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Old 01-27-2007, 04:34 PM   #1
page02wrx
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Post Take a look at my target boost table

Hey guys,
Target boost table will be for this set up:
VF34
650cc d-werks
35mm EWG
Injen FMIC
K&N Typhoon
HKS DP
Tanabe Catback


I literally just got into this and I figure the best way to learn is to grab the bull by the horns...

So, with no real knowledge of tuning, I decided to write my own target boost table and post it on here to see what you guys think.

Goals: 18psi in the midrange, taper to about 15psi at redline. Still keep some power during normal driving ex: passing some one. Keep anything under 50***37; throttle limited to about 7 psi

Code:
[Table3D]
      12	 24	 36	 50	  63	  76	  88	  100
1600	-0.93	1.23	2.31	2.78	2.93	2.93	2.93	2.93
2380	-1.39	2.47	5.55	5.86	6.32	12.80	14.65	14.65
2450	-2.47	1.54	5.55	6.32	7.87	13.73	15.58	15.58
2550	-2.78	1.23	5.40	7.10	8.79	14.65	16.97	18.51
2800	-4.01	1.08	5.24	7.87	9.56	15.58	17.74	18.51
4800	-4.78	2.93	6.63	7.87	9.87	16.50	18.51	18.51
5200	-6.17	1.85	5.55	7.71	9.72	16.35	18.51	18.51
5600	-7.25	1.08	4.78	7.87	8.02	15.73	17.89	18.05
6800	-9.87	0.31	3.55	6.79	7.25	11.41	15.12	15.12
Questions:

Will the jump between boost levels in the 63 and 76 Throttle position columns cause some surging? Should I try to smooth it out a little more throughout the table? My main goal was to get rid of PTFB but still spool aggressively at WOT.

How can I directly relate this table to WGDC?I have two theories... - remember these are just theories I have no experience with WGDC's:

1) during vacuum and during full boost my WGDC's should be higher.... this would allow the wastegate to be open and either not let the turbo spool to get good gasmileage, but keep it open under load to stop it from overboosting. I dont think this theory is true because boost opens the wastegate.... so technically the wastegate can't be open when theres no boost.

2) Smooth out the WGDC's like the boost table - Small #'s for small boost #'s, higher #'s for higher boost #'s.


And if anybody has any of their boost tables that is working out great, please post them.
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Last edited by page02wrx; 01-29-2007 at 07:01 PM.
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Old 01-27-2007, 05:27 PM   #2
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You probably ought to post what setup you're running. I'm assuming VF34 based on a quick search... that boost target curve is a bit agressive for a TD04...

As far as looking at the surface, if you plot that boost target versus throttle angle, there's a "dip" between about 40% and 75% that I believe would manifest itself as a funny flat-feeling throttle response. I'd look into trying to smooth that out a bit by bringing those points up.

As far as WGDC, Higher WGDC means the WG stays shut, making more boost. You're going to want to tweak the WGDC tables to get quick boost response while still being stable (no boost hunting). If you want mileage, you should work the target boost table in such a way that it's easy to drive in an un-boosted mode (I think your base looks decent for this). This makes it easier to stay out of boost and therefore stay closed loop. It also keeps backpressure and pumping losses down since you're not working the turbine as hard. Unfortunately, it also means your "road-load" turbine speed will be lower and turbo response is sacrificed for economy. For me, this is a valid tradeoff...
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Old 01-27-2007, 05:32 PM   #3
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Quote:
Originally Posted by TMessick View Post
You probably ought to post what setup you're running. I'm assuming VF34 based on a quick search... that boost target curve is a bit agressive for a TD04...

As far as looking at the surface, if you plot that boost target versus throttle angle, there's a "dip" between about 40% and 75% that I believe would manifest itself as a funny flat-feeling throttle response. I'd look into trying to smooth that out a bit by bringing those points up.

