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Old 12-06-2012, 06:34 PM   #1
EricInHoodRiver
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Default 2011 wrx Conservate stage 2 protune #'s?

While I realize "conservative" is a relative term, what would folks deem conservative torque and boost targets to be on a stage 2 2011 wrx dd Cobb protune using 92 octane? I have a Cobb catted dp and a Process West tmic. Everything else is stock.

I define conservative as more torque and power without dramatically--another subjective term--increasing engine risk. I am OCD on maintainence and don't drive like I stole it.

Stock boost is 14.7 and stock torque is about 240

Interested in folks' opinions/experiences.

Thanks
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Old 12-06-2012, 06:54 PM   #2
DabiDa
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My guess would be around 250-300 HP should be a pretty safe number,Not to sure as i have a 02 bugeye that does not make the kind of power the "Newer" model makes.Right now i have a Cobb intake,Sti V7 Upipe,HKS Downpipe,Tanabe exhuast,Cobb AP Stage 2 OTS map boost is @16psi Claimed 280HP.Stage 2 really wakes up the car and feels pretty solid im sure the numbers would be better for you than me and will keep you happy without any issues.
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Old 12-06-2012, 07:18 PM   #3
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Every single car reacts differently to tunes. If you're looking for conservative numbers as they relate to reliability, then there is no clear answer. Stock WRXs and STIs are blowing ringlands, bearings, and other components on stock tunes. While these issues are generally rare in the grand scheme of things, the truth of the matter is that there is no "safe" or "acceptable" power level that guarantees reliability or longevity of our platform. The best you can do is decide what modding level presents an acceptable risk/benefit ratio for you and go from there. Be smart about your tune and don't be afraid to leave some power on the table if it means it will offer you peace of mind with regards to reliability.

Lastly, and for what it's worth, many people are running stage 2 with great success in reliability. It's all about how you care for your car. If you are as anal as you claim to be, I have no doubts the level of power you achieve at the Stage 2+ tune will net you good reliability and a fun, quick car.
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Old 12-06-2012, 07:40 PM   #4
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My 12 made 230 whp on a mustang dyno. Supposedly about 12% lower numbers than a dyno jet. I was hitting full boost but was about 10.5 afr most of the way through the rev band. Thats pretty conservative. Expect mid, mid high 200s and higher 200s with a protune.
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Old 12-06-2012, 08:03 PM   #5
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Quote:
Originally Posted by Decipher View Post
Every single car reacts differently to tunes. If you're looking for conservative numbers as they relate to reliability, then there is no clear answer. Stock WRXs and STIs are blowing ringlands, bearings, and other components on stock tunes. While these issues are generally rare in the grand scheme of things, the truth of the matter is that there is no "safe" or "acceptable" power level that guarantees reliability or longevity of our platform. The best you can do is decide what modding level presents an acceptable risk/benefit ratio for you and go from there. Be smart about your tune and don't be afraid to leave some power on the table if it means it will offer you peace of mind with regards to reliability.

Lastly, and for what it's worth, many people are running stage 2 with great success in reliability. It's all about how you care for your car. If you are as anal as you claim to be, I have no doubts the level of power you achieve at the Stage 2+ tune will net you good reliability and a fun, quick car.
alot of truth. ive been stage 2 and now 3 for almost 4 of my cars 5 years of life. i do drive it pretty hard when its safe. never had an issue. even still on the stock clutch still!! torqued performance is what i use for tuning.
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Old 12-06-2012, 08:50 PM   #6
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Far too many variables to give you an idea. You will fall into the typical numbers of a Stage 2 tune for your year. Proven Power Bragging would be a good section to browse if you are interested. Without hitting a dyno you can only assume.
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Old 12-06-2012, 09:07 PM   #7
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You can decide on what power you want to be at. Some dynos will read a good Stg 2 setup at 300whp, some will read as low as 230. That's the lowest I've seen. Just talk with your tuner, explain your goals and desire for a conservative tune. They'll take care of you.
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Old 12-06-2012, 09:33 PM   #8
EricInHoodRiver
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The full story is I have been stage two for about 8 months. I had four custom maps made: 17.5/16/14/12 psi. I usually run the 16. My instructions to my tuner was to make me safe maps, but I want some fun too, but error on "safe.". I also told him to leave some hp on the table.

So I guess what my question really comes down to is, is the 16psi map significantly more "dangerous" than the 14? The tune was done by Cobb on Portland and I was super impressed with the whole process.
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Old 12-06-2012, 09:37 PM   #9
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No, they're probably all about as safe as eachother. Yeah sure, the 16psi map may be slightly, SLIGHTLY more dangerous, but I wouldn't worry. There's people running 20+psi without problems.
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Old 12-06-2012, 09:46 PM   #10
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PSI means little, I think you need to understand that.
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Old 12-06-2012, 10:33 PM   #11
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^^^
I for sure don't understand the importance/or lack thereof of boost psi and engine safety. It's all kind of vague to me. The relationship between timing, afr, boost pressure etc.

