I realize this is an old subject, especially since a search turned up a thread that was two years since the last post.

Used LS4 engines/trans are more plentiful that they were before with prices comparable to the used Northstar engines. I personally feel the LS4 will a more reliable and maybe even more economical over the long run. Since this would be a V8 to V8 swap I would think most electronics would be compatible as long you could get a workable PCM.

Are there any other drastic differences that would keep this from working?

The Northstar PCM and it'* modules/harnesses are inherent to it alone. And can't be altered, let alone altered to another engine. It also uses the 4T80e. Just so many things to fabricate, and changing/programming the PCM/TCM/Modules to work with a LS4 make for a nightmare of tech/programming whatever you choose to replace the original PCM. I suppose a GP/GXP PCM would be a start.

If you could get the PCM and entire drivetrain it should be succesfull

I know I've seen whole cradle setups on Ed Morads eBay store...I'm sure a harness and PCM could be had as well. If the Bonne GXP harness and fittings pose too much of a headache, I wonder if it would be any easier on an L36 to LS4 swap?

I know many will say just throw on a top swap of build an L67. I do realize the benefits and cost plus the performance potential of those ideas. I'm presently faced with those same questions with my 01 GP GT. The real bottom line is that ultimate performance is secondary since there is no sound a L67 will ever make that sounds like a N/A V8 engine. The intake growl and the exhaust note are all to itself.
I suppose just going to a GP GXP would be the easiest out or just dealing with the Northstar'* shortcomings. The engine just has such a bad reliability rap and high replacement price.

The G8 is not an option since I'm just too lukewarm on the car'* styling. I like the GP much better but a Bonne is just plain sexy.

It all comes down to what you want to do. If you like modding the GP GXP mught be thecar for you since the B GXP is what it is.

The 04' and '05 LD8 are a far cry from the older L37'*. And we haven't seen the head bolt snaps/warped heads/cracks, etc. Quite a few members reporting 100k-150k miles with no major problems. And cost is relative to where you shop. Ed Morads been selling LD8'* for decent prices. He has an entire drivetrain w56k miles right know for under $1200. I've been half tempted to take the truck out to Cleveland and jump on it.

I agree the G8 is butt ugly, and the GXP model just attenuates the ugliness.

In honest defense of the Northstar, I did read an online article yesterday by a mechanic in which he stated that the engine'* worst enemy were owners who puttered around town and made tons of short trips without ever revving the engine. He mentioned this caused a problem with ring wear, which in turn lead to oil consumption and ultimately death. So it seems the engine will live longer with the occasional trip to redline. If this is all it takes to make the engine live longer, there would no shortage of that with me...I do love a good blast up an interstate on-ramp

I have been working with N* engines for two years now on a daily basis as a transmission/engine tech with Capital Cadillac in Smyrna, GA. From my experience, which is somewhat limited, and more so from speaking with techs who have worked with the engine since it'* inception in 2003, the main problems with it are oil leaking from the lower crankcase and/or oil pan and head gaskets leaking/bolts pulling out of the block. Both problems are dealt with rather easily, but neither fix is for the DIY'er to tackle in the driveway.

I do know that the N* LOVES artificial atmosphere! Turbocharging a N* produces excellent results. I know a guy with a '98 STS turbo making over 500whp on pump gas. Not too shabby. And which is making more power/cu.in? The 6.2L Supercharged CTS-V at 550hp or the 4.4L Supercharged STS-V at 468/469HP? Easy, by over 20hp/L, they 4.4 */C engine makes 106hp/L. (The LS-based 6.2L engine makes 88hp/L) and IIRC, it uses less boost to do it.

My point is this, if you have a N* engine, keep it. 4 valves are always better than two. if you are contemplating a swap, go with the N* and do it up right with head bolt upgrade, etc before you install it. That is if you plan to do any performance with it. Otherwise, just put it in and enjoy!

Homies, the LS4 is an LS-series engine. You can buy an LS1 controller and hook it up, and then control the transmission much like Pontiac Jeff does. Jeff, care to re-enlighten us on your 4T80E controller?

I do understand the N* is a nice engine, but being that the LS4 is an LSX, it has more low end torque, comes with more power out of the box, has more displacement, and unlike Venom'* relatively true fear, the LS4 doesn't stop working well past 100K miles.

And in fact, ls1tech.com has an LS1 swap guide that actually explains how to swap the 5.3L truck engine or the LS4 since they're basically the same thing but cheaper. So, even they have no issues using the 5.3L V8 with an LS1 (LS series) PCM. A nicely tuned modern V8 Bonneville would be pretty sexy.

you could mod a L67 have more power than a N* and a LS4.

there have been pleanty of guys that have tried to mod the LS4, remember it already has LS6 heads, and a very similar cam. The Guys on LS4 tech are not turning impressive times even when modded, i have done alot of research, ( as i was looking to buy a GP GXP) and i decided to stick with my SSEi.

Modded VS Modded the SSEi will win