# max boost for stock engine?



## jedge1.8t (Jan 27, 2012)

What is the highest boost the stock 225 engine can put out? I only have a apr chip, tip and evo9 dvdv and right now my car is pushing nearly 24psi with my aem truboost. The car runs a little lean so can i just turn up the fueling a little to be more stoich? Just by using the v tune. The power is awesome but i don't want to damage anything. I have no surging or creep just a average 15 a/f Ratio


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## darrenbyrnes (Jan 4, 2005)

*sits back*


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## jedge1.8t (Jan 27, 2012)

You think im pushing the ko4 too hard?


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## toy4two2 (Feb 6, 2012)

rods break at 300whp, don't think you'll see that with the K04 unless you are running e85


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## jedge1.8t (Jan 27, 2012)

With the 20mm rods they say about 320 ft/lbs . I know i will never achieve this but I'm fine the power is good for me until i go f23. But given that i have no surging or creep, is running 24psi okay? The apr tune clearly isnt supporting those boost levels given that I'm running slightly lean but i believe i can up fueling with the V Tune. 

Maybe i will feel better when i got my water injection installed


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## Marcus_Aurelius (Mar 1, 2012)

I have pushed 30 psi and a boat load of torque on stock internals for a very long time. However, the AFR was kept fat (rich) when I ran on 100 octane. Then I finally added knock suppression of water injection and was able to run leaner at 0.80 lambda.

In your case, you have to worry about the lean AFRs detonating, and the in-cylinder combustion heat being too high due to a lack of fuel (this can be monitored by a pre-turbo EGT sensor/probe). If you can keep the AFR in check, you won't be producing torque spikes capable of killing the rods at only 24 psi of boost. It took me 360 AWTQ on E85 to finally bend the stock rods... if the tune is good with good AFR and acceptable EGT (lower than 900*C), 24 psi is nothing to worry about.

You mentioned some gibberish about wanting to be more stoich and averaging 15:1 AFR  . What's your lambda/AFR curve from boost onset to redline on WOT pull? Get that data and we'll be able to tell you if you need to add/remove fuel, and more importantly where and how much is needed to be safe.


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## 20v master (May 7, 2009)

This question makes my head hurt. :banghead::banghead::banghead:


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## jedge1.8t (Jan 27, 2012)

Is there a possibility to log afr curve with vag com? When I'm at idle I'm average like 14,.9 under wot it bounces between 13 and 15.5 but more common on the lab side - aem uego sensor


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> Is there a possibility to log afr curve with vag com? When I'm at idle I'm average like 14,.9 under wot it bounces between 13 and 15.5 but more common on the lab side - aem uego sensor


If you had a wideband car (BEA) you'd be able to log AFR accurately, but your AMU is narrowband so you have to rely on your wideband gauge. Maybe take a video of a pull with RPM visible when looking at the AFR gauge. Telling us what you average is not helping! :beer:


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## 20v master (May 7, 2009)

Marcus_Aurelius said:


> If you had a wideband car (BEA) you'd be able to log AFR accurately, but your AMU is narrowband so you have to rely on your wideband gauge. Maybe take a video of a pull with RPM visible when looking at the AFR gauge. Telling us what you average is not helping! :beer:


This is why any wideband that isn't loggable is worthless. Superior sampling rate FTW!


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## jedge1.8t (Jan 27, 2012)

alright ill try to get that in. the aem is loggable but i have to have some other AEM management system.

Ill try and get a vag log of RPMS with my Boost guage and AFR guage side by side.


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## Marcus_Aurelius (Mar 1, 2012)

20v master said:


> This is why any wideband that isn't loggable is worthless. Superior sampling rate FTW!


Yeah, for the average users and someone like the OP just getting their feet wet with tuning, a loggable wideband with good sampling rate is needed. However, I wouldn't say that a non-loggable lambda readout/gauge is worthless. In my case, I can't remember the last time the need to log AFR was truly felt. I find myself looking for analogue gauges (easy to spot at a glance or with peripheral vision while moving) and keeping things simple. If anything a rich and lean alarm at WOT is all need once my fueling is done, I am growing tired of needless needles moving up and down to tell me what I already know!


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## 20v master (May 7, 2009)

Marcus_Aurelius said:


> Yeah, for the average users and someone like the OP just getting their feet wet with tuning, a loggable wideband with good sampling rate is needed. However, I wouldn't say that a non-loggable lambda readout/gauge is worthless.


