4.8l 13.5 PSI: Tuning, IAT/Intercooler, 1/4mile time question
10-18-2015, 02:53 PM
#1
4.8l 13.5 PSI: Tuning, IAT/Intercooler, 1/4mile time question
Hey Guys,
My truck has been turbo'd and running well on 9psi for a few weeks. I ran a best time at the track of 12.33sec @ 111.4mph with a 1.83 60ft on 9psi last week.
This past Thursday I changed the WG springs and I'm now on 13.5psi. Set up is older Trick Kit with 76mm magnum, 90mm throttle body, holley hi-ram, isky triple 12, 3in down pipe to 4in cutout, 3.42 gears, trutrac, etc on 93 gas. After hitting the track on 13.5psi, I ran a best time of 12.2sec @ 111.9mph with a 1.83 60ft!!! Given that my time did not really reflect the increased boost as well as some new info from the logs, I had some questions and would like some recommendations if you have the time.
1) Tuning: The tune is a little rich and I could see where it was really killing my power and how long it would take the truck to recover from a 10.4 afr dip. My target AFR currently is 11.0 with 12 degrees of timing. I'm still leaning it out slowly to 11.0, but I was wondering what a good target AFR is for 13.5 psi, and whether 11.0 is still slightly too rich. From researching, I should be safe to take the timing up to 14-15 degrees but I was also wondering your thoughts and experiences?
2) IATs/Intercooler: With the increased boost, it seems that my IAT's have gotten about 20 degrees warmer. On Friday, the ambient temperature was 60 degrees. I started my burnout with IATs at 82, and ended the burnout at 95 degrees. Staging on the 2 step brought my IAT's up to 100, and by the end of the pass my IATs were at 126 degrees. So, 1) My IATs by the end of the run are almost 70 degrees warmer than ambient temp - is this normal, or is there a way to tell if my intercooler isn't doing its job? Do you have any suggestions on a more efficient intercooler brand, size, etc? 2) I begin to pull timing when my IATs hit 131 degrees, when are y'all beginning to pull timing due to IATs?
3) In general, I am kind of surprised that an increase of 4.5 psi only netted me .1 sec better 1/4 mile time as I should have added somewhere around 90+ hp. There is definitely power left in the tune between 2-3 more degrees of timing and getting the fueling dead on at 11.0 AFR, but is that going to equate to the 90hp increase I was expecting? What should my expected 1/4 mile time be on 13.5lbs if I ran a 12.33sec@111.4 on 9lbs?
I appreciate the help! Its been an awesome learning experience and I can't thank the members on this site enough for all of the help along the way. I can attach the log and tune if anyone would like to see it. Thanks!
My truck has been turbo'd and running well on 9psi for a few weeks. I ran a best time at the track of 12.33sec @ 111.4mph with a 1.83 60ft on 9psi last week.
This past Thursday I changed the WG springs and I'm now on 13.5psi. Set up is older Trick Kit with 76mm magnum, 90mm throttle body, holley hi-ram, isky triple 12, 3in down pipe to 4in cutout, 3.42 gears, trutrac, etc on 93 gas. After hitting the track on 13.5psi, I ran a best time of 12.2sec @ 111.9mph with a 1.83 60ft!!! Given that my time did not really reflect the increased boost as well as some new info from the logs, I had some questions and would like some recommendations if you have the time.
1) Tuning: The tune is a little rich and I could see where it was really killing my power and how long it would take the truck to recover from a 10.4 afr dip. My target AFR currently is 11.0 with 12 degrees of timing. I'm still leaning it out slowly to 11.0, but I was wondering what a good target AFR is for 13.5 psi, and whether 11.0 is still slightly too rich. From researching, I should be safe to take the timing up to 14-15 degrees but I was also wondering your thoughts and experiences?
2) IATs/Intercooler: With the increased boost, it seems that my IAT's have gotten about 20 degrees warmer. On Friday, the ambient temperature was 60 degrees. I started my burnout with IATs at 82, and ended the burnout at 95 degrees. Staging on the 2 step brought my IAT's up to 100, and by the end of the pass my IATs were at 126 degrees. So, 1) My IATs by the end of the run are almost 70 degrees warmer than ambient temp - is this normal, or is there a way to tell if my intercooler isn't doing its job? Do you have any suggestions on a more efficient intercooler brand, size, etc? 2) I begin to pull timing when my IATs hit 131 degrees, when are y'all beginning to pull timing due to IATs?
3) In general, I am kind of surprised that an increase of 4.5 psi only netted me .1 sec better 1/4 mile time as I should have added somewhere around 90+ hp. There is definitely power left in the tune between 2-3 more degrees of timing and getting the fueling dead on at 11.0 AFR, but is that going to equate to the 90hp increase I was expecting? What should my expected 1/4 mile time be on 13.5lbs if I ran a 12.33sec@111.4 on 9lbs?
I appreciate the help! Its been an awesome learning experience and I can't thank the members on this site enough for all of the help along the way. I can attach the log and tune if anyone would like to see it. Thanks!
10-19-2015, 12:04 PM
#4
The problem with trying to give you advice based on your numbers is that n AFR/Timing is correct for all setups. Each motor is a little different. My truck might run fastest on 12:1 and 14* of timing. While my neighbor might run fastest on 11.5:1 and 17* of timing. It sounds like you are pretty rich at the moment if its taking a while to recover from the 10.4 dip. I would just experiment a little bit. Lean it out a little bit and see how it runs. Add a little timing see how it runs. Keep in mind as you lean it out it will most likely create more heat. Your iats aren't out of control, but I would continue to monitor them. It might be time soon to make some adjustments.
10-19-2015, 05:17 PM
#6
And Gambler, completely understand that every motor is different and that additional adjustments are required and will yield better results, especially since I'm just street tuning it. I think I was just looking for peoples experience in terms of timing and afr on similar boost levels (didn't know if people had found 11:1 AFR too rich but 12:1 too lean, or 16 degrees is max recommended on 13.5lbs, etc, etc - ball park numbers and info). Ill keep the increased heat in mind. I will be making an air filter box to shield some heat off, and will be ceramic painting/baking my turbo inlet pipe and up-pipe as well as putting 1/8in insulating tape and wrapping that in foil take in an attempt to keep the IATs down...it might work lol.
Kyle, I had my commanded 12 degrees of timing through 1st gear and up until 5600rpm in 2nd gear...then the engine saw 11.5 degrees until 6000rpm, then 11 degrees through the 6800 shift point into 3rd. The IAT Table has been modded from stock a little bit, but its good to know that you think 130 degrees is an acceptable temp to start pulling some timing.
I appreciate the help and info guys! I'll see if I cant get these IAT's under control, get the AFR dialed in, and then the timing. I'm really hoping for a 11.5sec pass on 14lbs but based on last Friday's performance I'm not sure if that's going to happen LOL. As always, I'm in for more advice and suggestions!
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10-19-2015, 09:35 PM
#8
Formerly ScreamingL
Adding boost wont always gain you power
Things will easily kill power....if AFR is rich youll lose power......11.5 is your target for 13 psi
If you pulled timing that could cancel the boost out....for 13 psi you could give it easy 15-16*
Id lean it out and then add 2* of timing at a time and watch mph
Things will easily kill power....if AFR is rich youll lose power......11.5 is your target for 13 psi
If you pulled timing that could cancel the boost out....for 13 psi you could give it easy 15-16*
Id lean it out and then add 2* of timing at a time and watch mph
