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Old 05-22-2006, 08:04 PM   #1
xolosis
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Default Fuel, Timing Boost - Tuning Methods

Hey All,

I've read countless articles and forums posts but can't seem to get a clear cut answer on 'How to tune for more power safely?'. So I thought I would see what you guys thought...

Method 1: Run Rich with aggressive timing and low-medium boost. More prone to knock.

Method 2: Run Leaner keep Timing conserative with high boost. Can lead to lower final power output.

Other Methods: If you have another suggestions please add.

I had these thought after being on the dyno for 4 hours and I got knocking non stop with Method 1. However on the road no knock at all. What are peoples thoughts?
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Old 05-22-2006, 11:39 PM   #2
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Keep the flame front speed up so aim for 11.5 if possible. Run your turbo where its good...not high and not low. Do runs while logging airflow (g/s) and find out where adding boost doesn't increase the flow then stop. Timing should be dialed in last and will really be the determining factor in power output and safety.
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Old 05-23-2006, 12:54 AM   #3
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Quote:
Originally Posted by cdvma
Do runs while logging airflow (g/s) and find out where adding boost doesn't increase the flow then stop.
Very informative but can you elaborate on this? I'm a newbie and which column are we talking about within UTEC logging. So what your saying is this will determine the sweet spot for ones turbo in relation to boost. I have never been told about this...
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Old 05-23-2006, 01:01 PM   #4
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Yes there is a sweet spot related to boost. The turbo will make more power as you add boost up until a certain point and its efficiency starts to drop off. If you are looking exclusively at the UTEC pay attention to the 2nd column, MAF volts. You want to maximise that as there is a direct relationship between airflow (MAF volts) and power delivery. More MAF -> more power to be had.

Take the stock WRX turbo for example (with semi-accurate numbers but not gospel). You can run 18, 19 ish psi at 4000 RPM but when you start to increase towards redline you should drop it off to 13, 14 PSI. You won't make any more power (possibly less) running 18 to redline as you will overspin and run the turbo off its map. Often large turbos will run better at say 19 PSI versus 21. I believe the APS turbos exhibit this and are very picky about the range of their peak envelope.
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Old 05-23-2006, 01:34 PM   #5
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^ werd. If you push your turbo out of efficiency, you're going to get hot air (and very little more air, if any) and have to compensate with a richer mixture and less timing, killing off power that you're getting out of any extra air.

I think with pump gas trying to push the envelope on timing isn't a great idea. People seem to have pretty decent luck running 11.0-11.5 AFR on 93 octane, though. Watch your EGTs and watch for knock, but you can definitely lean out compared to the factory tune. This is probably more true for those who autocross or drag race. You may want to tend back to a richer mixture if you're running at high load for long periods of time to manage heat in the longer term, like running 20-30 minute HPDE sessions and such.

Maximize MAF with as little boost as possible, then run as lean as you can safely, and keep a reasonable timing map.
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Old 05-23-2006, 01:52 PM   #6
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1) load conservative fuel and ignition maps.
2) set up your desired boost curve.
3) adjust your fueling to desired AFRs.
4) adjust your ignition curve to maximize power.
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Old 05-24-2006, 03:36 AM   #7
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^^^ Invaluable information this. I'm frustrated that I didn't ask the questions sooner. I've got a bigger turbo and other bits going on the car as we speak. Will take this new found knowledge to the dyno.

Cheers All!
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Old 05-24-2006, 09:35 AM   #8
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Starting off on a base map, and assuming you're going to run OL fueling, here's a generic method:

1.) Set injector size to get you in the ball park
2.) Pull about 2 degrees from the entire map
3.) Lower CL Boost map values to 100 (puts you near WG psi)
3.) Dial in your AFR (without doing this, you'll struggle with the rest of the map)
4.) Since your boost is low already, start by increasing boost in 1-2psi increments to tune AFR in the upper load columns, i.e the 0-100% columns displayed in UTEC. Do this one by one.

At this point you should have a decently tuned, non-aggressive map.

5.) Now ramp up your boost onset/response. Too much and you'll over boost even though your boost map has lower settings.
6.) Now you can add a little timing back in. Start by adding 1* to the entire map (remember, you already pulled 2* initially).
7.) Start ramping up your timing in the low load columns and monitor your stock ECU timing to see what it's doing. Timing starts off low, like 12* at idle, and quickly ramps to 29* by the 3.5k rpm area. I usually use ECU timing in that area and all of the lower load columns FYI. Makes it smoother.You'll want your ECU to UTEC fixed timing numbers to transition easily. Just make sure there's not a huge jump, say 6* or so or it'll jolt.
8.) Now work on the rest of the timing for mid-range and upper-range rpms, one by one.

