Thinking of 4.11s instead of my 3.55s
07-31-2017, 09:51 PM
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Thinking of 4.11s instead of my 3.55s Hey i have a 70 el camino with a lq9 and 4l80e. Engine has a smaller 225/230 114lsa cam.This is mostly a street car so im still running the stock converter. Thing i dont like is the car just feels kinda weak down low off the line. Car runs 12.86 110 in the quarter.Has a 60 foot time of 2.10 for a idea of what its like, and this is not spinning. Im just wondering if I put 4.11s in this isnt going to hurt my time? Hopefully give me a bit more off the line and around town. The gearing just feels long. Any input is welcome.
08-01-2017, 12:02 AM
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...especially with the aftermarket cam. Going to a 4.11 won't do nearly as much good as adding a 3500-4000 stall speed (which is still perfectly streetable if you select a good quality unit with lock-up.)
Keep in mind that the 4L80E has a much less aggressive internal 1st gear ratio than a 4L60E, so a 4.11 + 4L80E will have no more mechanical advantage at launch than a 4L60E with a 3.31, all else being equal.
Something in the area of a 4.56 would wake up the launch for a 4L80E/TH400, even with the stock stall. That would be like a 3.73 with a 4L60E/700R4. But I'd rather have the lower cruising rpms of your current 3.55s matched with a high quality proper stall speed.
08-01-2017, 04:22 PM
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Your problem is the bolded part below...
...especially with the aftermarket cam. Going to a 4.11 won't do nearly as much good as adding a 3500-4000 stall speed (which is still perfectly streetable if you select a good quality unit with lock-up.)
Keep in mind that the 4L80E has a much less aggressive internal 1st gear ratio than a 4L60E, so a 4.11 + 4L80E will have no more mechanical advantage at launch than a 4L60E with a 3.31, all else being equal.
Something in the area of a 4.56 would wake up the launch for a 4L80E/TH400, even with the stock stall. That would be like a 3.73 with a 4L60E/700R4. But I'd rather have the lower cruising rpms of your current 3.55s matched with a high quality proper stall speed.
...especially with the aftermarket cam. Going to a 4.11 won't do nearly as much good as adding a 3500-4000 stall speed (which is still perfectly streetable if you select a good quality unit with lock-up.)
Keep in mind that the 4L80E has a much less aggressive internal 1st gear ratio than a 4L60E, so a 4.11 + 4L80E will have no more mechanical advantage at launch than a 4L60E with a 3.31, all else being equal.
Something in the area of a 4.56 would wake up the launch for a 4L80E/TH400, even with the stock stall. That would be like a 3.73 with a 4L60E/700R4. But I'd rather have the lower cruising rpms of your current 3.55s matched with a high quality proper stall speed.
08-02-2017, 08:53 AM
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basically with a stock converter normal driving from a stop you probably rev around 1500 rpm to accelerate. with a 3k / 3600 stall you'll rev to 2000 / 2500 rpm to normal acceleration. i did lose nearly 2 mpg however i feel thats due to my 2.73 gears forcing the converter to do all the work. the benefit from an aftermarket converter is when you hammer down you immediately jump to 3k rpm putting you engine in the sweet spot for rear wheel hp. lets say stock converter you kick it down maybe your at 2400 rpm putting 175 hp whereas an aftermkt stall at 3k rpm puts 250 rwhp to the wheel instantly. result your cars alot quicker! go4it!
08-02-2017, 08:22 PM
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Thanks for the help. I am going to keep the 3.55s and start making some calls to converter manufacturers. Glad I asked before i just went and bought the gears just to end up disappointed.