As far as WGDC, Higher WGDC means the WG stays shut, making more boost. You're going to want to tweak the WGDC tables to get quick boost response while still being stable (no boost hunting). If you want mileage, you should work the target boost table in such a way that it's easy to drive in an un-boosted mode (I think your base looks decent for this). This makes it easier to stay out of boost and therefore stay closed loop. It also keeps backpressure and pumping losses down since you're not working the turbine as hard. Unfortunately, it also means your "road-load" turbine speed will be lower and turbo response is sacrificed for economy. For me, this is a valid tradeoff...
Very good points thanks for the reply.

Yes it will be on a VF34, 650cc's, TBE, EWG, FMIC, Hopefully going back to a boost solenoid.

I see exactly where you're coming from on the boost table. I can easily see now that there would be some boost hunting. As far as WGDC's go, thanks a lot I had the #'s mixed up, I thought high meant it opened...

Another question is will the WGDC's work the same with an EWG opposed to the IWG?
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Old 01-27-2007, 05:52 PM   #4
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Quote:
Originally Posted by page02wrx View Post
Another question is will the WGDC's work the same with an EWG opposed to the IWG?
Given that you don't have an external wastegate, why would this be a question?
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Old 01-27-2007, 06:01 PM   #5
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Quote:
Originally Posted by Jon [in CT] View Post
Given that you don't have an external wastegate, why would this be a question?
I don't have an external wastegate? Why do you assume that?

http://forums.nasioc.com/forums/show....php?t=1130616



Last edited by page02wrx; 01-27-2007 at 06:18 PM.
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Old 01-27-2007, 06:27 PM   #6
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The revision

Code:
[Table3D]
        12	24	36	50	63	76	88	100
1600	-0.93	1.23	2.31	2.78	2.93	2.93	2.93	2.93
2380	-1.39	2.47	5.55	8.64	10.95	13.73	14.65	13.73
2450	-2.47	1.54	5.55	9.10	12.49	16.50	16.50	16.50
2550	-2.78	1.23	5.40	9.87	12.49	17.43	18.36	18.36
2800	-4.01	1.08	5.24	9.72	12.34	17.43	18.36	18.36
4800	-4.78	2.93	6.63	10.64	12.34	18.36	18.36	18.36
5200	-6.17	1.85	5.55	9.56	12.49	18.20	18.20	18.20
5600	-7.25	1.08	4.78	8.79	12.65	17.58	18.51	17.58
6800	-9.87	0.31	3.55	6.79	10.03	15.12	15.12	15.12
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Old 01-28-2007, 10:45 PM   #7
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Bump for input
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Old 01-28-2007, 11:20 PM   #8
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Whats management are you using to adjust the boost tables. Boost target table looks pretty good to me. What does your WGDC table look like? Give it shot. Report back with the results.

Last edited by ITP; 01-28-2007 at 11:26 PM.
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Old 01-29-2007, 10:42 AM   #9
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I would be wary of putting in high boost numbers at low RPM where you never have a chance of hitting that boost. It will cause integral windup, and boost spikes or overboost as you roll into boost. I don't know if your boost numbers are reasonable for your engine/turbo or not since you didn't state what you're running, but it is a general warning.
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Old 01-29-2007, 12:58 PM   #10
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IMO you need to rescale the RPM increments. It has too much resolution in the lower rpms.

I don't know if setting boost targets below wastegate pressure is worth anything.
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Old 01-29-2007, 01:17 PM   #11
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Quote:
Originally Posted by Master2192 View Post
IMO you need to rescale the RPM increments. It has too much resolution in the lower rpms.

I don't know if setting boost targets below wastegate pressure is worth anything.
Right, the ECU can't stop it from hitting wastegate level boost. It's completely mechanical.
Hence the warnings about PTFB and manual boost controllers.
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Old 01-29-2007, 03:20 PM   #12
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Quote:
Originally Posted by Master2192 View Post
IMO you need to rescale the RPM increments. It has too much resolution in the lower rpms.

