4.8L V8 Trucks

[jwright350]

Ok, so I've read though as much of the boards as humanly possible before posting this... so its not like I didn't try first.

Am I correct in figuring that my stock '03 Sierra 4.8L V8 dosen't make enough torque to need trans. torque management. Its output dosen't exceed the 360 lb/ft limit of the 4L60e... so might as well turn it all off.

I know the mood is currently "better safe than sorry" with it comes to TM... but I think if you don't need it, might as well turn it off.

I tried this, and set my shift points up to 6300 rpm and everything "seems" to be very happy... but if anyone has any input I'd like to hear it.

[havalanche]

Don't recommend shift points that high. I've got a 5.3L and try to keep mine at 6000 and under. You at the rev-limiter level, plus, that high doesn't make the motor too happy.

Definitely think you should get rid of some of the TM. I recently drove a stock 4.8 Silverado, and it wouldn't touch my Avalanche running 35" tires. And, the only performance mods I have is the exhaust, intake, and HPT (which I'm still tweaking).....

[jwright350]

My thoughts behind the 6300 RPM was that it was only 1000 over stock, and still less than some LS1 guys run. And since I have 9mm less stroke than a 5.3L (or 6.0L) I should be able to get away with more RPM.

I also moved the fuel cutoff RPM up (and shift mph) that way I don't hit the rev limiter... maybe I'm crazy.

Time will tell on this one!

[havalanche]

Another factor is the valve springs.....

As far as the 5.3, I'd heard the valve springs really don't want anything above the 6200 rpm, and it wouldn't surprise me if that was the same for the 4.8.

[Mongoose]

I have played with my 5.3 Silverado quite a bit and have mine over the past few months and have set them back to 5600 for 1-2 and 5500 2-3 Truck shifts great and just put the same in an 04 5.3 and he is love with them. Really happy with the TM also.

Retard vs tQ %LOSS
1 2 3 4 5 6 7 8 10 12 14 16 18 20 20 20 20 20 20 20 20 24 28 32 36 40 44 Then the rest 44. Seems to work good and I drive my truck very hard.

Goodluck
Brian

[chrisj6]

Man i have a Z06 cam w/springs in my 99 5.3L and still dont shift at 6300. I shift at 6200 and dont make power any higher. You want to shift 2-300rpm higher or so after you reach peak power. I would set them at 6000 or 6100 and leave em.

[jwright350]

Man i have a Z06 cam w/springs in my 99 5.3L and still dont shift at 6300. I shift at 6200 and dont make power any higher. You want to shift 2-300rpm higher or so after you reach peak power. I would set them at 6000 or 6100 and leave em.

For safety sake I might as well back it down... but remeber I don't have as much valve lift as you guys do... especially not as much as a Z06 profile.

How is that z06 cam btw? I figured it wouldn't make enough low end power for a truck....but I'm tempted to put one in just for kicks. Build up a baby Z06 motor!

[gman4dx266]

Those 4.8's are darn near rockets. If you start shifting -too- high you'll be shooting yourself in the foot, as you start loosing power and getting out of the engines powerband. (found that out big time when i started shifting my stock 4 and change 6 sparker @ 6500)

I think you should be fine with no trans TM. I took all mine out, though. (no way im gonna push the limits)

Still cant spin the tires from a stop...something is still in there, i just have to keep digging i guess...

Good luck man.