Okay, not worthless, but not much good when you can't accurately track and record results over rpm and share those results. As you said, your "average" AFR isn't much good for tuning purposes or trying to not melt a piston. :laugh:


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## jedge1.8t (Jan 27, 2012)

Its not worthless. If i didn't have it couldn't tell you i was running lean. The logging system i would have to purchase is software from aem. Expensive... Im going to try upping the fueling with vtune to see if i can run more on the rich side


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> Expensive... Im going to try upping the fueling with vtune to see if i can run more on the rich side


But first you need to have a solid baseline of your curve. Don't blindly go add fuel across the board without knowing for sure where and if needed in the WOT powerband. More often than not, AFR curves are in need of correction in certain regions more than others. You can totally fix one region of the curve and badly screw up another. Baseline first, than make changes accordingly!


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## jedge1.8t (Jan 27, 2012)

I don't think i can actually increase my fuel load with vtune. But no matter part throttle wot cruising or idle I'm running just a tad lean. A way to increase it just slightly would be nice rather than my guage reading about 15 most of the time


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## jedge1.8t (Jan 27, 2012)

with that said i dont want to take out my wideband just for a loggable one, which will likely be more expensive. Im just looking to stay out of the lean side. 

When i get my water injection running, will I be able to safely run more lean? Will ecu adapt to this and make the car run even more less lean?


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> I don't think i can actually increase my fuel load with vtune. But no matter part throttle wot cruising or idle I'm running just a tad lean. A way to increase it just slightly would be nice rather than my guage reading about 15 most of the time


Do you even realize that cruising and idle AFRs are completely different than full load or WOT fueling? What you run at idle/cruising is closed loop and using the narrowband sensor to target Stoichometric burn. At full load/WOT, once certain thresholds are meet (determined by your mapping), you go into open loop and fueling is mostly based on airflow seeing and *NOT THE O2 sensor*.

I'll repeat for you, get a baseline of your WOT AFR curve with an RPM reference. For part throttle and cruising you can log your trims to see what's going on, but any possible damage from your increased boost is going to come at full load/WOT (in open loop, so stop basing your judgment based on closed loop behavior).


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## 20v master (May 7, 2009)

jedge1.8t said:


> When i get my water injection running, will I be able to safely run more lean? Will ecu adapt to this and make the car run even more less lean?


What Marcus said. And stop thinking w/m injection is a cure for a WOT lean condition. You're just asking for trouble going down that road. No, the ECU won't adapt with w/m to correct the lean condition.


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## jedge1.8t (Jan 27, 2012)

As far as the difference between idle and wot i believe you should be running rich on wot and idle you should be running stioch.

WOT I run rich right as I hit the pedal, but as the rpms climb it immideately sets around [15 - 15.7] average is about 15.2

I know im not giving you loggable data, But pardon me for wanting to be more stioch without the hassle and expense of a AFR logger. 

I dont think i can post a video though because my digital display is dorted when i film it with a camera. Another thing to add to is my o2 sensor is after the flex section and not immideately after the turbo.


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> with that said i dont want to take out my wideband just for a loggable one, which will likely be more expensive. Im just looking to stay out of the lean side.


There is no need to replace your wideband gauge, just listen and go record AFR on a WOT pull with an RPM reference. Once you have that baselined, you can stop shooting in the dark and know exactly what's going on and what's needed.




jedge1.8t said:


> When i get my water injection running, will I be able to safely run more lean? Will ecu adapt to this and make the car run even more less lean?


Yes, the higher knock threshold of water injection will allow you run at ideal or at least closer to "lean for power". However, factors like EGT and timing corrections will determine how far you can go safely (not all water injection system will give the same level of results). Another thing worth noting is that there is a limit of how lean you want to go, even if the octane level can take it. Once you pass that point, you're just losing power and that's what is referred to as " lean AFR for power".


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## jedge1.8t (Jan 27, 2012)

I didnt say the W/M would solve my lean issue, I want to run more rich either way.

Im saying will the ECU o2 sensors read a more richer AFR when injecting water and alchohol or meth? Will this adjusts the cars fueling to run less fuel, meaning even more lean than already?

Im going to try to video the data right now.


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> As far as the difference between idle and wot i believe you should be running rich on wot and idle you should be running stioch.
> 
> WOT I run rich right as I hit the pedal, but as the rpms climb it immideately sets around [15 - 15.7] average is about 15.2
> 
> ...