I do trust my Cobb tuner

I will load my 14 psi map and see how it feels compared to my 16. The 17.5 map is pretty ($&$(((;;; terrific, but I was losing sleep so went to 16 which is still damn nice.

In a perfect world there would be an equation that one could use to predict engine safety as a function of boost, or afr or whatever. I'm getting the hint here that that's not gonna happen.

The problem/blessing of being ignorant is that everything sounds reasonable...
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Old 12-06-2012, 10:43 PM   #12
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pretty sure he is getting at with the psi means little comment bc 14psi on one turbo is not the same as 14psi on a larger turbo, the larger one will flow more air at the same psi as the smaller one. also there comes a point at which more psi becomes meaningless bc it is inefficient beyond a certain range. Its been a while since i have read all that info so you might want to read the turbo faq in the newbie section

Most people just look at afr bc its easily read off your cobb ap. I think of my boost gauge more of a diagnostic tool. You can also use the knock part of the ap to monitor for that and look and see if there is any timing being pulled at wot. but i dont ever really look at after i load it and drive around a couple times to ease my mind about the map.

if you load a map and like it just look to see what your afr's are, look to see what the timing is if any is being pulled and watch for knock. If everything seems ok they you will be fine. Like other guy said stock motor ringlands fail so whatever. btw you can log a third gear wot pull o nthe highway from like 3k rpm to redline then post it in the engine management section under access port and cobb guys will look at it and tell you if everything is ok
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Old 12-06-2012, 11:06 PM   #13
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Dmochowski, at a fixed temp and elevation, with any turbo, 14psi is 14psi. There is no difference between turbos. Yes, if your turbo is beyond its efficiency range, it will be hotter and cause a hotter 14psi, however, if your intercooler is efficient enough, it won't make a difference.

Eric, yeah, I understand where you're coming from, I've been there. Boost CAN cause reliability issues, but it isn't simply a direct correlation. Cylinder pressure is the major killer of these engines, this is mainly caused by detonation. Don't worry about which map you're on as far as boost goes, if they both prevent detonation and are at a good AFR, they're both safe (for the most part).
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Old 12-07-2012, 12:25 AM   #14
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Quote:
Originally Posted by drewvdw View Post
Dmochowski, at a fixed temp and elevation, with any turbo, 14psi is 14psi. There is no difference between turbos. Yes, if your turbo is beyond its efficiency range, it will be hotter and cause a hotter 14psi, however, if your intercooler is efficient enough, it won't make a difference.

Eric, yeah, I understand where you're coming from, I've been there. Boost CAN cause reliability issues, but it isn't simply a direct correlation. Cylinder pressure is the major killer of these engines, this is mainly caused by detonation. Don't worry about which map you're on as far as boost goes, if they both prevent detonation and are at a good AFR, they're both safe (for the most part).
Sorry drew but you're wrong about the boost portion. Different turbos will flow more air at the same boost pressure and temp, yes the output temp will be different obviously. A td04 at 20 psi with a ridiculously efficient air to ice water intercooler will not output the same airflow as a 40r blowing straight into the intake at 20 psi.
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Old 12-07-2012, 12:36 AM   #15
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How do you figure? 20psi of gas at X temp is 20psi of gas at X temp. You have a fixed volume in the post turbo intake tract. If it flows more air, the pressure will be higher. End of story.

If you have a turbo that supplies 20lbs of air per minute and an engine running at 1rpm (for the sake of simplicity) every revolution of that engine will take in approx. 20lbs (negating the volume of the intake tract as it is a constant).
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Old 12-07-2012, 12:50 AM   #16
EricInHoodRiver
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Very much appreciate the advice. I will continue to log and look at my afr, knock and DAM, but I won't be overly paranoid. Currently the car is running really well. I'm going to rest a bit easier now, and change maps up, or down to experiment.

Obliged,
Eric
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Old 12-07-2012, 01:05 AM   #17
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Sorry for thread jacking, but this is too interesting.

Let's say turbo A is capable of supplying 50lbs/min efficiently and turbo B is capable of flowing 100lbs/min efficiently. Let's also say that there's 100 cubic

Both are on identical cars running at 20psi. Both have identical intake temps as they go into the throttle body.

The ideal gas law is this: PV=nRT where
P is pressure
V is volume
n is number of moles
R is the gas constant
T is the temp

All of those things are constant between the two, so how can one "flow more air" at the same boost pressure?
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Old 12-07-2012, 01:40 AM   #18
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Bigger turbo = more volume, no?

Running lower boost on a bigger turbo to get similar power is a pretty common technique to save your stock internals.
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Old 12-07-2012, 01:41 AM   #19
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Quote:
Originally Posted by drewvdw View Post
Sorry for thread jacking, but this is too interesting.

