Stock vs Stage 1(no mods) tunes

[jamguitarist]

That's the thread I got them from: ) I'm in no rush to get anything done. And I appreciate the info I'm learning from you guys. I'd like it done right, and done by me. Expirience over instant gains imho.

[jamguitarist]

I'd be interested in the compressor map simply for the sake of learning. I have the turbo, it cost me nothing but an evening to look it over and learn some equations. Which would pay off when I upgrade turbos, same principles, different numbers.

[LatentWagen]

Stock tune:

 

800 0.97

2000 6.19

2400 13.54

2800 13.54

3600 13.54

4000 12.96

4800 11.99

5200 11.6

5600 11.22

6000 10.64

6400 10.25

6800 8.51

 

 

Stage 2 tune might be something like this:

800 0.97

2000 6.01

2400 12.12

2600 16.05

2800 17.64

3000 18

3200 18

3600 18

4200 17.89

5000 17.11

5800 14.41

6800 11.1

 

See how quickly it jumps off a cliff after 5K? That's not just a simple choice for tuning. It's because after about 5K the turbo loses steam and you have to dump massive amounts of WGDC into your tables to generate higher boost figures... Which means you are driving the turbo really hard, which means the turbo becomes a flamethrower. The goal isn't to just make boost; it's to make useful boost.

 

Great post, exactly to the point. To my original question, it looks like the stock tune doesn't drop off into the 9psi range until after 6500rpm.

 

The stock tune does have boost tapering slightly after 5k, that's less a turbo bottleneck, and more an exhaust restriction. Look at the minimal drop-off at 5k when you go to stage two (still making 17 out of 18psi).

 

However, anything out of that mid-range sweet spot, past 5500, and the fall-off is definitely much quicker.

[jamguitarist]

As iNVAR said, you can taper boost sharply, or advance timing to keep it safe. I'm assuming the factory tune has a combination of these done. Hence why you don't see the sharp taper. It sounds like he prefers to not advance timing, but to taper off way sharper than the factory tune, which can make better power in the band.

[jamguitarist]

If my understanding is correct, running a MBC can hold you at peak boost so your boost chart will say you've got 17 psi (say that's your target) all the way up in the rpm, but you have to advance your timing in a way that the motor is not using that boost to make power effectively anymore to stay safe. Thus making your turbo stay wound up even though you aren't using it all. By. Tapering the boost sharply, your turbo can spool down, reducing unneeded wear and tear.

Please correct me if I'm confused.

[LatentWagen]

It's an airflow question, really. Can the turbo keep up with the air being pumped by the motor, and how efficiently can it compress that air?

 

I'm used to the US & JDM 2.0s, so taper that early on a VF is new for me (the 2.5 is moving a a quarter more air than a 2.0 at any given boost/RPM). It's clear that the VF sized turbos do begin to choke flow at a certain boost/RPM, both being dependent variables. Not going to dispute where that point is, as it's different for every setup, and I am new to the 2.5 thing!

 

And it's definitely true, you can make power with timing or boost. I favor keeping timing conservative and boost a little higher through the rev range (stress the turbo, not the engine internals [there's a knock argument in there somewhere]), but that's my opinion. Do what works best for you

[jamguitarist]

I would definitley like to upgrade to a VF52 turbo, it seams like a mod that is worth the time and money. My car is at 137k, all documented and every bit of maintenance done since day one, and my vf40 is showing no signs of giving up yet. Which makes it difficult for me to pay out that much when I don't "need" it.

I'm completely new to Subaru, tuning, and turbos. I really have no clue about the 2.0s, even less than the little I know about 2.5s. The internet is a great resource though and 90% of everything I ask myself I can find somewhere. And what I need clarification on I come here and ask, which I'm very happy about the results.

I have already downloaded and read Bad Noodle's Complete Tuning Guide off NASIOC. Very good read and well written, 40 pages long but still left me with a few questions.

 

So far I have finished one ROM based on an Up Pipe and the rest is stock with recommended changes made. I will flash it and log and adjust it as needed. Next I will do a downpipe and boost increase tune that will be built on the first one and repeat the process as my mods continue. It appears that I wont need to make major changes until I go to what I would call Stage 2.5, Turbo, TMIC, and CBE. I probly will never need to get an aftermarket intake for my goals.

[jamguitarist]

Just ordered my VAG com cable. Made sure to get a ft232bl (thanks iNVAR for that chipset thread) but it's coming from China. We'll see how it turns out, plus I'm running Windows 8.1 on an ultra book. If nothing else I have a XP laptop I just rebuilt that I can use as a ridealong pc and transfer files by flash drive for editing.

