There is a lot of negativity towards the 4l60e in stock form regarding how capable it is at holding power, and rightfully so. Most people who badmouth the 4l60e have either:
- A: Never had one and are just regurgitating others online
- B: Had a single bad experience where their car making decent power blew the transmission
- C: Are correct
Truthfully, in our modified Camaro, we upgraded the transmission before doing any power upgrades to prevent being left stranded on the side of the road because the stock 4l60e decided it wanted to have 5 neutrals. With our cammed ls1 making right at 400 horsepower, the 4l60e in stock form may have lasted, but the question would have been for how long.
Our car had quite a bit of mileage on it, so based on that and pulling it any way to install an aftermarket converter, it made sense to just pony up the extra money to get a built 4l60e from Finish Line Transmissions.
While a lot of the criticism is correct that the stock 4l60e can’t hold a lot of power, there are certainly ways to do so. You can find a great write up on ls1tech.com that provides insights into how to make your stock 4l60e last longer with higher horsepower or at the drag strip.
As mentioned in the thread, the best ways to get a stock internal 4l60e to hold any decent power is to:
- Make sure transmission temps are cool. If you have a car making decent power, then odds are you’re aware that heat kills transmissions. The bigger the cooler, the better off you’ll be.
- Keep RPMs low or close to stock. Sure, this might make less power overall, but you’ll be able to drive the car more.
- Pull timing during the shift. This will help alleviate the “shock” of the shift so to speak.
Answering the question “how much power will a stock 4l60e hold?” is tough. There are a number of factors that impact the longevity of your 4l60e such as:
- Vehicle it’s in: The weight of the vehicle matters almost as much as the power it’s making. A 500 horsepower c5 Corvette has a much better chance of keeping a stock 4l60e alive over a 350 horsepower truck. Since the truck will require much more effort to get going and holding power, it’s going to stress a factory transmission much more than a lighter, more aerodynamic car like a c5.
- Type of power: Is this all motor power? Boost? Nitrous? While 500 horsepower is 500 horsepower, the means of power are vastly different. If you have the same car with a 125 shot of nitrous or an added 125 horsepower from a turbo setup, the nitrous will kill a 4l60e much faster than the turbo will. The initial torque spike from the nitrous can be quite violent and the transmission will take a beating, whereas the turbo builds boost gradually allowing the transmission to consistently apply the power vs all at once.
At the end of the day, if you plan on making any decent power or have a heavier vehicle, it’s best to get your 4l60e built the right way to keep it alive. Both the power and weight make a huge difference in how much power a stock 4l60e can hold, but really, it’s not going to be much on average.