PROS AND CONS OF DOING A 4L80E SWAP

One of the most asked question that I see on many LS forums is, how hard is it to swap out the 4L60E to a 4L80E, and is it worth it? To answer this question, I want to take a look into both of these transmissions, to really get a better understanding of the advantages and disadvantages of both transmissions, so you can make the best decision for your application.

The 4L60E transmission has gotten the reputation as an unreliable transmission for any big HP application due to so many of them breaking under use, but built by the right transmission builders using the right parts, they can hold up to a great deal of power and abuse, up to 750RWHP but this can become quite costly to do in most cases. The 4L60E transmission features a Gear Ratio of 3.06:1 first, 1.625:1 second, 1.00:1 third, and 0.70:1 fourth.

So, let's take a look at the 4L80E transmission, to see why everyone wants to do this swap. First and foremost, the 4L80E is a very strong transmission stock, and is built around the old turbo 400 platform and features the same gear ratio, however with the added advantage of a 0.75:1 overdrive to help reduce the engine's RPMs at highway cruising speeds, and if built correctly, the 4L80E transmission has been known to hold up to 1000+RWHP which is great for any big turbo or supercharged LS. Looking at the data so far it would seem like the 4L80E transmission is the better choice for most 750+ high RWHP applications. But before we say yes to this transmission swap there are several other modifications needed to make this swap work. The 4L80E transmission does not use the same plugin as the 4L60E so you will have to do some modifications to the existing wiring harness to make it work. The 4L80E also uses a different torque converter and slip yoke, plus the transmissions cross member will need to be modified as well. With all these extra modifications needed, and added cost of parts, this really needs to be taken into consideration.

So, let's see which transmission has the best performance and efficiency. The Gear Ratio in the 4L60E is quite impressive compared to the 4L80E, with a 3.06:1 first gear the 4L60E transmission has a 23% lower first gear than the 4L80E and since this is done before the final drive gear this will help a great deal to aid in the TQ multiplying factor, and will help to improve the efficiency of the vehicle in stop and go traffic, towing heavy loads, and will help to improve 60 foot track times. The 4L60E transmission also has a slightly lower second gear, 6.9% lower to be exact, which will help a little bit, but the 4L60E and the 4L80E share the same gear ratio in the third 1.00:1. The 4L60E fourth gear has a slightly higher gear than the 4L80E, 7.1% to exact, and will add up to around 200rpms lower engine speeds, increase fuel economy slightly too. For any vehicle making 750RWHP a PATC level 5 transmission,

https://transmissioncenter.net/shop/transmission-4l60e-4l65e-4l70e-level-5-extreme-raptor/ will do the job well. If you're making over 750RWHP in my opinion a built 4L80E transmission would be a better decision because of the extra durability. One of the disadvantages of doing this swap unfortunately is that you’re going to lose out on the 4L60E better gear ratios. Now this might not sound like much of a loss but after looking at the picture here.

We can clearly see that the loss In first gear is quite substantial, gaining 10mph and losing 1200RPM of pull power, this will have a more noticeable effect on NA vehicles making lower HP around 300RWHP to 500RWHP that would benefit more from a lower first gear. Looking at second gear we can also see that there is a 6mph gain and a loss of 400RPM of pulling power too, luckily PATC and other transmission builders have this issue covered with a 6 pinion planetary 2.97:1 first gear and a 1.57:1 second gear.

This upgrade will make up the majority of the difference, dropping the first gear down to only 2mph higher and a loss of 200RPM of pulling power. The 1.57:1 second gear helps too, dropping the second gear to only 3mph higher and a loss of 200RPM of pulling power, making the 4L80E transmission at this point the better choice hands down!

But what if I told you there is a transmission out there that can handle 1000+RWHP and will give you a gear ratio that is far superior than that of the 4L60E or 4L80E, giving you better track times, increased drivability and fuel economy. If you want the best of everything look no further than the 6L80E/

6L90E transmission, asylum motor sports have put this transmission on the map with the worlds fastest 6L80E transmission holding up to 1500+RWHP. Justin and his team have figured out the best way to build and tune these transmissions for insane power and durability.

The 6L80E/6L90E gear ratio of 4.02:1 first, 2.36:1 second, 1.52:1 third, 1.15:1 fourth, 0.85:1 fifth, 0.67:1 sixth. With the added advantage of a whopping 4.02:1 first gear, heavier vehicles such as a truck will have no problem improving their 60 foot time without having to use such a large stall converter to achieve the same result, while also decreasing the amount of time it takes for a vehicle equipped with forced induction to reach peak boost. The new gear ratio that the 6L80E/6L90E offers will allow you to run a much higher final drive gear and still achieve the same results as the old 4l80E with a much lower final drive gear seen in the picture below

As technology advances so do transmissions making them stronger, faster, and more efficient than ever before. Thanks to companies like Current Performance Wiring, doing the 6L80E/6L90E swap in a Gen3 vehicle is possible by using the E67 ECM and a new custom wiring harness. If you would like any additional information on the 6L80E/6L90E transmission swap Please feel free to contact me on Facebook at LS Performance Racing.