Welcome to the North American Subaru Impreza Owners Club Wednesday August 27, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Factory 2.5L Turbo Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 04-24-2006, 11:26 AM   #1
dexterous
Scooby Guru
 
Member#: 23553
Join Date: Aug 2002
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2005 STI - Insanity!
2014 WRX - Daily

Default 4 Pulls at very high EGTs - Do you think I will have an issue?

Guys,

After tuning my car I decided to do four high speed pulls to test everything. On the forth pull I noticed that my EGTs were getting as high as 960C/1760F. Obviously thats was not good. I fixed the issue but I am wondering if those four pulls have a potential to cause break anything. Obviously I am worried about valves, rings, etc... The car only has 4500 miles on it (forty five hundred) and I only really started modding it two weeks ago.
* Registered users of the site do not see these ads.
dexterous is offline   Reply With Quote
Old 04-24-2006, 11:32 AM   #2
supermarkus
Scooby Guru
 
Member#: 6971
Join Date: May 2001
Location: Edmonds, Washington, USA
Vehicle:
2008 WRX STi
SSM

Default

How are we to know without knowing your state of tune or mod list? "my car runs funny, what's wrong with it?" I've seen a fully built, rotated mount turbo'd STi run into the 920-940C range on 4th gear pulls up to ~8K. Scary, but the car is still running strong. You might want to direct questions specifically at tuners like phil at element tuning.
supermarkus is offline   Reply With Quote
Old 04-24-2006, 11:47 AM   #3
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

No, but sustained over a long period of time you are creating a lot of stress.

Thanks for driving Markus!!

It would be nice for me to creep up on 900C like I did with the stock turbo. However, with my big turbo, I'm far more likely to move from a state of retarded timing to more advance. That means I will always see over 900C first, and then have to add timing to bring down the EGTs (or lean out the mixture, that can work too--yes it's counterintutative). So I see over 900C pretty regularly while tuning, but I never leave it that way.

You might say why not tune with more advance and then retard the timing to bring the EGT up to 850-900C? Well you could easily be detonating with the added advance and then who cares about the EGT.

One way of looking at EGT that I find useful is to think about this: If the EGT is low and timing is advanced, all the heat is IN the combustion chamber. In other words you want to get you EGT about as high as possible or you are just heating up the combustion chamber more--and that has other consequences. Jorge (RiftsWRX) taught me that.

MBT stands for Maximum Brake Torque, but when tuning for EGT I think it stands for Minimum Best Timing.

Luego..
bboy is offline   Reply With Quote
Old 04-24-2006, 11:53 AM   #4
TheMadScientist
Scooby Guru
 
Member#: 23717
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Beverly, MA
Vehicle:
2005 Big red

Default

1700+ Daily.
For ~ 1year now and everything is fine. But if something goes wrong, it will go wrong very quickly.

TMS
TheMadScientist is offline   Reply With Quote
Old 04-24-2006, 12:14 PM   #5
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

Sizzlin!!
bboy is offline   Reply With Quote
Old 04-24-2006, 12:36 PM   #6
dexterous
Scooby Guru
 
Member#: 23553
Join Date: Aug 2002
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2005 STI - Insanity!
2014 WRX - Daily

Default

supermarkus: Know that, I am not an idiot. My question had nothing to do with my tune it was referring to running the block at 860C.

bboy: Interesting. Thanks. I had the car dynotuned by a professional tuner (Protune). The thing that kills me is that we tested every other thing but 5th gear at high RPM (no room in rush hour traffic). The day after the tune I discover the high EGT issue.

TheMadScientist: Are you running a stock block? I plan on swapping the block out for a better motor at some point about two or three years from now. I really only need to get about 75K miles out of my block. Even 50K would be ok but a rebuild for the rest of 2006 is not in the cards.
dexterous is offline   Reply With Quote
Old 04-24-2006, 12:40 PM   #7
TheMadScientist
Scooby Guru
 
Member#: 23717
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Beverly, MA
Vehicle:
2005 Big red

Default

Only forged pistons.
IMO The limit on EGT is the Exhaust valves. We have sodium filled valves to help cope with high temps. The one problem is that if you get even a micro crack in the valve stem the sodium will start to burn and the valve will melt.

