User 52121

Rogue_Ant

Yes, me too. I think a bit more transparent technical subjects is a good thing!

Eric,
Let me answer your question with a question, which your answer should answer the original question (lol).
Does your car produce the same intake manifold pressure at a given RPM, but different throttle positions? I.E. at 4000rpm and 25% throttle what is the manifold pressure vs. 4000rpm and 100% throttle?


Thanks Derek! Yep, after tuning many DSMs & 3000GT VR-4s, turbo Hondas, SRT-4s, ect, I was a bit taken back by the 2D WOT mapping! Changing the software to be a proper 3D map (regardless of load), was one of the first software changes I made.

Richgreenster

Joshua
Have you had a chance to dyno a cars changes when switched form 2D to 3D maps?

Maybe one with WOT pull and one with Part Throtle on both maps to show us the difference.

Dougs951S

I believe that at peak power and under 100% throttle, that output would be mostly the same. Josh's 3D maps might gain a bit more power, but I would think you would see most of the benefit in part throttle, WOT before max power, and in "smoothness" of that power applied. Joshua correct me if I am wrong.

Dave W.

I think you're right. A 3D map is extremely useful during transitions from closed or part throttle up to full throttle and full boost starting from different rpm's. The great benefit is for the road course/autox guys who will use a greater portion of the map.

User 52121

Yes.

This is where you will see the biggest gains - transitions. Transitioning through the boost range, rev range, and throttle range.

Around town the motor will feel like it has a lot more meat to it.

Eric_Oz_S2

At 25% throttle it is a PT map which is already 3D. My question was for WOT maps. At WOT the manifold pressure hardly varies at all except as a function of RPM. So the answer then is there is no benefit in 3D maps at WOT for my car.

Rogue_Ant

These guys are right on the money. At peak power, the difference will be minimal - assuming both cars are tuned well. The real gain is everywhere else.


Eric, I'm sure there is some benefit, but just not as much as a turbo car due to the nature of a superchargers fixed boost response.

Richgreenster

I assumed that as well, I am just curious to how much of a change there would be.
Because of the timing change, I imagine that the cars rev. would be much faster and thus the trubo would reach max boost at a lower rpm. Am I thinking corectly?
If so then your tune would make the 951 a much better Auto-X car.

Bri Bro

Agreed, the term vector just does not apply to a 2D Chart with a additive correction table.

What I see is a boost increase in low RPM. It is SO dependent on the turbo, head work, exhaust size, etc. If you want a track car, you really don't want a snap boost on a apex. If you want a street car ... go for it. Just depends on what you want to do with the car.

BTW, no idea what a soft string is.. my exposure to this term is to string instruments

Rogue_Ant

The rate that the turbo spools is mainly dictated by the physical characteristics of the setup (turbo sizing, exhaust sizing, cylinder head, ect), and only marginally dictated by the tuning (without considering anti-lag tuning).

What we expect for cars with our 3-D tuning is more power, and more linear delivery than other setups. This may not mean you get into boost much quicker, but rather the car has more power without being completely dependent on boost.

Rogue_Ant

I am not sure why you are so determined to try to find fault in such an unimportant detail of vector terminology...


Regardless, the term vector does apply just fine to this case. To explicitly spell it out, the WOT table is a collection of vectors:


The first vector has a start point of (1000, 20.5) and an end point of (1480, 20.5).
The second vector start point (1480, 20.5), end point (2000, 17.0).
The third vector start point (2000, 17.0), end point (2120, 13.0).
The fourth vector start point (2120, 13.0), end point (2240, 13.0).
The fifth vector start point (2240, 13.0), end point (2520, 13.0).
The sixth vector start point (2520, 13.0), end point (3000, 15.0).
The seventh vector start point (3000, 15.0), end point (3280, 17.7).
The eighth vector start point (3280, 17.7), end point (3520, 17.7).
The ninth vector start point (3520, 17.7), end point (4000, 19.1).
The tenth vector start point (4000, 19.1), end point (4520, 19.1).
The eleventh vector start point (4520, 19.1), end point (5000, 19.1).
The twelfth vector start point (5000, 19.1), end point (5520, 19.1).
The thirteenth vector start point (5520, 19.1), end point (5800, 20.5).
The fourteenth vector start point (5800, 20.5), end point (6000, 20.5).
The fifteenth vector start point (6000, 20.5), end point (6240, 20.5).


Any value on a vector line is a linear interpolation of the vector's starting and ending points. So, in this case, to find the timing advance at, say 3800rpm, the DME takes the ninth vector data, plugs in the starting and ending points into a linear interpolation function, and calculates an ignition timing advance of ~18.5°.


------------------------------------------------------------------------------------


Now, for the 2D + modifier case:
The DME does an additional step, a similar linear interpolation using the boost table:


First vector start point (-8.0, 15.0), end point (-4.0, 9.5).
Second vector start point (-4.0, 9.5), end point (0.0, 4.8).
Third vector start point (0.0, 4.8), end point (5.0, 4.1).
Fourth vector start point (5.0, 4.1), end point (10.0, 0.7).
Fifth vector start point (10.0, 0.7), end point (15.0, -2.0).
Sixth vector start point (15.0, -2.0), end point (20.0, -5.5).


The DME then takes the first ignition advance found from the WOT table, 18.5°, and adjust it by the value calculated from the boost table interpolation function. So, i.e. at 18psi, the resulting interpolated value is -4.1°.

Thus: 18.5° - 4.1° = 14.4°


Therefore the final timing value is 14.4°BTDC.

White_951

Well...I ain't no rocket surgeon....but the M-Tune zapped my throttle response from 0-3000 like a flux capacitor....them my Turbo takes over...

Bri Bro

What I see is a collection of line segments. You are defining each one of your endpoint in what you call "vectors" in the in rectangular coordinate system (lines), not the polar coordinate system (vectors). The 8751 CPU ( in the DME) does not have a math co-processor so it just doesn't do trig functions efficiently. It does not use vectors in any of the code, the 8751 does look up tables and line interpretation.

Why are you making this look so complicated? The real issue is does your software work the way it is specified.

Bri Bro

I would be interested in seeing how this is done. The 951 is just a slow car below 3K RPM.