Turbo owners step inside please
 

You guys may have seen my post about the turbo going on my SS Trailblazer. I have had several transmission shops tell me that the 4L70 is going to be blown to pieces when the turbo kicks in. It should make somewhere in the 550-600 range with over 600 lbs of torque. I have the 2nd/4th gear servo upgrades. Are any of you running a 4l60/4l70 with a turbo? How is it holding up? Should I turn the boost way down and try to make around 500rwhp? The trans has to survive long enough for me to get a 4l80 built up and get the rest of the pieces made. I would like your thoughts.

Thanks

I have only first gear at the moment if that helps at all. My tranny lasted about 10,000mi behind the turbo. Honestly I'm surprised it lasted that long. The only thing I did was the vette servo and raised the line pressure though. If you have the patience turn down the boost.

it is in the tuning. you will need a cooler and shift kit at the least. when you blow it up after those mods you can put some hard parts inside. MAKE SURE YOUR TUNE is good, espically the trans/shift point stuff. I am interested in the 80, the SSS guys have never swapped over, it is a difficult process, we just build the 65's up. good luck with your TT project

I have a built 4l60 in my truck but to be honest I don't think I beat on mine as bad as some here do. I did fry my 3-4 cluthes one month after the turbo was installed. That may have been tune or faulty PCM, I will never know.
Had a beast sunshell put it, the extra clutch pack disks, shift servo and tuned to hold line presuure properly. I don't really know jack about the tuning since mine was done by Nelson.
I thought the 4l70 was the non-electronic version of the 4l60?
The amount of power you say it will be putting out makes me think it will not last long, many people here have had failures when going over 500hp some of them were catostrophic, gears exploding, teeth shearing off etc...
Good luck with yours, I really do hope it last long enough toget you 4l80 done.

I have a 06 Silverado with the 4l70. Mine is blown up right now. I have a radix and made about 425hp to the wheels. I installed the radix with 1500 miles on the truck, and the trans went about 1000 miles later. I have a 80e sitting in the garage waiting to go in.....

I definitely recommend the vacuum line pressure mod. You'll need the boost check valve but it keeps the tranny alive if built right.

Its mostly in the tune I built my tranny myself. I installed a beast (hd reaction shell) a Zpac (hd 3-4 clutch pack) hd 4l65 carriers a transgo hd2 shift kit a sonnex 4th servo and a corvette 2nd servo. The rest of the clutches and the band are stock replacement. My theory is not to make the trans shift to quick or hard. It is cheaper to throw a set of cluches in than to replace hard parts. Leave in at least 60% of the torque management. When you are given it hell run in d3 and tow hall and watch the hard downshifts the 4-2 downshift and the 3-1 downshift is when most 4l60 type trannys die.