TR></TABLE>

depends on the setup, some are more picky than others. there is no "magic" number

98vtec

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">

depends on the setup, some are more picky than others. there is no "magic" number</TD></TR></TABLE>

mostly because different engine managements have different ignition definitions.

for instance, Crome is wack and inconsistent and you cant turn off the ghost therefore the numbers truely dont mean much. Tune and inspect plugs to really get an idea of where you stand in that department.

Neptune and eCtune can both turn off the ghost and run straight from the maps besides the IAT, ECT...etc compensation tables.

Standalones will run exactly what the map says to run pending conditions.

All in all, dont trust the number the computer screen is giving you.

JDogg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">
All in all, dont trust the number the computer screen is giving you.</TD></TR></TABLE>
yup!

rorik

What about the s300?

98vtec

what about it?