TMS
TheMadScientist is offline   Reply With Quote
Old 04-24-2006, 12:45 PM   #8
dexterous
Scooby Guru
 
Member#: 23553
Join Date: Aug 2002
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2005 STI - Insanity!
2014 WRX - Daily

Default

TheMadScientist,

So let me see if I understand this. EGTs primarily effect the valves/heads correct? Cylinder pressure causes cracked rings, correct? Lean AFR's melt pistons, correct? If not, please correct me. Thanks.
dexterous is offline   Reply With Quote
Old 04-24-2006, 12:50 PM   #9
TheMadScientist
Scooby Guru
 
Member#: 23717
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Beverly, MA
Vehicle:
2005 Big red

Default

Quote:
Originally Posted by dexterous
TheMadScientist,

So let me see if I understand this. EGTs primarily effect the valves/heads correct?
IMO yes.

Quote:
Originally Posted by dexterous
Cylinder pressure causes cracked rings, correct?
IMO no. Det causes broken ring lands.

Quote:
Originally Posted by dexterous
Lean AFR's melt pistons, correct? If not, please correct me. Thanks.
The reason turbo cars run so rich is to cool the charge air to stave off det. Lean afrs can be run as long as you can keep away from det. I tune to 12.8:1 and higher when water injection is used. I just tune a car to 25psi and 12:1 AFR with 28* of timing at redline.


TMS
TheMadScientist is offline   Reply With Quote
Old 04-24-2006, 12:56 PM   #10
cronic
Scooby Guru
 
Member#: 9749
Join Date: Aug 2001
Chapter/Region: SWIC
Vehicle:
-

Default

Quote:
Originally Posted by TheMadScientist


IMO no. Det causes broken ring lands.




TMS
I agree, but what would you say Det does to cyl pressure?
cronic is online now   Reply With Quote
Old 04-24-2006, 01:04 PM   #11
TheMadScientist
Scooby Guru
 
Member#: 23717
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Beverly, MA
Vehicle:
2005 Big red

Default

IMO Most of the time when talking to other tuners. Cylinder pressure is a reference to the power being made with normal combustion. And yes I agree that det does raise cylinder pressure tremendously. But det is a non-normal combustion condition.

TMS

Quote:
Originally Posted by cronic
I agree, but what would you say Det does to cyl pressure?
TheMadScientist is offline   Reply With Quote
Old 04-24-2006, 01:15 PM   #12
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

EGT-->valves #1 >> exhaust system turbo turbine #2

To melt a piston you'll need to be either 1) very lean for a long time 2) scuffing the cylinder (as in no oil, no coolant, leads to siezure) or 3) detonating for a long time, but other stuff will break before the engine melts.

Likewise on tuning with WI. I'm at 12:1 AFR with water, but ~11:1 without.
bboy is offline   Reply With Quote
Old 04-24-2006, 01:34 PM   #13
Nixlimited
Scooby Newbie
 
Member#: 86730
Join Date: May 2005
Chapter/Region: TXIC
Location: Austin, TX
Vehicle:
2005 STi
460 WHP @ 28 PSI

Default

I was seeing 960C at the top of 4th gear pulls and I pulled the boost back a bit at redline. Now I am seeing 910C worst case. I am tuned for 11:1 AFR. Thus far engine is running strong. Soon I will be getting WI to get those numbers hopefully down to 850C max.
Nixlimited is offline   Reply With Quote
Old 04-24-2006, 04:26 PM   #14
supermarkus
Scooby Guru
 
Member#: 6971
Join Date: May 2001
Location: Edmonds, Washington, USA
Vehicle:
2008 WRX STi
SSM

Default

I wasn't implying that you were an idiot, just that it is difficult to know what to expect from your setup without details. Sorry if you took it that way. It would be nice to know exactly what level of modification you're dealing with.

bboy, thanks for letting me drive. I'm still gushing on about it to my friends. The power and EGT are alarming, but kinda expected given what I've seen posted by others in the past.