There's obviously more but that will get you in the game I agree 100% on what the others said about boost psi too. Regardless of what turbo you've got, stop increasing boost when you don't see MAF voltage going up anymore. Or stop increasing boost if you're getting knock detection and your timing is already really low

Last edited by tmarcel; 05-24-2006 at 09:42 AM.
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Old 05-25-2006, 01:48 PM   #9
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^^^
Very true, I neglected the basics like setting your injector size, calibrating your TPS, and calibrating your MAPv (if necessary). Always do those, if they apply to you, before you begin your tuning.
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Old 05-25-2006, 08:17 PM   #10
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I'm very serious when it comes to calibrating and went through each and every step before tuning even had begun.

How can one expect a accurate tune if all your calibrations are off.

cdvma turbo efficiency, tmarcel generic method and other tuners comments has given much better insight on how to tune. Again I'm peeved at myself as I was off the mark adding too much timing and boost whilst not concentrating on fuel.
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Old 05-25-2006, 09:56 PM   #11
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It might be a good idea to use higher octane fuel while tuning the a/f ratio as to not get knock. I mean, ya usually know around what a/f ratio you're shooting for on a given tune in different areas of the tune, so to get around where you want without knock is probably a good idea. Also, it's always good to start on the conservative side and work to agressive. Starting at low boost and working your way up would probably be a good idea. Same with using retarded timing and a richer a/f ratio then you think is necessary. Ya might wanna try lower the octane a little at a time after adjusting fueling until ya get knock. Depending on what octane you're downto when the knock occurs, it can help ya figure out where and how much timing and fuel to add/remove, and what the boost should be. Maybe that's backwards? eh,

peace

Last edited by hippy; 05-25-2006 at 10:06 PM.
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Old 05-25-2006, 10:10 PM   #12
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Nah man, don't be peeved. If you give yourself some time, you can tune with the best of them. Maybe not overnight, but after doing it over and over on your car, you'll be a strong tuner if you understand what to do based on sensor feedback. It's all in the feedback really!
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Old 05-27-2006, 01:12 AM   #13
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I agree, shouldn't be hard on myself. Practive makes perfect...

EBCS, AVO 400L (Similiar to SBR GT12 as its Garrett based), Tuner Pro and other supporting bits went on the car as of yesterday.

Well I can't believe how rich I was acutally running 9.8:1 > 10.5:1 so no wonder I could add more timing like it let me. I'm tuning the car as we speak and will aim for 11.5:1 AFR and already lowered my boost and using a conservative timing map.

Can't wait to put this on the dyno.
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Old 05-27-2006, 06:12 AM   #14
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subscribing...
very nice description for those who havent tuned before...
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Old 06-13-2006, 08:26 PM   #15
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ditto
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Old 06-14-2006, 07:48 AM   #16
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You will want to set your boost table first. Vary your boost by a couple of pounds and watch your AFRs change drastically. If you try to tune your fuel first, you will get frustrated constantly retrimming your fuel maps every time you vary your boost.

You typically know what sort of boost you can run on your given turbo based on the compressor map. Shoot for something in the sweet spot of the efficiency zone (at least that is a good starting point). When you first set your tables on a brand new tune, load some very conservative timing. If you are working up an existing map, pull 2-4 degrees across the board. Then load a conservative (rich) fueling map, and set up your desired boost curve via the boost table. Don't worry about tuning the fuel or timing until you get the boost close to your desired values. Once you are very close on your boost, THEN adjust your AFR, shooting for your desired targets across the load/rpm table. Work and rework your fueling to get it spot on. Then, begin adding timing, being very watchful of knock events and EGTs. I add 1-2 degrees across the board until I get in the ballpark of what I think will be my targets. You will eventually get to the point where you will see some knock events. I see knock events most common near the torque peak, and just before the torque peak. Another common problem for knock is when you get on the throttle hard from a steady state cruise. These problems need to be fixed one at a time. I block adjust the cells where the events occur and pull 1 degree of timing. Rarely I will add fuel, especially if the timing does not seem to remedy the situation.

Don't just do dyno pulls or drag race type pulls on the street when you tune. That is unless you just want your car to perform well in those situations, and not in everyday driving. Drivability can make a car so much more enjoyable to drive around town. Throttle response and smooth, early spooling of the turbo are good goals that really help drivability. Throttle response is helped by more timing and less fuel (generally). These are also things that generally give more power as well. Getting your turbo to spool quickly and smoothly can be aided by pulling a bit of fuel and running a little bit lean during the spooling. Remember, this is also when you typically see our Subie engines try to knock, so this is a balancing act. Sometimes it seems to help driveability to pull some timing to allow the higher ARFs in this spooling phase.