:banghead: You keep repeating "wanting to be more stoich" and that's 14.7:1 AFR on conventional fuel and way too lean for WOT. At stoich on WOT, you're still in the danger zone and loosing a lot of power (12.5:1 is best lean AFR for power in your case with the fuel you run, but you might not be able to run that lean without knock and corrections). So yes, 15 AFR is bad and need immediate attention but 14.7 (stoich) is equally as bad and not what you need except a idle.

Unfortunately without AFR data vs RPM, nobody can help you correct your problem. This shows that Adam is correct in saying that a non-loggable wideband is worthless if you can't have and use the data it's reporting to you.


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## Kacz07 (Mar 4, 2012)

It doesn't matter. You're still not going to beat a stock SI...


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## jedge1.8t (Jan 27, 2012)

marcus you even quoted me and yet your saying things that are un true.

You want to be rich on WOT, and stioch at idle. I understand that. never said i want to be stioch at WOT, i simply said i want to be more stioch over all.

I did a few hard pulls and the car runs rich on wot, so im trying to test part throttles. now

heres a start from 3rd, 4th and a little of 5th, this is on 70% Duty cycle on tru-boost


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## 20v master (May 7, 2009)

jedge1.8t said:


> marcus you even quoted me and yet your saying things that are un true.
> 
> You want to be rich on WOT, and stioch at idle. I understand that. never said i want to be stioch at WOT, i simply said i want to be more stioch over all.
> 
> ...


Stop using "rich", "lean", and "stoich" in your posts. Use numbers, like 12.0, 14.7, 15.5. Yes, you want to be rich on WOT. But do you want 14.6, 14.0, 13.0, 11.0? See the problem? Anything on either side of 14.7 for gas is rich or lean. They are broad terms that don't tell anything specific, which should be your goal here. This whole time you've been saying lean on WOT, now you're saying it runs rich on WOT, so nobody knows what you're really trying to say/correct. THIS IS WHY A GRAPH FROM A LOGGABLE WIDEBAND WOULD HELP US HELP YOU.


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> marcus you even quoted me and yet your saying things that are un true.


Why I am still trying to help you? I don't know!


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## 20v master (May 7, 2009)

Marcus_Aurelius said:


> Why I am still trying to help you? I don't know!


Exactly what I almost posted. Maybe jedge should just go be put through the ringer in id=27. :laugh:


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## G'D60 (Mar 11, 2002)

At first I was like:


Kacz07 said:


> *It doesn't matter. You're still not going to beat a stock SI...*


And then I was like:


Marcus_Aurelius said:


> *Why I am still trying to help you? I don't know!*


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## Marcus_Aurelius (Mar 1, 2012)

Marcus_Aurelius said:


> But first you need to have a solid baseline of your curve. Don't blindly go add fuel across the board without knowing for sure where and if needed in the WOT powerband. More often than not, AFR curves are in need of correction in certain regions more than others. You can totally fix one region of the curve and badly screw up another. Baseline first, than make changes accordingly!


I am quoting myself to show how true my guidance was. You are running pig rich at 10:0 from midrange - up, yet you were blindly adding fuel chasing some mythical "more stoich overall". You are wasting fuel and power running that fat. Remember, your original post is about how much boost the motor can take safely and at what AFR. Well, that's WOT fuel tuning and you are running on the opposite spectrum of what you were preaching.

Anyway, you need to remove fuel until you get your AFR at least in the high 11s. Just be careful not to create a lean island at boost onset (log timing correction from 2500 rpm to 3500 rpm and unusual correction would be an indication).

Idle and part throttle can be leaner than stoich and that is fine (it's actually desired to have lean spool and lean cruise for better fuel efficiency and gas mileage). :wave:


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## seth_3515 (Dec 26, 2008)

Quit making excuses about logging. If you want an reliable, optimal running engine you will need to be able to log your AFR's so you can adjust accordingly.. 

W/m will not make the sensor reader "richer" it only acts as a buffer to deter knock. Which won't help at the AFRs you are describing. 

The average AFR is absolutely useless in a turbod setup. Absolute values at a specific rpm and boost pressure are crucial. 

- if you don't heed the advice others have given you, you will **** your car up


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## jedge1.8t (Jan 27, 2012)

There is some useful information, instead of "you cant do anything cause you dont have a log"

when Im driving normally, cruising, and idle the slightly over 14.7 is normal from your take. 

