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Thread: ATR Tuning, anyone had a crack

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    Quote Originally Posted by wyvernone View Post
    I got my Cobb AP late last year and was very excited.

    First I ran stage 0 OTS. Found out that doesn't offer much and is just like stock so I went to Safe mode OTS - that unlocked a few things and gave me some ear to ear grins :-) Did a few WOT logs and monitored the fuel pump pressure to see if it holds. Since mine is a gen 1 MPS I am lucky to have a good fuel pump so I upped to Stage 1 OTS and still kept monitoring. All stock except for the 3 engine mounts.

    Then I made a map after studying Bucker and Abilor's tuning guides and all their stickies and then also added MPG tuning in cruise range as well. I had a great time learning about the ECU and engine management. All fun and after 20 revisions of the map I think I got it all sorted.

    I am pretty happy with the car now I just need to tune my driver mod to make good launches.
    have you done a virtual dyno thingy, remiving boost restrictions i doubt there is anyway to launch these things, just breathing too heavy in the direction of the loud pedal in 1st gear lights the tires up

  2. Default

    Quote Originally Posted by EdgeAutosport.com View Post
    You have to be careful when playing with timing, but optimizing timing is where a lot of the power comes from.

    The goal when setting up the spark advance is to achieve peak cylinder pressure at 15* after top dead center (TDC). That is also known as MBT (max best torque). You have to be careful because you don't want to go past MBT as this can cause some very high cylinder pressures which can result in head lift and broken rods. The other problem with setting up the proper timing is that as you are knock limited on certain fuels. MBT may be around 18-20*, but due to the octane rating of the fuel you are using, you may only be able to get to 14-15* of spark advance before you become knock limited, and detonation is another great way to get rid of those rods.
    Been doing some reading and it seems to be that the best way to work out point of Maximum Best Torque (MBT) is with a Dyno. Obviously having the flame front hit the piston at 15* ATDC will mean you'll need to adjust the timing for piston speed (revs).

    Is there any way to get to MBT just by doing WOT logs without a dyno? Can you rely on KR detection as an indicator of being close to or having passed MBT?

  3. #43
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    On normal pump gas you will get knock before you reach MBT on our cars. The only time you need to worry about reaching MBT is if you use E85, methanol injection or any type of octane booster. If you are using 98 octane you can just tune until you get consistent knock in multiple logs, then remove .5-1* of timing in that rev range. So I would say it's not safe to tune for MBT without a dyno as every log you do on the street will be different and you need consistency to see when you stop making MOAR POWA
    Last edited by ledfootrob; 04-05-2013 at 08:06 PM.

  4. Default

    Thanks @ledfootrob, that approach makes sense.

    I am running Cobb Stage 1 - 98. How many more degrees in the mid range and upper ranges is there to be gained from the Stage 1 OTS map on 98 octane? Wondering how much fat there is to trim (or are they fairly agressive as they are).

    Also, does anyone know if running more timing puts additional pressure on the stock HPFP? My guess is no, but wanted to be sure. Certainly don't want to venture too far until i do get upgraded HPFP internals

  5. #45
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    Quote Originally Posted by allo80 View Post
    Thanks @ledfootrob, that approach makes sense.

    I am running Cobb Stage 1 - 98. How many more degrees in the mid range and upper ranges is there to be gained from the Stage 1 OTS map on 98 octane? Wondering how much fat there is to trim (or are they fairly agressive as they are).

    Also, does anyone know if running more timing puts additional pressure on the stock HPFP? My guess is no, but wanted to be sure. Certainly don't want to venture too far until i do get upgraded HPFP internals
    I wouldn't personally go past stage 1 OTS on the stock pump.. The risk just doesn't add up.

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  6. Default

    Tuning until you get a little knock on pump gas is the best way to maximize timing on the street. However if you have access to higher octane fuels that allow you to run past mbt before seeing KR, you will need to dyno tune to ensure you do not go past MBT. Going past MBT can actually be worse for the car than getting KR, because cylinder pressures drastically increase in a negative way once you have gone past MBT. Also, for street tuning, and if you have the octane to get there, I wouldn't go past 18* of spark advance this seems to be pretty close to where most cars MBT is. Another thing to take note of is that every car will be different. On the MPS motor, the crank position sensor has a tolerance of +/- 3* so no car will have exactly the same MBT.

  7. Default

    Nope the only dyno I've done is the butt dyno :-). And you're right, even the APP translation tables aren't working for me. I clamp down 1st and 2nd gear to about 50% but the datalog still show APP going to 99% when I put the foot down.

    Quote Originally Posted by shaneski View Post
    have you done a virtual dyno thingy, remiving boost restrictions i doubt there is anyway to launch these things, just breathing too heavy in the direction of the loud pedal in 1st gear lights the tires up

  8. #48
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    Anyway to monitor realative throttle position?

    Quote Originally Posted by wyvernone View Post
    Nope the only dyno I've done is the butt dyno :-). And you're right, even the APP translation tables aren't working for me. I clamp down 1st and 2nd gear to about 50% but the datalog still show APP going to 99% when I put the foot down.
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  9. #49
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    Quote Originally Posted by wyvernone View Post
    Nope the only dyno I've done is the butt dyno :-). And you're right, even the APP translation tables aren't working for me. I clamp down 1st and 2nd gear to about 50% but the datalog still show APP going to 99% when I put the foot down.
    I think you need to drop 1st right down to 35-40% to get traction and 2nd to about 60% but it will most probably be different for you than what I tried due to tires etc. I got it setup well traction wise but it made my car feel slow and no where near as fun to take off. You could also play around will load limiting. You have me interested in trying it myself now

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