Last edited by supermarkus; 04-24-2006 at 04:33 PM.
supermarkus is offline   Reply With Quote
Old 04-24-2006, 04:50 PM   #15
izzodesh
Scooby Specialist
 
Member#: 68274
Join Date: Aug 2004
Chapter/Region: NESIC
Location: Buffalo
Vehicle:
2013 FJ Cruiser
cardomain.com/id/izzodesh

Default

wow that is hot assuming u broke it in fine the valves will be fine but i would worry about the rings...
that thing must have been smoking!
izzodesh is offline   Reply With Quote
Old 04-24-2006, 04:50 PM   #16
Crawford/I-Speed
Vendor
 
Member#: 12347
Join Date: Nov 2001
Chapter/Region: SCIC
Location: Oceanside, CA
Vehicle:
ECU ReProgramming
Dynapack AWD Dyno

Default

Quote:
Originally Posted by dexterous
Guys,

After tuning my car I decided to do four high speed pulls to test everything. On the forth pull I noticed that my EGTs were getting as high as 960C/1760F. Obviously thats was not good. I fixed the issue but I am wondering if those four pulls have a potential to cause break anything. Obviously I am worried about valves, rings, etc... The car only has 4500 miles on it (forty five hundred) and I only really started modding it two weeks ago.
High EGT's just means you are making power, of course there is a point at which EGT's will be far too high. This usually is due to improper tuning, and the ECU is pulling out timing due to detonation.

I would ask people that have had higher EGT's for extended period of time what problems they have had, such as TheMadScientist.

Also note, low EGT's mean you are not making much power and are playing on the conservative side. This is a good option for those people playing tuner on their own vehicle. Otherwise unless you know what to look/listen for you might have a really large paper weight on your desk.

Cheers,
William T. Knose Jr.
Lead Programmer
I-Speed USA
Crawford/I-Speed is offline   Reply With Quote
Old 04-24-2006, 04:52 PM   #17
dexterous
Scooby Guru
 
Member#: 23553
Join Date: Aug 2002
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2005 STI - Insanity!
2014 WRX - Daily

Default

supermarkus, its cool. Your post really had nothing to do with my question though.
dexterous is offline   Reply With Quote
Old 04-24-2006, 04:55 PM   #18
dexterous
Scooby Guru
 
Member#: 23553
Join Date: Aug 2002
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2005 STI - Insanity!
2014 WRX - Daily

Default

Quote:
Originally Posted by Crawford/I-Speed
High EGT's just means you are making power, of course there is a point at which EGT's will be far too high. This usually is due to improper tuning, and the ECU is pulling out timing due to detonation.

I would ask people that have had higher EGT's for extended period of time what problems they have had, such as TheMadScientist.

Also note, low EGT's mean you are not making much power and are playing on the conservative side. This is a good option for those people playing tuner on their own vehicle. Otherwise unless you know what to look/listen for you might have a really large paper weight on your desk.

Cheers,
William T. Knose Jr.
Lead Programmer
I-Speed USA

Thanks for the info. Whats the max EGTs you like to see on stock blocks?
dexterous is offline   Reply With Quote
Old 04-24-2006, 04:59 PM   #19
TheMadScientist
Scooby Guru
 
Member#: 23717
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Beverly, MA
Vehicle:
2005 Big red

Default

Quote:
Originally Posted by Crawford/I-Speed
High EGT's just means you are making power, of course there is a point at which EGT's will be far too high. This usually is due to improper tuning, and the ECU is pulling out timing due to detonation.

I would ask people that have had higher EGT's for extended period of time what problems they have had, such as TheMadScientist.

Also note, low EGT's mean you are not making much power and are playing on the conservative side. This is a good option for those people playing tuner on their own vehicle. Otherwise unless you know what to look/listen for you might have a really large paper weight on your desk.

Cheers,
William T. Knose Jr.
Lead Programmer
I-Speed USA
I have a better understanding of Quirt's reply to my EGT question on your board.

The purpose and more importantly the PERSON that drives the car determines the upper bounds of EGT more than anything else.


TMS

Last edited by TheMadScientist; 04-24-2006 at 05:35 PM.
TheMadScientist is offline   Reply With Quote
Old 04-24-2006, 06:27 PM   #20
supermarkus
Scooby Guru
 
Member#: 6971
Join Date: May 2001
Location: Edmonds, Washington, USA
Vehicle:
2008 WRX STi
SSM

Default

Quote:
Originally Posted by dexterous
supermarkus, its cool. Your post really had nothing to do with my question though.