However you feel the 10/- under WOT AFR on mid to high RPMs is too much fueling, I can agree with that too that doesn't seem right, i feel i should be in 11s at the very least.

So summary, my car is running rather normally, but I have a too rich (10/-) WOT pull.

I wish they made guage pillars for the TT, it would be better if i could see them near my dash.


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> There is some useful information, instead of "you cant do anything cause you dont have a log"
> 
> when Im driving normally, cruising, and idle the slightly over 14.7 is normal from your take.
> 
> ...


Correct! Lean of stoich at cruise and spool up is a good thing when controlled (I set my cruise at around 16.5:1 in the evos to get unbelievable gas mileage). You are fine at the level that you are right now, what needs attention is your WOT that is overly rich from midrange up. I can't tell you exactly from what RPM because I don't have a reference. 

You could easily relocate your AFR to the far left driver vent, or mount it on top of the steering column on a pod. The empty space left by the wideband can be filled by an EGT gauge .


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## jedge1.8t (Jan 27, 2012)

Yeah i had the vag-com with engine RPMS next to the guage but i couldn't find a way to blow it up so you could actually see it on the video.

I dont really want to take the dash apart again. after all my huge stereo project i dread everytime i gotta remove something. 

Turns out AEM has a loggable A/F Guage. its about $300 and shows boost and A/f with usb loading software, should of bought that but it was $180 more than my uego.

So my questions now, this relating to the Original post, my spike of about 24psi and falling down to 16-17psi okay for the 225q to handle? i feel that fall in boost is rather steep personally, but it is essentially a all stock motor.

Also is there way to lean my WOT AFR a little?


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> So my questions now, this relating to the Original post, my spike of about 24psi and falling down to 16-17psi okay for the 225q to handle? i feel that fall in boost is rather steep personally, but it is essentially a all stock motor.
> 
> Also is there way to lean my WOT AFR a little?


Yes, the stock motor will handle the torque provided by a 24 psi boost spike safely for extended period of time. The boost tapering is normal but not a function of the motor but rather resulting from the turbo's inability to flow at higher RPM, and also the wastegate actuator wasting/bleeding energy because the internal spring is too weak (designed to handle the stock 15 psi but not your 24 psi target). 

There are plenty of ways to lean out your on-boost AFR. The one I would recommend for your particular situation is lowering fuel enrichment under load with Unisetting. This will effectively lean out the curve as the loads ramp up from boost onset. Since this has less effect on the beginning of boost onset and more effect the further the RPM and load ramp up, it would work better IMO than adding fuel everywhere. The reason behind my reasoning is that adding fuel everywhere via the primary fuel channel will cure things up top, but make onset too lean (like mentioned before, you don't want to fix one part and mess up another). :beer:


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## jedge1.8t (Jan 27, 2012)

Alright so maybe with the spring mod I can see possibly some higher psi in the higher RPMS?

and should lower the fuel load increase? or fuel load decreased? there both options in V-tune and Unisettings


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## Marcus_Aurelius (Mar 1, 2012)

jedge1.8t said:


> Alright so maybe with the spring mod I can see possibly some higher psi in the higher RPMS?
> 
> and should lower the fuel load increase? or fuel load decreased? there both options in V-tune and Unisettings


Correct, the spring mod will give you a more appropriate hot side efficiency and help reduce the boost tapering margin. 

The fuel under load is an enrichment to a main or base curve. So, increasing the value above what is preset in your mapping (if any) will add fuel as the load increase (not what you're after and making the overall curve richer). Decreasing the value will lower the enrichment or fuel added under load and lower the AFR curve overall (that is what you're after). Unisetting or V-tune should get you going! :beer:


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## jedge1.8t (Jan 27, 2012)

both softwares aren't allowing me to connect, probably a good thing lol. I got a genuine HEX-COM usb cable from Rosstech, but wont let me communicate to the ECU via Unisettings or V-tune. It trys for a minute but then losses communication.

I will get the spring in asap and do a gear pull with VAG-COM(found out how to zoom in) on my laptop and next to my truboost and A/F guage.

