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Old 07-24-2009, 06:14 PM   #1
budman5201
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Default Safe boost Level PORSCHE 914 Jdm Ej20 T05

I have a porsche 914 with a JDM Ej20 with a TD05 turbo. Equal length header, stock uppipe, exhaust is only a LONG 30" glasspack. I have a Stand Alone Link Storm ECU and at the Dyno on 100 Octane we were pulling 252hp and 262 torque to the wheels. The dyno showed 20 lbs boost. No knock detected, but also no knock controller. no boost controller at the time but a valve T-'d in the middle between turbo outlet to IC and wastegate. (opened 3/4 way open)

Now....for my question. I have it way turned down on boost, but what is a safe level for boost on the most common crappy 91 octane gas here in AZ. ??

I now have a gm boost controller and i am slowly dialing it in....

thanks guys again
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Old 07-24-2009, 07:26 PM   #2
shemoves
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As high as you can go without knocking...lol. Your AFRs, Timing, and Exhaust Gas Temps are going to affect (among other things) a safe boost level. Something you may want to clarify is if your TD05 is the stock WRX turbo (manufactured by Mitsubishi) or a 16g. Also, do you have an intercooler?

The chassis that your powertrain is connected to is not going to affect your safe boost levels (I guess technically the reduced load from the decreased weight theoritically could affect it). I'm pretty sure most tuned "stage 2" WRXs have boost set around 16 to 18 PSI. Although this is on the weaker USDM EJ20, knock is knock. A stronger motor means it can handle more overall power, but is not neccessarily more resistant to detonation. That is the main concern. I would imagine they have a better head and could handle a bit higher EGTs, but that is also still a concern.

Really what it comes down to is that there are too many unknown variables to say accurately, but my personal, conservative start point would prolly be 12 PSI. That is what the USDM WRX (pre 2009) is set at from the factory. If you don't already have the ability, I highly recommend you getting whatever you need to monitor Knock, AFR, and EGT before turning it up.

So ya know, I'm not a tuner, just trying to help. You may get more answers if you could have a mod forward this to either "engine mgmt and tuning," or SWIC.

Last edited by shemoves; 07-24-2009 at 07:31 PM.
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Old 07-24-2009, 07:54 PM   #3
budman5201
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During Dyno the fuel map was set. Think idle 14.7 and WOT down to 11 AFR at wide open throttle and 19.5 lbs boost.. INtercooler is a frozenboost smallest water to air intercooler with HUGE heat exchanger up front and the intake temps are about 15 degrees above ambient, until a WOT thrashing then they are 50 degreees above ambient.....Timing was set up by a guy who runs sandrails with these ej20 tubos all day, so he has it on the WOT all the time conservative side. On a street car, my WOT pulls last about 5 seconds, then i am way too fast for the law. SO i slow down.

oh its a mitsubishi td05 stock turbo, my engine originally came with the mitsubishi td04 if that helps. It was bad after i got it started (internal oil leak)



Yeah i did think about getting a knocklink from linkecu.com for the knock sensing.
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Old 07-24-2009, 07:37 PM   #4
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12 is too high for my liking. Whack it down to 9 for the meantime.
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Old 07-24-2009, 08:09 PM   #5
shemoves
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My asssumption is that your turbo is a TD05-16g, is this correct? Good that you have an IC...wasn't sure. As far as tuning goes, I would start going with one of the local tuners that is familiar with the Link setup and street cars (not a rail tuner). You will probably see better power numbers. I would assume that someone that normally tunes rails is used to doing things pretty conservatively because of how hard driving the dunes is on an engine. It is a lot of on/off the throttle under very high load (sand + paddles + long, steep hills). He is also likely unconcerned with being able to adjust for fuel economy while on the freeway... These are all things you could take advantage of.

If funds are limited, just get the knock sensing stuff first and make getting retuned a priority before any of the other guages. Your tuner should be able to monitor your AFR and EGT while he is tuning with a short probe up the exhaust pipe (sorry, don't know how else to say it). If Link's knock monitoring stuff is way expensive, you could also get a Knocklite form TurboXS, but you may also need to purchase the microphone (if the engine doesn't already have it).
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Old 07-24-2009, 08:38 PM   #6
Matt Monson
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20psi is outside the efficiency range of the Td05-16 on that engine. Dial it back to 1.1bar or so. It will also help to extend the lifespan of the transmission at the same time. These engines are a bit much for the lowly little 901 based 914 transmission.
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Old 07-25-2009, 12:40 AM   #7
budman5201
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I just turned up my duty cycle of my gm boost selinoid to 46 from 43 and the boost didnt even rise at all. Is that too short of a duty cycle change. I calculated it out, i am only getting 14 lbs max boost with that cycle. I am trying to go baby steps so i dont blow the motor.
The runtime graph shows a GREAT control of boost at 13.5-14 psi max. I could up the duty cycle tomorrow and see what i get. I was reading on a post in here that 53 should be the max duty for gm boost controller, but mine isnt hooked up the same. silver nipple to turbo ic side and the other nipple to wastegate and 3rd to fresh air. I think there is a guy on here that says hook it up different, maybe thats my problem.