Really? My impression is that you were worried about damage done to your engine. I cited an example of high egts in a highly modified car and how it is running just fine, I might add that we saw virtually no sign of knock during our tuning pulls. Then I asked for more specifics about your state of tune to help us put your egts into context and suggested getting professional tuners in on the thread. Of course the high egt pulls have the potential to cause damage, but like the others are saying, max egts can vary with the build and intended output of a motor. I'm sorry if you don't think this is pertinent, I just feel like you're singling my posts out to dismiss, when I really am trying to help. Yes, it was a bad first post, I apologized for that already. Try not to hold it against me.

If it helps i'm sure I could cite some past posts that deal with high egts.

Last edited by supermarkus; 04-24-2006 at 06:45 PM.
supermarkus is offline   Reply With Quote
Old 04-24-2006, 07:39 PM   #21
Nixlimited
Scooby Newbie
 
Member#: 86730
Join Date: May 2005
Chapter/Region: TXIC
Location: Austin, TX
Vehicle:
2005 STi
460 WHP @ 28 PSI

Default

Quote:
Originally Posted by TheMadScientist
The purpose and more importantly the PERSON that drives the car determines the upper bounds of EGT more than anything else.
TMS
For me that is <900C
Nixlimited is offline   Reply With Quote
Old 04-24-2006, 07:49 PM   #22
TheMadScientist
Scooby Guru
 
Member#: 23717
Join Date: Aug 2002
Chapter/Region: NESIC
Location: Beverly, MA
Vehicle:
2005 Big red

Default

Quote:
Originally Posted by Nixlimited
For me that is <900C
I don't think any of the well known tuners will let a subaru out of thier shop with 1700F EGT's. But I don't think any one has any long term data to sugest 1700 is bad. I really don't know. I have been running 1700 for ~20K miles, I guess I will see how long it lasts.

TMS
TheMadScientist is offline   Reply With Quote
Old 04-24-2006, 09:07 PM   #23
dexterous
Scooby Guru
 
Member#: 23553
Join Date: Aug 2002
Chapter/Region: MAIC
Location: Slippery Rock, PA
Vehicle:
2005 STI - Insanity!
2014 WRX - Daily

Default

supermarkus, I am in no way singling you out.

So here are my mods: I have a TBE, Walbro 255lph fuel pump, helix 860cc injectors, borla headers, Perrin turbo inlet pipe, and a Cobb intake.

My car put down 335whp on the dyno when it was protuned a week ago. Strangely I have never seen EGTs above 890C until the four pulls in question. This was verified time after time using my defi peak button. I wonder if this is somehow related to the last tank of gas or something. I wont be able to take the car out again for another week but I think I will get a fresh tank of sunoco 94 and see what happens.

Any way, what do you think I should set as my do not exceed mark?
dexterous is offline   Reply With Quote
Old 04-25-2006, 02:39 PM   #24
supermarkus
Scooby Guru
 
Member#: 6971
Join Date: May 2001
Location: Edmonds, Washington, USA
Vehicle:
2008 WRX STi
SSM

Default

I'm wondering if it has something to do with the way dyno tuning loads the engine versus street driving. Is it possible for you to go out with your tuner and do some road tuning? I'm sure he would be happy to resolve the problem for you if you voice your concerns. IMHO, I would not want to see anything above 900C.
supermarkus is offline   Reply With Quote
Old 04-25-2006, 11:05 PM   #25
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

Tuned today and saw over 900C on most pulls (probably 15) with two at 1000C. We worked to get those down to around 900C, but I'm not sweating 900-940C myself. The lower the better, but you can only add so much timing before you start to detonate.

Tuning is all about balance.

Too much load on a dyno will definitely elevate EGT. You can prove this to yourself by measuring EGT in different gears. The lower the gear, the less load, and the lower the EGT.
bboy is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Do you think Obama will have a monument in DC for being the first black president? urgewrx Political Playground 36 11-19-2008 02:17 PM
Do you think they will ever make an iPod for PC's?? Sephro Off-Topic 35 01-25-2006 11:34 AM
Do you think they will ever have a 6 cylinder STi? 1/500yellowwrx News & Rumors 88 12-16-2004 12:03 PM
do you think we will have a "bad" winter? YaZahX Tri-State Area Forum 19 10-08-2003 09:06 AM
yet another "How much HP do you think I will have?" thread Davenow Factory 2.0L Turbo Powertrain 0 02-04-2003 03:41 PM


All times are GMT -4. The time now is 03:10 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.