2017 Silverado L86 Twin Turbo

[brewster]

Posting for a friend of mine, he has a 2017 Silverado with L86 6.2L 8 speed 8L90. It has LT4 injectors, 30% over HPFP, Low pressure system is beefy and fuel is holding good with twin 76mm turbos making 900rwhp atm. Problem he is having with the 8 speed is for the first 4 gears or so it yanks 50% throttle and knocks timing down to 10 deg, basically loses everything between shifts. Trying to find out if there is something missing in the software to be able to control this stuff or if its in the calibration. Are guys making this kind of power with the 8 speed in the trucks successfully or I hear some guys are converting to previous years 6 speed 6L trans as there is no way to make the 8 speed in the trucks work properly calibration wise?

[Ben Charles]

8 speed is better then the 6 speed in every way.... those of us who know can make spark whatever we like

[jasonz28camaro]

8 speed is better then the 6 speed in every way.... those of us who know can make spark whatever we like

I like that reply. Reminds me of a Dr. Seuss book lol.

I got a 10 speed, I love it, also love the 8 speeds, not so much feeling the 6speed autos though.

So I?m familiar with keeping the timing up while shifting but I haven?t gotten around to messing with it. What kind of difference would one expect? The 10 speed shifts so quick I can?t even tell it pulls timing but it sure does when you review the logs.

[Tapout Tuning]

Posting for a friend of mine, he has a 2017 Silverado with L86 6.2L 8 speed 8L90. It has LT4 injectors, 30% over HPFP, Low pressure system is beefy and fuel is holding good with twin 76mm turbos making 900rwhp atm. Problem he is having with the 8 speed is for the first 4 gears or so it yanks 50% throttle and knocks timing down to 10 deg, basically loses everything between shifts. Trying to find out if there is something missing in the software to be able to control this stuff or if its in the calibration. Are guys making this kind of power with the 8 speed in the trucks successfully or I hear some guys are converting to previous years 6 speed 6L trans as there is no way to make the 8 speed in the trucks work properly calibration wise?

I recently added almost the same exact mods to my 2018 G.M.C. 6.2 liter. Only thing I didn't do was the fuel cam, so we have the OEM HPFP maxed out at 7 psi of boost and 585 whp. Didn't have any throttle closing issues at that power level though.

By the way , are you able to say what bottom end modifications were required in order to support your 900 whp level?

[brewster]

We just installed Carrillo Rods and pistons as the L86 comes with a Forged steel crank, cam / valvetrain mods like rocker trunions, push rods, lifters, locked out the vvt and a bunch of ARP hardware. Engines running great so far just have to get the shifting figured out. I'm not tuning this one but a local guy is and he's super good at what he does, just needs a little more seat and keyboard time. Were just trying to confirm that it can be done up at this power level with the 8 speed.