03sierraslt

iTrader: (22)

So what exactly is the difference between a GenIII and Gen IV 4.8? I wasnt aware there was a 4.8 that was considered a GenIV.

ME Performance

Well I spoke with a shop that orders shortblocks and crate engines.. They did tell me that if I swapped out the crank for a newer one then there should be no problem.. he was explaing to me that the LS1 based cranks come with a 24 spline count for the knock sensors (not sure if thats the exact number) and the new ones come with a 52-54 spline count.....

Does this ring any bells to any of the mechanics around here?

ME Performance

GENIII 4.8L = LR4

GENIV 4.8L = LY2

Engine codes of course. They have the same power output, so not sure if slapping some new heads would enable GM to put them under a different engine code or from what has been said, the GENIV blocks are based around the LS2 blocks..

BLACKND

iTrader: (5)

Don't know of this will help what you're looking for or not, but I found this a while back when I first bought my 07 NNBS 4.8 trying to get info on it. This page breaks down all the new Gen IV powertrains by displacement and applications, and you can click on the links in the lineup and it will explain similarities and differences in the models.

If you go up toward the top there is a link for previous models and you can go back and look at Gen III Powertrains also for comparison.

http://media.gm.com/us/powertrain/en...RTEC48LGENIVV8

ME Performance

thanks that really helped... i could see from the new block that wat looks to be where you add the power steering fluid is in a different place compared to the old block... the GENIV 4.8, 5.3, 6.0 and 6.2 blocks look alllll the same!! Only difference is in the lower part of the block... The difference in colour and the oil chambers that aid in AFM(DoD) in the 5.3s and up.

Seen as this won't be a direct swap over specially using all accessories.. i might as well just get the rods, crank and pistons from a 6.0-6.2L and bore out my block... what do u think?

ME Performance

bump pp

WFOsierra

iTrader: (1)

cam sensors are in the front on the nnbs trucks. Older models are in the back of the block.

Wide Open

You will have to use the engine mounts from the 08 because they are a couple of inches taller to clear the crossmember and other stuff. You will definitely need a crank with the 58x relucter wheel. The knock sensors are on the sides of the block (not sure if your LQ9 is on the sides or not). You will need different injectors because the GEN IV uses a different style electrical connection. As mentioned previously the cam sensor is up front not in the rear. All of the accessories will bolt up without any issues. I think that is about it but there could be other things I am forgetting.