Timing by gear possible?

[Hookey]

Im guessing this is not possible but wouldn't it be great. 

Running enough spring pressure to get to 24psi. At zero wgdc its about 14 ish psi. On e85 this is still enough to blow the tires in 1st and 2nd. 285 r20s as well. 

Even if it was just the highest load line of the blk table split into gears?. 

[Puffwagon]

Use a 4 port boost controller then you can run very low and very high boost.

It's as easy as connecting 2 wires for the solenoid and using an actuator with a vacuum source on either side of the diaphragm.

[Roland@pcmtec]

4 Port controller with closed loop boost control would probably be what you need. 

I think you can torque limit based on gear in the ZF though which would pull throttle in the lower gears and potentially work well? 

[Hookey]

Your right I could widen my boost control. However timing is so instant. You could keep boost higher and timing low, then hit the next gear and boom bring the timing back in.  Boost by gear is great but it still has to build boost when shifting to a higher gear.

[Puffwagon]

Building boost after a shift wasn't the issue you initially raised. That is an entirely different conversation which I'm sure many of us would like to have.

Using timing instead of boost to limit power over the range you're describing isn't a good idea.

Going from 14 to 24psi on E85 can be as much as a 300kw difference with a barra. Timing is worth about 25kw per degree so you're looking to remove 10 to 14 degrees to limit the power. Given that you are running between 16 and 18 degrees of timing you'll end up with uncontrollable boost levels due to the antilag effect the timing will have. It will create a lot of heat, be very inefficient with fuel, it'll feel doughy af to drive and isn't how a street car should run. Dedicated drag car yes, street car no.

Having a combination of timing and boost control per gear is what you want. Due to the other options available for traction I doubt we'll see that developed. Would be cool if it was tho.

Let's assume for a minute you don't want to change your tyre and wheel combo for something that has more sidewall and hence more grip, you don't want to change your actuator and install a 4 port solenoid and in general don't want to spend money or physically change anything.

You can keep your traction control enabled, you can probably use some torque control in those earlier gears which would literally pull timing and close the throttle and you can use some throttle control aka don't floor it everywhere.

I'm on mobile now, I'll fire up the laptop later and see if there is something in there for you. What strategy are you using and is it custom os?

[Hookey]

Yea thanks for the reply puff. Im  not serious or worried about it enough to persue it heavily or write lengthy posts. Im just saying in 2nd gear when at times it almost grips running a few degrees less timing would help get it to hook up. First might need a few more lol. Combined with the boost by gear I think it would be  good. If it cant be done then thats fine no biggie.  But you cant deny a few degree less timing would help at times

[Puffwagon]

It's all relative, my car is awd with big sidewalls so I'm pretty sorted for traction.

Because you're operating over a large boost range you can probably just pull timing out of the map where it's running 14psi, then just have it at full timing in the bottom row. Dunno why I didn't think of that before.

 

Edit: it is a good idea tho and that's why we see that feature in aftermarket ecus.

Edited December 5, 2022 by Puffwagon
I just love editing

[Roland@pcmtec]

1 hour ago, Hookey said:

Yea thanks for the reply puff. Im  not serious or worried about it enough to persue it heavily or write lengthy posts. Im just saying in 2nd gear when at times it almost grips running a few degrees less timing would help get it to hook up. First might need a few more lol. Combined with the boost by gear I think it would be  good. If it cant be done then thats fine no biggie.  But you cant deny a few degree less timing would help at times

If you run less boost you can run a timing hole in that area. Eg pull timing out of the upper midrange which you don't usually hit. If you map trace the torque curve with lower boost and set up extended resolution spark tables you could make the timing flat from ~2.0 -> 3.0 load at higher rpm. This won't affect spool if you only do it from 3.5-4k and only from 2.0 load upwards (eg ~14psi). It isn't going to affect the upper gears as the torque curve will go around the hole.

This is a pretty hacky looking spark table, but you get the drift. I've tried to draw a map trace of what your torque curve probably looks like. Might feel a bit doughy at part throttle but if you run the multi tune and only do this in 1 tune slot as a low power test.

I've never tried it but if its a ZF you could try modifying these tables. These tables are in the ZF itself though, so you would need to reflash the ZF to change from low/high boost mapping via this method.

This is max torque "when towing" which is in the PCM which you might be able to make work.

 

[Puffwagon]

Those ZF tables look interesting, it would be hard to do decent testing without a dyno tho. The towing scalars also seem worth a look.

[Roland@pcmtec]

If you have an FG you can also use the cam timing to control boost which might let you get it a few psi lower.

You could put silly numbers in the these adders to reduce torque also. Eg move the inlet cam by 20 degrees on the high error. Thinking about it more this is probably your best option as you can drastically influence torque with cam timing.

[Puffwagon]

I was also thinking along the lines of cam timing, it is easy soften the power ramp quite significantly. Make things more linear they are less likely to spin the tires.

[Hookey]

Thanks Roland and Puff. Ill give the cam timing a go when I get some more ethanol. Sounds like a good idea

[Hookey]

If I am in closed loop 1st or second gear for example command zero DC and 8 PSI through the whole Rev Range, but can only get it down to 14psi like it does now, then I guess this will envoke a "boost error" that I can adjust by commanding values below 14psi for the desired boost in these gears. This will bring auf3264 into play and reduce torque.  Am I thinking about this correctly?

[Puffwagon]

Boost error is how far off the target boost you are and will always be there, except at idle. It's a number that constantly changes, it isn't a changed state of the pcm. It will either be a negative number or a positive number and due to the nature of a closed loop system it will vary from your target a small amount once it is spooled up.

Log boost error and you will see a large error before it spools up, then less as it reaches the desired boost.

[Hookey]

Yea I get all that Puff. Tuned a lot of cars.  The table has positive numbers for boost error, except the first row. Seeing as they are all positive except the first row I am picking they are for fixing or helping an under boost situation as overboost errors are negative boost error numbers. Therefore because I want to make underboost worse not better I need to put positive numbers from 3.4 to 9.8. That's the question I am asking. 

 

 

After thinking about this a bit more, I'm not sure this will work because on spool up as you said it is always underboost so will run this table. This will work for the lower gears, but the higher gears when I want it to have high boost it will be sluggish on spool. See boost error below on spool up

Edited December 5, 2022 by Hookey

[Roland@pcmtec]

You change the overboost side not underboost. Then make your desired boost like 8psi so when it shoots to 14psi you get a high overboost error that you won't see in the high gears and this will kill torque. 

You don't want to adjust the underboost adder as this will affect high gears. 

[hjtrbo]

It sure does kill torque. From my experience it used ETC which is a slow acting actuator, not sure if that will be as fast and precise as you want. From memory auF0072 is in play.