So the 4t60e is handling the LS4? How much HP should that transmission be handling at a maximum? From what I understand, it really isn't much stronger than the 4t65e, and its limit was 300HP.

 

If I remember reading things correctly, It's pretty much maxed out right out of the box.

 

Does the 5.3 require 91 octane fuel? Or can you run 87 on it?

 

You CAN run it, but it's recommended to be ran on premium, which I always use.

 

x2 If you go with a supercharger, or the Z28 you will need premium too.

 

i thought the ls4 cars could be run on regular with the factory tune? i never have just thought it was an option. i do believe you are correct about the trans being close to maxed out, but i thought there were a bunch of hardened parts and what not put in specifically because of ls4. actually it might just be that trans in general was beefed up.

4T65E-HD Information

These are the upgrades that GM made to the MN7 version of the 4T65E-HD transmission to mate with the 5.3L LS4. Attached is the spec sheet for the MN7. One thing to add is that for the 2006 model year GM changed from Dexron V to Dexron VI fluid.
Quote:
- 258mm, RI 15 Torque Converter
- Enhanced Heavy Duty 3.29 Final Drive
- 2.93 Effective Final Drive
- Transmission case for transmission mounted starter
- Net-formed Input Sun Gear
- Ceramic bead Peened Final Drive Sun Gear
- Input/Reaction Carrier Assembly- Shot-peened Final Drive Sun shaft
- Upgraded Drive sprocket Thrust washers (new for high speed capability)

 

Wow that's good info MonteMan. And yes, you can run regular gas.

 

Usually factory transmissions have a max torque rating, and max gross vehicle weight- not a horsepower rating. I'm not sure what the torque rating is between the 65 and 80- but I could've swore the 4t65 was always just a pinch higher than the L67 put out (280ish)- and they bumped it up a little with some new parts for the LS4.

4t60 has been gone for awhile IIRC- all these cars use the 4t65 or 4t65HD (on the L67, and LS4 models). I believe they did do a few minor changes to it when the LS4 started being used though. As I said above, I've never seen the factory use a HP rating- its usually a max gross vehicle weight, and a max torque rating

No, 4t65HD on the LS4. And, its pretty much at the factory max out of the box- it was even close to maxed on the L67's. Obviously there is some engineering safety factored in- but as you can see with all the failures (and years of people racing L67's with 4t65's) that there isn't a lot of extra design factored in.

Due to the faster computer systems- they now say 'premium recommended' (not required like it used to be on older GTP's)- all it does is sense all the extra knock, and drop you down to a lesser spark table- meaning less power.

IMO, if you're even considering running regular gas- don't buy a performance car. It really defeats the purpose of buying a higher power car, just to put crappy gas in it and run at a lower power level, you know?

 

I had always thought "I'm gonna avoid that car it requires premium" But if you stop and think about it, premium goes for .20-.24 a gallon more then regular. I usually wind up putting around 12 gallons in the Impala or Z28 at a time, that comes to less then $3 a fill-up. Not that bad for making sure the engine gets what it needs and wants.

 

I've been reading that the 5.3 V8 has something called "active fuel management" I think. It says something about shutting down 4 cylinders during normal highway cruising, so the car may achieve up to 28MPG highway driving.

This is a relatively uncommon technology, and I wasn't expecting this to come with the SS. Does it come with all 5.3's? Is it a good addition? Does it work well? Have any problems? Can you control it manually? Not sure how to take it, I was prepared to deal with a V8 fuel consumption.