Oh well, this info will hopefully get you in the ballpark, and I have already written too much. If anything I have written is not correct, I know that more savvy tuners will pipe up and set the record straight.
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Old 06-14-2006, 03:17 PM   #17
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THe more I read stuff like this the more I realize that alot of you know nothing. Sure you mean well. Sure you are trying to help and thats cool.. But where did you learn this? By reading on the internet?

The only volumn knob for power is boost. There is only one correct fuel and timing setting. If you are trying to make less power by running less timing you simply running the wrong setting. What you dont realize is that you doing so actualy causes more stress. I have tried to outline this many times even with graphs posted. Good luck

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Old 06-14-2006, 03:36 PM   #18
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Quote:
Originally Posted by AZScoobie
THe more I read stuff like this the more I realize that alot of you know nothing. Sure you mean well. Sure you are trying to help and thats cool.. But where did you learn this? By reading on the internet?

The only volumn knob for power is boost. There is only one correct fuel and timing setting. If you are trying to make less power by running less timing you simply running the wrong setting. What you dont realize is that you doing so actualy causes more stress. I have tried to outline this many times even with graphs posted. Good luck

Clark
Clark,

That's the beauty here. There's more than one way to skin a cat I agree only to an extent that there's only "one" correct AFR and timing. That's too blanketed IMO but I'll assume you meant for a given car. Not telling you anything that you don't already know but every car is different. Why don't you give us your way of doing it?

Todd
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Old 06-14-2006, 03:48 PM   #19
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ignition advance and AFR are the two things that determine how COMPLETE (this optimizes power) the burn is. once you get that sorted out, you can determine how much air (boost) you can shove into the cylinder.

there is one proper ignition advance and AFR curve for every car on a given fuel. proper being defined as the one that produces the most power with the greatest efficiency.
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Old 06-14-2006, 04:33 PM   #20
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[quote=bcbluesGetting your turbo to spool quickly and smoothly can be aided by pulling a bit of fuel and running a little bit lean during the spooling.[/QUOTE]

Are you sure about this one? i thought spool up was aided by a rich mixture, causing combustion in the headers and creating fster spool, similar to how antilag works...
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Old 06-14-2006, 04:38 PM   #21
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Quote:
Originally Posted by BensonRST
Are you sure about this one? i thought spool up was aided by a rich mixture, causing combustion in the headers and creating fster spool, similar to how antilag works...
Thats only if you blow up the mixture in the exhaust. Not worky so well for a normal combustion cycle.
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Old 06-15-2006, 10:24 AM   #22
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Quote:
Originally Posted by happasaiyan
ignition advance and AFR are the two things that determine how COMPLETE (this optimizes power) the burn is. once you get that sorted out, you can determine how much air (boost) you can shove into the cylinder.

there is one proper ignition advance and AFR curve for every car on a given fuel. proper being defined as the one that produces the most power with the greatest efficiency.

^^^agreed
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Old 06-15-2006, 08:09 PM   #23
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AZScoobie: OK, I admit that I am not Mr Ubertuner, and I am still learning the craft (as I expect that I will continue to do as long as I tune, regardless of how "good" I get). If you would be so kind as to point out and offer correction to any glaring errors? I admit that most of my tuning experience is in non-Subies, and rotaries are quite a bit different. But I thought that at least I was approaching my Subie tuning in a sensible manner. Of course, I am not vain enough to refuse to learn.... so enlighten me, please.
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Old 06-15-2006, 08:33 PM   #24
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Quote:
Originally Posted by BensonRST
Are you sure about this one? i thought spool up was aided by a rich mixture, causing combustion in the headers and creating fster spool, similar to how antilag works...

I suggest you not try tricks like this one. Some say lean it out to spool turbo. Others say richen up. I say always tune for power. Who cares what your boost gauge is doing. I care about how much power the engine is making. Things like this rarely work out in the power dept.

Clark
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Old 06-16-2006, 11:00 AM   #25
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Quote:
Originally Posted by happasaiyan
ignition advance and AFR are the two things that determine how COMPLETE (this optimizes power) the burn is. once you get that sorted out, you can determine how much air (boost) you can shove into the cylinder.
yeah, but when you have a denser charge in the chamber you need less advance...
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