Then i can get a pherhaps a usable informative video on speed, RPMs, Manifold pressure, and A/F ratio +Gear


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## darrenbyrnes (Jan 4, 2005)

Getting my money's worth out of this thread...

opcorn:opcorn:opcorn:


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## seth_3515 (Dec 26, 2008)

jedge1.8t said:


> both softwares aren't allowing me to connect, probably a good thing lol. I got a genuine HEX-COM usb cable from Rosstech, but wont let me communicate to the ECU via Unisettings or V-tune. It trys for a minute but then losses communication.
> 
> I will get the spring in asap and do a gear pull with VAG-COM(found out how to zoom in) on my laptop and next to my truboost and A/F guage.
> 
> Then i can get a pherhaps a usable informative video on speed, RPMs, Manifold pressure, and A/F ratio +Gear


go in vagcom on your computer and make sure you unclick intelligent mode then open Uni or V settings or whatever.. I had the same issue with Lemmiwinks and Unisettings

-also, dont video your computer with Vagcom running and expect us to be able to read it.. (thats what it sounds like you are planning on doing) LOG the readings. This will put it into an Excel style spread sheet that can be read very easily and can be used to make graphs to visualize the different parameters and how smooth your AFR curve is or isnt..


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## jedge1.8t (Jan 27, 2012)

guess you have to reflash your cable to "dumb" mode if you got the HEX+USB for unisettings.

So i went on to Unisettings, adjusted the fuel load increase % down just a notch. set my duty cycle for 90% and did a 3rd gear pull

UEGO didnt hit any lower then 10.6 this time.

It was only one pull though, and it started pouring rain so I called a rain check.

I will mess with it another time, but big thankyou marcus for helpin me out on this, the key thing that made me want to post this is watch my AFR fluctuate around 15 area on idle, cruise, and normal driving(part throttle?). I thought this was do to setting my boost high. 

Ill take your word for and say thats normal for a turbo car. And Ill try to be more technical and get more usable information next time i need tech help.


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## jedge1.8t (Jan 27, 2012)

seth_3515 said:


> go in vagcom on your computer and make sure you unclick intelligent mode then open Uni or V settings or whatever.. I had the same issue with Lemmiwinks and Unisettings..


Beat you to it, but you beat my post



seth_3515 said:


> -also, dont video your computer with Vagcom running and expect us to be able to read it.. (thats what it sounds like you are planning on doing) LOG the readings. This will put it into an Excel style spread sheet that can be read very easily and can be used to make graphs to visualize the different parameters and how smooth your AFR curve is or isnt..


I have a narrowband so i cant log any AFR with vagcom, And i dont have any other logging devices. If i had a 5V input logging device i could though with my guage.

If you know a better way than my ghetto video of RPMS, boost, and AFR please tell me(besides spending hundreds on a log device)


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## seth_3515 (Dec 26, 2008)

jedge1.8t said:


> guess you have to reflash your cable to "dumb" mode if you got the HEX+USB for unisettings.
> 
> So i went on to Unisettings, adjusted the fuel load increase % down just a notch. set my duty cycle for 90% and did a 3rd gear pull
> 
> ...


- just realized you are rich in WOT and not lean like you said in your first post. If you are running 10.6 WOT you are wasting gas and power but you are not going to blow the engine like you would if you are running lean. (meaning you can drive it worry free and adjust when ou have time) If its just fluctuating a bit at idle, part throttle (+/- .5 or so) I wouldnt worry too much about it. 

-Just thought of this- If he is spiking and seeing most of his power in the midrange wouldnt a rich WOT make sense for his setup? Since he is running pretty much stock (cant hold boost til redline) Could that indicate his AFR's at peak power are "probably" where they should be at full boost, but decline as the boost pressure falls off? Im just curious now..


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## jedge1.8t (Jan 27, 2012)

good point...

Considering im stretching the power of my turbo through a near complete stock engine.

Another thing to bring up is im not using the N75, its plugged in but replaced by AEM wastegate solenoid. Not 100% sure if my guage is smart enough to decrease boost over the revline like the stock system, but i thought with most boost controller it will flatten out your boost curve rather than drop it. I suppose thats what setting the wastegate spring pressure is for.


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## seth_3515 (Dec 26, 2008)

jedge1.8t said:


> good point...
> 
> Considering im stretching the power of my turbo through a near complete stock engine.
> 
> Another thing to bring up is im not using the N75, its plugged in but replaced by AEM wastegate solenoid. Not 100% sure if my guage is smart enough to decrease boost over the revline like the stock system, but i thought with most boost controller it will flatten out your boost curve rather than drop it. I suppose thats what setting the wastegate spring pressure is for.


