I think immediately, but thats me.

 

1. Tune the mivec map
2. Tune the AFR
3. Set the boost
3. Tune the AFR
4. Tune the timing
5. Set the final boost
6. Refine the timing
7. Refine tune AFR
8. Refine the timing
9. Verify results under multiple specific driving conditions.

 

I'm not understanding what you explained here. I see six different conditions, but only four sets of traces. What "JDM Map" are you talking about? Fuel? Ignition? Which of the dyno traces corresponds to the three runs with the "JDM Map"?

 

Does anyone know how much overlap there is with the MIVEC advance set to 0 deg?

 

Dude, its been so long i cant really remember...lol.

I think the jdm map refers to the timing and fuel maps found in the jdm IX gt map floating around. I would not recommend using it. My tune now is completely custom and tuned for my elevation.

I didn't post every condition listed, just enough to illustrate my point.

 

I'm still trying to understand this. Doesn't a greater amount of intake cam advance give better cylinder filling and thus better VE in this rpm range? If so, wouldn't it be better to leave the intake cam at max advance and then tweak fuel or timing to deal with the knock?

 

You could probably do it that way as well, but I noticed on the dyno that there was this dip when it was full advance and then you roll it back and it would flatten back out. I dont remember there being knock or erratic AFR's just a slight drop in torque.

The intake cam has a 130* centerline, 120* lobecenter seperation angle because the exh has a 110* centerline. This yields 18* of overlap with stock cams.

 

Seems that the lower the pressure on the exhaust side before the turbine, the better the chance of this working. I thinking that with a stock exhaust, its not worth it to advance the the intake past 5000 rpm, but on a TBE with test pipe, it may be worth it.

 

I have a question. Is there a relationship between ignition timing and mivec adjustment? If there is, then what is it?

 

more mivec=less timing

I fail to understand why more overlap at 5k rpm + gives less power...
I think the more overlap (boost supporting) at 5k rpm + should give a gain in top end???

 

I'm not sure more MIVEC requires less ignition timing (not in the midrange anyway), I've not observed this personally. I run 30 degrees MIVEC midrange and 7 degrees of timing at 25 PSI with knock sums 3 or below on 93 PON/99RON. Since I hold this boost to 6000 RPM then peak power does arrive early. As I mentioned before, perhaps we should 3d map the MIVEC rather than just define it by RPM. We do this with ignition timing, and it makes sense that load is a proxy for VE as higher load on a smaller turbo will give lower VE as the EGBP rises when the turbine chokes (or the compressor chokes and the turbine is spinning faster to overdrive it).

More overlap when the exhaust manifold pressure exceeds the inlet manifold pressure tends to give more pollution of the fresh air charge from the end products of combustion that remain in the cylinder. This encourages knock. I've noted this on my engine, but I push the top end boost harder than most on a given size of turbo because I get more airflow. If I don't swing the inlet cam back to zero at high revs I get detonation and the car accelerates no faster.

If you run tame top end boost or a big turbo then it may tolerate more overlap, and might even improve VE from having the overlap as the exhaust gas momentum helps pull in the inlet charge.

 

Been reading from the start and posted once along the way as i don’t get paid to give away too many tuning secrets.

Fully agree with this last post. I think there needs to be a clear distinction between changing the VVT when using the stock turbo and exhausts components and aftermarket turbos, cams, exhausts etc.

I have tested with a multitude of variants (including cossie cams which are the best I have seen so far) right through to GT3076 with an external WG and a 3' pipe.

On a large turbo (35/30 etc) and assuming cams are ground to a 131 centre line employing 3 deg at ~7200 and 5 deg at ~6500 makes a huge difference in how the car responds up top (careful you will need to tune AFR on these changes). It does not add more power, that’s your timing, but it flattens and carries the power curve.

On a stock turbo I suggest you leave the vvt at 0 above 6000. EGBP os too high and you looking for trouble regardless of meth or high octane use. (dynapack hub dyna tests)

Interesting discussion. Keep on testing!

 

What troubles are expected if the overlap is increased above 6500 rpm?

I have observed that the AFR gets richer if overlap is increased (10 deg), especially above 6000 rpm.

Would your comments above apply to the Evogreen too?

Thanks!

Any more tips???

 

He's referring to what we had already mentioned... exhaust gasses blowing out the intake valve during early opening.

 

It's amazing the amount of power that can be extracted by tuning even on a 100% Stock Evolution.


That JDM Map and Radical mivec, where did that come from????