Let's say turbo A is capable of supplying 50lbs/min efficiently and turbo B is capable of flowing 100lbs/min efficiently. Let's also say that there's 100 cubic

Both are on identical cars running at 20psi. Both have identical intake temps as they go into the throttle body.

The ideal gas law is this: PV=nRT where
P is pressure
V is volume
n is number of moles
R is the gas constant
T is the temp

All of those things are constant between the two, so how can one "flow more air" at the same boost pressure?
Drew, you're forgetting airflow does not equal pressure. Two completely seperate things. Volume is what changes, pressure does not. I understand what you're saying but it just doesn't work that way in real life. There is more to it than just the ideal gas law. Hence why you cannot just adjust the temp compensation for fueling with the ideal gas law (believe me I tried). It will not work 100%. Not only that but every turbo flows differently at different psi, this is why we have compressor maps, yes they do tell you how efficient they are but if you were to try to make a td04 put out the power equal to a 40r you'd need to precool the intake charge to compensate for how much the compressor wheel will heat up the air when it is pressurized, for something like that you'd be looking at something like -400 degree farenheit pre turbo intake temps to combat the inefficiency of the turbo. Even then it probably wouldn't function as intended because you are still stuck with the inefficiencies of the turbine wheel.
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Old 12-07-2012, 01:44 AM   #20
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So drew unless you want to try to run that ramjet we've been discussing along with lots of nitrous, good luck buddy xD
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Old 12-07-2012, 01:58 AM   #21
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Drew and sorrowfulkiller are both right in their own regards. Yes, based on the ideal gas law all the numbers will add up and air flow will end up being equivalent regardless of turbo size or any other variable. And even though the ideal gas law is only accurate for IDEAL gases, the difference between our real and ideal gases for this case specifically is insignificant so for argument's sake we can go with it. The difference arises here, where sorrowful states "A td04 at 20 psi with a ridiculously efficient air to ice water intercooler." The more efficient intercooler will change the properties of the gas, thereby changing the values of the variables in the ideal gas law equation. Cooling gases decreases pressure, decreases volume, keeps the number of moles constant (actually a change from gas state to liquid state would technically increase the moles of substance), and certainly the cooling will cause the temperature to decrease.

In summary, if, when a person states that a different turbo will have different flow rates at the same PSI, they are taking into account chemical changes in the properties of the gas (eg. through differences in cooling), then yes, they are correct in assuming so. BUT based purely on the ideal gas law and the turbos ONLY, with no chemical changes to the gas, as Drew hypothesized, there would be no ideal difference in air flow from two different turbos.

Someone please correct me if im wrong this is all from undergrad physics and MCAT studying from two years ago so I may be a bit rusty.
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Old 12-07-2012, 01:59 AM   #22
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Volume doesn't change though. There's a set volume of space in the intake tract as well as a set volume in the cylinders. As we agree, pressure will stay the same. It simply doesn't make sense. On two vastly different turbos, absolutely, but say a GT30 vs. a GT35, if they're both running 20psi which is well within the efficiency range, they won't be heating the intake air a whole lot more than what a good intercooler will account for.
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Old 12-07-2012, 02:02 AM   #23
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Quote:
Originally Posted by backseatwindowsup View Post
Drew and sorrowfulkiller are both right in their own regards. Yes, based on the ideal gas law all the numbers will add up and air flow will end up being equivalent regardless of turbo size or any other variable. And even though the ideal gas law is only accurate for IDEAL gases, the difference between our real and ideal gases for this case specifically is insignificant so for argument's sake we can go with it. The difference arises here, where sorrowful states "A td04 at 20 psi with a ridiculously efficient air to ice water intercooler." The more efficient intercooler will change the properties of the gas, thereby changing the values of the variables in the ideal gas law equation. Cooling gases decreases pressure, decreases volume, keeps the number of moles constant (actually a change from gas state to liquid state would technically increase the moles of substance), and certainly the cooling will cause the temperature to decrease.

In summary, if, when a person states that a different turbo will have different flow rates at the same PSI, they are taking into account chemical changes in the properties of the gas (eg. through differences in cooling), then yes, they are correct in assuming so. BUT based purely on the ideal gas law and the turbos ONLY, with no chemical changes to the gas, as Drew hypothesized, there would be no ideal difference in air flow from two different turbos.

Someone please correct me if im wrong this is all from undergrad physics and MCAT studying from two years ago so I may be a bit rusty.
Well I'm not doing so bad for a highschool physics dropout I always hated all the ****ing equations and all that ****. I already knew how the majority of everything worked
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Old 12-07-2012, 08:19 AM   #24
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Basically in a perfect world you could make a tiny turbo make as much power as a huge one. But in real world situations it ain't happening.
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Old 12-07-2012, 08:25 AM   #25
BigRob74
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my TP stage 2 #'s catless DP only 267/325 19psi mustang dyno

i run this map all day, one day the IC will explode though..lol

Last edited by BigRob74; 12-07-2012 at 04:17 PM.
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