Think I answered my own question but not 100%. The ECU should be able to adjust off 02 sensor MAF and MAP readings. If thats the case it SHOULD be able to adjust. Im just not 100% on how APRs program runs  

Your EBC shouldnt decrease fueling it at all. There should be a Vac line hooked up to the FPR that adjust fuel. The Truboost CAN/WILL smooth out the boost curve only if you set the duty cycle to do so. You could set the duty cycle to 75% or so at onset and reduce it to 25% or so when you are seeing your boost hit. At least thats how my Apexi AVCR runs. Never personally played with Truboost. WG spring/pressure can be thought of as 100% duty cycle until it sees the correct pressure then breaks open. The EBC controls the boost pressure after this point to fine tune the boost curve. You are seeing a drop in pressure because of varies things like your manifold, IC setup, etc.. The drop in pressure is perfectly normal in a stock setup.


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## jedge1.8t (Jan 27, 2012)

The tru-boost has just one duty cycle% setting, not a onset and boost hit.

It does have a scramble boost, i havent messed with it though, but basicly you set your scramble Duty% and scramble time. Not sure what the benefits are.

I am wondering though if the APR program designed the car to run super rich on WOT
I hope thats not how they consider there reliability.

I still feel a more suitable 11.5 AFR on WOT mid range boost would be better


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## seth_3515 (Dec 26, 2008)

jedge1.8t said:


> The tru-boost has just one duty cycle% setting, not a onset and boost hit.
> 
> It does have a scramble boost, i havent messed with it though, but basicly you set your scramble Duty% and scramble time. Not sure what the benefits are.
> 
> ...


11.5 at WOT to redline would be perfect :thumbup:

-I dont know what setting the Truboost has  I wish i could help you more but I just havent messed with them enough to give any reliable info. With the AVCR I can put in 75% until 4200rpms then run a 25% duty cycle or whatever I desire. Im not sure what the scramble boost controls either. Its probably named something different in other models but has the same function.. :banghead: either way though your AFRs are much more important. 

-Be an optimist, its much better to be rich than lean IMO. You can always drive around on it and fix it when you have time. Lean issues need to be fixed right away..


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## jedge1.8t (Jan 27, 2012)

True it is good to know im on the better than bad side.

Now that i know how to adjust these pieces im gonna move on to my spring and water injection.

Ill dial in the AFR afterwards so it can be done with all existing mods


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## Marcus_Aurelius (Mar 1, 2012)

seth_3515 said:


> -Just thought of this- If he is spiking and seeing most of his power in the midrange wouldnt a rich WOT make sense for his setup? Since he is running pretty much stock (cant hold boost til redline) Could that indicate his AFR's at peak power are "probably" where they should be at full boost, but decline as the boost pressure falls off? Im just curious now..


Not really! 

*Spool up:*
Spool up is always better on the lean side to get the car off its face and moving. This is what is called "lean spool" in the tuning world and it's desirable trait. It is safe because the rpm are not high enough to create high cyl pressures (and heat) in the spool up region. So, even conventional fuel with relatively low octane levels, will accept a lean spool without too much knock sensor activity and help with power. 

*Midrange:*
In the midrange, you must move to a richer AFR profile because peak TQ is approaching and rpm are climbing. Failure to do so will result in higher knock sensor activity and most likely trigger some correction from the ECU. This is where you usually see most properly tuned fuel curve drop a significant amount (richer) to avoid knock or corrections. Various tuning philosophies will call for different AFR points but fuel octane and combustion chamber designs are also driving determinants of where you want the midrange AFR curve to settle at. In the OP's case, high 11's is not a bad idea.

*Upper range:*
This is where you will find the most disagreements between tuners. Some like to have the curve taper quite a bit (in a gradual fashion) towards redline. Others (including myself) like to keep the the curve flat from midrange to redline. One can make a case that the richening taper is done to provide a safety buffer and I don't disagree with that (although some tuners get out of hand with it). In my personal cars, because I know what the consistency is, and tweak things myself with usually some failsafes (water injection, high ethanol content), I like to keep the curve as flat as possible to redline. The result is more power (unless fuel is needed to be dumped to keep things cool) and no hesitations. 

To conclude, you always want a lean spool, fatter at midrange or around peak TQ, and maybe a slight taper as a safety net heading towards redline. Always! :beer:


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