I don't know if setting boost targets below wastegate pressure is worth anything.
there is an internal table in the ecu map which is referenced by "boost error" on one axis (rpm on the other, iirc).

an ignition timing offset is derived from a lookup in this table.

therefore having a wide discrepancy between actual boost and target boost MAY cause an ignition timing adjustment. i haven't verified this yet myself, though.
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Old 01-29-2007, 06:59 PM   #13
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Quote:
Originally Posted by ride5000 View Post
there is an internal table in the ecu map which is referenced by "boost error" on one axis (rpm on the other, iirc).

an ignition timing offset is derived from a lookup in this table.

therefore having a wide discrepancy between actual boost and target boost MAY cause an ignition timing adjustment. i haven't verified this yet myself, though.
Oh really? I wish enginuity broke it down into futher increments, I'll try to smooth out my 60+Throttle position

Makes sense though, I'll edit in my set up
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Old 01-29-2007, 07:02 PM   #14
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Quote:
Originally Posted by ITP View Post
Whats management are you using to adjust the boost tables. Boost target table looks pretty good to me. What does your WGDC table look like? Give it shot. Report back with the results.
I'm not really sure how to integrate my target boost into WGDC's.... still reading up on that part
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Old 01-29-2007, 09:26 PM   #15
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Quote:
Originally Posted by page02wrx View Post
I'm not really sure how to integrate my target boost into WGDC's.... still reading up on that part
I'd say start looking at the stock map. Looks at the boost map and than correlate it to WGDCs. Get a feel for how many WGDCs it takes to build certain pressure, at a given RPM range. Get a rough idea and start there.

There's only one problem though. You're on a different turbo The exercise should still be helpful to get a feel for what it takes to get certain pressure. Once you get a baseline and some feedback in form of a log, you'll know what you need to do next.
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Old 01-29-2007, 09:32 PM   #16
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Quote:
Originally Posted by tachrev View Post
Right, the ECU can't stop it from hitting wastegate level boost. It's completely mechanical.
Please note that the WG solenoid is referenced to the compressor outlet, not the intake manifold, so while it's true that you can't keep the turbo from spooling below "stock" compressor outlet pressure, this does not directly correlate the the intake manifold pressure. In addition to pressure drop due to flow losses, you've (hopefully) got a throttle blade between the compressor outlet and the MAP sensor. As such, even with a 7psi WG actuator, it's entirely possible to have "realistic" numbers less that +7 in the target boost table due to throttle and flow losses.

Actually, I think it'd be interesting to characterize the stock WRX throttle by running WG boost and seeing what actual manifold pressure was as a function of RPM and throttle angle. Bosst ould be higher at lower RPM and higher throttle angles making a neat warped shape.
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Old 01-29-2007, 09:43 PM   #17
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Originally Posted by TMessick View Post
Please note that the WG solenoid is referenced to the compressor outlet, not the intake manifold, so while it's true that you can't keep the turbo from spooling below "stock" compressor outlet pressure, this does not directly correlate the the intake manifold pressure. In addition to pressure drop due to flow losses, you've (hopefully) got a throttle blade between the compressor outlet and the MAP sensor. As such, even with a 7psi WG actuator, it's entirely possible to have "realistic" numbers less that +7 in the target boost table due to throttle and flow losses.

Actually, I think it'd be interesting to characterize the stock WRX throttle by running WG boost and seeing what actual manifold pressure was as a function of RPM and throttle angle. Bosst ould be higher at lower RPM and higher throttle angles making a neat warped shape.
Right, boost generated is entirely load dependant.
Hmm...suppose I didn't think of that. If wastegate spring pressure at 25% throttle would generate say, 3 psi, and you had mapped out 6psi, then you could still bleed off some signal to the wastegate through the solenoid to hit your 6 psi at 25% TPS target.
I suppose I totally missed that angle, although it seems obvious now...am I correct that this is what you where getting at?
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Old 01-29-2007, 10:01 PM   #18
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Yeah -- more or less. For the 7psi actuator you're maybe at 3psi manifold pressure at 3000 RPM, 25***37; throttle (I'm making up these numbers). At 6000 RPM, 25% throttle you may be at -3psi due to throttling and higher mass flow. In the end, there definitely IS a minimum manifold pressure you can control to, it's just not equal to WG pressure.

