Ly6/6l90e?
 

I came across this setup for a very reasonable price, with uncut harness and ECM included. Does anyone have experience with this swap? Will I regret going with the 6 speed rather than a tried and true 4L80E? Going in a C20, which I want to be able to use as a 3/4 ton truck sometimes.

Re: Ly6/6l90e?
 

Check out the 68 farm truck build in my signature.

Re: Ly6/6l90e?
 

The 6L90E's are doing pretty well even in newer 1 ton 4x4 crew cab dually's that are A lot heavier than your truck & a higher GVW/GCWR.
If you stay within the legal weight limits of your truck....You wont tax that 6L90E at all!
The LY6 is a GREAT engine for a 3/4 ton with its VVT!

I personally don't care for 6L80E/6L90E transmissions for performance applications, Only because I HAVE TO rely on a tuner (Enter Pimpled faced Kid here) to modify shift firmness, Line pressure rise, ETC. For these units to hold power.

With a units like a 4L60E/4L80E, I can adjust everything but shift timing Hydraulically to suit the need.

Re: Ly6/6l90e?
 

Being allied with a fairly prolific tuner, and doing some tuning myself...you now discovered why WE love the 6speeds ;)

The 6spd TuTd transmissions have also become slightly known for being less-than-graceful under fire. They don't like being dumped on sticky tires, they REALLY don't like going from 5th to 2nd in a hurry (which is commanded). They do have some really nice benefits for street use cars, but for high-po stuff or drag racing, the 80e will get my vote.

If you need more than 4 gears, get a GV unit.

Re: Ly6/6l90e?
 

You would HATE 700R4's & 2004R's....;)

https://www.youtube.com/watch?v=KMy1zO8m8sM

Re: Ly6/6l90e?
 

How are the 6L80Es? The setup I was looking at got away but I found <50k L99/6L80E for a little less. I'm thinking I probably want an iron truck engine rather than a more high strung aluminum performance car engine, though.

Re: Ly6/6l90e?
 

You can get a L99 for less? I would usually agree with an iron block....But a 6.2L L99 is bad a$$! It will have zero problems in your truck, The only difference between a 6L80E & 6L90E are the Planetary gear set contact areas (longer gears in the 90E)

I would delete the AFM....8 standard lifters, 4 Lifter trays, 2 Head gaskets, Head bolt set, LS3 Valley Cover, & LS3 PCV hose are the parts you need.

The stock L99 cam with functioning VVT has a real flat torque curve! Not high strung at all.

Re: Ly6/6l90e?
 

The trans itself is fine. The concern with ANY of the 6 speeds (sans allison) is shock loading the trans. If you want to keep it alive, don't go from cruising in top gear and mat the pedal. Thats the 5-2 shift or 6-2 shift that no bueno.

Re: Ly6/6l90e?
 

Have you met anyone with that kind of self control:lol:

Re: Ly6/6l90e?
 

Hell it took me a while to break the habit of doing it from 4locked down to 2.
Manually going down to 3 saves that huuuuuge load when it kicks to 2.

Cline, the best way to do it is just duff the hell out of the tune for kickdown for a while (with customer understanding) and train them out of it. I literally had to take 3 rides in a customer car with the tuner, owner, shop owner and like 3 other people on various times...because the owner was an idiot and couldn't drive. When a customer has problems that "only happen when they drive it"....time for the driver mod.

Re: Ly6/6l90e?
 

While I'd like to have a little fun, this is more for using as a work truck than racing. I'm more concerned about pulling a reasonably heavy enclosed trailer up to Reno than mashing the gas from 6th.

Re: Ly6/6l90e?
 

There is a reason that Allison's come behind heavy haulers. Not saying you can't do it, but you just need to be cautious about od lockup with a trailor, and kickdown. I would suggest against any "performance" changes to the shift timing or line pressure thresholds in the trans. Do that, put a GOOD cooler on it, and it'll live.

Re: Ly6/6l90e?
 

You will be fine, Keep in mind new 3/4 & 1-ton gas trucks come with 6L90E's that are identical to a 6L80E sans the Planetary gear sets, The Planets are not what gives up....Its the Frictions (Clutches) that give up when abused.

The only concern I have is....You will need a functioning Tow/Haul mode when towing heavy.

Re: Ly6/6l90e?
 

Good to know. Does that prevent lockup, or just prevent top gear, or what?

And it isn't something I'll be doing very often, but I don't want to blow a tranny when I do.

Re: Ly6/6l90e?
 

Some info....

"Tow/haul mode is a function within the vehicle's software/calibration that optimizes transmission gear selection for operation during towing or with heavy loads. This optimization includes improving acceleration performance during launches, reducing shift busyness, assisting brake performance and speed control during engine braking situations, and improving vehicle speed control while requiring less throttle pedal activity.

In general, tow/haul mode maintains lower gears longer and increases shift pressures. It is designed to be most effective when the vehicle and trailer combined weight is at least 75% of the vehicle's Gross Combined Weight Rating (GCWR)"

Re: Ly6/6l90e?
 

Are there any plug and play harnesses that work with geniv and six speeds? Preferably allowing a tow mode and maybe cruise control.

Re: Ly6/6l90e?
 

Also... how about T56 or similar trannys, will they hold up in a truck that gets used like a truck sometimes?

Re: Ly6/6l90e?
 

The T56 does not like towing, As many SRT/10 Dodge truck owners have fallen victim too failures when towing......

Re: Ly6/6l90e?
 

I didn't think they even made enough SRT10's for anyone to use them for towing :)
I knew someone who bought one and immediately hated it...ended up on CL for a loss a few months later. Never buy a $40k used truck that isn't a diesel.

Re: Ly6/6l90e?
 

They used to be everywhere around here, And of course the guys that bought them tried to tow Boats with them even though they didn't have a tow rating or a really low one IIRC.

Re: Ly6/6l90e?
 

Makes sense. I forgot where you were located. I'm sure out in Big Bear or Tahoe it's the same. Up here, the "show your money" truck is the Raptor.

Re: Ly6/6l90e?
 

So if I want a manual I guess the options are pretty much NV4500 and NV5600. Hell, maybe I should have my eyes open for the right deal on one and try it before the engine swap... I'm not too worried about cutting a hole in the floor, the truck is far from pristine.

Re: Ly6/6l90e?
 

I think the combination works great. I have it in my 66 C10. However, try finding a '09 or newer 6l90. The earlier versions had flaring issues. Some due to the tune, others due to the seal design in the front pump I believe. The seal design in the older versions allowed the seals to rotate during operation causing a leak and aforementioned flaring.

Re: Ly6/6l90e?
 

What's a decent price for an NV4500? How about NV5600?