Questions regarding GMBCS

[autonuerotic]

I just installed a GMBCS on my WRX. Ive zeroed out the WGDC to run just WG boost and not overboost. Has anyone tuned a GMBCS themselves? I understand that the duty cycles will be less with the GMBCS, but I cant find a good ball park figure to reduce them by. Is there a chart somewhere that gives a ball park figure illustrating the WGDC percentage to approximate boost? Dont get me wrong, I dont want someone to do the work for me, for free, but it would really help if someone had a few good pointers and links. Ive done some research, but entering "GMBCS" doesnt yeild much in tuning for it....

[dumdum]

Try reducing the intial wgdc figures by 30% and go from there.You will also have to take in account your wastegate duty cycle IAT compensation table as well.It will need to be adjusted but also taken into account.It took me months to tune mine because I tuned in winter and once spring hit I had to retune again due to my compensation table being off.Easier way is to make your compensationtable 0 out at the currentent temp you are tuning at and go from there or just retune the comp table as the season changes which is no biggie.

Full DIY: GM solenoid install (56k warning) - NASIOCScoobypedia | Trusted knowledge for everything Subaru | Knowledge / Boost Mapping
RomRaider • View topic - Turbo dynamics and boost control explained
CobbTuning.com - How Subaru’s Factory Boost Control System Works

[autonuerotic]

Thanks dumdum. So... if Im understanding you correctly, just drop the top row(s) 30%? As an example instead of my value being 96.1, it will be 66.1 Good idea on the IAT compensations.

96.1 96.1 96.1
96.1 96.1 96.1
55.1 55.1 55.1

changed to...

66.1 66.1 66.1
66.1 66.1 66.1
55.1 55.1 55.1

[dumdum]

What are you using to tune?If it like Romraider and has a 2D map with throttle % vs RPM you need to reduce the whole map 30% or you will over boost in the higher rpm.The #'s you posted don't mean much without the complete table.Do a screen shot if you are using some else besides Opensource.

[autonuerotic]

Im using rom raider... what I typed up was just a visual example. Ill drop the whole map 30%. I read somewhere that the minimun value for the GMBCS is 10%? So for anything under 11psi (wastegate PSI) I can zero the WGDC in the area right? The reason I ask is because there are areas on the map that if I remove 30% the final value is under 10% and I believe boost is under 11psi. Is there anything wrong with zeroing the WGDC under 11psi? Does it hurt spool or anything?

One other thing...Why do people taper off boost at their designated redline? I know there are drastic differences between a roots supercharger and a turbo, but my truck doesnt taper boost at redline.... why should my car? I can see why boost is tapered with the TDO4, its out of breath, is there any reason I should taper with my VF30?

[dumdum]

Originally Posted by autonuerotic

Im using rom raider... what I typed up was just a visual example. Ill drop the whole map 30%. I read somewhere that the minimun value for the GMBCS is 10%? So for anything under 11psi (wastegate PSI) I can zero the WGDC in the area right? The reason I ask is because there are areas on the map that if I remove 30% the final value is under 10% and I believe boost is under 11psi. Is there anything wrong with zeroing the WGDC under 11psi? Does it hurt spool or anything?

One other thing...Why do people taper off boost at their designated redline? I know there are drastic differences between a roots supercharger and a turbo, but my truck doesnt taper boost at redline.... why should my car? I can see why boost is tapered with the TDO4, its out of breath, is there any reason I should taper with my VF30?

The #'s you posted you didnot change the higher rpm value (55.1).Generally you don't just change parts of the primary WGDC map,you reduce all of it by 20-30% and then retune it to hit your target values.It would take me quite a while to explain this but comparing it to your supercharger is comparing apples to oranges.Turbos can produce 45psi+ of boost pressure and spin past 100K rpms.Tapering your VF30 will all depend on your max boost pressure and the compressor efficiency.If I ran 13psi across the board on a TD04-13T I would not have to taper at redline.But I don't.I run the turbo almost to it's max efficiency of 20psi in the midrange and have to taper down to 13psi by redline.Your VF30 is the same way as any other turbo.It all comes down to airflow and compressor efficiency.If you want to zero out the WGDC under 10% you can but I don't.Depending on how you tune it you can loose alittle spool up.

Stealth 316 - Turbocharger Compressor Flow Maps

[autonuerotic]

Where can I find a compressor map for the vf30, Ive googled and yahoo'd around...nothing. I know it can flow 460cfm @ 18psi and thats all I can find. I tried 0%wgdc under 10psi, its a dog. The TDO4 has a lot more to offer than I originally thought, I just got tired of not feeling confident passing cars in the upper rpms with it. Ive read about CL/OL trasition problems on certain cars, is it only the 02'and 03's or is it possibly an issue with my particular model as well? As far as the boost map, should it ramp up slowly or build fast how would you recommend setting it up? One last thing how do I post screen shots?

[dumdum]

IHI does not publish it's compressor maps as publicly as the other manufacturers.You post screen shots by either hitting the "Prt SC" button and pasting it Microsoft Paint and saving it as a jpeg or gif.It depends on what operating system you are using.Google search "screen shot" with whatever operating system you are using.Tuning boost with the 3 port is personal preference.You can make it act like an MBC but you will get PTFB just the same.It might be more benificial for you to purchase an Opensource etune for your mods to get you started and then just fine tweak it from there.This isn't exactly something your going to get over night.It takes alot of logging and reflashing to get sorted out if you have never done it before.Spend some time on RomRaider looking at the tuning faq's and reading the post I linked earlier at NASIOC.This is what my wgdc map looks like on my TD04 with GM BCS.

[autonuerotic]

I made a log last night 2000RPM to 7000RPM 100% throttle. I hit 18psi at 3500 rpms and it tapered to 12.62. At 100% throttle my target boost was 15psi, when logged it showed my target at 12.62 and the ecu adjusted by itself. Is it just my wgdc are too low or is timing involved in the target being 12psi when it should have been 15psi?

[Kjott21]

I had a very well tuned map for my 04 WRX with a VF30/Pinks/GM BCS/Cobb SRI setup.
This is what the WG Tables looked like:


Turbo Dynamics tables:


PM me your email address and I will send you the whole map if you want.

[dumdum]

/\ Yup.Almost looks like mine for the TD04.Can you post your Turbo Dynamics tables as well?OP,your intial WGDC is way to low if you compare yours to Kjott21.Also I would use Romraiders logger instead since your using the editor.

[Kjott21]

Originally Posted by dumdum

/\ Yup.Almost looks like mine for the TD04.Can you post your Turbo Dynamics tables as well?OP,your intial WGDC is way to low if you compare yours to Kjott21.Also I would use Romraiders logger instead since your using the editor.

Edited my post to add the TD tables right before you posted that. +1 on the logger. The TARI Racing software is out of date, and not very user friendly.

[autonuerotic]

Got it... Thank you! This will help a great deal, Ill try it out and log it.

[Kjott21]

Originally Posted by autonuerotic

Got it... Thank you! This will help a great deal, Ill try it out and log it.

Copy all the tables into your 05 ROM. Do not load the 04 ROM onto your ECU. I believe they are different.

[Kjott21]

Update? Have you been too busy enjoying the map to let us know that you got it fixed?