My Turn @ Pulling the Trigger on a Twin Turbo

6 Shooter

Well-Known Member
Been hacking away doing at least 15 slow rev data logs on an gradual uphill street in my area. Now have access to more parts of the SCT tune and the section I was most interested in was the Front O2 bias section. Was getting most often a 10% more lean in the driver's side than the passenger side. With all the data logs and tune experimentation, have now gotten the results to mostly 1-3% differences. To make changes actually occur, multiple tables must be changed such as timing, bank to bank bias, MAF A/F ratios, O2 upper and lower limits and O2 Transport delay to name a few. The process is not so simple as changing a single number and watching the car respond. Part of the challenge is trying to interpret what Ford Engineers had intended and then guessing where a change or batch of changes needs to occur. And, the changes occur in Closed Loop where the PCM tries to fight the changes a tuner wants/needs to make. The challenge is to trick the PCM after increasing the fuel injectors and the MAF by 500%. It's been doable, but a challenge and many data log analyses.
 

6 Shooter

Well-Known Member
Hard to believe, but my photos have been resurrected from the dead. Was able to recover about 99%, all the way back to the beginning of this thread.!! Long story, but got my Photobucket account back, but that was not the fix. Ultimately, the new format of this forum allowed me to go back and edit all grayed out photos and replace them with ones still on my computer.
 

6 Shooter

Well-Known Member
Finally made it to the track. Perfect conditions, late afternoon, temps in low 80s, and winds under 10 mph. No clouds to speak of. Last out was spinning the tires on the 1-2 shift with the street tune (10psi) at the same track and the rear moving slightly to the left. Second pass on higher boost (15psi) was even worse. Followup analysis showed some improvements in shift points would help. Same with lower rear tire pressure. Well, it did.

First pass was 15psi, rear tire pressured lowered to 16 psi from 20. Also added a can of Torco Accelerator which raised the 93 octane fuel at the pump to 110 octane for peace of mind and protection from detonation, just in case. The car ran perfectly straight and no spinning of the tires. On the 1/8 mile track, the car ran 104.2 mph in 7.1 seconds. My reaction time was .26 seconds which could easily be lowered with some practice. 60 foot time was 1.86 seconds. And, was so happy that I kept the foot on WOT for the entire length of the track. Have had a habit of letting up on the gas which was fixed on this pass.



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Second pass was worse. Was going for the gold with 21psi of boost. Started and ran straight, but spun the tires on the 1-2 shift and I let off the gas somewhat. Then, did a poor job of not going WOT as the data log showed I kept the throttle at just half of WOT. Even still, the speed was almost the same at 100mph, and the time was 1/2 second slower. Subsequently, have studied the data logs and re-looked at the transmission shifting speeds and the torque converter lock and unlocks. Think I made some small improvements there for the next outing.

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Will try to post the data logs later if possible.
 

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6 Shooter

Well-Known Member
Thanks. Hope to make some gains on the SP3 tune which raises the rear whp to over 600. Have spent the day going over the myriad transmission tuning adjustments for shift points by mph, torque tables, torque friction tables, TQ clutch fill times, TQ lock and unlock points. Can say that a careful and detailed analysis of my very good 500 rear whp data logs have been a tremendous help in fine tuning the transmission. The goal is to make the tables very close to the actual performance of the car, transmission, and motor HP during an optimal run. Hope the next outing will show the 1-2 and 2-3 shifting not quite so hard and slightly slower to help avoid spinning the tires during the shifts. The turbos produce maximum boost at 3000 RPMs, but the rear whp continues to rise. Was shifting at 6500 (1-2), 6700 (2-3), and still in third gear at 104 mph at just 4400 RPMs. Also determined that my rear wheel height is a bit taller than the stock Mustang tires. Thus, my speedometer was low by 10 mph at 94 on the dyno vs 104 on the track slip. One of the hard parts is that no where in the data logs is information on engine torque. However, a number of tables are based on torque. Luckily, I had a dyno run 4 years ago which on the SP2 tune showed 500 rwhp and 593..6 ft lb of torque and around 5500 RPMs. So that number gave me the upper limit of the torque table at WOT and 6000 RPMs. Net result of the data slowed that the torque table needed a 10% reduction across the board.
 
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