[iNVAR]

In general, as boost increase, timing should DECREASE. Advancing timing usually yields more power, as does increasing boost. Decreasing boost usually allows you to run more timing. Increasing boost usually lowers the amount of timing you can run.

 

Again, the key is making **useful** boost.

 

The VF40 at above 5000 is clearly out of its efficiency range. If you were to throw an MBC into it which is boost feedback driven and then you dialed it into say... 18PSI, then at 3k-5K you'd be merrily making your 18PSI since you're still within your turbo's efficiency range. Above that, the MBC would bleed less and less pressure from your turbo's WG actuator, thereby driving the turbo harder and harder still trying to make that 18PSI when it's physically (as in "acccording to the laws of physics") impossible to do so.

 

Your turbo may be able to generate 18 PSI at 100,000RPM for your engine at 4KRPM.... But as it moves out of efficiency, it may have to be driven to 150,000RPM to generate only 12 PSI for your engine at 6500RPM. You could try to drive it harder to 200,000RPM and maybe eek out 14 PSI instead of 12 PSI, but you're not only killing your turbo there, you're making useless boost since the air will be superheated. (I'm making up numbers here BTW, just to illustrate a point.)

[jamguitarist]

I see OsEcu does not have much traffic anymore. Is there anywhere I can post a tune for review by knowledgeable people to see what they think, if it's safe to install and start logging? This is a tune I compiled from many others and picked what I liked and changed what I didn't.

[covertrussian]

iNVAR hit the nail on the head!

 

Can you post it in this section? It is the tuning section afterall. There is also Romraider.

[jamguitarist]

How can I upload the entire ROM? I've tried as a .csv and as the .hex, both to big to be allowed.

[jamguitarist]

Or if anyone would be interested in taking a look I'd be more than happy to send it in an email or PM if possible.

[covertrussian]

I would post it up at Romraider, there might be more qualified folks to help.

[jamguitarist]

I got my Vag Com finally. Set it up yesterday and everything is working as it should. Logged on my stock car and my friends stage 2 car just to familiarize myself with the logger software. I will pull my factory rom here in a bit and make the stage 0 safety tune changes to it as recommended then work up the courage to press the flash button for the first time. II have been reading many articles on how to read and interpret issues that could arise in logs.

[jamguitarist]

After pulling the ROM and reviewing, I've found that factory boost approaches 13.5 around 3k RPM. By 4800 it has tapered to 11.99 and by 6k it is at 10. Peak boost looks like it is only attempted from 2400 to 3600. After that it starts dropping.

[evilkowz]

Subscribed!!

[Istoc]

Any updates on this thread? It's been a while. I'm just curious as I'm going to running a stock (to my knowlede) tune afteri receive my cable and do some proper logging to make sure I'm not having knock issues etc.

[covertrussian]

After pulling the ROM and reviewing, I've found that factory boost approaches 13.5 around 3k RPM. By 4800 it has tapered to 11.99 and by 6k it is at 10. Peak boost looks like it is only attempted from 2400 to 3600. After that it starts dropping.

 

That's because the turbo is small and stops being efficient with higher RPM's, at that point it becomes a blow dryer. More boost doesn't always mean more power.

[jamguitarist]

Finally after all this, I flashed the car. The results have been almost to good. I have no knock issues that I see anywhere in my logs, from either fine learning or feedback, I do have knock correction but it corresponds with the logs I took on the factory ROM. The knock summary corresponds with stock as well, I would get random knock events from this log, normally when I stop or push in the clutch at low engine load. I will update if anything comes up. BTW IAM was also at 1.000 after running the new ROM less than a minute, sounds good.

[08qsm]

I've been looking at those stage 0 tunes but I have an 08 and there are certainly a lot of differences between the 05/06 and 07+ models.

 

Are there any stage 0 or stage 1 tunes for the 07+? I'd love to get better gas mileage or free up a little bit of hp/tq in the meantime. I just bought a Tactrix and have plans to go stage 2 eventually, but I'm saving up for the rest of the parts for now. Didn't mean to steal thread but along the same lines just different year cars.

[jamguitarist]

Look on RomRaider and OSEcuroms.org. Both area great sources for info on tuning different models and years. OSEcuroms seems to be a dead forum but there is still a lot of info on there, possibly for your make as well. You'll need to make an account, which could take a few days to be accepted.

[08qsm]

Look on RomRaider and OSEcuroms.org. Both area great sources for info on tuning different models and years. OSEcuroms seems to be a dead forum but there is still a lot of info on there, possibly for your make as well. You'll need to make an account, which could take a few days to be accepted.

 

Thanks for the tips, hope you're enjoying the new tune! I'm sure it's worth all the work, can't wait to get mine done in the near future.