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Technical Chat Ask and answer technical car questions. |
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#26 | |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
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The ECU + stock EBC seems to do a pretty good job of reaching target boost at altitude, but I believe it's at the cost of turbo efficiency. The difference between a cool 14.5 psi and a hot 16 psi is probably negligable, or worse, faster at lower boost if the ECU has to pull timing to prevent knock on a hot motor. Remember, the stock WRX intercooler is pretty small. ![]() And 17.5 psi on a stock WRX turbo! ![]() ![]()
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#27 |
EJ22
Join Date: Aug 2005
Location: Reno, NV
Posts: 110
Car: 04 wrx, bunch of mods
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How much for the seal? Speaking of boost, 17-17.5psi at 4500ft is probably pretty safe. I know a person who was pushing 19psi with only exhaust. You probably understand that the more boost you pump into your engine, means the more force you are putting on you pistons and seals. So you are defenitly wearing out the engine faster with higher boost, which is why I am satisfied with 14.5 psi at 4500ft.
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#28 | |
EJ22
Join Date: Apr 2005
Location: Hayward, CA
Posts: 191
Car: Zee L
Load, Efficiency, MAP etc etc etc
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#29 | |
Candy Mountain
Real Name: Cody Join Date: May 2005
Location: Californication
Posts: 7,751
Car: 03 Pussy Wagon, now with more pink!
Class: TESP
OMG Internet!
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Wouldn't you say that a better gauge of how much extra wear and tear the motor sees is your max power output? I mean, I never really thought that the stock turbo could put "excessive" wear and tear on the engine as long as you aren't detonating or running lean. Any upgraded turbo will push more CFM than the stocker which I think translates to more pressure on the internals. Correct me if I'm wrong. I've heard anthing over 15 psi on the stock turbo and your just blowing hot air, but that's just one person's opinion. Blowing hot air just means a less Oxygen...not necessarily more wear on the engine right?
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#30 | |
EJ205
Real Name: Matt Taylor Join Date: Jun 2005
Location: Cousin-F*ck, Carolina
Posts: 1,474
Wish in one hand and sh*t in the other...
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#31 | |
EJ22
Join Date: Apr 2005
Location: Hayward, CA
Posts: 191
Car: Zee L
Load, Efficiency, MAP etc etc etc
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#32 | |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
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The hotter the intake charge, the easier it is for the car to pre-detonate when the pistons compress that A/F mixture. That's why we use intercoolers, water/alcohol injection, etc. Gotta get the intake charge as cool as possible, so we can compress as much oxygen as possible to make as much power as possible. If the air is so hot that the car starts pinging, then the ECU has to pull timing to protect the motor, in which case you may be running a ton of boost, but making less power because of the retarded timing.
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Is you is, or is you ain't, my con-stit-u-ints? |
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#33 |
The Doink
Real Name: Scott Join Date: Nov 2002
Location: Portland, OR
Posts: 20,335
Car: '09 OBXT, '02 WRX, '96 Miata
Class: PDX/TT-6
The way out is through
|
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For those of you that missed the post, take a look at what Mike Shields had to say about tuning their rally car for the Pike's Peak Hill Climb:
http://www.seccs.org/forums/showthre...ght=pikes+peak There's some interesting info in there about turbo efficiency and altitude.
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Is you is, or is you ain't, my con-stit-u-ints? |
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#34 | |
Candy Mountain
Real Name: Cody Join Date: May 2005
Location: Californication
Posts: 7,751
Car: 03 Pussy Wagon, now with more pink!
Class: TESP
OMG Internet!
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Slow and low, that is the tempo. |
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#35 |
EJ22
Join Date: Apr 2005
Location: Hayward, CA
Posts: 191
Car: Zee L
Load, Efficiency, MAP etc etc etc
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Not sure how you would be tuned for the excessive charge air temps when pushing the turbo that hard though.
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#36 |
Candy Mountain
Real Name: Cody Join Date: May 2005
Location: Californication
Posts: 7,751
Car: 03 Pussy Wagon, now with more pink!
Class: TESP
OMG Internet!
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dunno, the car feels strong and shows no sign of detonation. I wish I had a knock indicater, but I don't.
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Slow and low, that is the tempo. |
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#37 | |
EJ22T
Join Date: Sep 2003
Location: Reno
Posts: 9,445
Car: '93/'01 GF6, mostly red
Class: 19 FP
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A post-turbo exhaust leak only makes noise, it doesn't affect performance much, unless it's a gigantic leak that actually reduces backpressure.
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FWD is the new AWD |
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#38 | |
EJ22T
Join Date: Sep 2003
Location: Reno
Posts: 9,445
Car: '93/'01 GF6, mostly red
Class: 19 FP
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FWD is the new AWD |
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#39 |
Candy Mountain
Real Name: Cody Join Date: May 2005
Location: Californication
Posts: 7,751
Car: 03 Pussy Wagon, now with more pink!
Class: TESP
OMG Internet!
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So then the question is, am I making les power at 17psi than I would at 15 psi, because my tune has to defend against detonation?
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