Figure anything you run above min pressure helps in turbo response (time lag) since you're spinning the turbo faster, but hurts fuel economy since you're working against more backpressure.

Last edited by TMessick; 01-29-2007 at 10:02 PM. Reason: For some reason, I can't spell when I type.
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Old 01-30-2007, 06:50 AM   #19
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the other thing to keep in mind is that it is pointless to have the turbo generate more pressure just so you can knock it back down across the throttle. in fact, not only pointless, but counterproductive as a greater compressor pressure ratio means a greater turbine pressure ratio, and more exhaust gas backpressure.

for that reason i generally keep boost very low in the midrange of tps and ramp up exponentially at high angles. this tends to keep the wastegate open as far and as long as possible.

hth
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Old 01-30-2007, 12:23 PM   #20
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Quote:
Originally Posted by ride5000
the other thing to keep in mind is that it is pointless to have the turbo generate more pressure just so you can knock it back down across the throttle. in fact, not only pointless, but counterproductive as a greater compressor pressure ratio means a greater turbine pressure ratio, and more exhaust gas backpressure.

for that reason i generally keep boost very low in the midrange of tps and ramp up exponentially at high angles. this tends to keep the wastegate open as far and as long as possible.

hth
ken
Exactly, maybe it would be best to setup a boost gauge on the turbo outlet side and then another reading manifold pressure. That way you could tell if you are trying to target a boost level that just can't get past the throttle I.E. you are seeing 10 psi after the turbo but only 3 psi in the manifold and your target is 6 psi. If I am going to continue my venture into maximum fuel efficiency with awesome full throttle power, I may have to do this.
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Old 01-30-2007, 12:52 PM   #21
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master, quick and dirty method is to datalog MRP at various TPS/RPM with only wastegate boost. you'll see there's a TPS which allows the MRP to hit the wastegate boost. probably around 40***37; in most cases.

imho, you certainly do not want to target a higher MRP at a lower TPS than that.

if you can, postpone the higher boost levels to the last little bit of throttle. below that point where you're still in wastegate boost levels, set fuel to ~12.5-13:1 (best torque) and then push the timing.
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Old 01-30-2007, 01:03 PM   #22
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Quote:
Originally Posted by ride5000
master, quick and dirty method is to datalog MRP at various TPS/RPM with only wastegate boost. you'll see there's a TPS which allows the MRP to hit the wastegate boost. probably around 40% in most cases.

imho, you certainly do not want to target a higher MRP at a lower TPS than that.

if you can, postpone the higher boost levels to the last little bit of throttle. below that point where you're still in wastegate boost levels, set fuel to ~12.5-13:1 (best torque) and then push the timing.
Soo.. Make a test map with WGDC set to Zero below 50% and Boost targets in high negatives to keep the solenoid closed. Then do some logs, my bet is you could then shift the throttle values in the boost targets and WGDC maps to give you better resolution at higher throttle openings where it is needed.

Thanks for the input on the AFRs to target.
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Old 01-30-2007, 01:18 PM   #23
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yes.

easier than having to reflash yourself a map with all zero wgdc, just run a hose from the compressor nipple to the wastegate actuator. no boost control solenoid, no restrictor pill--just a hose from comp to wga.
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Old 01-30-2007, 04:27 PM   #24
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Hmm...interesting point. It seems to make sense. But, isn't the ECU referencing the target boost post TB plate? Meaning, pre-TB plate pressure might be 6psi but if you're targeting 3psi, that is the actual pressure in the manifold. No?

Quote:
Originally Posted by ride5000 View Post
the other thing to keep in mind is that it is pointless to have the turbo generate more pressure just so you can knock it back down across the throttle. in fact, not only pointless, but counterproductive as a greater compressor pressure ratio means a greater turbine pressure ratio, and more exhaust gas backpressure.

for that reason i generally keep boost very low in the midrange of tps and ramp up exponentially at high angles. this tends to keep the wastegate open as far and as long as possible.

hth
ken
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