You're right I'm sorry. PCM's are set up differently in this regard depending on model car/engine/car itself, etc...BUT there is more tuning that can be done using HPTuners beyond what it was designed to do from the factory


No way your stock timing is that low...Yes you pull timing from stock, but stock should be 22-25*

 

Here's a little info on why timing needs to be pulled:

Why do we need to Pull Timing? Nitrous increases the speed of the flame front, so you're bringing the advance back to properly time the pressure spike to the retreating piston. Meaning, preignition can occur, and lead to detonation with to much timing (stock and/or added advance). What this is saying is, the nitrous causes the cylinder to fire early, like when it's coming up on the compression stroke, this can do big time damage, and is prob the #1 reason the ring lands go. Also, you can see this early firing is less than optimal for ultimate power, and thus, not very volumetric efficient. You want it to fire at the time period when the piston wants to go down for the power stroke, not fighting an up traveling piston (preignition). I hope this makes sense, and if anyone else reading along has additional input or clarification, that would be great.

With a stock motor and stock timing we can get away with no timing pulled on small hits due to the fact that cylinder pressures will not be that great. However, pulling some out while spraying not only gives a safety margin should you have an issue, it will have the potential to perform at it's greatest volumetric efficacy IE: more power. You are correct when you said it's a blanket statement to pull this amount as per manufacture suggestion. they are trying to cover their butts. depending on your size hit, that will be the factor in how much to pull, because the Vettes have come from the factory with less timing than most cars.

The Interface can be set to pull what ever amount you desire using the advanced mode and HP Tuners. The 1st pic is my stock Z06 look up table. targeting the 158° we can see that stock we would pull for the most part 4° of timing. The 2nd picture is what I set up on my car for a 200 or 250 shot I did. It's all dependent on what row you choose and/or what amount you enter after selecting the corresponding dip switches for that temp/row. You can even use the Interface to fine tune your a/f ratio on your wet kit.




Hope this helps a little bit.
Robert

 

So let me see if im reading those pages right....when ur car sees 158* air coming in it will pull the amount of timing u selected....I see u only changed it at 158*, is there a reason? I would assume that if it for some reason saw 167 it would go back to 5*....So im assuming the resistor or setting on ur interface is set to 158*..yes?

 

Im a little confused too I was under the impression It should be blended. No big "JUMPS". I think that was an example?

 

This is your WOT timing pull. Starts when ever you activate your nitrous. we are not tuning part throttle timing. So what ever rpm you choose to spray, it will correspond to the cylinder airmass (g/cyl) or the air you are flowing and pull the additional timing you added in your temp column.

So now when you log your run your timing will look like this (what your amount will be). This log is from another setup of mine but you get the idea. without the nitrous spraying the 18° boxes would be showing my n/a timing of 24°. Do a search on my name and google and you will find some additional tuning info for dry hits. You can see where the spray was activated, 3200rpm and we were flowing .96 g/cyl of air at that time. beause of the timing pull I put into the look up table I am limited to 18° timing at any load area of the engine. what is cool for the advanced users is we can add some timing back in after we pass our torque peak at 5200rpm in the original look up table.

Robert

 

I will check it out
Thanks Robert!

 

Robert one more thing will you be doing a write up on the WET kit tuning
like the Dry one you did? Definately looking forward to that!

 

Thats correct.

You should never see 158, and for that matter 167. It doesnt really matter (high or low) as long as its a temperature you will never see under normal/racing situations.

In addition to the IAT spark correction table you can use the IAT multiplier table to help control idle/off idle timing.

 

That I may just do, as there are now ways to also adjust the wet hit in 5hp increments for a/f ratio which is so much easier than having hand fulls of jets.
Robert

 

Hey Robert, I only have the HSW Micro Edge, I was told I can pull 4 degrees of timing without the interface, with just HPtuners. Why just the 158 gpc??
Thanks Mike
Did you update the wet kit timing retard on your site yet? I dont see it?

 

I have a timing pull write up for the pre MAF dry hits only. with out a timing puller (Interface or Timing Tuner) the only way to do it really with HP Tuner it will effect the n/a tune; unless you do the timing resistor trick that is covered with my other tuning documents, I can't link, but can be found via google under my name. the 158 degree column is just what i chose to use, and we can use any column as the traget, or multiple columns for different pull combos and jsut flip a couple dip sws to access.
Robert

 

Robert56 - Do you have any info/insight into a BIAS** table I've been hearing about?

I've been hearing (for example) if you were to set up your IAT mod to CUT the signal completely (which on my car sends it to the bottom column/cell (-38*) this can be dangerous because the "BIAS" table on the car might be set up to ADD timing at this temperature?? This is something totally different than the BASE/MULTIPLIER tables...

Basically i was hearing as temperature goes down it may add timing, up and it pulls timing...? Any truth to this "BIAS" table?

 

yes your correct, to a point. the actual wot timing we see is a combo of commanded and multipliers which can add and/or subtract timing for what we see in actual. Low high octane tables are an example. but in actual use, I haven't heard of anyone getting timing added when using the IAT resistor trick, but that doesn't mean it can't happen. The best way to do the resistor trick is to add a POT rather than a fixed resistance resistor and we should never see the IAT signal cut. Not sure I answered anything, lol, just put some stuff out there. I have tried using the power adder vs IAT fuel multiplier table to add fuel by targeting some pretty low temps with the dry, and never saw an increase in timing. Try it n/a logging and see if you get any added timing? I can't think of a "Bias Table" off hand, but don't have my HP Tuner handy. good luck and if you get any insight yourself be sure to let us know.
Robert

 

Rule of thumb is 2 degrees of timing pulled from your tune for every 50hp of spray. Thats a good place to start, BUT what you should really be doing is pulling plugs. Below is a link of what you should be looking for in order to get the A/F and timing dialed in.

http://www.dragstuff.com/techarticle...ead-plugs.html

 

Robert - yes I'm using a Potentiometer on my car, 1-1k i believe, but I'm targetting the middle of 1 column. I'm targetting 154*, that way its 4/5* away from breaking into the next column of cells should it move even a little bit.

Its really the BIAS table I'm curious about, the IAT base/multiplier + low octane/high octane maps I'm pretty familiar with.

I'll talk to my friend again about this BIAS table he is talking about, but as simply as i can put it, it is its own stand alone table that directs timing based on IAT & coolent temps i believe. Apparently it is tuneable, but for now thats why i did NOT go to the very end of the IAT spectrem (low -38*, or high ~240*) as i assume the higher/lower you go the more aggressive it will correct timing. Besides The 158* column is realisticlly out of the range of IAT's that I'd ever see even during a hot summer day here in TX anyway...

Whatever i find out I will report back!

 

So the only adjustment you have to do is pull timing respectful to the size of the shot you're running? So, if I was to get the Lingenfelter Launch Control Module and use it to retard the timing on Nitrous Activation, could I effectivly change the timing retard while watching my Wideband and Aeroforce (Knock Retard).

 

Robert can you post up a screenshot of what my Iat Spark table should look like for an LS2?
Thanks Mike