I am looking to get in the 17-18 range. 20 lbs driving was INSANE fast.

oh my tuner and i did a lot of work before the dyno at all freeway speeds (on the frewway and actual street driving) for fuel, so right on the money AFR. But your prob right, how do i know the timing is right for those conditions, since his tune is prob conservative so his customers dont blow engines.

Hey would my runtime values help? I can give exact numbers for timing, AFR, air inlet temp and at what rpm and boost value.
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Old 07-25-2009, 03:59 AM   #8
shemoves
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Quote:
Originally Posted by budman5201 View Post
I just turned up my duty cycle of my gm boost selinoid to 46 from 43 and the boost didnt even rise at all. Is that too short of a duty cycle change. I calculated it out, i am only getting 14 lbs max boost with that cycle. I am trying to go baby steps so i dont blow the motor.
The runtime graph shows a GREAT control of boost at 13.5-14 psi max. I could up the duty cycle tomorrow and see what i get. I was reading on a post in here that 53 should be the max duty for gm boost controller, but mine isnt hooked up the same. silver nipple to turbo ic side and the other nipple to wastegate and 3rd to fresh air. I think there is a guy on here that says hook it up different, maybe thats my problem.

I am looking to get in the 17-18 range. 20 lbs driving was INSANE fast.

oh my tuner and i did a lot of work before the dyno at all freeway speeds (on the frewway and actual street driving) for fuel, so right on the money AFR. But your prob right, how do i know the timing is right for those conditions, since his tune is prob conservative so his customers dont blow engines.

Hey would my runtime values help? I can give exact numbers for timing, AFR, air inlet temp and at what rpm and boost value.
You are beyond my knowledge level at this point. I don't know if I would keep going without being able to monitor knock though. You can't hear light detonation if you have a loud exhaust. I tend to play it safe though.
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Old 07-25-2009, 01:17 AM   #9
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Quote:
Originally Posted by Matt Monson View Post
20psi is outside the efficiency range of the Td05-16 on that engine. Dial it back to 1.1bar or so. It will also help to extend the lifespan of the transmission at the same time. These engines are a bit much for the lowly little 901 based 914 transmission.
he's not running 100 octane anymore. 1.1 would prolly be too high currently, but perhaps ok after tuning for the 91 octane. yay or nay?

as a side note, if you live close to a station that has e85 (such as Z's at 59th ave and olive), it mixes like 100 octane. I regularly run about 15% e85.
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Old 07-25-2009, 10:36 AM   #10
Matt Monson
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Quote:
Originally Posted by shemoves View Post
he's not running 100 octane anymore. 1.1 would prolly be too high currently, but perhaps ok after tuning for the 91 octane. yay or nay?
Yeah, it kind of goes without saying that if one isn't going to run 100 octane all the time, then they've got to retune it for what they are going to run. If the car is going to be run on the street on 91 most of the time, he definitely needs a 91 map in addition to the one he already has.

Also, just for clarity, when I say something like 1.1 bar of boost, I am talking about peak boost. With a proper tune, that will be tapering towards redline and will be marginally different in each gear. That 1.1 is a max number, not any sort of average number.

In addition to knock sensing, I would stronglyu suggest getting a good EGT gauge. EGT's tell you a lot in a range where you may not be experiencing knock but still need to make changes to the tune. The more information the better. I pulled a boost number out of my arse based on what makes the turbo happy. What makes the rest of the set up happy based on the cooling, exhaust, fuel injectors, etc has the potential for being significantly different from what we see in the Subaru chassis and we can only point in the right direction. Hell, the fact that the 914 is 700-800lbs lighter than a GC even comes into play since the engine is less stressed because it's pushing around 30% less weight than in a stock Sube.
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Old 07-27-2009, 01:08 AM   #11
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http://www.viatrack.ca/

That is about all you should spend on knock sensing. Unless you can pay what the OEMs pay dont rely on a knock detector that much because you cant tune the sensitivity to include RPM in anything affordable. Look at it this way. If you have to turn your detector down so it doesnt go off on the high end you can have knock in the mid range but wont detect it because you turn the sensitivity down for the high end.


EGT will show DET events if you have a fast acting enough sensor. IIRC it will drop several hundred degrees if you get det because more heat is transfered to the head and piston than in a normal cumbustion event. Your EGT should be mostly steady and not too jumpy if you have fuel and spark close to optimum.
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Old 07-27-2009, 02:03 AM   #12
budman5201
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sounds good guys, thanks for the advice. One question.....what frequency do you run your gm boost controllers at?? Mine is at 20hz and i am not getting a correct response from it. I am stuck at 14 lbs boost, even though i ran the boost table to look just like a MBC for 18 lbs boost. I tested my engine and put a T in the middle of my turbo and wastegate with a 3/4 open valve and i get my boost target easily at 18 lbs, so i determined my gm boost controller is not working properly. It is connected from turbo boost side to gm boost controller and from controller to wastegate.
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Old 07-27-2009, 10:46 PM   #13
Jaxx
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wow 19 psi on 440cc injectors
15 psi should be static
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Old 07-28-2009, 04:50 AM   #14
budman5201
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they are not 440CC injectors. My fuel injectors duty cycle at top boost was 91% , 11 AFR

Yep thats the way i have it hooked up. Silver to compressed side, black port to wastegate. i'll try it this weekend with that 19.5 hz. I agree i dont think a half hz will do anything.
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