LS6BEAST

I called the dealer just to see how much they would charge to swap the engine and they said $1750, but they don't seem to knowlegable. I would like to take it to a shop where they know what they are doing but I don't know of any shops here in Miami that work on LS's. I have thought of just doing it myself in the back of the house but because its a new truck it's intimidating. I have done 2 LS1 conversions on S10's. Also I just ordered the Ground Force 2.5" rear drop kit from Jegs because the kit comes with the 2*shims compaired to the others that don't. I have read that some people get a vibration after performing the rear drop but after installing the 2* shims the vibration is gone.

Question, if I replace the gears to 4.10 from 3.23 will that put more stress or less stress on the tranny?

niugnep

I did the 2" drop shackles and pulled the block out for a total of 3.25 or so on my 07 RCSB. I had the vibe and have 2 degree shim in there (calculations showed it to be about 1.75 degrees out). Nobody else I talked to with a RCSB had any issues, the extended cabs seem more touchy from what I hear.

The last question is a loaded one!! I'd stick with the 3.23's until you drive it with new engine then see how it works.

Yogi Bear

If you used the same tires, the 4.10 would reduce the stress on the engine / tranny. Bigger or wider tires would increase the stress.

LS6BEAST

I did replace the factory 17"s for the factory 20" rims and tires.

Yogi Bear

Going from a 3.23 axle ratio to a 4.10 would yield a 26.9% increase in mechanical advantage. The engine revs for a given road speed would go up by 26.9% while the torque load on the tranny would reduce by 26.9%.

The change in load resulting from a tire change depends on the overall diameter of the wheel and tire. A 20" wheel is 17.6% larger than a 17" wheel. I don't know how the diameter of the two tire sizes compare, but the 20" tire probably has a lower aspect ratio, so the combination wheel and tire would not be 17.6% different. Let's assume that the difference is 15.0%.

So, the net change from a lower axle ratio and a bigger tire would be 26.9% - 15.0% = 11.9% reduced torque load on the tranny from the two changes together.

niugnep

The 20's and 17's" (assuming stock tire size) are within a .25" of each other diameter wise. I agree with the load reduction due to mech advantage but don't forget you will be spinning everything faster all the time for a given speed and that creates stress as well, just in a different way. The lower a gearset the more tendency toward noise and vibration as well. Depends what you want out of the vehicle. Be a hell of a launch though!!

LS6BEAST

The reason I was thinking of the 4.10 gears is because thats what my TBSS had. It was pretty fast stock. Also I found out that the TBSS is 4800LBs compaird to the rcsb Silverado at 4400LBS, plus take take out the difference between the wieght of the iron block 4.8L to the aluminum block LS2. My goals for the truck are basicly to come as close as I can to the feel of a TBSS in a pickup truck.

niugnep

I'll buy that, reasonable plan and now you have me thinking too...

One of the reasons that I really like the L92/6spd combo though is that the 6 speed auto has a deep 4.03 first gear compared to the 4 speeds 3.06 first gear. That tranny with the 3.23's would be the same as the 4 speed with the 4.10's plus you get a slightly better overdrive (.67 to .70)...so you get that awesome launch and accel yet still have mild cruiser gears for the highway.

Course the 6 speed auto is kinda tough to find right now but I think in a year or two should be some kicking around. Hopefully in all the trucks by MY 09 (trade in?). The only issue will be actual truck programming, the BCM is part of the whole system yet none of the aftermarket tuners do anything with it (ie so will the readout on the dash be correct? manual shift button work?). I have confirmed they are the same p/n's on all the gmt-900's (including denali which is 6.2L/6spd) so programming is all that is needed. Have to find a GM dealer I guess who likes to modify things...

So many ways, only so much money....

LS6BEAST

Thats why I scraped the idea of doing the L92 with the auto 6 speed, because the cost compaired to just swapping the 4.8L to the LS2 and that the amount of work involved to get the L92 working correctly is much more due to the VVT system and programing, also alot of dealers I have delt with don't seem to excited about doing any kind of conversions. From what I understand the LS2 is just a drop in with no extra programing, unless someone can tell me different.

niugnep

Price is the big difference. A used L92/6.2L with harness and ECM will plug in, done, nothing needed. But currently they are about 8-10K. Ouch. The LS2 would need some software tweaks, but thats about it.

So... are you gonna order up an engine?? If you do, make sure to take pics and document the swap, lots of guys would be interested in that I am sure.